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Blastomycosis
Clinics in Dermatology (2012) 30, 565–572
Blastomycosis Rubén López-Martínez, MD, DrSc a,⁎, Luis Javier Méndéz-Tovar, MD, DrSc b a
Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ave. Universidad 3000, México D.F. 04510, México b Laboratory of Dermatology and Medical Mycology Research, Hospital de Especialidades, Centro Médico Nacional, IMSS, Av. Cuauhtémoc 330, Colonia Doctores, Ciudad de México, 06725, México
Abstract Blastomycosis is a systemic mycosis with a high prevalence in the Midwest of the United States. The fungus inhabits soil, and human infection occurs through inhalation. Its asexual phase is called Blastomyces dermatitidis and its sexual phase, Ajellomyces dermatitidis. It is more common in men. Signs and symptoms are usually severe, starting with an infection resembling pneumonia that later disseminates to the skin, bones, and central nervous system. Infection in dogs is common in endemic areas. The diagnosis can be achieved by identifying the organism with direct microscopy, culture, histopathology, serologic tests, and molecular techniques, although these are still in trial phase. The treatments of choice are azoles (itraconazole, fluconazole, and posaconazole), and in severe cases, amphotericin B. © 2012 Published by Elsevier Inc.
Introduction In May 1894, T. Caspar Gilchrist described at the American Dermatological Association in Washington, DC, microscopic sections from a case of cutaneous disease in Philadelphia under the care of Louis A. Duhring, who had sent an excised specimen for microscopic examination. The parasitic bodies initially were interpreted as plant rather than fungal forms. These bodies were later recognized as forms of blastomycetes. This case was fully described and illustrated by Gilchrist under the title “A Case of Blastomycetic Dermatitis in man.”1 Two years later, the organism was isolated for the first time in culture from a second patient, and in 1898, the causal agent was named Blastomyces dermatitidis.2 The disease was later reproduced in the lungs and other organs of experimental animal models.3 The first systemic infection caused by this fungus was reported in an autopsy report in 1902.4 Its dimorphic nature was documented in 1907, when the tissue isolates from four different patients with this infection were ⁎ Corresponding author. E-mail address: [email protected] (R. López-Martínez). 0738-081X/$ – see front matter © 2012 Published by Elsevier Inc. http://dx.doi.org/10.1016/j.clindermatol.2012.01.002
studied.5 This study helped clarified and define the etiology and pathogenesis of this mycosis. For many years, American blastomycosis was known as Gilchrist's disease or Chicago's disease. Around that time, the etiologic agents of many mycoses were being studied for the first time, and many cases of blastomycosis were confused with cryptococcosis, coccidioidomycosis, and paracoccidiodomycosis. 6,7 It was in the 1930s, when investigators distinguished the different agents of blastomycosis, paracoccidioidomycosis, and others, such as cryptococcosis, whose histopathologic images can easily be confused with blastomycosis.8-10 During the first half of the past century, systemic and cutaneous blastomycosis were believed to be two different expressions of the same disease. The first was thought to be transmitted through the respiratory tract and the other through traumatic inoculation. This belief was clarified in 1951, when it was discovered that there was only one clinical picture: pulmonary disease with systemic dissemination.11 These results were confirmed in 1955 in a study of four patients with cutaneous inoculation of B dermatitidis, whose histologic skin lesions differed from the granulomatous lesions seen in patients with systemic dissemination of blastomycosis.12
566 The first reports of infection in dogs were published in 1952.13 Today, susceptibility to this infection has been reported in numerous animal species13; however, the disease still predominates in dogs.14,15 In 1960, isolation of the organism from the soil was intensely pursued, but with only partial success. The habitat of B dermatitidis has not been established.16-18 In 1968, the sexual phase of the fungus was discovered and received the name of Ajellomyces dermatitidis. It was placed under the family Onygenaceae of the Ascomycetes phylum.19 Transmission of this infection through prostatic fluid, which is a unique characteristic among systemic mycosis, was documented in 1983. This characteristic can make this mycosis a potential sexually transmitted disease.20
Epidemiology Geographic distribution Blastomycosis was originally thought to be a disease exclusive to the midwestern United States, as can be deduced from the initial names the disease received: Chicago's disease and North American blastomycosis.7 Later reports showed it to be widespread in Minnesota, Wisconsin, Michigan, and northern Ohio, as well as in Louisiana, Mississippi, Alabama, and southern Georgia. Most of the reported cases come from the Mississippi River basin, Ohio, Missouri,21,22 and the western margins of Lake Michigan. There are also reports from states as far as California, but in most, a history of travel or residence in an endemic area was confirmed.23 Recent reports suggest that the area affected by blastomycosis in the United States is expanding, as was demonstrated by reports from Colorado.24 Canada is not immune, with reports from Quebec and the Maritime provinces. In Ontario, 309 cases were published between 1994 and 2003.25 In daily medical practice, it is often hard to confirm the diagnosis, and many medical visits and a correlation with the geographic distribution of the disease is required to make a diagnosis.26,27 A few cases have been published in Mexico, all involving immigrants. The first was reported more than 50 years ago.28 Recently, a case report of cutaneous dissemination caused by B dermatitidis was published in Mexico.29 Two other geographic regions where cases of blastomycosis have been reported are Africa (especially South Africa and Zimbabwe)30 and India, where this agent was first isolated in 1983.31 Currently, most cases are reported from the northern region of India.32 Other countries where this mycosis is known are Lebanon,33 south Arabia, and Israel.34
Host The disease most commonly occurs in adults in the fourth decade of life. It is uncommon in children. Most experts
R. López-Martínez, L.J. Méndéz-Tovar agree this could be due to longer environmental exposure to the agent as an individual ages.26,27 Blastomycosis predominates in men. In contrast to what occurs in paracoccidioidomycosis, where estradiol inhibits the parasite's transformation,35 in blastomycosis, it is due to occupational factors. Recreational activities such as fishing, camping, or outdoors professions, such as forest ranger, are frequently associated with this disease.36 Although African American patients are more susceptible for infection, ethnicity is not implicated; rather, factors associated with low socioeconomic status or concomitant diseases, such as diabetes, are responsible for this susceptibility. To date, no relationship with a histocompatibility antigen has been found.37,38 AIDS infection does not increase the frequency of the disease; however, it does predispose patients to a chronic disease with early systemic dissemination, frequent relapses, and an increased mortality despite treatment.39 Infection in dogs is frequent, as was published in a review of the years 1885 to 1968, where a large number of cases were documented on the borders of the Ohio and Mississippi rivers.21 In 1985, another study from the Wisconsin area reported 136 to 200 cases of blastomycosis in dogs.40 There have been no large studies in animals in recent years; however, the publication of cases of infection in dogs has been constant, with no predominance for a particular breed.15 The occurrence of infection in dogs in some endemic areas gives support to the idea that there could be subclinical infection in humans.41
Etiologic agent As a result of the study of the ribosomal subunits, the fungus can be placed under the phylum Ascomycota of the family Onygenaceae, with a close genetic resemblance to Paracoccidioides brasiliensis, Emmonsia parva, and Histoplasma capsulatum.42 Blastomyces dermatitidis is a holomorphic fungus. Its asexual phase is dimorphic, and clinical specimens cultivated and incubated at room temperature on a Sabouraud dextrose agar medium start to grow after 2 to 4 weeks. Initially, the colony is white and acquires a grayish color with time. It is composed of a fine mycelium, 2 to 3 μm in diameter, and sparse conidia with an ovoid to piriform shape, 3 to 5 μm in diameter, that derive from short conidiophores or directly from hyphae. These microconidia are tightly bound to the filament and require humidity to fall off.43 These characteristics support the geographic distribution of the infection, which includes locations with high humidity. In its natural habitat, it is associated with the presence of salamanders of the Necturus genus.44 Its conversion from mycelial to yeast phase (tissue phase) is influenced by temperature and nutrients. The conidia inoculated in a brain-heart infusion medium and incubated at 37°C develop in 10 to 15 days with the formation of soft colonies with a cerebriform surface resembling butter. Direct microscopy shows single budding yeasts with a wide base 8 to 12 μm in diameter, a thick wall, and double contour.
Blastomycosis Compared with conidia, which have only one nucleus, yeasts present two to four nuclei.45 In tissue, most yeasts are 8 to 14 μm long, although some authors report the presence of microyeasts measuring 3 to 10 μm that, in some cases, have been confused with Histoplasma capsulatum.46 Other authors argue the existence of large yeast cells, up to 40 μm in diameter, that can cause histopathologic confusion with P brasiliensis and Coccidioides immitis.47 The sexual phase, Ajellomyces dermatitidis, gives rise to a gymnothecium that bears ascogenic hyphae. These can be globular or subglobular with asci of 6 to 8 μm in diameter that contain eight ascospores with smooth or warty walls of 1.5 to 2 μm. Major and minor strains have been described; however, it is unknown, which is more virulent.48
Virulence factors For tolerance to human temperature, the fungus' dimorphism is important for the pathogenicity of the disease. The presence of an adherence factor named BAD1 (blastomyces adhesion), which most likely allows the beginning of infection but at the same time suppresses the release of tumor necrosis factor-α (TNF-α), has been demonstrated.49 The cell wall of yeast contains 95% α-3 glucan, which is its major virulence factor, whereas mycotic filaments contain αglucan and β-glucan in a similar proportion.50 Another virulence factor is the production of melanin, which is seen in culture and in infection. Melanin protects the fungus from the oxidative reactions of leukocytes.51 The presence of a large amount of yeasts of B dermatitidis in tissues gives rise to a late hypersensitivity reaction that causes tissue damage in the form of abscesses, hemorrhagic lesions, and in the chronic forms, the formation of fibrosis and granulomas.52
Clinical picture Pathogenesis Most cases are acquired through the respiratory tract by inhalation of conidia or mycelial fragments. This gives rise to a primary pulmonary infection. As a result of the ability of the infection to disseminate to the testes, the epididymis, and the prostate, there are reports of sexual transmission, without the presence of cutaneous lesions.53 Infection can be acquired by unusual mechanisms such as traumatic inoculation through the skin; there are even reports of its transmission to humans through dog bites,54,55 and in 1983, the first case of intrauterine transmission was published.56
Classification and clinical signs Most authors describe two clinical forms: pulmonary and extrapulmonary. The first is the most frequent, and is generally the clinical form associated with systemic dissemination.
567 Primary pulmonary blastomycosis The incubation period of the infection has not been determined but has been estimated to range from 21 to 106 days, with an average of 45 days. Other investigators report an insidious onset.57 In either case, the clinical signs and symptoms are variable and depend on the host parasite and environment interaction. A review of 200 patients with blastomycosis found the most frequent manifestations were cough (35.8%), weight loss (27.8%), thoracic pain (26.2%), cutaneous lesions (25.8%), fever (22.7%), hemoptysis (20.7%), and localized swelling (13.6%).58 As has been observed in other mycosis, some patients may remain asymptomatic, whereas others portray mild signs and symptoms that can be confused with a viral respiratory infection and some have moderate to severe disease. This last group has been compared in severity to pulmonary histoplasmosis. Pulmonary infections can be classified into three groups: (1) resolution of the pulmonary infection with dissemination to other organs; (2) resolution of the pulmonary infection without evidence of residual disease in other organs; and (3) severe and progressive pulmonary disease. The patient in the first group may complain of cough, chest pain, and hoarseness, accompanied by mild fever. The formation of pulmonary calcifications may not appear; nevertheless, dissemination may occur because the disease is carried through macrophages into the systemic circulation, and chronic cutaneous lesions frequently develop.59 In the second group, which includes patients who heal without evidence of residual disease in other organs, symptoms include productive cough, arthralgias, myalgias, and hyperthermia associated with moderate to severe chest pain. A review of 48 patients showed only 46% were asymptomatic.57 The progressive, severe form of the disease is characterized by the development of acute lobar pneumonia, productive cough with purulent expectoration and streaks of blood, high fever, weight loss, asthenia, adynamia, and adult respiratory distress syndrome with severe arterial hypoxemia. Dissemination of the pulmonary focus to the skin can occur in the form of fistulas or subcutaneous abscesses.59,60 Despite the severity of the disease, the prognosis may be favorable in many patients, resulting in spontaneous or treatment-induced healing; nevertheless, some patients may develop a carrier state with a chronic pulmonary focus. When immunologic surveillance is weakened by internal or external factors, reactivation of latent infection can induce systemic dissemination and even death.61 Some severe progressive forms of the disease can be associated with severe immunosuppression, as seen in patients with AIDS or in patients who receive long-term corticosteroid therapy.62,63 Extrapulmonary blastomycosis (A) Cutaneous. This is the most frequent extrapulmonary form. Primary cutaneous forms are produced by traumatic inoculation of the skin that is usually associated with work exposure, as in veterinarians54,55 and mycology laboratory
568 personnel.64 Signs and symptoms include the presence of papules that may progress to pustules with regional lymphadenopathy that generally undergoes spontaneous resolution in weeks to months without medical treatment. Secondary cutaneous forms are more frequent. Skin lesions can have an ulcerated or warty appearance of various sizes. These may extend with progression of the disease over the years. Some may even display a necrotic, ulcerated spot that can confer an appearance similar to basal cell carcinoma of the skin, squamous cell carcinoma, pyoderma gangrenosum, or keratoacanthoma (Figures 1-4).65 In some cases, subcutaneous abscesses can resemble panniculitis or WeberChristian disease.66 (B) Bone. Bone is affected in 6% to 48% of patients. The bones most frequently involved include long bones, vertebra, ribs, and the cranium, in the form of osteomyelitis,67 with dissemination to the joints, where it may cause septic arthritis.68 (C) Genitourinary. The prostate and epididymis are most frequently involved. The diagnosis can be made with laboratory evaluation of secretions obtained by prostatic massage.69 A few cases are reported in women, one of whom had sexual contact with a man with genitourinary blastomycosis without cutaneous lesions.70 Reactivation of the disease can be observed in women as a consequence of dissemination of a pulmonary focus. Fallopian tubes and ovaries can be involved, with the development of abscesses that can be confused with ovarian cancer.71 (D) Central nervous system. Extrapulmonary blastomycosis affects this area in about 5% to 10% of patients. Patients may manifest signs and symptoms of meningitis, cerebral abscess, or granuloma formation associated with the presence of B dermatitidis.72 A laboratory diagnosis is hard to establish. The best samples available for culture should be obtained through a ventricular puncture, which yields a positivity of 85% compared with 9% positivity from a spinal tap.73 (E) Other sites of infection. North American blastomycosis can infect any organ or tissue, among these the
Fig. 1 Blastomycosis affecting the upper lip. (Photo courtesy of Larry E. Millikan, MD, Meridian, MS.)
R. López-Martínez, L.J. Méndéz-Tovar
Fig. 2 Ulcerated lesion resembling pyoderma. (Photo courtesy of Larry E. Millikan, MD, Meridian, MS.)
monocyte-phagocyte system, the breasts, eyes,74 ears,75 thyroid, adrenal glands, myocardium, pericardium, or digestive tract.65 In many cases, the presence of extrapulmonary lesions allows identification of chronic or relatively asymptomatic pulmonary lesions or blastomycosis with an atypical clinical course.76
Diagnosis Microbiologic tests Direct microscopy Specimens should be obtained from skin scales from warty lesions, purulent material from microabscesses, bronchioalveolar lavage, sputum, urine, or cerebrospinal fluid, etc. In positive cases, single budding yeasts with a wide fusion base, a double-wall contour, and a size of 8 to 14 μm are observed (Figure 5).77 Other methods to obtain useful specimens for microbiologic examination include
Fig. 3 Granulomatous lesion on the dorsum of the hand. (Photo courtesy of Larry E. Millikan, MD, Meridian, MS.)
Blastomycosis
Fig. 4 Cutaneous lesion of the face. (Image courtesy of VisualDx, ©Logical Images Inc, Rochester, NY.)
invasive techniques, such as fine-needle biopsy aspiration in prostatic involvement.78 Histopathology Histologic samples stained with the Gomori-Grocott and periodic acid-Schiff techniques allow observation of single budding yeasts with the characteristics described above (Figure 6). Sometimes, these may show multiple budding and can be observed in the intracellular or extracellular space. Tissue samples stained with hematoxylin and eosin may display a mixed cellular inflammatory reaction with polymorphonuclear cells, neutrophils, and noncaseating granulomas that include histiocytes and giant multinucleated cells. Other areas may display fibrosis. The number of yeasts observed decreases as granulomas develop.79 The differential morphologic diagnosis includes P brasiliensis yeasts, Cryptococcus spp, and Histoplasma capsulatum as well as Coccidioides spp spherules.
569
Fig. 5 Direct microscopy of a blastomycosis case; budding yeasts with a wide fusion base are seen (original magnification ×400).
Culture growth usually begins after 10 to 15 days; however, this period can be longer when few yeasts are present in the specimen cultured. As a result, culture of samples from a patient with symptoms suggestive of blastomycosis should not be considered negative before 4 weeks. The first colonies have a whitish, smooth appearance, and days later they may be grayish or brownish, with a hairy appearance (Figure 7). Microscopically, a fine mycelium (1 to 2 μm in diameter) and piriform conidia (2 × 3 or 4 μm in diameter) may originate directly from hyphae or from short to large conidiophores (Figure 8). Its morphology may be similar to that seen in some contaminating fungi or P brasiliensis. Mycelial-to-yeast conversion confirms the fungus classification when a culture isolate is cultivated in a brain-heart infusion agar medium and incubated at 37°C. After 7 to 10 days, single budding thick walled B dermatitidis yeasts that contain 2 to 4 nuclei are observed.45 Culture identification of the filamentous phase using only morphologic features can be considerably difficult. As a result of this, new tests, such as the production of exoantigens
Culture Petri dishes must be avoided when culturing this agent because many highly infective conidia can be released into the environment, causing an occupational hazard. All specimens must be cultured in 150- × 15-mm test tubes that contain plain Sabouraud dextrose agar supplemented with antibiotics or potato dextrose agar. Tissues should be macerated in sterile conditions, cultivated in a brain-heart infusion agar, and incubated at 25° to 30°C. Blastomyces dermatitidis belongs to level 3 of the Biological Hazard Classification, which corresponds to agents that can cause disease in man and represent a danger to workers with the risk of propagation and for which there is effective treatment and prophylaxis as a result. The handling of these cultures must always be done in a laminar flow hood.80
Fig. 6 Histologic image of a blastomycosis case where budding yeasts with a wide fusion base are observed (original magnification ×400).
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in liquid cultures, have been developed.81 A new molecular biology technique that allows identification of cultures in less than 2 hours using probes for identification of the yeast and mycelia phases has recently been made available.82
Immunologic studies The identification of B dermatitidis antibodies has been available for a couple of years; however, it is not very useful because of its low sensibility (55%) and specificity (30%).83 Antigen detection in different body fluids is very useful, however. The specimens that can be used include cerebrospinal fluid, bronchioalveolar lavage, pleural effusion, and urine, with sensitivity greater than 90%.84,85 Molecular techniques useful for the diagnosis of infection in humans and animals are not yet available. Preliminary trials have been promising, however, and these new techniques may be available commercially in the future.86
Management Treatment should be prescribed without exception to all patients with chronic pulmonary blastomycosis, systemic dissemination to any organ, and immunosuppression. In the primary pulmonary forms with mild symptoms, triazole drugs are indicated. The treatment of choice consists of oral itraconazole, 200 mg twice daily for 4 to 6 months, achieving a cure rate of 90% to 95%.87 An alternative is oral posaconazole, 800 mg daily for 2 to 3 months.88,89 This latter triazole has the advantage of a wider antifungal spectrum and significant lower antifungal resistance. Treatment duration should be prolonged or shortened according to clinical evolution and results of immunologic testing. Other triazole drugs that can be used are oral fluconazole, 400 to 600 mg daily, and oral voriconazole, 200 mg every 12 hours, for 3 to 4 months.90,91 When asymptomatic primary pulmonary forms or mild symptoms are present, surveillance is indicated with close
Fig. 8 Direct microscopy of a culture of Blastomyces dermatitidis stained with blue dye. Septate hyaline filaments and ovoid to round microconidia are observed (original magnification ×1000).
examination of symptoms and immunologic tests.92 If symptoms persist, and radiologic signs and immunologic tests are positive, itraconazole or voriconazole must be given at the indicated doses. In severe pulmonary blastomycosis or with systemic dissemination, intravenous amphotericin B desoxycholate, at a dose of 0.7 to 1 mg/kg on alternate days, is indicated without surpassing a total maximum dose of 2 to 3 grams. Lipid formulations of amphotericin B have also been administered at a daily dose of 3 to 5 mg/kg.93,94 In pediatric patients, the dose of amphotericin B should be adjusted according to age and total body weight in addition to close surveillance of intolerance and systemic toxicity. Once the amphotericin B treatment has concluded, it must be followed by the administration of several months of triazole drugs. Prophylactic measures are not well established, but generally include the same precautions used to avoid other systemic mycosis. It is advisable to offer a prophylactic dose of fluconazole (150 mg/d) or posaconazole (800 mg/d). These recommendations, however, have not been tested and validated.95 Immunosuppressed patients are advised not to travel to endemic zones and to avoid contact with dogs in these regions, due to reports of transmission of disease through dog bites.54,55
Conclusions
Fig. 7 Sabouraud dextrose agar medium culture incubated at 37°C for 15 days with growth of white-to-grayish colonies with a hairy appearance.
Blastomycosis is an infection with a limited geographic distribution. Its frequency outside of the USA or Canada is not well established. The natural habitat of Blastomyces dermatitidis usually includes humid areas close to the forest. In addition to humans, the fungus is capable of infecting several species of mammals, mainly dogs; what creates a growing demand for veterinarian personal must be alert to this infection in canines. Most human cases are asymptomatic; however, in immunosuppressed patients the infection could be disseminated, first to lungs and latter to several organs, such as bone, skin, genitourinary, and central
Blastomycosis nervous system. Its frequency as a cause of death in immunosuppressed patients has not been determined. The diagnosis is made under microbiology bases; however, the development of newer molecular tests will be the standard in the next few years. Even though most patients do not receive treatment, disseminated infections are usually treated with itraconazole or voriconazole, and even amphotericin B (desoxycholate, liposomal, etc.). Prophylaxis for patients at risk should be made with fluconazole or posaconazole. The B dermatitidis antigenic complexity has made impossible to develop a vaccine, is a similar situation to other systemic mycoses, where artificial immunization may be the solution to infection in populations living in endemic areas.
References 1. Gilchrist TC. Protozoan dermatitis. J Cutan Genitourin Dis 1894;12: 496-9. 2. Gilchrist TC, Stokes WR. The presence of an Oidium in the tissues of a case of pseudo-lupus vulgaris. Preliminary report. Bull Johns Hopkins Hosp 1896;7:129-33. 3. Gilchrist TC, Stokes WR. A case of pseudo-lupus vulgaris caused by Blastomyces. J Exp Med 1898;3:53-78. 4. Walker JM, Montgomery FH. Further report of a previously recorded case of blastomycosis of the skin: systemic infection with blastomycosis. Death autopsy. JAMA 1902;38:867-71. 5. Hamburger WW. A comparative study of four strains of organisms isolated from four cases of a generalized blastomycosis. J Infect Dis 1907;4:201-9. 6. Hektoen L. Systemic blastomycosis and coccidioidal granulomas. JAMA 1907;49:1070-7. 7. Conant NF, Smith BT, Baker RD, et al. Blastomicosis. In: Conant NF, Smith BT, Baker RD, Callaway JL, editors. Micología. 3rd ed. México City: Interamericana; 1976. p. 65-104. 8. Almeida FP. Estudos comparativo do granulomcoccidioidico nos Estados Unidos e no Brazil. Novo genero para a parasita brazileiro. An Fac Med Univ Sao Paulo 1930;5:125-41. 9. Benham RW. Criptococosis and blastomycosis. Ann N Y Acad Sci 1950;50:1299-314. 10. Conant NF. Laboratory study of Blastomyces dermatitidis Gilchrist and Stokes. Proc 6th Pacific Sci Congr 1939;5:853-62. 11. Schwarz J, Baum GL. Blastomycosis. Am J Clin Pathol 1951;21: 999-1029. 12. Wilson JW, Cawley EP, Weidman FD, et al. Primary cutaneous North American blastomycosis. Arch Dermatol Syphilol 1955;71:39-45. 13. Ramsey FK, Carter GR. Canine blastomycosis in the U.S. J Am Vet Med Assoc 1952;120:93-8. 14. Wilson JH, Olson EJ, Haugen EW, et al. Systemic blastomycosis in a horse. J Vet Diagn Invest 2006;18:615-9. 15. Bateman BS. Disseminated blastomycosis in a German shepherd dog. Can Vet J 2002;43:550-2. 16. Denton JF, McDonough ES. Isolation of Blastomyces dermatitidis from soil. Science 1961;133:1126-7. 17. Denton JF, Di Salvo AF. Isolation of Blastomyces dermatitidis from natural sites at Augusta, Georgia. Am J Trop Med 1964;13:716-22. 18. Denton JF, Di Salvo AF. Additional isolations of Blastomyces dermatitidis from natural sites. Am J Trop Med Hyg 1979:697-700. 19. McDonough ES, Lewis AL. The ascigerous stage of Blastomyces dermatitidis. Mycologia 1968;60:76-83. 20. Dyer ML, Young TL, Kattine AA, et al. Blastomycosis in a Papanicolaou smear. Report of a case of possible venereal transmission. Acta Cytol 1983;27:285-7.
571 21. Furculow ML, Chick EW, Busei JF, et al. Prevalence and incidence studies of human and canine blastomycosis. Am Rev Respir Dis 1970;102:60-7. 22. Furcolow ML, Smith CD. A new interpretation of the epidemiology, pathogenesis and ecology of Blastomyces dermatitidis. Trans N Y Acad Sci 1973;35:421-30. 23. Casad DE, Waldmann JW, Levan NE, et al. North American blastomycosis in California. Diagnosis of a case and a survey with 28 California observed cases. Cal Med 1967;106:20-7. 24. Hannah EL, Bayley AM, Hajjeh R, et al. Public health response to 2 clinical cases of blastomycosis in Colorado. Clin Infect Dis 2001;32: 151-3. 25. Morris SK, Brophy SE, Richardson R, et al. Blastomycosis in Ontario, 1994-2003. Emerg Infect Dis 2006;12:274-9. 26. Bernstein S, Brunner H, Summerbell R, et al. Blastomycosis acquired by three children in Toronto. Can J Infect Dis 2002;13:259-63. 27. Kesselman EW, Moore S, Embil JM. Using local epidemiology to make a difficult diagnosis: a case of blastomycosis. Can J Emerg Med 2005;7: 171-3. 28. Martínez-Baez M, Reyes-Mota A, González-Ochoa A. Blastomicosis Norteamericana en México. Rev Inst Salubr Enferm Trop 1954;14: 225-32. 29. Velázquez R, Muñóz-Hernández B, Arenas R, et al. An imported case of Blastomyces dermatitidis infection in Mexico. Mycophatologia 2003;156:263-7. 30. Baily GG, Robertson VJ, Neill P, et al. Blastomycosis in Africa: clinical features, diagnosis, and treatment. Rev Infect Dis 1991;13:1005-8. 31. Randahwa HS, Khan Z, Gaur S. Blastomyces dermatitidis in India: first report of its isolation from clinical material. Sabouraudia 1983;21: 215-21. 32. Di Salvo AF. The epidemiology of blastomycosis. In: Al-Doory Y, Di Salvo AF, editors. Blastomycosis. New York: Plenum Medical Book Co; 1992. p. 75-104. 33. Hassan FM, Jarrah T, Nassar V. The association of adenocarcinoma of the lung and blastomycosis from an unusual geographical location. Br J Dis Chest 1978;72:242-6. 34. Kuttin ES, Beemer AM, Levij J, et al. Occurrence of Blastomyces dermatitidis in Israel. First autoctochtonous Middle Eastern case. Am J Trop Med Hyg 1978;27:1203-5. 35. Restrepo A, Salazar ME, Cano LE, et al. Estrogens inhibit mycelium-toyeast transformation in the fungus Paracoccidioides brasiliensis: implications for resistance of females to paracoccidioidomycosis. Infect Immun 1984;46:346-53. 36. Crampton TL, Light RB, Berg GM, et al. Epidemiology and clinical spectrum of blastomycosis diagnosed at Manitoba hospitals. Clin Infect Dis 2002;34:1310-6. 37. Lemos LB, Baliaga M, Guo M. Blastomycosis: the great pretender can also be an oportunistic. Initial clinical diagnosis and underlying diseases in 123 patients. Ann Diagn Pathol 2002;6:194-203. 38. Cano MV, Ponce-de-León GF, Tippen S, et al. Blastomycosis in Missouri: epidemiology and risk factors for endemic disease. Epidemiol Infect 2003;131:907-14. 39. Wheat J. Endemic mycosis in AIDS: a clinical review. Clin Microbiol Rev 1995;8:146-59. 40. Archer JR, Trainer DO, Schell RF. Epidemiologic study of canine blastomycosis in Wisconsin. J Am Vet Med Assoc 1987;190:1292-5. 41. Sarosi GA, Eckman MR, Davies SF, et al. Canine blastomycosis as a harbinger of human disease. Ann Intern Med 1979;91:733-5. 42. Byalek R, Ibricevik A, Fothergill A, et al. Small subunit ribosomal DNA sequence shows Paracoccidioides brasiliensis closely related to Blastomyces dermatitidis. J Clin Microbiol 2000;38:3190-3. 43. Mc Donough ES, Wisniewski RT, Penn LA, et al. Preliminary studies on conidial liberation of Blastomyces dermatitidis and Histoplasma capsulatum. Sabouraudia 1976;14:199-204. 44. Borelli D, Marcano C, Feo M. Actividades de la sección de Micología Médica, Instituto de Medicina Tropical (Caracas), durante el año 1968. Dermatol Venez 1969;8:887-904.
572 45. Clemons KV, Hurley SM, Treat-Clemens LJ, et al. Variable colonial phenotypic expression and comparison to nuclei number in Blastomyces dermatitidis. J Med Vet Mycol 1991;29:165-8. 46. Schwarz J, Blastomycosis SalfelderK. A review of 152 cases. Curr Topics Pathol 1977;65:165-200. 47. Watts JC, Chandler FW, Mihalov ML, et al. Giant forms of Blastomyces dermatitidis in the pulmonary lesions of blastomycosis. Potential confusion with Coccidioides immitis. Am J Clin Pathol 1990;93:575-8. 48. Rippon WJ. Tratado de Micología Médica. México, DF: Ed Interamericana; 1990. p. 511. 49. Di Salvo AF, Klein BS. Blastomycosis. In: Merz WG, Hay RJ, editors. Topley and Wilson's microbiology and microbial infections. Medical mycology. London: Hodder Arnold; 2005. p. 479-501. 50. Kanetsuna F, Carbonell LM. Cell wall composition of the yeast like and mycelial forms of Blastomyces dermatitidis. J Bacteriol 1971;106:946-8. 51. Nosanchuc JD, van Duin D. Mandai P, et al. Blastomyces dermatitidis produces melanin in vitro and during infection. FEMS Microbial Lett 2004;239:187-93. 52. Bradsher RW. Blastomycosis. Infect Dis Clin North Am 1988;2: 877-98. 53. Murray JJ, Clark CA, Lands RH, et al. Reactivation blastomycosis presenting as a tuboovarian abscess. Obstet Gynecol 1984;64:828-30. 54. Graham WR, Callaway JL. Primary inoculation blastomycosis in a veterinarian. J Am Acad Dermatol 1982;7:785-6. 55. Gnann JW, Bressler GS, Bodet III CA, et al. Human blastomycosis after a dog bite. Ann Intern Med 1983;98:48-9. 56. Watts EA, Gard PD, Tuthill SW. First reported case of intrauterine transmission of blastomycosis. Pediatr Infect Dis 1983;2:308-10. 57. Klein BS, Vergeront JM, Weeks RJ, et al. Isolations of Blastomyces dermatitis in soil associated with eight large outbreaks of blastomycosis in Wisconsin. N Engl J Med 1986;31:529-34. 58. Blastomycosis Cooperative study of the Veterans Administration. Blastomycosis a review of 198 collected cases in Veterans Administration Hospitals. Ann Rev Respir Dis 1964;89:659-72. 59. Skillrud DM, Douglas WW. Survival in adult respiratory distresses syndrome caused by Blastomyces dermatitidis. Mayo Clin Proc 1985;60: 266-9. 60. Cherniss EI, Waisbren BA. North American blastomycosis: a clinical study of 40 cases. Ann Intern Med 1956;44:105-23. 61. Laskey WK, Sarosi GA. Endogenous activation in blastomycosis. Ann Intern Med 1978;88:50-2. 62. Pappas PG, Pottage JC, Powderly WG, et al. Blastomycosis in patients with the acquired immunodeficiency syndrome. Ann Intern Med 1992;116:847-53. 63. Pappas PG, Threlkeld MG, Bedsole GD, et al. Blastomycosis in immunocompromised patients. Medicine 1993;72:311-25. 64. Schwarz J. Laboratory infections with fungi. In: Di Salvo AF, editor. Occupational mycosis. Philadelphia: Lea & Febiger; 1983. p. 215-27. 65. Bradsher RW, Martin MR, Wilkes TD, et al. Unusual presentations of blastomycosis: ten case summaries. Infect Med 1990;7:10-9. 66. Maioriello RP, Merwin CF. North American blastomycosis presenting as an accutepanniculitis and arthritis. Arch Dermatol 1970;102:92-6. 67. Gehweiler JA, Capp MP, Chick EW. Observations on the roentgen patterns in blastomycosis of bone. Am J Roentgenol Radium Ther Nucl Med 1970;108:497-510. 68. Sanders LL. Blastomycosis arthritis. Arthritis Rheum 1967;10:91-8. 69. Inoshita T, Yougberg GA, Boelden LJ, et al. Blastomycosis presenting with prostatic involvement: report of 2 cases and review of the literature. J Urol 1983;130:160-2. 70. Farber ER, Leahy MS, Meadows TR. Endometrial blastomycosis acquired by sexual contact. Obstet Gynecol 1968;32:195-9. 71. Mouzin EL, Beilke MA. Female genital blastomycosis: case report and review. Cin Infect Dis 1996;22:718-9. 72. Roos KL, Bryan JP, Maggio WW, et al. Intracranial blastomycosis. Medicine (Baltimore) 1979;66:224-35.
R. López-Martínez, L.J. Méndéz-Tovar 73. Kravitz GR, Davies SF, Eckman MR, et al. Chronic blastomycosis meningitis. Am J Med 1981;71:501-5. 74. Lopez R, Mason JO, Parker JS, et al. Intraocular blastomycosis: case report and review. Clin Infect Dis 1994;18:805-7. 75. Istorico LJ, Sanders MR, Jacobs RF, et al. Otitis media due to blastomycosis: report of two cases. Clin Infect Dis 1992;14:355-8. 76. Bradsher RW. Blastomycosis. In: Dismukes W, Pappas PG, Sobel JD, editors. Clinical mycology. Oxford: New York; 2003. p. 299-310. 77. López-Martínez R, Méndez-Tovar LJ, Hernández-Hernández F, et al. Micosis sistémicas. In: López-Martínez R, Méndez-Tovar LJ, Hernández-Hernández F, et al, editors. Micología Médica. Procedimientos para el diagnóstico de laboratorio. México, DF: Trillas; 2004. p. 83-98. 78. Neal PM, Nikolai A. Systemic blastomycosis diagnosed by prostate needle biopsy. Clin Med Res 2008;6:24-8. 79. Chandler FW, Kaplan W, Ajello L. Blastomycosis. In: Chandler FW, Kaplan W, Ajello L, editors. Histopathology of mycotic diseases. Color atlas and text. Chicago: Year Book Medical Publisher; 1980. p. 39-41. 80. Borrel N, Mesquida X, Alomar P. Protección de los trabajadores contra los riesgos relacionados con la exposición a agentes biológicos durante el trabajo. Real Decreto 664-1997, de 12 de Mayo. B.O.E. No. 124, de 24 de Mayo y adaptación contenida en la Orden de 25 de Marzo de 1998. España. p. 1-13. 81. Sekhon AS, Standard PG, Kaufman L, Garg AK. Reliability of exoantigens for differentiating Blastomyces dermatitidis and Histoplasma capsulatum from Chrysosporium and geomyces species. Diagn Microbiol Infect Dis 1986;4:215-21. 82. Pounder JI, Hansen D, Woods GL. Identification of Histoplasma capsulatum, Blastomyces dermatitidis and Coccidioides species by repetitive-sequence-based PCR. J Clin Microbiol 2006;44:2977-92. 83. Turner S, Kaufman L, Jalbert M. Diagnostic assessment of an enzymelinked immunosorbent assay for human and canine blastomycosis. J Clin Microbiol 1986;23:294-7. 84. Durkin M, Wittt J, LeMonte A, et al. Antigen assay with the potential aid in diagnosis of blastomycosis. J Clin Microbiol 2004;42:4873-5. 85. Tarr M, Marcinak J, Mongkolrattanothai K, et al. Blastomyces antigen detection for monitoring blastomycosis in a pregnant adolescent. Infect Dis Obst Gynecol 2007;2007:89059. 86. Bialek R, Gonzalez GM, Begerow D, et al. Coccidioidomycosis and blastomycosis: advances in molecular diagnosis. FEMS Immunol Med Microbiol 2005;45:355-60. 87. Dismukes WE, Bradsher RW, Cloud GA, et al, and the NIAID Mycoses Study Group. Itraconazole therapy for blastomycosis and histoplasmosis. Am J Med 1992;93:489-97. 88. Lortholary O, Denning DW, Dupont B. Endemic mycoses: a treatment update. J Antimicrob Chemother 1999;43:321-31. 89. Greer ND. Posaconazole (Nosafil): a new triazole antifungal agent. Proc (Bayl Univ Med Cent) 2007;20:188-96. 90. Vermes A, Guchelaar HJ, Dankert J. Flucytosine: a review of its pharmacology, clinical indications, pharmacokinetics, toxicity and drug interactions. J Antimicrob Chemother 2000;46:171-9. 91. Ta M, Flowers SA, Rogers PD. Le rôle du voriconazole dans la blastomycose du système nerveux central. Ann Pharmacother 2009;43: 1696-700. 92. Champman SW, Bradsher RW, Campbell Jr GD, et al. Practice guidelines for the management of patients with blastomycosis. Clin Infect Dis 2000;30:679-83. 93. Cornely OA, Maertens J, Bresnik M, et al. Liposomal amphotericin B as initial therapy for invasive mold infection: a randomized trial comparing high-loading dose with standard dosing (Ambiload trial). Clin Infect Dis 2007;44:1289-97. 94. Garbino J, Adam A. Use of high-dose liposomal amphotericin B: efficacy and tolerance. Acta Biomed 2006;77:19-22. 95. Ullmann AJ, Lipton JH, Vesole DH, et al. Posaconazole or fluconazole for prophylaxis in severe graft-versus-host disease. N Engl J Med 2007;356:335-47.
Blastomycosis Rubén López-Martínez, MD, DrSc a,⁎, Luis Javier Méndéz-Tovar, MD, DrSc b a
Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ave. Universidad 3000, México D.F. 04510, México b Laboratory of Dermatology and Medical Mycology Research, Hospital de Especialidades, Centro Médico Nacional, IMSS, Av. Cuauhtémoc 330, Colonia Doctores, Ciudad de México, 06725, México
Abstract Blastomycosis is a systemic mycosis with a high prevalence in the Midwest of the United States. The fungus inhabits soil, and human infection occurs through inhalation. Its asexual phase is called Blastomyces dermatitidis and its sexual phase, Ajellomyces dermatitidis. It is more common in men. Signs and symptoms are usually severe, starting with an infection resembling pneumonia that later disseminates to the skin, bones, and central nervous system. Infection in dogs is common in endemic areas. The diagnosis can be achieved by identifying the organism with direct microscopy, culture, histopathology, serologic tests, and molecular techniques, although these are still in trial phase. The treatments of choice are azoles (itraconazole, fluconazole, and posaconazole), and in severe cases, amphotericin B. © 2012 Published by Elsevier Inc.
Introduction In May 1894, T. Caspar Gilchrist described at the American Dermatological Association in Washington, DC, microscopic sections from a case of cutaneous disease in Philadelphia under the care of Louis A. Duhring, who had sent an excised specimen for microscopic examination. The parasitic bodies initially were interpreted as plant rather than fungal forms. These bodies were later recognized as forms of blastomycetes. This case was fully described and illustrated by Gilchrist under the title “A Case of Blastomycetic Dermatitis in man.”1 Two years later, the organism was isolated for the first time in culture from a second patient, and in 1898, the causal agent was named Blastomyces dermatitidis.2 The disease was later reproduced in the lungs and other organs of experimental animal models.3 The first systemic infection caused by this fungus was reported in an autopsy report in 1902.4 Its dimorphic nature was documented in 1907, when the tissue isolates from four different patients with this infection were ⁎ Corresponding author. E-mail address: [email protected] (R. López-Martínez). 0738-081X/$ – see front matter © 2012 Published by Elsevier Inc. http://dx.doi.org/10.1016/j.clindermatol.2012.01.002
studied.5 This study helped clarified and define the etiology and pathogenesis of this mycosis. For many years, American blastomycosis was known as Gilchrist's disease or Chicago's disease. Around that time, the etiologic agents of many mycoses were being studied for the first time, and many cases of blastomycosis were confused with cryptococcosis, coccidioidomycosis, and paracoccidiodomycosis. 6,7 It was in the 1930s, when investigators distinguished the different agents of blastomycosis, paracoccidioidomycosis, and others, such as cryptococcosis, whose histopathologic images can easily be confused with blastomycosis.8-10 During the first half of the past century, systemic and cutaneous blastomycosis were believed to be two different expressions of the same disease. The first was thought to be transmitted through the respiratory tract and the other through traumatic inoculation. This belief was clarified in 1951, when it was discovered that there was only one clinical picture: pulmonary disease with systemic dissemination.11 These results were confirmed in 1955 in a study of four patients with cutaneous inoculation of B dermatitidis, whose histologic skin lesions differed from the granulomatous lesions seen in patients with systemic dissemination of blastomycosis.12
566 The first reports of infection in dogs were published in 1952.13 Today, susceptibility to this infection has been reported in numerous animal species13; however, the disease still predominates in dogs.14,15 In 1960, isolation of the organism from the soil was intensely pursued, but with only partial success. The habitat of B dermatitidis has not been established.16-18 In 1968, the sexual phase of the fungus was discovered and received the name of Ajellomyces dermatitidis. It was placed under the family Onygenaceae of the Ascomycetes phylum.19 Transmission of this infection through prostatic fluid, which is a unique characteristic among systemic mycosis, was documented in 1983. This characteristic can make this mycosis a potential sexually transmitted disease.20
Epidemiology Geographic distribution Blastomycosis was originally thought to be a disease exclusive to the midwestern United States, as can be deduced from the initial names the disease received: Chicago's disease and North American blastomycosis.7 Later reports showed it to be widespread in Minnesota, Wisconsin, Michigan, and northern Ohio, as well as in Louisiana, Mississippi, Alabama, and southern Georgia. Most of the reported cases come from the Mississippi River basin, Ohio, Missouri,21,22 and the western margins of Lake Michigan. There are also reports from states as far as California, but in most, a history of travel or residence in an endemic area was confirmed.23 Recent reports suggest that the area affected by blastomycosis in the United States is expanding, as was demonstrated by reports from Colorado.24 Canada is not immune, with reports from Quebec and the Maritime provinces. In Ontario, 309 cases were published between 1994 and 2003.25 In daily medical practice, it is often hard to confirm the diagnosis, and many medical visits and a correlation with the geographic distribution of the disease is required to make a diagnosis.26,27 A few cases have been published in Mexico, all involving immigrants. The first was reported more than 50 years ago.28 Recently, a case report of cutaneous dissemination caused by B dermatitidis was published in Mexico.29 Two other geographic regions where cases of blastomycosis have been reported are Africa (especially South Africa and Zimbabwe)30 and India, where this agent was first isolated in 1983.31 Currently, most cases are reported from the northern region of India.32 Other countries where this mycosis is known are Lebanon,33 south Arabia, and Israel.34
Host The disease most commonly occurs in adults in the fourth decade of life. It is uncommon in children. Most experts
R. López-Martínez, L.J. Méndéz-Tovar agree this could be due to longer environmental exposure to the agent as an individual ages.26,27 Blastomycosis predominates in men. In contrast to what occurs in paracoccidioidomycosis, where estradiol inhibits the parasite's transformation,35 in blastomycosis, it is due to occupational factors. Recreational activities such as fishing, camping, or outdoors professions, such as forest ranger, are frequently associated with this disease.36 Although African American patients are more susceptible for infection, ethnicity is not implicated; rather, factors associated with low socioeconomic status or concomitant diseases, such as diabetes, are responsible for this susceptibility. To date, no relationship with a histocompatibility antigen has been found.37,38 AIDS infection does not increase the frequency of the disease; however, it does predispose patients to a chronic disease with early systemic dissemination, frequent relapses, and an increased mortality despite treatment.39 Infection in dogs is frequent, as was published in a review of the years 1885 to 1968, where a large number of cases were documented on the borders of the Ohio and Mississippi rivers.21 In 1985, another study from the Wisconsin area reported 136 to 200 cases of blastomycosis in dogs.40 There have been no large studies in animals in recent years; however, the publication of cases of infection in dogs has been constant, with no predominance for a particular breed.15 The occurrence of infection in dogs in some endemic areas gives support to the idea that there could be subclinical infection in humans.41
Etiologic agent As a result of the study of the ribosomal subunits, the fungus can be placed under the phylum Ascomycota of the family Onygenaceae, with a close genetic resemblance to Paracoccidioides brasiliensis, Emmonsia parva, and Histoplasma capsulatum.42 Blastomyces dermatitidis is a holomorphic fungus. Its asexual phase is dimorphic, and clinical specimens cultivated and incubated at room temperature on a Sabouraud dextrose agar medium start to grow after 2 to 4 weeks. Initially, the colony is white and acquires a grayish color with time. It is composed of a fine mycelium, 2 to 3 μm in diameter, and sparse conidia with an ovoid to piriform shape, 3 to 5 μm in diameter, that derive from short conidiophores or directly from hyphae. These microconidia are tightly bound to the filament and require humidity to fall off.43 These characteristics support the geographic distribution of the infection, which includes locations with high humidity. In its natural habitat, it is associated with the presence of salamanders of the Necturus genus.44 Its conversion from mycelial to yeast phase (tissue phase) is influenced by temperature and nutrients. The conidia inoculated in a brain-heart infusion medium and incubated at 37°C develop in 10 to 15 days with the formation of soft colonies with a cerebriform surface resembling butter. Direct microscopy shows single budding yeasts with a wide base 8 to 12 μm in diameter, a thick wall, and double contour.
Blastomycosis Compared with conidia, which have only one nucleus, yeasts present two to four nuclei.45 In tissue, most yeasts are 8 to 14 μm long, although some authors report the presence of microyeasts measuring 3 to 10 μm that, in some cases, have been confused with Histoplasma capsulatum.46 Other authors argue the existence of large yeast cells, up to 40 μm in diameter, that can cause histopathologic confusion with P brasiliensis and Coccidioides immitis.47 The sexual phase, Ajellomyces dermatitidis, gives rise to a gymnothecium that bears ascogenic hyphae. These can be globular or subglobular with asci of 6 to 8 μm in diameter that contain eight ascospores with smooth or warty walls of 1.5 to 2 μm. Major and minor strains have been described; however, it is unknown, which is more virulent.48
Virulence factors For tolerance to human temperature, the fungus' dimorphism is important for the pathogenicity of the disease. The presence of an adherence factor named BAD1 (blastomyces adhesion), which most likely allows the beginning of infection but at the same time suppresses the release of tumor necrosis factor-α (TNF-α), has been demonstrated.49 The cell wall of yeast contains 95% α-3 glucan, which is its major virulence factor, whereas mycotic filaments contain αglucan and β-glucan in a similar proportion.50 Another virulence factor is the production of melanin, which is seen in culture and in infection. Melanin protects the fungus from the oxidative reactions of leukocytes.51 The presence of a large amount of yeasts of B dermatitidis in tissues gives rise to a late hypersensitivity reaction that causes tissue damage in the form of abscesses, hemorrhagic lesions, and in the chronic forms, the formation of fibrosis and granulomas.52
Clinical picture Pathogenesis Most cases are acquired through the respiratory tract by inhalation of conidia or mycelial fragments. This gives rise to a primary pulmonary infection. As a result of the ability of the infection to disseminate to the testes, the epididymis, and the prostate, there are reports of sexual transmission, without the presence of cutaneous lesions.53 Infection can be acquired by unusual mechanisms such as traumatic inoculation through the skin; there are even reports of its transmission to humans through dog bites,54,55 and in 1983, the first case of intrauterine transmission was published.56
Classification and clinical signs Most authors describe two clinical forms: pulmonary and extrapulmonary. The first is the most frequent, and is generally the clinical form associated with systemic dissemination.
567 Primary pulmonary blastomycosis The incubation period of the infection has not been determined but has been estimated to range from 21 to 106 days, with an average of 45 days. Other investigators report an insidious onset.57 In either case, the clinical signs and symptoms are variable and depend on the host parasite and environment interaction. A review of 200 patients with blastomycosis found the most frequent manifestations were cough (35.8%), weight loss (27.8%), thoracic pain (26.2%), cutaneous lesions (25.8%), fever (22.7%), hemoptysis (20.7%), and localized swelling (13.6%).58 As has been observed in other mycosis, some patients may remain asymptomatic, whereas others portray mild signs and symptoms that can be confused with a viral respiratory infection and some have moderate to severe disease. This last group has been compared in severity to pulmonary histoplasmosis. Pulmonary infections can be classified into three groups: (1) resolution of the pulmonary infection with dissemination to other organs; (2) resolution of the pulmonary infection without evidence of residual disease in other organs; and (3) severe and progressive pulmonary disease. The patient in the first group may complain of cough, chest pain, and hoarseness, accompanied by mild fever. The formation of pulmonary calcifications may not appear; nevertheless, dissemination may occur because the disease is carried through macrophages into the systemic circulation, and chronic cutaneous lesions frequently develop.59 In the second group, which includes patients who heal without evidence of residual disease in other organs, symptoms include productive cough, arthralgias, myalgias, and hyperthermia associated with moderate to severe chest pain. A review of 48 patients showed only 46% were asymptomatic.57 The progressive, severe form of the disease is characterized by the development of acute lobar pneumonia, productive cough with purulent expectoration and streaks of blood, high fever, weight loss, asthenia, adynamia, and adult respiratory distress syndrome with severe arterial hypoxemia. Dissemination of the pulmonary focus to the skin can occur in the form of fistulas or subcutaneous abscesses.59,60 Despite the severity of the disease, the prognosis may be favorable in many patients, resulting in spontaneous or treatment-induced healing; nevertheless, some patients may develop a carrier state with a chronic pulmonary focus. When immunologic surveillance is weakened by internal or external factors, reactivation of latent infection can induce systemic dissemination and even death.61 Some severe progressive forms of the disease can be associated with severe immunosuppression, as seen in patients with AIDS or in patients who receive long-term corticosteroid therapy.62,63 Extrapulmonary blastomycosis (A) Cutaneous. This is the most frequent extrapulmonary form. Primary cutaneous forms are produced by traumatic inoculation of the skin that is usually associated with work exposure, as in veterinarians54,55 and mycology laboratory
568 personnel.64 Signs and symptoms include the presence of papules that may progress to pustules with regional lymphadenopathy that generally undergoes spontaneous resolution in weeks to months without medical treatment. Secondary cutaneous forms are more frequent. Skin lesions can have an ulcerated or warty appearance of various sizes. These may extend with progression of the disease over the years. Some may even display a necrotic, ulcerated spot that can confer an appearance similar to basal cell carcinoma of the skin, squamous cell carcinoma, pyoderma gangrenosum, or keratoacanthoma (Figures 1-4).65 In some cases, subcutaneous abscesses can resemble panniculitis or WeberChristian disease.66 (B) Bone. Bone is affected in 6% to 48% of patients. The bones most frequently involved include long bones, vertebra, ribs, and the cranium, in the form of osteomyelitis,67 with dissemination to the joints, where it may cause septic arthritis.68 (C) Genitourinary. The prostate and epididymis are most frequently involved. The diagnosis can be made with laboratory evaluation of secretions obtained by prostatic massage.69 A few cases are reported in women, one of whom had sexual contact with a man with genitourinary blastomycosis without cutaneous lesions.70 Reactivation of the disease can be observed in women as a consequence of dissemination of a pulmonary focus. Fallopian tubes and ovaries can be involved, with the development of abscesses that can be confused with ovarian cancer.71 (D) Central nervous system. Extrapulmonary blastomycosis affects this area in about 5% to 10% of patients. Patients may manifest signs and symptoms of meningitis, cerebral abscess, or granuloma formation associated with the presence of B dermatitidis.72 A laboratory diagnosis is hard to establish. The best samples available for culture should be obtained through a ventricular puncture, which yields a positivity of 85% compared with 9% positivity from a spinal tap.73 (E) Other sites of infection. North American blastomycosis can infect any organ or tissue, among these the
Fig. 1 Blastomycosis affecting the upper lip. (Photo courtesy of Larry E. Millikan, MD, Meridian, MS.)
R. López-Martínez, L.J. Méndéz-Tovar
Fig. 2 Ulcerated lesion resembling pyoderma. (Photo courtesy of Larry E. Millikan, MD, Meridian, MS.)
monocyte-phagocyte system, the breasts, eyes,74 ears,75 thyroid, adrenal glands, myocardium, pericardium, or digestive tract.65 In many cases, the presence of extrapulmonary lesions allows identification of chronic or relatively asymptomatic pulmonary lesions or blastomycosis with an atypical clinical course.76
Diagnosis Microbiologic tests Direct microscopy Specimens should be obtained from skin scales from warty lesions, purulent material from microabscesses, bronchioalveolar lavage, sputum, urine, or cerebrospinal fluid, etc. In positive cases, single budding yeasts with a wide fusion base, a double-wall contour, and a size of 8 to 14 μm are observed (Figure 5).77 Other methods to obtain useful specimens for microbiologic examination include
Fig. 3 Granulomatous lesion on the dorsum of the hand. (Photo courtesy of Larry E. Millikan, MD, Meridian, MS.)
Blastomycosis
Fig. 4 Cutaneous lesion of the face. (Image courtesy of VisualDx, ©Logical Images Inc, Rochester, NY.)
invasive techniques, such as fine-needle biopsy aspiration in prostatic involvement.78 Histopathology Histologic samples stained with the Gomori-Grocott and periodic acid-Schiff techniques allow observation of single budding yeasts with the characteristics described above (Figure 6). Sometimes, these may show multiple budding and can be observed in the intracellular or extracellular space. Tissue samples stained with hematoxylin and eosin may display a mixed cellular inflammatory reaction with polymorphonuclear cells, neutrophils, and noncaseating granulomas that include histiocytes and giant multinucleated cells. Other areas may display fibrosis. The number of yeasts observed decreases as granulomas develop.79 The differential morphologic diagnosis includes P brasiliensis yeasts, Cryptococcus spp, and Histoplasma capsulatum as well as Coccidioides spp spherules.
569
Fig. 5 Direct microscopy of a blastomycosis case; budding yeasts with a wide fusion base are seen (original magnification ×400).
Culture growth usually begins after 10 to 15 days; however, this period can be longer when few yeasts are present in the specimen cultured. As a result, culture of samples from a patient with symptoms suggestive of blastomycosis should not be considered negative before 4 weeks. The first colonies have a whitish, smooth appearance, and days later they may be grayish or brownish, with a hairy appearance (Figure 7). Microscopically, a fine mycelium (1 to 2 μm in diameter) and piriform conidia (2 × 3 or 4 μm in diameter) may originate directly from hyphae or from short to large conidiophores (Figure 8). Its morphology may be similar to that seen in some contaminating fungi or P brasiliensis. Mycelial-to-yeast conversion confirms the fungus classification when a culture isolate is cultivated in a brain-heart infusion agar medium and incubated at 37°C. After 7 to 10 days, single budding thick walled B dermatitidis yeasts that contain 2 to 4 nuclei are observed.45 Culture identification of the filamentous phase using only morphologic features can be considerably difficult. As a result of this, new tests, such as the production of exoantigens
Culture Petri dishes must be avoided when culturing this agent because many highly infective conidia can be released into the environment, causing an occupational hazard. All specimens must be cultured in 150- × 15-mm test tubes that contain plain Sabouraud dextrose agar supplemented with antibiotics or potato dextrose agar. Tissues should be macerated in sterile conditions, cultivated in a brain-heart infusion agar, and incubated at 25° to 30°C. Blastomyces dermatitidis belongs to level 3 of the Biological Hazard Classification, which corresponds to agents that can cause disease in man and represent a danger to workers with the risk of propagation and for which there is effective treatment and prophylaxis as a result. The handling of these cultures must always be done in a laminar flow hood.80
Fig. 6 Histologic image of a blastomycosis case where budding yeasts with a wide fusion base are observed (original magnification ×400).
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R. López-Martínez, L.J. Méndéz-Tovar
in liquid cultures, have been developed.81 A new molecular biology technique that allows identification of cultures in less than 2 hours using probes for identification of the yeast and mycelia phases has recently been made available.82
Immunologic studies The identification of B dermatitidis antibodies has been available for a couple of years; however, it is not very useful because of its low sensibility (55%) and specificity (30%).83 Antigen detection in different body fluids is very useful, however. The specimens that can be used include cerebrospinal fluid, bronchioalveolar lavage, pleural effusion, and urine, with sensitivity greater than 90%.84,85 Molecular techniques useful for the diagnosis of infection in humans and animals are not yet available. Preliminary trials have been promising, however, and these new techniques may be available commercially in the future.86
Management Treatment should be prescribed without exception to all patients with chronic pulmonary blastomycosis, systemic dissemination to any organ, and immunosuppression. In the primary pulmonary forms with mild symptoms, triazole drugs are indicated. The treatment of choice consists of oral itraconazole, 200 mg twice daily for 4 to 6 months, achieving a cure rate of 90% to 95%.87 An alternative is oral posaconazole, 800 mg daily for 2 to 3 months.88,89 This latter triazole has the advantage of a wider antifungal spectrum and significant lower antifungal resistance. Treatment duration should be prolonged or shortened according to clinical evolution and results of immunologic testing. Other triazole drugs that can be used are oral fluconazole, 400 to 600 mg daily, and oral voriconazole, 200 mg every 12 hours, for 3 to 4 months.90,91 When asymptomatic primary pulmonary forms or mild symptoms are present, surveillance is indicated with close
Fig. 8 Direct microscopy of a culture of Blastomyces dermatitidis stained with blue dye. Septate hyaline filaments and ovoid to round microconidia are observed (original magnification ×1000).
examination of symptoms and immunologic tests.92 If symptoms persist, and radiologic signs and immunologic tests are positive, itraconazole or voriconazole must be given at the indicated doses. In severe pulmonary blastomycosis or with systemic dissemination, intravenous amphotericin B desoxycholate, at a dose of 0.7 to 1 mg/kg on alternate days, is indicated without surpassing a total maximum dose of 2 to 3 grams. Lipid formulations of amphotericin B have also been administered at a daily dose of 3 to 5 mg/kg.93,94 In pediatric patients, the dose of amphotericin B should be adjusted according to age and total body weight in addition to close surveillance of intolerance and systemic toxicity. Once the amphotericin B treatment has concluded, it must be followed by the administration of several months of triazole drugs. Prophylactic measures are not well established, but generally include the same precautions used to avoid other systemic mycosis. It is advisable to offer a prophylactic dose of fluconazole (150 mg/d) or posaconazole (800 mg/d). These recommendations, however, have not been tested and validated.95 Immunosuppressed patients are advised not to travel to endemic zones and to avoid contact with dogs in these regions, due to reports of transmission of disease through dog bites.54,55
Conclusions
Fig. 7 Sabouraud dextrose agar medium culture incubated at 37°C for 15 days with growth of white-to-grayish colonies with a hairy appearance.
Blastomycosis is an infection with a limited geographic distribution. Its frequency outside of the USA or Canada is not well established. The natural habitat of Blastomyces dermatitidis usually includes humid areas close to the forest. In addition to humans, the fungus is capable of infecting several species of mammals, mainly dogs; what creates a growing demand for veterinarian personal must be alert to this infection in canines. Most human cases are asymptomatic; however, in immunosuppressed patients the infection could be disseminated, first to lungs and latter to several organs, such as bone, skin, genitourinary, and central
Blastomycosis nervous system. Its frequency as a cause of death in immunosuppressed patients has not been determined. The diagnosis is made under microbiology bases; however, the development of newer molecular tests will be the standard in the next few years. Even though most patients do not receive treatment, disseminated infections are usually treated with itraconazole or voriconazole, and even amphotericin B (desoxycholate, liposomal, etc.). Prophylaxis for patients at risk should be made with fluconazole or posaconazole. The B dermatitidis antigenic complexity has made impossible to develop a vaccine, is a similar situation to other systemic mycoses, where artificial immunization may be the solution to infection in populations living in endemic areas.
References 1. Gilchrist TC. Protozoan dermatitis. J Cutan Genitourin Dis 1894;12: 496-9. 2. Gilchrist TC, Stokes WR. The presence of an Oidium in the tissues of a case of pseudo-lupus vulgaris. Preliminary report. Bull Johns Hopkins Hosp 1896;7:129-33. 3. Gilchrist TC, Stokes WR. A case of pseudo-lupus vulgaris caused by Blastomyces. J Exp Med 1898;3:53-78. 4. Walker JM, Montgomery FH. Further report of a previously recorded case of blastomycosis of the skin: systemic infection with blastomycosis. Death autopsy. JAMA 1902;38:867-71. 5. Hamburger WW. A comparative study of four strains of organisms isolated from four cases of a generalized blastomycosis. J Infect Dis 1907;4:201-9. 6. Hektoen L. Systemic blastomycosis and coccidioidal granulomas. JAMA 1907;49:1070-7. 7. Conant NF, Smith BT, Baker RD, et al. Blastomicosis. In: Conant NF, Smith BT, Baker RD, Callaway JL, editors. Micología. 3rd ed. México City: Interamericana; 1976. p. 65-104. 8. Almeida FP. Estudos comparativo do granulomcoccidioidico nos Estados Unidos e no Brazil. Novo genero para a parasita brazileiro. An Fac Med Univ Sao Paulo 1930;5:125-41. 9. Benham RW. Criptococosis and blastomycosis. Ann N Y Acad Sci 1950;50:1299-314. 10. Conant NF. Laboratory study of Blastomyces dermatitidis Gilchrist and Stokes. Proc 6th Pacific Sci Congr 1939;5:853-62. 11. Schwarz J, Baum GL. Blastomycosis. Am J Clin Pathol 1951;21: 999-1029. 12. Wilson JW, Cawley EP, Weidman FD, et al. Primary cutaneous North American blastomycosis. Arch Dermatol Syphilol 1955;71:39-45. 13. Ramsey FK, Carter GR. Canine blastomycosis in the U.S. J Am Vet Med Assoc 1952;120:93-8. 14. Wilson JH, Olson EJ, Haugen EW, et al. Systemic blastomycosis in a horse. J Vet Diagn Invest 2006;18:615-9. 15. Bateman BS. Disseminated blastomycosis in a German shepherd dog. Can Vet J 2002;43:550-2. 16. Denton JF, McDonough ES. Isolation of Blastomyces dermatitidis from soil. Science 1961;133:1126-7. 17. Denton JF, Di Salvo AF. Isolation of Blastomyces dermatitidis from natural sites at Augusta, Georgia. Am J Trop Med 1964;13:716-22. 18. Denton JF, Di Salvo AF. Additional isolations of Blastomyces dermatitidis from natural sites. Am J Trop Med Hyg 1979:697-700. 19. McDonough ES, Lewis AL. The ascigerous stage of Blastomyces dermatitidis. Mycologia 1968;60:76-83. 20. Dyer ML, Young TL, Kattine AA, et al. Blastomycosis in a Papanicolaou smear. Report of a case of possible venereal transmission. Acta Cytol 1983;27:285-7.
571 21. Furculow ML, Chick EW, Busei JF, et al. Prevalence and incidence studies of human and canine blastomycosis. Am Rev Respir Dis 1970;102:60-7. 22. Furcolow ML, Smith CD. A new interpretation of the epidemiology, pathogenesis and ecology of Blastomyces dermatitidis. Trans N Y Acad Sci 1973;35:421-30. 23. Casad DE, Waldmann JW, Levan NE, et al. North American blastomycosis in California. Diagnosis of a case and a survey with 28 California observed cases. Cal Med 1967;106:20-7. 24. Hannah EL, Bayley AM, Hajjeh R, et al. Public health response to 2 clinical cases of blastomycosis in Colorado. Clin Infect Dis 2001;32: 151-3. 25. Morris SK, Brophy SE, Richardson R, et al. Blastomycosis in Ontario, 1994-2003. Emerg Infect Dis 2006;12:274-9. 26. Bernstein S, Brunner H, Summerbell R, et al. Blastomycosis acquired by three children in Toronto. Can J Infect Dis 2002;13:259-63. 27. Kesselman EW, Moore S, Embil JM. Using local epidemiology to make a difficult diagnosis: a case of blastomycosis. Can J Emerg Med 2005;7: 171-3. 28. Martínez-Baez M, Reyes-Mota A, González-Ochoa A. Blastomicosis Norteamericana en México. Rev Inst Salubr Enferm Trop 1954;14: 225-32. 29. Velázquez R, Muñóz-Hernández B, Arenas R, et al. An imported case of Blastomyces dermatitidis infection in Mexico. Mycophatologia 2003;156:263-7. 30. Baily GG, Robertson VJ, Neill P, et al. Blastomycosis in Africa: clinical features, diagnosis, and treatment. Rev Infect Dis 1991;13:1005-8. 31. Randahwa HS, Khan Z, Gaur S. Blastomyces dermatitidis in India: first report of its isolation from clinical material. Sabouraudia 1983;21: 215-21. 32. Di Salvo AF. The epidemiology of blastomycosis. In: Al-Doory Y, Di Salvo AF, editors. Blastomycosis. New York: Plenum Medical Book Co; 1992. p. 75-104. 33. Hassan FM, Jarrah T, Nassar V. The association of adenocarcinoma of the lung and blastomycosis from an unusual geographical location. Br J Dis Chest 1978;72:242-6. 34. Kuttin ES, Beemer AM, Levij J, et al. Occurrence of Blastomyces dermatitidis in Israel. First autoctochtonous Middle Eastern case. Am J Trop Med Hyg 1978;27:1203-5. 35. Restrepo A, Salazar ME, Cano LE, et al. Estrogens inhibit mycelium-toyeast transformation in the fungus Paracoccidioides brasiliensis: implications for resistance of females to paracoccidioidomycosis. Infect Immun 1984;46:346-53. 36. Crampton TL, Light RB, Berg GM, et al. Epidemiology and clinical spectrum of blastomycosis diagnosed at Manitoba hospitals. Clin Infect Dis 2002;34:1310-6. 37. Lemos LB, Baliaga M, Guo M. Blastomycosis: the great pretender can also be an oportunistic. Initial clinical diagnosis and underlying diseases in 123 patients. Ann Diagn Pathol 2002;6:194-203. 38. Cano MV, Ponce-de-León GF, Tippen S, et al. Blastomycosis in Missouri: epidemiology and risk factors for endemic disease. Epidemiol Infect 2003;131:907-14. 39. Wheat J. Endemic mycosis in AIDS: a clinical review. Clin Microbiol Rev 1995;8:146-59. 40. Archer JR, Trainer DO, Schell RF. Epidemiologic study of canine blastomycosis in Wisconsin. J Am Vet Med Assoc 1987;190:1292-5. 41. Sarosi GA, Eckman MR, Davies SF, et al. Canine blastomycosis as a harbinger of human disease. Ann Intern Med 1979;91:733-5. 42. Byalek R, Ibricevik A, Fothergill A, et al. Small subunit ribosomal DNA sequence shows Paracoccidioides brasiliensis closely related to Blastomyces dermatitidis. J Clin Microbiol 2000;38:3190-3. 43. Mc Donough ES, Wisniewski RT, Penn LA, et al. Preliminary studies on conidial liberation of Blastomyces dermatitidis and Histoplasma capsulatum. Sabouraudia 1976;14:199-204. 44. Borelli D, Marcano C, Feo M. Actividades de la sección de Micología Médica, Instituto de Medicina Tropical (Caracas), durante el año 1968. Dermatol Venez 1969;8:887-904.
572 45. Clemons KV, Hurley SM, Treat-Clemens LJ, et al. Variable colonial phenotypic expression and comparison to nuclei number in Blastomyces dermatitidis. J Med Vet Mycol 1991;29:165-8. 46. Schwarz J, Blastomycosis SalfelderK. A review of 152 cases. Curr Topics Pathol 1977;65:165-200. 47. Watts JC, Chandler FW, Mihalov ML, et al. Giant forms of Blastomyces dermatitidis in the pulmonary lesions of blastomycosis. Potential confusion with Coccidioides immitis. Am J Clin Pathol 1990;93:575-8. 48. Rippon WJ. Tratado de Micología Médica. México, DF: Ed Interamericana; 1990. p. 511. 49. Di Salvo AF, Klein BS. Blastomycosis. In: Merz WG, Hay RJ, editors. Topley and Wilson's microbiology and microbial infections. Medical mycology. London: Hodder Arnold; 2005. p. 479-501. 50. Kanetsuna F, Carbonell LM. Cell wall composition of the yeast like and mycelial forms of Blastomyces dermatitidis. J Bacteriol 1971;106:946-8. 51. Nosanchuc JD, van Duin D. Mandai P, et al. Blastomyces dermatitidis produces melanin in vitro and during infection. FEMS Microbial Lett 2004;239:187-93. 52. Bradsher RW. Blastomycosis. Infect Dis Clin North Am 1988;2: 877-98. 53. Murray JJ, Clark CA, Lands RH, et al. Reactivation blastomycosis presenting as a tuboovarian abscess. Obstet Gynecol 1984;64:828-30. 54. Graham WR, Callaway JL. Primary inoculation blastomycosis in a veterinarian. J Am Acad Dermatol 1982;7:785-6. 55. Gnann JW, Bressler GS, Bodet III CA, et al. Human blastomycosis after a dog bite. Ann Intern Med 1983;98:48-9. 56. Watts EA, Gard PD, Tuthill SW. First reported case of intrauterine transmission of blastomycosis. Pediatr Infect Dis 1983;2:308-10. 57. Klein BS, Vergeront JM, Weeks RJ, et al. Isolations of Blastomyces dermatitis in soil associated with eight large outbreaks of blastomycosis in Wisconsin. N Engl J Med 1986;31:529-34. 58. Blastomycosis Cooperative study of the Veterans Administration. Blastomycosis a review of 198 collected cases in Veterans Administration Hospitals. Ann Rev Respir Dis 1964;89:659-72. 59. Skillrud DM, Douglas WW. Survival in adult respiratory distresses syndrome caused by Blastomyces dermatitidis. Mayo Clin Proc 1985;60: 266-9. 60. Cherniss EI, Waisbren BA. North American blastomycosis: a clinical study of 40 cases. Ann Intern Med 1956;44:105-23. 61. Laskey WK, Sarosi GA. Endogenous activation in blastomycosis. Ann Intern Med 1978;88:50-2. 62. Pappas PG, Pottage JC, Powderly WG, et al. Blastomycosis in patients with the acquired immunodeficiency syndrome. Ann Intern Med 1992;116:847-53. 63. Pappas PG, Threlkeld MG, Bedsole GD, et al. Blastomycosis in immunocompromised patients. Medicine 1993;72:311-25. 64. Schwarz J. Laboratory infections with fungi. In: Di Salvo AF, editor. Occupational mycosis. Philadelphia: Lea & Febiger; 1983. p. 215-27. 65. Bradsher RW, Martin MR, Wilkes TD, et al. Unusual presentations of blastomycosis: ten case summaries. Infect Med 1990;7:10-9. 66. Maioriello RP, Merwin CF. North American blastomycosis presenting as an accutepanniculitis and arthritis. Arch Dermatol 1970;102:92-6. 67. Gehweiler JA, Capp MP, Chick EW. Observations on the roentgen patterns in blastomycosis of bone. Am J Roentgenol Radium Ther Nucl Med 1970;108:497-510. 68. Sanders LL. Blastomycosis arthritis. Arthritis Rheum 1967;10:91-8. 69. Inoshita T, Yougberg GA, Boelden LJ, et al. Blastomycosis presenting with prostatic involvement: report of 2 cases and review of the literature. J Urol 1983;130:160-2. 70. Farber ER, Leahy MS, Meadows TR. Endometrial blastomycosis acquired by sexual contact. Obstet Gynecol 1968;32:195-9. 71. Mouzin EL, Beilke MA. Female genital blastomycosis: case report and review. Cin Infect Dis 1996;22:718-9. 72. Roos KL, Bryan JP, Maggio WW, et al. Intracranial blastomycosis. Medicine (Baltimore) 1979;66:224-35.
R. López-Martínez, L.J. Méndéz-Tovar 73. Kravitz GR, Davies SF, Eckman MR, et al. Chronic blastomycosis meningitis. Am J Med 1981;71:501-5. 74. Lopez R, Mason JO, Parker JS, et al. Intraocular blastomycosis: case report and review. Clin Infect Dis 1994;18:805-7. 75. Istorico LJ, Sanders MR, Jacobs RF, et al. Otitis media due to blastomycosis: report of two cases. Clin Infect Dis 1992;14:355-8. 76. Bradsher RW. Blastomycosis. In: Dismukes W, Pappas PG, Sobel JD, editors. Clinical mycology. Oxford: New York; 2003. p. 299-310. 77. López-Martínez R, Méndez-Tovar LJ, Hernández-Hernández F, et al. Micosis sistémicas. In: López-Martínez R, Méndez-Tovar LJ, Hernández-Hernández F, et al, editors. Micología Médica. Procedimientos para el diagnóstico de laboratorio. México, DF: Trillas; 2004. p. 83-98. 78. Neal PM, Nikolai A. Systemic blastomycosis diagnosed by prostate needle biopsy. Clin Med Res 2008;6:24-8. 79. Chandler FW, Kaplan W, Ajello L. Blastomycosis. In: Chandler FW, Kaplan W, Ajello L, editors. Histopathology of mycotic diseases. Color atlas and text. Chicago: Year Book Medical Publisher; 1980. p. 39-41. 80. Borrel N, Mesquida X, Alomar P. Protección de los trabajadores contra los riesgos relacionados con la exposición a agentes biológicos durante el trabajo. Real Decreto 664-1997, de 12 de Mayo. B.O.E. No. 124, de 24 de Mayo y adaptación contenida en la Orden de 25 de Marzo de 1998. España. p. 1-13. 81. Sekhon AS, Standard PG, Kaufman L, Garg AK. Reliability of exoantigens for differentiating Blastomyces dermatitidis and Histoplasma capsulatum from Chrysosporium and geomyces species. Diagn Microbiol Infect Dis 1986;4:215-21. 82. Pounder JI, Hansen D, Woods GL. Identification of Histoplasma capsulatum, Blastomyces dermatitidis and Coccidioides species by repetitive-sequence-based PCR. J Clin Microbiol 2006;44:2977-92. 83. Turner S, Kaufman L, Jalbert M. Diagnostic assessment of an enzymelinked immunosorbent assay for human and canine blastomycosis. J Clin Microbiol 1986;23:294-7. 84. Durkin M, Wittt J, LeMonte A, et al. Antigen assay with the potential aid in diagnosis of blastomycosis. J Clin Microbiol 2004;42:4873-5. 85. Tarr M, Marcinak J, Mongkolrattanothai K, et al. Blastomyces antigen detection for monitoring blastomycosis in a pregnant adolescent. Infect Dis Obst Gynecol 2007;2007:89059. 86. Bialek R, Gonzalez GM, Begerow D, et al. Coccidioidomycosis and blastomycosis: advances in molecular diagnosis. FEMS Immunol Med Microbiol 2005;45:355-60. 87. Dismukes WE, Bradsher RW, Cloud GA, et al, and the NIAID Mycoses Study Group. Itraconazole therapy for blastomycosis and histoplasmosis. Am J Med 1992;93:489-97. 88. Lortholary O, Denning DW, Dupont B. Endemic mycoses: a treatment update. J Antimicrob Chemother 1999;43:321-31. 89. Greer ND. Posaconazole (Nosafil): a new triazole antifungal agent. Proc (Bayl Univ Med Cent) 2007;20:188-96. 90. Vermes A, Guchelaar HJ, Dankert J. Flucytosine: a review of its pharmacology, clinical indications, pharmacokinetics, toxicity and drug interactions. J Antimicrob Chemother 2000;46:171-9. 91. Ta M, Flowers SA, Rogers PD. Le rôle du voriconazole dans la blastomycose du système nerveux central. Ann Pharmacother 2009;43: 1696-700. 92. Champman SW, Bradsher RW, Campbell Jr GD, et al. Practice guidelines for the management of patients with blastomycosis. Clin Infect Dis 2000;30:679-83. 93. Cornely OA, Maertens J, Bresnik M, et al. Liposomal amphotericin B as initial therapy for invasive mold infection: a randomized trial comparing high-loading dose with standard dosing (Ambiload trial). Clin Infect Dis 2007;44:1289-97. 94. Garbino J, Adam A. Use of high-dose liposomal amphotericin B: efficacy and tolerance. Acta Biomed 2006;77:19-22. 95. Ullmann AJ, Lipton JH, Vesole DH, et al. Posaconazole or fluconazole for prophylaxis in severe graft-versus-host disease. N Engl J Med 2007;356:335-47.