Infections due to Chlamydia

MEDICAL PROGRESS

Infections due to Chlamydia J. Patrick Hieber, M.D., Dallas, Texas

CHLAMYDIA is responsible for a spectrum of infectious diseases in both animals and man. Thi s paper summarizes current information regarding chlamydial disease in the pediatric age range and indicates areas of ongoing investigation.

THE ORGANISM The Chlamydia refers to a genus of infectious agents for which the taxonomy and terminology have been controversial and confusing. They have been variously characterized as large viruses or small bacteria? The evolution of taxonomy based on such factors as host species, geographic location of the isolate, tissue tropism, and the investigator led to the introduction of a bewildering array of terms for these organisms: Chlamydozoon, Riekettsioformis, Ptvwazekia, Bedsonia, Rakeia, and Miyogawanel162. 3 Recent studies'-" have clarified the classification (Table I). The genus Chlamydia is a unique class of microorganisms composed of nonmotile spheroids (0,3 to 1,0 t~ in diameter) containing both DNA and RNA, which are obligate intracellular parasites of vertebrate cells. Like bacteria, they are inhibited by antibiotics and are capable of limited independent metabolism of substances such as lysine and folic and muramic acids; like viruses, they are incapable of replication outside the host cell. They are stained by Giemsa, but not by Gram stain. Electron microscopic studies 7- ~ of the life cycle of the Chlamydia further emphasize the unique blend of viral and bacterial characteristics noted in this genus. The infectious form, the elementary body, enters the host cell cytoplasm by unknown mechanisms. It then begins a 12From the Department of Pediatrics, University of Texas Health Science Center at Dallas. Supported in part by United States Public Health Service Biomedical Research Grant 5-S07-RR 0542615. Reprint address: 5323 Harry Hines Blvd., Dallas, Texas 75235.

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hour eclipse phase similar to that observed in viral reproduction. During this period the organisms are morphologically undetectable. During the next 36 hours a reticular, periodic acid-Schiff-positive, juxtanuclear inclusion develops containing one or more large (approximately 1.0 # in diameter) initial bodies. In the ensuing 24 to 48 hours, binary fission and budding (analogous to bacterial replication) of the initial bodies produce increasing numbers of elementary bodies. These spheres are composed of a compact electron-dense core surrounded by a rim of "clear cytoplasm" contained by a rigid cell wall. These elementary bodies increase in number until they eventually rupture out of the host cell to encounter new cells in which to repeat the cycle, Differences in host range, antigenic characteristics, disease manifestations, morphology, and glycogen content of the cytoplasmic inclusion, and differential inhibition by antibiotics allow separation of the genus into two major species: Chlamydia trachomatis (subgroup A) and Chlamydia psittaci (subgroup B) (Table I), Chlamydia trachomatis is associated primarily with localized diseases. These parasites produce rigid, compact glycogen-positive inclusions and are inhibited by several antibiotics. In contrast, Chlamydiapsittaci is responsible for awide range of animal diseases but only psittacosis/ornithosis and some cases of Reiter syndrome in man; multisystem disease with vasculitis may occur. C. psittaci produces large, diffuse, glycogen-negative inclusions.

LABORATORY METHODS Culture, The agents of psittacosis and lymphogranuloma venereum were first grown in the yolk sac of embryonated hen eggs during the 1930s, but it was not until 1957that the agent of trachoma was successfully propagated in a similar system.' This technique was cumbersome and contamination of samples with bacteria was a constant problem. Workers recently ~~ have pointed out that although routine tissue culture cell lines will not support the replication of Chlamydia, prelreat-

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Table I Chlamydia General features

Obligate intracellular parasites of vertebrate cells, non-motile spheroid 0.3-1.0/~ in diameter, genome contains DNA and RNA, limited independent metabolism, solely intracellular replication, stained by giemsa but not gram's stain, inhibited by several antibiotics, common complement fixing antigen, Chlamydia trachomatis [A]

Human disease

Chlamydia psittaci [B]

Veterinary disease

Ophthalmic: trachoma, sporadic conjunctivitis, ophthalmia neonatorum Genito-urinary: NGU, PGU, LGV ? Interstitial pneumonia of infants? Mouse pneumonitis

Extent of disease

Usually localized

Morphology of inclusion In vitro antibiotic inhibition

Smaller, rigid, compact, glycogen-positive Tetracycline, sulfonamide, penicillin G, ampicillin, erythromycin Immunotypes A thru L and LGV-types I, II, III

Subtypes by microimmunofluorescence

ment of the McCoy cell line with X-irradiation or 5-iodo2-deoxy-uridine, or pretreatment of HeLa cells with DEAE-dextran, will permit propagation of these organisms. These tissue culture techniques have been shown to be four times more sensitive than the yolk sac method and are faster, less expensive, more reproducible, and less liable to cross-contamination? Recently ':~ genusspecific chlamydial antibody has been reacted with clinical specimens; subsequently, fluorescin or ferritinlabeled anti-globulin was applied and the specimen was examined for specific staining in a fluorescent or electron microscope. The reaction is specific and as sensitive as tissue culture methods, and has the advantage of identifying Chlarnydia whether viable or not, thus obviating the need for special handling of specimens. Serology. All Chlamydia share a common complementfixing antigen which is weakly antigenic in man. The recent development of a microimmunofluorescence test has allowed the antigenic differentiation of the two species as well as subclassification of C traehomatis and C psittaei into at least 15 and three immuno-types, respectively, a technique which helps in defining the epidemiology of these agents. TM Antibiotic sensitivity. Early investigators ~ found that bacitracin, ristocetin, and streptomycin did not prevent the growth of these organisms in ovo; various combinations of similar antibiotics are added in modern tissue culture methods to prevent bacterial contamination without interfering with the recovery of Chlamydia. Application of tissue culture techniques to antibiotic

Psittacosis/ornithosis, Reiter syndrome

Ornithosis, epizootic chlamydiosis of hares, feline pneumonitis, bovine encephalomyelitis, sheep polyarthritis, Often hematogenous dissemination with vasculitis and multi-system involvement Larger, diffuse, glycogen-negative Tetracycline, chloramphenicol, rifampin Immunotypes JH, 207 and 33-L

sensitivity testing TM revealed that a standard strain of C. trachomatis was sensitive in vitro to clinically attainable concentrations of oxytetracycline, erythromycin, penicillin G, ampicillin, and sulfamethoxazole, but resistant to streptomycin, gentamicin, spectinomycin, and trimethoprim. Investigation with the electron microscope into the mode of action of penicillin and tetracycline against C trachomatis disclosed that penicillin induced greatly enlarged initial bodies which were prevented from fissuring into smaller elementary bodies; tetracycline reduced the number of initial bodies without inducing a morphologic change. '7 Tetracycline and chloramphenicol have been shown to inhibit binary fission of C. psittaci by inhibition of protein synthesis, whereas rifampin effected a similar morphologic effect primarily by inhibition of RNA synthesis? 8 Unfortunately, the diagnosis of chlamydial disease by culture, serologic conversion, and antibiotic sensitivity testing of clinical isolates depends on laboratory techniques currently available in a limited number of research laboratories. Until a more general dispersion of these methods occurs, diagnosis will depend on clinical suspicion and identification of juxtanuclear cytoplasmic inclusions in the infected secretions. SPECTRUM OF HUMAN DISEASE A T T R I B U T E D T O C. T R A C H O M A T I S Ocular disease. The concept has evolved that C. trachomatis causes a spectrum of ophthalmic pathology including "benign" neonatal inclusion conjunctivitis,

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sporadic inclusion conjunctivitis in adults, and nonendemic as well as endemic trachoma. In the last category spread is thought to occur within families from eye to hand to eye, whereas in the former three entities exposure to infected secretions at birth or venereal contact later in life is thought to be responsible for genital to eye spread. Endemic trachoma 19-2" is a chronic follicular conjunctivitis which results in pannus (vascularized scar tissue encroaching on the cornea from the limbus) formation, conjunctival scarring, and eventual blindness. The term trachoma was coined by a Sicilian physician in 69 AD, but the syndrome was well described as early as 1500 Bc in the Ebers papyrus. The disease was widespread {hen and later, affecting such notable persons as Paul of Tarsus, Cicero, and Horace. The disease was spread to Europe by returning crusaders and later by Napoleon's troops returning from the middle East and Egypt; hence the term, military ophthalmia. Since World War II, trachoma has become much less prevalent in the United States and Europe. Improved living conditions appear to be a primary factor in this decline. Endemic foci go hand in hand with poverty and crowded living conditions throughout the world. In the United States, the disease is still a problem among Indians on reservations of'the Southwest. Trachoma remains the most common cause of acquired blindness in the world today. 2~ Exudate from infected eyes (trachoma or mild inclusion conjunctivitis) has been shown to cause similar disease in the eyes of blind volunteers and experimental monkeys.22. 23 Longitudinal epidemiologic studies of families in endemic areas have disclosed that a single encounter with the organism is not sufficient to induce severe, progressive trachoma. Rather, it appears that family members repeatedly reinfect each other over a period of years, inducing multiple episodes of progressively more severe conjunctivitis. Only those individuals repeatedly "sensitized" to the agent develop progressive trachoma. Sensitization is reflected in increased serum and tear antibodies to a particular immuno-type o f C. trachomatis in several members of a given family or village. This concept is bolstered by experience from vaccine trials in human beings and experimental animals, wherein prior sensitization of the subject with a killed chlamydial vaccine induced increased conjunctival reaction upon initial ocular challenge with the live wild strain. It is postulated that nonendemic trachoma follows an epidemiologic pattern similar to that of endemic disease. In this instance, patients experience recurrent episodes of conjunctivitis due to C. trachomatis with immuno-types

The Journal of Pediatrics December 1977

recoverable from patients in the same geographic area with genital disease. Depending on the number of episodes, the process may present as a spectrum from nonspecific, sporadic conjunctivitis to chronic, progressive disease with varying degrees of visual impairment. Neonatal inclusion conjunctivitis is a common cause of ophthalmia neonatorum. 25-~9 Mothers acquire the C. trachomatis venereally and become chronic carriers with a mild cervicitis, or they may remain totally asymptomatic. The agent is transmitted to the offspring at delivery and, after an incubation period of three to 21 days (average seven to ten days), purulent conjunctivitis of variable degree appears. The exudate contains polymorphonuclear cells primarily. Scrapings of the palpebral conjunctivae with a blunt curette yield epithelial cells containing typical cytoplasmic inclusions. Untreated, the inflammation gradually subsides over two to three weeks to a subacute or chronic purulent conjunctivitis which may persist for weeks to years. Follow-up examinations have revealed residual micropannus and conjunctival scarring in several patients in whom specific diagnosis and therapy were delayed 10 to 12 days. Visual impairment has not been documented in the absence of recurrent infections. Therapy of all the ocular diseases caused by C. trachomatis depends primarily on interruption of the cycle of reinfection, without which progression of disease usually will not occur. Topical antimicrobial therapy with ophthalmic preparations of tetracycline or sulfonamide has been shown to promote prompt resolution of the acute inflammatory episode within two to three days in the newborn infant. Arbitrarily the recommended duration of therapy is 14 to 21 days. Genitourinary disease. The manifestations of C. trachomatis in the genitourinary tract may range from an asymptomatic carrier state to varying degrees of acute or chronic inflammation of the cervix, vagina, bladder, and urethra.3O. 3~ Recent studies 32-37document that C. trachomatis is very commonly transmitted venereally, either as a primary agent or along with the gonococcus. In the former instance, C. trachomatis accounts for up to 40% of episodes of nonspecific nongonococcal urethritis. The agent is recoverable from up to 60% of patients with recurrent Urethritis following successful eradication of the gonococcus with penicillin, ampicillin, or spectinomycin; hence, the appellation: postgonococcal urethritis syndrome. In either syndrome, therapy with tetracycline or sulfamethoxazole has been shown to eradicate the C. trachomatis and produce clinical cure2 ~ Lymphogranuloma venereum is a venereal disease characterized by transient genital ulcers followed by

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inguinal adenitis, proctocolitis, rectal strictures, and fistula formation. It is diagnosed most frequently in patients between 20 and 40 years of age. 39 Changing sexual mores may be responsible for the occurrence of this disease in younger patients 4~ and for its occurrence at extragenital sites. 41 Serologic screening and immunotyping of clinical isolates from patients with iymphogranuloma venereum have shown that it is due to strains of Chlamydia which are antigenically related to the species C. trachomatis. These strains of lymphogranuloma venereum are distinguishable from those responsible for ocular and other forms of genitourinary disease by minor antigenic differences and greater virulence in mouse intracerebral inoculation testsY -'~ Diagnosis may be made by recognition of the clinical syndrome, isolation of the organism from an aspirate of the fluctuant bubo, increases in complement-fixing antibody titer, and positive reaction to the Frei skin test; the latter three tests are diagnostic in 54%, 83%, and 36% of suspect cases, respectively.4~ Oral tetracycline for three to four weeks produces clinical cure in most cases? 9 Pulmonary disease. Interstitial pneumonia of early infancy is a common clinical problem for which viruses such as rubella and cytomegalovirus are often incriminated. Most cases resolve slowly over weeks to months without a specific diagnosis. Following the association of C. trachomatis with this syndrome by Schacter and associates? 6 initially, Beem and Saxon ~7 reported a group of infants in whom colonization of nasopharyngeal secretions with C. trachomatis in 18 of the 20 studied was associated with a distinctive clinical presentation. These infants, between one and three months of age, experienced gradually progressive tachypnea and staccato coughing associated with post-tussic cyanosis and vomiting without an inspiratory whoop. The majority of patients were afebrile males with inspiratory rales but few wheezes. The chest roentgenographic pattern was a combination of hyperexpansion and diffuse interstitial and patchy alveolar infiltrates. Inclusion conjunctivitis could be diagnosed in only 50% of patients using history, physical examination, and culture. Although upper respiratory tract colonization by C. trachomatis was associated with the pneumonia syndrome, open lung biopsy of two of these patients late in the clinical course failed to reveal the organism in the lung parenchyma. Frommelt and associates48 have recently reported the isolation of C. trachomatis and cytomegalovirus from the biopsied lung of an eight-week-old male infant with a chronic interstitial pneumonia, which slowly and spontaneously resolved over two to three months. Serologic studies confirmed both of these organisms as etiologic agents. The

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occurrence of a dual infection in this patient is interesting since both cytomegalovirus and C. trachomatis were also recovered from the nasopharyngeal secretions of four of the patients reported by Beem and SaxonW SPECTRUM OF HUMAN DISEASE A T T R I B U T E D T O C. P S I T T A C I In contrast to the wide range of veterinary diseases associated with this organism (partial list in Table I), only two human diseases have been ascribed to C. psittaci to date. Psittaeosis/ornithosis. Chlamydia psittaci infection in man produces an acute infectious disease in which fever, malaise, headache, myalgia, and interstitial pneumonia with paroxysmal cough are prominent features? ~ Early reports identified psittacine birds (parrots, parakeets, cockatoos, and budgerigars) as the sole vectors, but subsequent studies have shown that nonpsittacine species (pigeons, finches, turkeys, and ducks) are currently the major vectors in the United States. The more inclusive term, ornithosis is preferable for both human and avian illness due to this organism? ~ Although the majority of cases occur in adults with a vocational (poultry processors, pet store personnel) or an avocational exposure to infected birds, a small number of infections have been reported in children? ~', ~' The invasive capacity of this organism is emphasized by the recovery of the agent from the blood, tissues, respiratory, and cloacal discharges of infected birds; occasional disseminated disease is detected in human beings with prolonged chlamydemia and inflammatory lesions of the heart, pericardium, brain, meninges, and liver. 52 Tetracycline for 14 to 21 days is the drug of choice, with chloramphenicol as an alternative. Reiter syndrome. Schacter ~:~has succinctly summarized the status of Chlamydia as causative agents of the classic tetrad: nongonococcal urethritis, seronegative polyarthrifis, conjunctivitis or uveitis or both, and mucocutaneous lesions. The majority of patients are men between 20 and 40 years of age; the disease may wax and wane spontaneously for months to years. Although isolation of Chlamydia from synovial, urethral, and conjunctival fluids, and serologic studies have confirmed a significant association between chlamydial infection and Reiter syndrome, the detection of similar disease following infection with Mycoplasma hominis and Shigella and wide geographic variation in the results of chlamydial studies have led to the concept that Reiter syndrome is a multifactorial disease. In view of a high degree of association between the genetic marker HLA-W27 and Reiter syndrome, it is interesting to speculate that only a small subpopulation is predisposed to develop Reiter syndrome upon exposure to

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The Journal of Pediatrics December 1977

one or more infectioUs agents. Tetracycline therapy will often eliminate the urethritis, but the other manifestations appear to be unaffeCted by antibiotic therapy, another clue that more than simple infection is involved in the pathogenesis of this syndrome. SPECULATIONS FUTURE STUDY

7.

8.

AND AREAS FOR

Most of the data 3~ concerning Chlamydia and genitourinary disease have been collected in postpubertal patients. Because nongonococcal and postgonococcal urethritis as well as nonspecific vaginitis are c o m m o n problems in piepUbertal patients) ', ~5 the role of Chlamydia in pediatric genitourinary disease requires investigation. Recurrence of inclusion conjunctivitis following the currently recommended 21-day course of topical antimicrobial therapy is a well-documented p h e n o m e n o n ? .... Studies defining the true incidence and pathologic significance of such recurrences, as well as the effect of appropriate Systemic antibiotics on the natural history of the disease, remain to be performed? 6 Finally, the association of interstitial p n e u m o n i a of infancy With chlamydial infection '6' 47 and the possible interaction with cytomegalovirus 4~needs to b e confirmed. T h e q u e s t i o n of antimicrobial therapy for this p n e u m o n i c syndrome remains to be answered in a controlled fashion, but preliminary data suggest that oral therapy with sulfisoxazole Or erythromycin for 14 days hastens clinical recovery and clearance of Chlamydia from the nasopharynx? 7 The patient of Fr0mmell and associates ~6recovered over a three-month period without specific antimicrobial therapy. The data presented indicate tfiat Chlamydia may be responsible for a greater range of pediatric diseases than previously recognized. Increased awareness of this possibility by clinicians will facilitate recognition of these syndromes and hasten the definition of optimal therapy.

REFERENCES

i. Moulder JW: The life and death of the psittacosis virus, Hosp Pract 2:35, 1968. 2. Page L: Proposal for the recognition of two species in the genus Chlarnydia, Int J System Bacteriol 18:51, 1968. 3. Meyer K: Taxonomy of the psittacosis group, Ann NY Acad Sci 56:545, 1953. 4. Grayston J, and Wang S: New knowledge of Chlamydia and the diseases they cause, J Infect Dis 132:87, 1975. 5. Gordon F, and Quan A: Occurrence of glycogen in inclusions of the psittacosis-lymphogranuloma venereumtrachoma agents, J Infect Dis 115:186, 1965. 6. Chou C, Wang S, and Grayston J: Differentiation of Tric

9.

10..

11.

12.

13.

14.

15. 16.

17.

18.

19. 20. 21.

22.

23. 24.

25.

and LGV organisms based on enhancement of infectivity of DEAE-dextran in cell culture, J Infect Dis 125:313, 1972. Mitsui Y, Masahiro K, Akira N, Katsumoto K: Morphology of trachoma agent in conjunctiva and chick embryo, Ann NY Acad Sci 98:13i, 1962. Armstrong J, Valentine R, and Fildes C: Structure and replication of the trachoma agent in cell culture as shown by electron microscopy, J Gen Microbiol 30:59, 1963. Gordon F, Harper I, Quan A, Treharne J, Dwyer R, and Garland J: Detection of Chlamydia (Bedsonia) in certain infections of man I. Laboratory procedures: Comparison of yolk sac and cell culture for detection and isolation, J Infect Dis 120:451, 1969. Wentworth B, and Alexander E: Isolation of Chlamydia trachomatis by use of 5-iodo-2-deoxyuridine treated cells, Appl Microbiol 27:912, 1974. Schacter J, Dawson C, Balas S, and Jones P: Evaluation of laboratory methods for detecting acute Tric agent infection, Am J Ophthal 70:375, 1970. Hobson D, Johnson F, Rees E, and Tait A: Simplified method for diagnosis of genital and ocular infections With Chlamydia, Lancet 2:555, 1974. AshleY C, Richmond S, and Caul E: Identification of the elementary bodies of Chlamydia trachomatis in the electron microscope by an indirect immunoferritin method, J Clin Microbiol 2:327, 1975. Wang S, and Grayston J: Immunologic relationship between genital, Tric, lymphogranuloma venereum and related organisms in new microtiter indirect immunofluorescence test, Am J Ophthal 70:367, 1970. Gordon F, and Quan A: Drug susceptibilities of the psittacosis and trachoma agents, Ann NY Acad Sci 98:261, 1962. Ridgway G, Owen J, and Oriel J: A method for testing the antibiotic susceptibility of Chlamydia trachomatis in a cell cultui'e system, J Antimicrob Chemother 2:71, 1976. Kramer M, and Gordon F: Ultrastructural analysis of the effects of penicillin and chlortetracycline on the deVelopment of a genital tract Chlamydia, Infect Immun 3:333, 1971. Tribby I, Friis R, and Moulder J: Effect of chloramphenicol, rifampin, and nalidixic acid o n Chlamydia psittaci growing in L cells, J Infect Dis 127:155, 1973. Craighead J: Trachoma and vaccination, J Infect Dis i31:749, 1975. Thygeson P: Trachoma virus: Historical background and review of isolates, Ann NY Acad Sci 98:6, 1962. Gi'ayston J, Gale J, Lung Y, and Yang C: Pathogenesis and immunology of trachoma, Trans Assoc Am Physicians 85:203, 1972. Wang S, and Grayston J: Pannus with experimental trachoma and inclusion Conjunctivitis agent infection of Taiwan monkeys, Am J Ophthal 62:1133, 1967. Grayston J, and Wang S: Trachoma vaccine studies on Taiwan, Ann NY Acad Sci 98:352, i962. Dawson C, Mordhorst C, and Thygenson P: Infection of Rhesus and Cynomolgus monkeys with egg-grown viruses of trachoma and inclusion conjunctivitis, Ann NY Acad Sci 98:167, 1962. Jones B, Collier L, and Smith C: Isolation of virus from inclusion blennorrhea, Lancet 2:902, 1959.

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26. 27. 28.

29.

30. 31.

32.

33. 34.

35. 36.

37.

38.

39. 40.

41.

42.

Goscienski P: Inclusion conjunctivitis in the newborn infant, J PEDIATR 77:19, 1970. Goscienski P: Follow-up studies in neonatal inclusion conjunctivitis, Am J Dis Child 124:180, 1972. Mordhorst C, and Dawson C: Sequelae of neonatal inclusion conjunctivitis and associated disease in parents, Am J Ophthal 71:861, 1971. Forster R, Dawson C, and Schacter J: Late follow-up of patients with neonatal inclusion conjunctivitis, Am J Ophthal 69:467, 1970. Chlamydia and genital infection, Lancet Editorial, Lancet 1:264, 1974. Holmes K, Swanson J, Eschenbach D, and Alexander E: Light and electron microscopic study of Chlamydia trachomatis infection of the uterine cervix, J Infect Dis 131:678, 1975. Schaeter J, Hanna L, Hill E, Massad S, Sheppard C, Conte J, Cohen S, and Meyer K: Are chlamydial infections the most prevalent venereal disease? JAMA 231:1252, 1975. Holmes K, Handsfield H, Wang S, et al: Etiology of nongonococcal urethritis, N Engl J Med 292:1199, 1975. Richmond J, Hilton A, and Clarke J: Role of Chlamydia subgroup A in nongonococcal and postgonococcal urethritis, Br J Vener Dis 48:437, 1972. Jacobs N, and Kraus S: Gonococcal and nongonococcal urethritis in man, Ann Intern Med 82:7, 1975. Dunlop E, Jackson J, Doragar S, and Jones B: Chlamydial infection in non-specific urethritis, Br J Vener Dis 48:425, 1972. Oriel J, Reeve P, Powis P, Miller A, and Nicol C: Isolation of Chlamydia from patients with non-specific genital infection, Br J Vener Dis 48:429, 1972. Bowie W, Floyd J, Miller Y, et al: Differential response of chlamydial and ureaplasma-associated urethritis to sulphafurazole (sulfisoxazole) and aminocyclitols, Lancet 2:1276, 1976. Becker L: Lymphogranuloma venereum, Int J Dermatol 15:26, 1976. McLelland B, and Anderson P: Lymphogranuloma venereum: Outbreak in a university community, JAMA 235:56, 1976. Thorsteinsson S, Musher D, Min K, et al: LymphogranuIoma venereum: A cause of cervical adenopathy, JAMA 235:182, !976. Jones B, and Treharne J: Microimmunofluorescence type specific serologic tests for chlamydial infection, Proc Soc Med 67:735, 1974.

Infections due to C h l a m y d i a

43,

44.

45.

46. 47.

48.

49.

50. 51. 52.

53.

54.

55. 56.

57.

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Dwyer R, Treharne J, Jones B, and Herring J: Chlamydial infection: Results of microimmunofluorescence tests for the detection of type specific antibody in chlamydial infections, Br J Vener Dis 48:452, 1972. Philip R, Hill D, Greaves A, et al: Study of chlamydiae in patients with lymphogranuloma venereum and urethritis attending a venereal disease clinic, Br J Vener Dis 47:114, 1971. Schacter J, Smith D, Dawson C, et al: Lymphogranuloma venereum. I. Comparison of the Frei test, complement fixation test, and isolation of the agent, J Infect Dis 120:372, 1969. Schacter J, Lure L, Gooding C, and Ostler B: Pneumonitis following inclusion blennorrhea, J Pediatr 87:779, 1975. Beem M, and Saxon E: Respiratory tract colonization and a distinctive pneumonia syndrome in infants infected with Chlamydia trachomatis, N Engl J Med 296:306, 1977. Frommell G, Bruhn F, and Schwartzman J: Isolation of Chlamydia trachomatis from infant lung tissue, N Engl J Med 296:1150, 1977. Center for Disease Control Annual Summary of Psittacosis for 1973, DHEW Publ. No. (CDC) 75-8260, November, 1974. Meyer K: The present state of psittacosis-orinthosis, Arch Environ Health 19:461, 1969. Berman S, Freundlich E, Gtasser K, et al: Ornithosis in infancy Pediatrics 15:75Z 1955. Liu C: Nonbacterial pneumonia, in Hoeprich P, editor: Infectious diseases, New York, 1972, Harper & Row, Publishers, Chapter 30. Schacter J: Can chlamydial infections cause rheumatic disease? in Dumonde D, editor: Infection and immunology in the rheumatic diseases, Oxford, 1975, Blackwell Scientific Publications, Chapter 20. Nelson J, Mohs E, Dajani A, and Plotkin S: Gonorrhea in pre-school and school-aged children, JAMA 236:1359, 1976. Heller R, Joseph J, and Davis H: Vulvovaginitis in the premenarchal child, J PEDIAa'R 74:370, 1969. Taylor P, and Friedland G: Uncertainties in the treatment of chlamydial infections in infants, letter. N Engl J Med 296:1223, 1977. Beem M, and Saxon E: Letter, N Engi J Med 296:1150, 1977.