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Cardiobacterium hominis Endocarditis in a Patient With a Prolapsed Mitral Valve
Case Report
Cardiobacterium hominis Endocarditis in a Patient With a Prolapsed Mitral Valve Andrea Layman, B.S., M(ASCP)SM, 1 Russell A. Rawling, M.S., M(ASCP)SM, RM(NRM)SM,1 and Paul A. Granato, Ph.D.,1,2 Microbiology Section, Laboratory Alliance of Central New York, Liverpool, NY, 2 Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse, New York
1
Cardiobacterium hominis is a well-known but rare cause of bacterial endocarditis, with fewer than 70 cases reported in the English literature (1). The most common risk factor for the development of C. hominis endocarditis is the presence of preexisting cardiac disease involving anatomic defects of the aortic and mitral valves. Other important risk factors are the presence of a prosthetic valve implant or a history of rheumatic fever. This report describes a case of C. hominis endocarditis in a previously
Mailing Address: Paul A. Granato, Ph.D., Department of Microbiology & Immunology, WH 2204, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY 13210. Tel.: 316-464-7653. Fax: 315-464-4417. E-mail: [email protected].
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healthy 50-year-old male with a known history of mitral valve prolapse and serves to remind readers of the significance of this organism as a cause of serious infection in patients with predisposing risk factors.
Case Report A 50-year-old male in previous good health but with a history of a prolapsed mitral valve was evaluated by his personal physician for intermittent cough and a vague bilateral pain below his ribs 2 weeks after a dental procedure. The patient also had night sweats accompanied by the development of a “heat rash” on his upper trunk. During the 2-week interval following his dental work, he also experienced a 10-pound weight loss. On physical examination, the patient was noted to have a grade III to IV/VI holosystolic murmur, a temper© 2008 Elsevier
ature of 101°F taken orally, and a distal splinter hemorrhage on his left third fingernail. The patient was admitted to the hospital for workup and evaluation of possible bacterial endocarditis. A transesophageal echocardiogram was performed on the patient, which revealed the presence of severe mitral valve regurgitation and a vegetation on the anterior valve leaflet. Three sets of BacT/ALERT (bioMérieux, Durham, NC) blood culture bottles were collected from the patient, followed by the empiric administration of 1.5 g of vancomycin intravenously, every 12 h, and 2 g of ceftriaxone intravenously, every 24 h. After 36 h of incubation, all three sets of blood cultures grew a gram-negative rod in both the aerobic and anaerobic bottles. The organism grew slowly on 5% sheep blood and chocolate agar Clinical Microbiology Newsletter 30:18,2008
media, producing small, nonhemolytic colonies when incubated at 35oC in 5% CO2. The isolate was oxidase positive and catalase negative, and its identity was established as C. hominis by using the RapID NH System (Remel, Lenexa, KS). An antimicrobial susceptibility test was not performed on this organism, but Clincal and Laboratory Standards Institute (CLSI) methods and interpretation standards are available to do so (2). Following 2 weeks of therapy with ceftriaxone, the patient was referred to the cardiac surgery service, where his infected valve was replaced with a porcine mitral valve. Postoperatively, the patient was continued on antibiotic treatment for 4 weeks and recovered uneventfully.
Discussion C. hominis, a member of the HACEK group (Haemophilus parainfluenzae, Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, and Cardiobacterium, Eikenella, and Kingella spp.) is a fastidious, gram-negative bacillus that is part of the normal flora of the human upper respiratory tract and possibly, also the gastrointestinal and genitourinary tracts (3). The organism is an uncommon cause of human infection and was first reported by Tucker et al. (4) in 1962 as the etiologic agent in four patients with infective endocarditis. Tucker had originally described these isolates as Pasteurella-like, but they were later designated “group II-D” by the CDC. Subsequently, Slotnick and Dougherty (5) characterized the group and proposed the adopted name Cardiobacterium hominis for the organism. Characteristically, endocarditis caused by C. hominis has an insidious onset with symptoms occasionally persisting as long as 9 months before diagnosis (6). Some patients have a history of dental procedures before the development of infection, but no portal of entry can be readily identified for most patients (6). In one study of 61 reported cases of C. hominis endocarditis (1), the most common symptoms were fever (74%), fatigue/malaise (53%), weight loss/
Clinical Microbiology Newsletter 30:18,2008
anorexia (40%), and night sweats (24%). The most common risk factors for the development of infection were preexisting cardiac disease (61%), the presence of a prosthetic valve (28%), and a history of rheumatic fever (20%). In the 61 patients reported in that study, 24 (39%) had infections of the aortic valve, followed by 19 (31%) with mitral valve infections. C. hominis may also form large, friable vegetations that are associated with a significant risk of cerebral embolization in 30% of cases (6) or the development of mycotic aneurysm in 10% of patients (7). After sterilization of the vegetation with appropriate antimicrobial therapy, valve replacement may be indicated for patients who develop symptomatic heart failure (6) or to prevent embolic sequelae (7). Most isolates of C. hominis are susceptible to penicillin, so most cases of C. hominis endocarditis can be treated successfully with a 3-week course of antibiotics by using amoxicillin alone or in combination with an aminoglycoside (6). However, rare isolates of betalactamase-producing C. hominis strains have been reported (8,9). Because of this, a third-generation cephalosporin, such as ceftriaxone, is now regarded as the drug of choice for treating C. hominis infections, as recommended by the American Heart Association (1). Importantly, erythromycin and vancomycin resistance have also been reported (10), and these antibiotics should not be considered appropriate therapy in the penicillin-allergic patient unless guided by reliable susceptibility data (11). Methods and interpretive breakpoints for commonly used antimicrobial agents are found in the CLSI document M45-A (2).
Summary This case report describes a previously healthy, middle-aged patient with a prolapsed mitral valve who developed C. hominis endocarditis, most likely following a dental procedure. The patient was successfully treated with ceftriaxone, followed by a porcine mitral valve implant, and made an uneventful recovery.
© 2008 Elsevier
References 1. Malani, A.N. et al. 2006. Cardiobacterium hominis endocarditis: two cases and a review of the literature. Eur. J. Clin. Microbiol. Infect. Dis. 25:587-595. 2. Clinical and Laboratory Standards Institute. 2006. CLSI document M45-A. Methods for antimicrobial dilution and disk susceptibility testing of infrequently isolated or fastidious bacteria; approved guideline. Clinical and Laboratory Standards Institute, Wayne, PA. 3. vonGraevenitz, A., R. Zbinden, and R. Mutters. 2007. Actinobacillus, Capnocytophaga, Eikenella, Kingella, Pasteurella, and other fastidious or rarely encountered gram-negative rods, p. 621635. In P.R. Murray et al. (ed.), Manual of clinical microbiology, 9th ed. ASM Press, Washington, DC. 4. Tucker, D.N. et al. 1962. Endocarditis caused by a Pasteurella-like organism; report of four cases. N. Engl. J. Med. 267:913-916. 5. Slotnick, I.J. and M. Dougherty. 1964. Further characterization of an unclassified group of bacteria causing endocarditis in man: Cardiobacterium hominis gen. et sp. nov. Antonie van Leuwenhoek. J. Microbiol. Serol. 30:261-272. 6. Wormser, G.P. and E.J. Bottone. 1983. Cardiobacterium hominis: review of microbiologic and clinical features. Rev. Infect. Dis. 5:680-691. 7. Robinson, W.J. and A.S. Vitelli. 1985. Infectious endocarditis caused by Cardiobacterium hominis. South. Med. J. 78:1020-1021. 8. Lu, P.L. et al. 2000. Infective endocarditis complicated with progressive heart failure due to b-lactamase-producing Cardiobacterium hominis. J. Clin. Microbiol. 38:2015-2017. 9. Maurissen, W. et al. 2008. Beta-lactamase-positive Cardiobacterium hominis strain causing endocarditis in a pediatric patient with tetralogy of Fallot. Clin. Microbiol. Newsl. 30:132-133. 10. Prior, R.B., V.A. Spagna, and R.L. Perkins. 1979. Endocarditis due to a strain of Cardiobacterium hominis resistant to erythromycin and vancomycin. Chest 75:85-86. 11. Lane, T. et al. 1983. Cardiobacterium hominis — an elusive cause of endocarditis. J. Infect. 6:75-80.
0196-4399/00 (see frontmatter)
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Cardiobacterium hominis Endocarditis in a Patient With a Prolapsed Mitral Valve Andrea Layman, B.S., M(ASCP)SM, 1 Russell A. Rawling, M.S., M(ASCP)SM, RM(NRM)SM,1 and Paul A. Granato, Ph.D.,1,2 Microbiology Section, Laboratory Alliance of Central New York, Liverpool, NY, 2 Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse, New York
1
Cardiobacterium hominis is a well-known but rare cause of bacterial endocarditis, with fewer than 70 cases reported in the English literature (1). The most common risk factor for the development of C. hominis endocarditis is the presence of preexisting cardiac disease involving anatomic defects of the aortic and mitral valves. Other important risk factors are the presence of a prosthetic valve implant or a history of rheumatic fever. This report describes a case of C. hominis endocarditis in a previously
Mailing Address: Paul A. Granato, Ph.D., Department of Microbiology & Immunology, WH 2204, SUNY Upstate Medical University, 750 East Adams St., Syracuse, NY 13210. Tel.: 316-464-7653. Fax: 315-464-4417. E-mail: [email protected].
140
0196-4399/00 (see frontmatter)
healthy 50-year-old male with a known history of mitral valve prolapse and serves to remind readers of the significance of this organism as a cause of serious infection in patients with predisposing risk factors.
Case Report A 50-year-old male in previous good health but with a history of a prolapsed mitral valve was evaluated by his personal physician for intermittent cough and a vague bilateral pain below his ribs 2 weeks after a dental procedure. The patient also had night sweats accompanied by the development of a “heat rash” on his upper trunk. During the 2-week interval following his dental work, he also experienced a 10-pound weight loss. On physical examination, the patient was noted to have a grade III to IV/VI holosystolic murmur, a temper© 2008 Elsevier
ature of 101°F taken orally, and a distal splinter hemorrhage on his left third fingernail. The patient was admitted to the hospital for workup and evaluation of possible bacterial endocarditis. A transesophageal echocardiogram was performed on the patient, which revealed the presence of severe mitral valve regurgitation and a vegetation on the anterior valve leaflet. Three sets of BacT/ALERT (bioMérieux, Durham, NC) blood culture bottles were collected from the patient, followed by the empiric administration of 1.5 g of vancomycin intravenously, every 12 h, and 2 g of ceftriaxone intravenously, every 24 h. After 36 h of incubation, all three sets of blood cultures grew a gram-negative rod in both the aerobic and anaerobic bottles. The organism grew slowly on 5% sheep blood and chocolate agar Clinical Microbiology Newsletter 30:18,2008
media, producing small, nonhemolytic colonies when incubated at 35oC in 5% CO2. The isolate was oxidase positive and catalase negative, and its identity was established as C. hominis by using the RapID NH System (Remel, Lenexa, KS). An antimicrobial susceptibility test was not performed on this organism, but Clincal and Laboratory Standards Institute (CLSI) methods and interpretation standards are available to do so (2). Following 2 weeks of therapy with ceftriaxone, the patient was referred to the cardiac surgery service, where his infected valve was replaced with a porcine mitral valve. Postoperatively, the patient was continued on antibiotic treatment for 4 weeks and recovered uneventfully.
Discussion C. hominis, a member of the HACEK group (Haemophilus parainfluenzae, Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, and Cardiobacterium, Eikenella, and Kingella spp.) is a fastidious, gram-negative bacillus that is part of the normal flora of the human upper respiratory tract and possibly, also the gastrointestinal and genitourinary tracts (3). The organism is an uncommon cause of human infection and was first reported by Tucker et al. (4) in 1962 as the etiologic agent in four patients with infective endocarditis. Tucker had originally described these isolates as Pasteurella-like, but they were later designated “group II-D” by the CDC. Subsequently, Slotnick and Dougherty (5) characterized the group and proposed the adopted name Cardiobacterium hominis for the organism. Characteristically, endocarditis caused by C. hominis has an insidious onset with symptoms occasionally persisting as long as 9 months before diagnosis (6). Some patients have a history of dental procedures before the development of infection, but no portal of entry can be readily identified for most patients (6). In one study of 61 reported cases of C. hominis endocarditis (1), the most common symptoms were fever (74%), fatigue/malaise (53%), weight loss/
Clinical Microbiology Newsletter 30:18,2008
anorexia (40%), and night sweats (24%). The most common risk factors for the development of infection were preexisting cardiac disease (61%), the presence of a prosthetic valve (28%), and a history of rheumatic fever (20%). In the 61 patients reported in that study, 24 (39%) had infections of the aortic valve, followed by 19 (31%) with mitral valve infections. C. hominis may also form large, friable vegetations that are associated with a significant risk of cerebral embolization in 30% of cases (6) or the development of mycotic aneurysm in 10% of patients (7). After sterilization of the vegetation with appropriate antimicrobial therapy, valve replacement may be indicated for patients who develop symptomatic heart failure (6) or to prevent embolic sequelae (7). Most isolates of C. hominis are susceptible to penicillin, so most cases of C. hominis endocarditis can be treated successfully with a 3-week course of antibiotics by using amoxicillin alone or in combination with an aminoglycoside (6). However, rare isolates of betalactamase-producing C. hominis strains have been reported (8,9). Because of this, a third-generation cephalosporin, such as ceftriaxone, is now regarded as the drug of choice for treating C. hominis infections, as recommended by the American Heart Association (1). Importantly, erythromycin and vancomycin resistance have also been reported (10), and these antibiotics should not be considered appropriate therapy in the penicillin-allergic patient unless guided by reliable susceptibility data (11). Methods and interpretive breakpoints for commonly used antimicrobial agents are found in the CLSI document M45-A (2).
Summary This case report describes a previously healthy, middle-aged patient with a prolapsed mitral valve who developed C. hominis endocarditis, most likely following a dental procedure. The patient was successfully treated with ceftriaxone, followed by a porcine mitral valve implant, and made an uneventful recovery.
© 2008 Elsevier
References 1. Malani, A.N. et al. 2006. Cardiobacterium hominis endocarditis: two cases and a review of the literature. Eur. J. Clin. Microbiol. Infect. Dis. 25:587-595. 2. Clinical and Laboratory Standards Institute. 2006. CLSI document M45-A. Methods for antimicrobial dilution and disk susceptibility testing of infrequently isolated or fastidious bacteria; approved guideline. Clinical and Laboratory Standards Institute, Wayne, PA. 3. vonGraevenitz, A., R. Zbinden, and R. Mutters. 2007. Actinobacillus, Capnocytophaga, Eikenella, Kingella, Pasteurella, and other fastidious or rarely encountered gram-negative rods, p. 621635. In P.R. Murray et al. (ed.), Manual of clinical microbiology, 9th ed. ASM Press, Washington, DC. 4. Tucker, D.N. et al. 1962. Endocarditis caused by a Pasteurella-like organism; report of four cases. N. Engl. J. Med. 267:913-916. 5. Slotnick, I.J. and M. Dougherty. 1964. Further characterization of an unclassified group of bacteria causing endocarditis in man: Cardiobacterium hominis gen. et sp. nov. Antonie van Leuwenhoek. J. Microbiol. Serol. 30:261-272. 6. Wormser, G.P. and E.J. Bottone. 1983. Cardiobacterium hominis: review of microbiologic and clinical features. Rev. Infect. Dis. 5:680-691. 7. Robinson, W.J. and A.S. Vitelli. 1985. Infectious endocarditis caused by Cardiobacterium hominis. South. Med. J. 78:1020-1021. 8. Lu, P.L. et al. 2000. Infective endocarditis complicated with progressive heart failure due to b-lactamase-producing Cardiobacterium hominis. J. Clin. Microbiol. 38:2015-2017. 9. Maurissen, W. et al. 2008. Beta-lactamase-positive Cardiobacterium hominis strain causing endocarditis in a pediatric patient with tetralogy of Fallot. Clin. Microbiol. Newsl. 30:132-133. 10. Prior, R.B., V.A. Spagna, and R.L. Perkins. 1979. Endocarditis due to a strain of Cardiobacterium hominis resistant to erythromycin and vancomycin. Chest 75:85-86. 11. Lane, T. et al. 1983. Cardiobacterium hominis — an elusive cause of endocarditis. J. Infect. 6:75-80.
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