Mitral Bioprosthetic Valve Endocarditis Caused by an Unusual Microorganism, Gemella morbillorum , in an Intravenous Drug User

Abstract

We report a case of Gemella morbillorum mitral bioprosthetic valve endocarditis with perivalvular extension in a 44-year-old human immunodeficiency virus-positive man who is an active intravenous drug user together with review of all published cases. This is only the second reported case of Gemella morbillorum endocarditis in a patient with a prosthetic valve. CASE REPORTA 44-year-old human immunodeficiency virus-positive man with a history of active intravenous drug use and a mitral valve replacement only 9 months earlier for native-valve endocarditis due to Staphylococcus aureus was admitted complaining of pleuritic chest pain, shortness of breath, fever, and chills.Physical examination revealed a temperature of 99.8°F, blood pressure of 114/70 mm Hg, a regular heat rate at 98 beats per min, and a grade III/VI holosystolic murmur radiating to the axilla. No clinical signs of congestive heart failure (such as pulmonary rales or peripheral edema) were noted.An electrocardiogram was notable for a first-degree atrioventricular block (an increased PR interval of 0.22 s) and nonspecific T wave changes. Laboratory investigations were significant for a normocytic anemia with a hemoglobin level of 10.9 g/dl and an elevated erythrocyte sedimentation rate of 108 mm per h. However, neither the total white blood cell count nor the percentage of banded neutrophils was elevated (3.72 ϫ 10 9 /liter and 4% bands, respectively). Three sets of blood cultures were obtained prior to initiating antibiotic therapy. Blood samples were incubated in a continuous-monitoring culture system (Bac T/Alert; Becton Dickinson, Organon Teknika, Durham, N.C.) at 37°C. After 24 h of incubation, growth in the anaerobic bottle was noted. The samples were then subcultured at 37°C on MacConkey's agar, sheep blood agar, anaerobic CDC blood agar, and chocolate agar incubated in CO 2 .After 24 h of subculture incubation, an alpha-hemolytic organism grew on all plates except the MacConkey agar. The organism was further characterized as being a gram-positive coccus that was both catalase and bile solubility negative.These initial findings suggested that the organism was Streptococcus viridans. However, on further evaluation with an API 20 streptococcus identification system (Bio Merieux, Vitek Inc., Hazelwood, Mo.), the organism was identified as Gemella morbillorum with 98% confidence.Antimicrobial susceptibility by disk diffusion method showed the organism to be sensitive to ceftriaxone, clindamycin, levofloxacin, tetracycline, and vancomycin, while the Etest showed sensitivity to penicillin G.A transthoracic echocardiogram revealed severe regurgitation through incompetent leaflets of the bioprosthetic mitral valve. On spectral Doppler recording of the prosthetic inflow, a severely elevated mean diastolic gradient of 22 mm Hg at a sinus heart rate of 75 beats per min was noted. Since there were no echocardiographic signs of prosthetic stenosis (the pressure half-time was only 77 ms), this gradient was indicative of severely elevated left atrial pressure...

Cerebellar abscess by Gemella morbillorum in a patient with inter-atrial communication

“…Gemella species, including Gemella morbillorum, a microaerophilic Gram-positive coccus, are part of the normal fl ora of the human oropharynx, upper respiratory, urogenital and gastrointestinal tract rarely causing human infection. Although uncommonly pathogenic, they have been implicated in a variety of human infections, some of them with serious consequences, most notably infective endocarditis [1][2][3][4][5][6][7] . Dental instrumentation appears to be the usual source of infection 1 .…”

Evidence of active endocarditis, caused by Gemella morbillorum, related to acute embolic stroke

“…Zakir has recently summarized 23 cases of IE and reported 11 cases among them were associated with dental diseases [1]. The present patient had many dental caries, and the dental route may be responsible for the onset of IE.…”

“…However, among IE, G. morbillorum is an unusual pathogen; a comprehensive review of the literature reveals only less than 30 cases [1][2][3]. We present a case of acute embolic stroke due to IE caused by this microorganism.…”

Second Fatal Case of Infective Endocarditis caused by Gemella bergeriae

“…[5][6][7][8] This report describes a fatal case of IE caused by G.bergeriae, which is part of the normal flora of the human oral cavity, slow growing fastidious bacteria, which can insidiously lead to a fulminant fatal outcome. [5][6][7][9][10][11][12][13][14] We present the second fatal case of IE caused by G.bergeriae.…”