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Gemella Haemolisans Endocarditis
J.M. Urbano Gálvez
Infanta Cristina University Hospital
Introduction: Gemella haemolysans is a gram-positive coccus, commensal of the upper respiratory, gastrointestinal and genitourinary tract in humans. Occasional cases of systemic infection due to G. haemolysans have been reported in humans; these cases include endocarditis, septicaemia and meningitis. We report the case of a 37-year-old man admitted for mitral and tricuspid valve endocarditis due to Gemella haemolysans. The portal of entry was a colonic adenocarcinoma. The outcome was favourable following prolonged antibiotic therapy (vancomycin and imipenen for 40 days). Gemella haemolysans is a rare cause of endocarditis (only ten cases are reported in the literature) and a colonic portal of entry has not previously been described. Rare microorganisms are increasingly incriminated in endocarditis because of improvements in their identification and because of a change in the spectrum and/or habits in using antimicrobial therapy. Gemella haemolysans, a saprophytic bacterium, can cause endocarditis. The case we report is unusual in two respects: firstly, because of the causative agent and secondly, because of a possible colonic portal of entry
Clinical Case: We report the case of a 37 years-old woman with colonic adenocarcinoma stadium IV that presented fever of several weeks of evolution without apparent focal symptoms. The physical examination and the complementary studies, except for to 16300 leukocytes/mm3 (granulokytes 89.4%) in blood count, they were anodyne. Cultures of three separate blood specimens drawn over 72 hours yielded gram-positive cocci. The isolated organism was identified as G. haemolysans by the ATB - System. The organism was sensitive to penicillin, vancomycin, and gentamicin (MICs < 1mcg/mL). A transthoracic echocardiogram showed two vegetations on the mitral valve and one on tricuspid valve (Fig. 1). The mitral and tricuspid valve function was normal. The patients condition improved clinically after antibiotic treatment with vancomycin 500 mg. iv. 6 hourly and imipenem 500 mg. iv. 6 hourly was started, and several cultures of blood drawn after completion of antibiotic therapy (40 days) were negative. The fever did not recur after completion of treatment.
Conclusions: Gemella haemolysans septicaemia is rare, and our report is only the twelfth case of endocarditis due to Gemella haemolysans in the literature (Table 1).
Gemella haemolysans has only been considered pathogenic over the last 10 years. It belongs to the commensal flora of the upper respiratory tract and is present on the oropharyngeal mucosa of 30% of subjects. Microscopically, this microorganism is a gram-positive diplococcus which tends to bunch or form short chains. Gemella haemolysans shares a number of characteristics with Streptococcus morbillorum. Bacteriological identification presents some difficulties related to the morphological resemblance to Neisseria and biochemical characteristics in culture which are close to those of some streptococci of the viridans group (e.g. Streptococcus sanguis and mitts). Antibiotic susceptibility is similar to that of streptococci for penicillin G. macrolides, chloramphenicol and vancomycin; Gemella haemolysans is highly sensitive to aminosides and betalactamine-aminoside combinations are synergistic (table 2).
The clinical picture in Gemella haemolysans endocarditis is entirely non-specific. Our observation resembles those in the literature in terms of the mitral valve localization, the absence of hyperleukocytosis and the sensitivity of the organism to the usual antibiotics. It differs, however, by the absence of an oropharyngeal portal of entry and the existence of a colonic neoplasm. The fact that several blood cultures were positive for the same microorganism is highly suggestive of septicaemia. The presence of Gemella haemolysans, a commensal saprophyte present in the upper respiratory tract and upper digestive mucosa, has not been reported in the colonic flora, the colonic neoplasm in our patient may have been the portal of entry.
The association of endocarditis with colorectal cancer has been known since 1977 and the pathogen generally incriminated is Streptococcus bovis. Since that date, an association between subacute infective endocarditis due to Streptococcus bovis and colonic or rectal cancer has been reported several times. A similar association has been reported with other gastrointestinal tumors and following endoscopic resections. Indeed, Streptococcus bovis septicaemia is an indication for thorough examination of the digestive tract . It therefore also appears logical to explore the digestive tract in patients with Gemella haemolysans endocarditis and no detectable oropharyngeal lesions. It is probable that Gemella haemolysans endocarditis is usually mistaken for streptococcal endocarditis, given the difficulty in its microbiological characterization.
We report the first case of multiple healthy native valve endocarditis by G. haemolysans , being the second in the one that it objective association among infection for G. haemolisans and colonic adenocarcinoma. It is no clear how colorectal cancer predisposes to an increased risk of enterogenous by some bacteria such as S. bovis or G. haemolysans. This case suggest that patients with colonic carcinoma who have a prolonged fever history without any apparent source of bacteremia, should undergo a work-up to exclude a G. haemolysans endocarditis. The election treatment is penicillin more an aminoglycosid, and like alternative in allergic rifampin more erythromycin. The answer to the treatment is good and it is uncommon to have to carry out substitution valvular.
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