Bacteriologie des infections mixtes

[Therapeutic impact of streptococcal and enterococcal bacteremia in hematology patients]

From January 1999 to May 2000 (17 months), 21 strains of streptococci and four strains of enterococci have been isolated from 74 blood cultures in 25 infectious episodes in hematologic patients. They concerned 21 patients, of 21 to 77 years old. These patients suffered from acute leukaemia (14 cases), chronic lymphoid leukaemia (two cases), non-Hodgkin's lymphoma (two cases) or myeloma (three cases). Seventeen patients displayed a single streptococcal or enterococcal episode, two had two episodes in the course of a single stay in the hospital, two others in the course of two different stays. During 16 episodes (64%), the bacteremia occurred within 15 days after the onset of neutropenia consecutive to antimitotic chemotherapy, and in nine episodes (36%) it has occurred after a period exceeding 15 days. In six cases the patients had already received antibiotics with a large antibacterial activity (beta-lactam, fluoroquinolone and/or glycopeptide +/- aminoside) and in four cases a single antibiotic (synergistine or cotrimoxazole). Most streptococci (20/21) were oral streptococci (ten Streptococcus mitis, five S. oralis, two S. sanguis, three S. pneumoniae). A single strain of beta-hemolytic streptococci has been identified as S. dysgalactiae subsp. equisimilis. The enterococci were one strain of Enterococcus faecalis and three E. faecium. Ten streptococci were susceptible to 0.25 mg/L of penicillin G, ten were less susceptible (0.5 < or = MIC < 32 mg/L), and a strain was resistant (MIC = 32 mg/L). Eighteen strains were susceptible to amoxicillin and cefotaxime. For three strains, the MICs of amoxicillin and cefotaxime (8-16 mg/L and 8-32 mg/L, respectively) were higher. Levels of resistance of the enterococci to the beta-lactam (penicillin, amoxicillin, and piperacillin) were variable. All species were susceptible to glycopeptides. Three patients were transferred in intensive care unit for respiratory distress or shock syndrome. Their evolution has remained severe under antibiotherapy comprising beta-lactam or vancomycin associated with an aminoside. This results demonstrate the interest of species identification to adapt the antibiotic treatment and confirms the frequency of oral streptococci in severe bacteremia in neutropenic patients.