Impact of susceptibility to antibiotics of streptococci & enterococci isolated from patients with infective endocarditis on antibiotic treatment

Abstract

Background & objectives: Streptococci and enterococci are the most frequent pathogens causing infective endocarditis. In order to update the recommendations for both curative and prophylaxis treatment, the susceptibility to antibiotics of the most prevalent species of Streptococcaceae isolated from the patients with infective endocarditis was determined.

Methods: Streptococcal and enterococcal isolates (n=133) isolated from confirmed cases of infective endocarditis during a one-year prospective survey conducted in 1999 in France were studied. The identification of 106 streptococci and 27 enterococci to the species level was carried out by conventional methods. Their susceptibility to ten antibiotics used in curative or prophylactic treatment was measured. Minimal inhibitory concentrations were determined by agar dilution method.

Results: All the streptococcal and enterococcal isolates were susceptible to 4 mg/l or less of penicillin or amoxicillin. High levels of resistance to aminoglycosides were observed in two species, Streptococcus gallolyticus subsp. gallolyticus and Enterococcus faecalis. All isolates were susceptible to glycopeptides. Resistance to erythromycin, clindamycin, and pristinamycin was restricted to some species.

Interpretation & conclusion: Curative treatments recommended for streptococcal or enterococcal endocarditis, including penicillin, amoxicillin or vancomycin in association with gentamicin were found to be appropriate for 98.5 per cent of cases. The emergence of erythromycin resistance in oral streptococci led to the use of pristinamycin in oral prophylactic treatment in patients allergic to beta-lactams.