New group D streptococcal species.

BACKGROUND & OBJECTIVES: The heterogeneity of group D streptococci led to the identification of various biotypes of Streptococcus equinus and Streptococcus bovis and to the description of new species. The objective of the present study was to improve the phenotypic delineation between species and to clarify their respective phylogenetic position. METHODS: Physiological and genomic analyses were carried out in 84 representative strains of the group D streptococci. Biotypes were determined with the API 20 strep and rapid ID 32 STREP systems of identification. Quantitative DNA-DNA hybridization under stringent conditions and values of the deltaT(m) allowed to delineate species and subspecies. The phylogenic position of the different genomic groups was determined by comparing the sequences of their 16S rDNA. RESULTS: Four DNA-clusters, including seven species or subspecies, were characterized. Differential associations of biochemical characters allowed their identification. S. equinus and the type strain of S. bovis belonged to a single species. S. gallolyticus, S. bovis biotype II.2, and S. macedonicus formed a single DNA-cluster including three different subspecies. These were designated as S. gallolyticus subsp. gallolyticus, S. gallolyticus subsp. pasteurianus, and S. gallolyticus subsp. macedonicus. The two other DNA-clusters corresponded to the two subspecies of S. infantarius, and to S. alactolyticus. INTERPRETATION & CONCLUSION: This study presented a new classification associated with an identification scheme of group D streptococci. The changes in this classification demonstrate the interest of a polyphagic approach of the bacterial identification.

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

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.

Epidemiological markers of group A streptococcal infections in France.

BACKGROUND & OBJECTIVES: A limited number of biotypes, T-types, and emm-types have been found to be associated with invasive isolates of group A streptococci, confirming the involvement of the M protein in virulence and its importance as an epidemiological marker. In this study, the epidemiological markers in the clinical isolates of group A streptococci were compared in invasive and non invasive isolates. METHODS: From 1998 to 2001, 141 invasive and 353 non invasive isolates in France were studied and their biotype, T-type, and emm-type were determined. RESULTS: The invasive isolates were mostly obtained from blood whereas the non invasive isolates were isolated from throat. Most of the isolates were of biotype 1. The invasive isolates were mostly of the T-type 1 associated with emm-type 1. The T-type 4 associated with emm-type 4 and the T-type 28 associated with emm-type 28 were also frequent. Invasive isolates responsible for puerperal sepsis and non invasive isolates were mostly of the T-type 28 associated with emm-type 28. INTERPRETATION & CONCLUSION: This study confirms the high prevalence of isolates of biotype 1, T-type 1, and emm-type 1 among invasive isolates of group A streptococci. The emm-type 28 associated with T-type 28 was frequently observed in non-invasive isolates. A prospective study is being conducted to update the prevalence of the different emm-types in France, which will be of importance for the development of future vaccines.