SEROTYPING AND SUSCEPTIBILITY TO MACROLIDES AND OTHER ANTIMICROBIAL DRUGS OF STREPTOCOCCUS-PYOGENES ISOLATED FROM PATIENTS WITH INVASIVE DISEASES IN SOUTHERN ISRAEL

Fifty-seven strains of Streptococcus pyogenes isolated from septic pat ients and 52 isolates from nonbacteremic patients in southern Israel w ere investigated for their susceptibility to new macrolides and other antimicrobial drugs. In addition, typing of the isolates by M protein and T antigen was performed, All organisms were susceptible to penicil lin and chloramphenicol, 59% to tetracycline, and 7% to trimethoprim-s ulfamethoxazole. All isolates but one (99%) were susceptible to clarit hromycin, azithromycin, erythromycin, and clindamycin, The MIC90 of cl arithromycin, erythromycin, and clindamycin was 0.064, 0.125, and 0.09 4 mu g/ml, respectively, Overall, 96% of the isolates could be typed b y T antigen, but only 43% were M-protein typeable. No predominance of any particular M-protein type was observed. No significant differences between blood isolates and organisms derived from other sources were observed in the antibiotic susceptibility patterns or the distribution of serotypes. It is concluded that invasive Streptococcus pyogenes in fections in southern Israel are caused by multiple unrelated strains. The organism remains susceptible to macrolides and clindamycin.