[Antibiotic resistance genetic basis of human origin streptococci (author's transl)].

One hundred strains of group A, B, C, D (S faecalis, S. faecium, S. bovis) F, G, S. pneumoniae and viridans streptococci were studied. All these strains were clinical isolates from infective endocarditis and fron upper respiratory, skin, genital and urinary tract infections. These stains were resistant to one or several antibiotics : tetracycline, macrolide and related drugs, chloramphenicol, aminoglycosides (high-level resistance to streptomycin, kanamycin, gentamicin), and penicillin. Conjugative transfer of antibiotic resistance markers (except penicillin) into streptococcal recipients was obtained at a high frequency (10(-1) to 10(-4)) for 12 strains and at a low frequency (10(-5) to 10(-8)) for 29 strains. R plasmids carrying various groups of resistance markers were isolated with different molecular weights. Enzyme restriction analysis showed the existence of different molecular species of streptococcal plasmids. All attempts to detect extrachromosomal DNA in 17 wild-type strains and in the corresponding transconjugants were unsuccessful.