R Plasmids in Streptococcus agalactiae (Group B) THEA HORODNICEANU,* D. H. BOUANCHAUD, G. BIETH, AND Y. A. CHABBERT Service de Bacteriologie Medicale, Institut Pasteur, 75015 Paris, France
Received for publication 20 April 1976 Two plasmids determining resistance to tetracycline .(RIP500) and to chloramphenicol, erythromycin, lincomycin, and pristinamycin I (RIP501) were isolated from a strain of Streptococcus agalactiae. The frequency-of-resistance loss is very low for RIP500 (