PHAGE-TYPING MODIFICATIONS INDUCED BY INVITRO TRANSFER OF R-PLASMIDS .1. PHAGE TYPING OF SALMONELLA-TYPHI

Abstract

The phage-typing modifications induced by transfer of antibiotic-resistance plasmids were studied in 2 S. typhi Vi+ strains: n.degree. 2411 (phage-type A) and Ty2 (phage-type E1a). Forty-one R plasmids belonging to 22 incompatibility groups were investigated. Twenty-two plasmids did not produce any phage-typing modifications. Among the groups of plasmids with phage-typing restriction capacity, 4 (I1, 10.B.O., N and W) groups were heterogeneous in this property and one (F1 group) caused significant modifications of the phage-types defined by the Vi phage-typing international system.