CHARACTERIZATION OF SALMONELLA-VIRCHOW PHAGE TYPES BY PLASMID PROFILEAND IS200 DISTRIBUTION

The type strains of the 57 phage types of Salmonella virchow have been characterized by plasmid profile and by distribution of the insertion sequence IS200. Thirty-two strains carried plasmids and 21 profile ty pes were identified; 17 strains were resistant to antimicrobial agents . In contrast only six of the type strains carried IS200 elements and three patterns were identified. Within Salm. virchow phage type 31, fi ve of 10 wild-type isolates carried plasmids and two plasmid profiles were identified; in contrast, an IS200 element was identified in the g enome of only one of these strains. It is concluded that for Salm. vir chow, IS200 is unlikely to significantly extend the degree of discrimi nation achieved by phage typing which may be supplemented when appropr iate by plasmid profile typing.