Characterization of Salmonella virchow phage types by plasmid profile and 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 types 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, five of 10 wild-type isolates carried plasmids and two plasmid profiles were identified; in contrast, an IS200 element was identified in the genome of only one of these strains. It is concluded that for Salm. virchow, IS200 is unlikely to significantly extend the degree of discrimination achieved by phage typing which may be supplemented when appropriate by plasmid profile typing.