Multiple drug resistance and genetic characterization of Salmonella typhimurium isolated at Chandigarh.

A total of 1072 strains of S. typhimurium were isolated in Chandigarh during 1985-1988. Genetic characterization of 'R' plasmids was attempted in 21 multiple drug resistant strains (ACKSSu TT p-19, ACKSSu, TP-I, AKSSu Tp-1). All the 21 strains were sensitive to gentamicin, furoxone and nalidixic acid. Level of resistance to different antimicrobial drugs varied from 200 to 1000 mg/L. Majority of the strains were untypable by the present set of 31 typing phages (Ut-17, Phage type 21-2, Phase type 99-2). All the plasmids belonged to class I transfer system. All the plasmids restricted some or all the typing phages of S. typhimurium and 39 also restricted phage phi 2. These plasmids belonged to F1me or I1 incompatibility groups and did not inhibit the function of fertility factor (fi-).