Transferable drug resistance in Salmonella typhi strains isolated from an outbreak at Calcutta in the recent past.

Transferable drug resistance, phage type, biotype and minimum inhibitory concentration to different drugs were studied in 50 Salmonella typhi strains isolated during recent outbreak of enteric fever at Calcutta. The antibiotic sensitivity test showed that 44% strains were sensitive to multiple drugs including chloramphenicol. The minimum inhibitory concentrations of the drugs tested were well above the normal level. The transferable drug resistance test suggested that all the resistant strains were carrying transferable multidrug resistant gene containing ampicillin, chloramphenicol, streptomycin, tetracycline resistance factor. From phage typing it was observed that 30% strains belonging to phage type 51, and among them 80% strains were carrying transferable drug resistant factor containing ampicillin, chloramphenicol, streptomycin and tetracycline.