Isolation, Molecular Detection and Antibiogram of Multi-drug Resistant Salmonella Typhimurium DT104 from Selected Dairy Farms in Mymensingh, Bangladesh

The Salmonella typhimurium DT104, an emerging cause of human illness has received an increasing attention due to its multidrug resistant properties. Since it has been isolated from human and other sources including food-producing animals around the world; it has become a worldwide public health concern. Therefore, the present study was designed to isolate, identify and study the antibiogram profile of multidrug resistant S. typhimurium DT104 from several dairy farms in Mymensingh district, Bangladesh. A total of 135 fecal samples from diarrhoeic cattle were collected aseptically and subjected for bacterial isolation, molecular detection using PCR followed by antibiogram study. Salmonella spp. could be isolated from a total of 39 (28.88%) samples based on cultural and staining methods which were further confirmed by PCR using invA gene specific primers. However, out of 39 Salmonella spp., 6 isolates were confirmed as S. typhimurium DT104 strain. Results of the antibiotic resistance patterns demonstrated that 100% (39/39) isolates were resistant to erythromycin followed by tetracycline (73.68%), colistin (89.47%), ampicillin (47.36%), gentamicin (21.05%), ciprofloxacin (31.57%), streptomycin (42.10%), enrofloxacin (10.52%) and chlormphenicol (31.57%). Moreover, about 23.07% isolates were resistant to more than 5 antibiotics. However, all the isolates were found to be sensitive to amikacin. These results suggest that antibiotic resistant S. typhimurium DT104 strain has been circulating in dairy cattle in Bangladesh which is alarming and may impose threat to livestock and public health due to lack of proper hygienic management. This study will be helpful for the selection of proper antibiotics against salmonellosis in cattle.