Multiple Drug Resistance and Virulence Profiling of Salmonella enterica Serovars Typhimurium and Enteritidis from Poultry Farms of Faisalabad, Pakistan

The zoonotic serovars of Salmonella enterica particularly Typhimurium and Enteritidis pose a continuous global threat to poultry industry and public health. We report the prevalence of Salmonella Typhimurium and Salmonella Enteritidis serovars in local poultry, phenotypic antimicrobial resistance profiling, and molecular detection of antimicrobial resistance and virulence genes. A total of 340 clinical samples were collected and 239 carried Salmonella, which were identified by genus-specific PCR (invA gene) and by matrix-assisted laser desorption/ionization time-of-flight. The 68 and 22 isolates were confirmed as Salmonella Typhimurium (stm gene) and Salmonella Enteritidis (sdfI gene) respectively. Pulsed-field gel electrophoresis (PFGE) revealed 27 and 9 PFGE types of Salmonella Typhimurium and Salmonella Enteritidis respectively. Among 24 antimicrobials tested, highest resistance was observed against pefloxacin while highest susceptibility was found for ertapenem in Salmonella Typhimurium and aztreonam in Salmonella Enteritidis. All isolates were found multiple drug resistant, 98.8% as motile and 8.8% as extended spectrum beta lactamase producers. Most prevalent resistance gene in Salmonella Typhimurium was parE (69.1%) while in Salmonella Enteritidis blaTEM-1 (72.7%). High prevalence of SopE gene in Salmonella Typhimurium (91.1%) and Salmonella Enteritidis (81.8%) indicated their zoonotic potential. The study is first of its kind from this region and highlights the emerging trends of antimicrobial resistance of global concern.