Antimicrobial Susceptibility and Prevalence of bla and qnr Genes in Salmonella Enterica Isolated from Slaughtered Pork

Abstract

Background: Salmonella enterica is known as one of the most common foodborne pathogens worldwide. While salmonellosis is usually self-limiting, severe infections may require antimicrobial therapy. However, increasing resistance of Salmonella to antimicrobials, particularly fluoroquinolones and cephalosporins, is of utmost concern. The present study aimed to investigate the antimicrobial susceptibility of S. enterica isolated from pork, the major contributor in Philippine livestock production.Results: Our results show that 61.2% of the isolates carried antimicrobial resistance genes qnrS and blaTEM. While qnrA (12.9%) and qnrB (39.3%) were found less frequently, co-carriage of blaTEM and one to three qnr subtypes was observed in 45.5% of the isolates. Co-carriage of blaTEM and blaCTX-M was also observed in 3.9% of the isolates. Antimicrobial susceptibility testing revealed that majority of the isolates were non-susceptible to ampicillin and trimethoprim/sulfamethoxazole, and 13.5% of the isolates were multidrug-resistant.Conclusions: High prevalence rates of S. enterica carrying antimicrobial resistance genes (ARG), specifically the presence of isolates co-carrying resistance to both ß-lactams and fluoroquinolones, raise a concern on antimicrobial use in the Philippine hog industry and on possible transmission of ARG to other bacteria.