Detection of Colistin and Quinolone Resistance Genes in Bacterial Pathogens Isolated from Poultry

Abstract

The current study aimed at detection of antimicrobial resistance genes AMR genes against colistin and quinolones in two selected avian pathogens E. coli and Salmonella recovered from poultry in Pakistan. For this purpose, 31 isolates of E. coli and 30 isolates of Salmonella, that had been declared resistant against the colistin and quinolones (nalidixic acid, ciprofloxacin, enrofloxacin and norfloxacin) by antibiotic sensitivity testing, were taken from the repository of NRLPD. Their genomic DNA was extracted PCRs were conducted for detection of 17 genes responsible for resistance against colistin (mcr-1 to mcr -9) and quinolones (qnrA, qnrB, qnrC, qnrD, qnrS, gyrA, gyrB and oqxA). The results revealed that only two colistin resistance genes responsible mcr-2 and mcr-9 were detected in both E. coli and Salmonella however mcr-9 was more prevalent in Salmonella (16.67%) than in E. coli (3.23%). Mcr-2 and mcr-9 have not been reported previously in colistin resistant bacteria isolated from poultry in Pakistan. Additionally, mcr-1 gene reported previously was also not detected in particular isolates. Furthermore, four quinolone resistance genes (qnrA, qnrD, qnrS and gyrB) were detected in E. coli and Salmonella; qnrS (77.42%) and gyrB (12.90%) were detected in E. coli while qnrA, qnrD and qnrS were detected in Salmonella. QnrS was the most prevalent gene for quinolone resistance in E. coli, and it was more prevalent in E. coli (77.42%) than in Salmonella (13.33%) while in Salmonella the most prevalent quinolone resistance gene was qnrD (40%). The rising number of resistance genes against different antibiotics in E. coli and Salmonella is a potential threat to the health of poultry. These resistance genes can transfer to other bacteria that cause infection in chicken, other animals and humans by conjugation or mobilizable plasmids and thus possess the potential to spread these resistance genes widely and cause a global crisis of antibiotic resistance in poultry. Therefore, the misuse of antibiotics in poultry sector needs to be checked. More information concerning phenotypic AMR profiles along with detailed molecular analysis through genome sequencing is needed for a better knowledge of the AMR burden in poultry pathogens and to develop efficient AMR containment measures