Antimicrobial susceptibility patterns and molecularcharacterization of plasmid-mediated quinolone resistance determinantsamong Salmonella and Shigella spp. isolated from pediatric patients

Background and Aim : Diarrhea remains a serious public health problem, which could be lifethreateningin children. Different pathogens can cause acute diarrhea in children, where entericbacteria, such as Salmonella and Shigella, are among the main responsible agents.Fluoroquinolones are the most common antibiotics prescribed to treat Shigella and Salmonellainfections; however, increasing rate of resistance and its spread through plasmid- mediatedquinolone resistance (PMQR) genes should be considered for medication in each country. Toachieve this aim, the current study was conducted to determine the frequency of quinoloneresistance plasmid genes in Shigella and Salmonella isolates of pediatric patients with acutediarrhea.Methods : In this study, Shigella and Salmonella isolates from fresh stool samples of diarrheapatients were included from May ۲۰۱۷ to May ۲۰۱۸. All the isolates were characterized byconventional phenotypic and molecular methods. The antibiotic resistance profiles and thefrequency of PMQR genes were determined by standard susceptibility and molecular test methods.Results : The highest antibiotic resistance rate among Shigella and Salmonella isolates was relatedto trimethoprim-sulfamethoxazole (۳۷/۴۰; ۹۲.۵%) and cefoxitin (۵/۴۵; ۱۱.۱%), respectively.Although qnrS, qepA, and aac(۶)-Ib-cr genes were characterized in ۳۲.۵%, ۲.۵%, and ۲.۵% of theShigella strains, qepA (۱۷.۷%) and qnrS (۴.۴%) were among the common PMQR determinants inthe Salmonella isolates, respectively. The reduced susceptibility to ciprofloxacin was detectedamong ۲۵% and ۲۲.۲% of PMQR-harboring strains of Shigella and Salmonella, respectively.Conclusion : Low rates of ciprofloxacin resistance and low frequency of MDR Salmonella andShigella isolates were characterized in this study. Most of the isolates that carried PMQRdeterminants presented only low-level resistance and reduced susceptibility to ciprofloxacin

کلیدواژه ها:

Antibiotic resistance ، Salmonella ، Shigella ، Pediatric ، Plasmid-mediated quinoloneresistance (PMQR)