Molecular Detection of Mutations within the Quinolone Resistance-Determining Regions in Non Typhoidal Salmonella Isolates from Malaysia

Fadzilah Mohd-Nor, Noor Aini Abu-Bakar, Norzilawati Mohd-Isa, Zubaidah A. Wahab, Zaini Mohd-Zain
2017 Health (Irvine, Calif.)  
The efficacy of chemotherapy in bacteraemia caused by nontyphoidal Salmonella (NTS) is compromised by antibiotic resistance. Objective: This study was undertaken to describe the mechanism of resistance among clinical NTS isolates. Materials & Methodology: Thirty of NTS were isolated from blood (n = 19), stool (n = 10) and bronchioalveolar lavage (BAL; n = 1) respectively. These isolates were tested for susceptibility testing by disc diffusion method against ampicillin, gentamicin, tetracycline,
more » ... icin, tetracycline, co-trimoxazole, nalidixic acid, ciprofloxacin and ceftriaxone. Epsilometer tests (E-test) for nalidixic acid and ciprofloxacin were performed for nalidixic acid resistant isolates by disc diffusion method. DNA sequencing was carried out on six of the nalidixic acid resistant Salmonella Enteritidis isolates to identify mutations within quinolones resistance determining regions (QRDR) of gyrA, gyrB, parC and parE genes. Results: Resistance rates of NTS isolates from blood, stool, and BAL were respectively 37%, 20% and 0% for ampicillin, 79%, 40% and 0% for tetracycline, 32%, 40% and 0% for co-trimoxazole, 37%, 10% and 100% for nalidixic acid. Eight isolates were resistant to nalidixic acid and had exhibited reduced susceptibility towards ciprofloxacin by E-test. Mutation within QRDR was detected in gyrA gene (n = 6; Asp 47 → His [3], Asp 51 → Asn [1], Asp 73 → Gly [1], and Gly 48 → Asp [1]) and double mutation was detected in parE gene (n = 3; Gly 48 → Asp [3], Glu 82 → Ser [3] ). Out of six isolates, three isolates were found to have both gyrA and parE gene mutations. Conclusions: There was no mutation observed in gyrB and parC gene. Muta-How to cite this paper: Mohd-Nor, F.,
doi:10.4236/health.2017.94045 fatcat:ee6vjkjus5eldijfwnzi72zds4