Correlation of quinolone-resistance, qnr genes and integron carriage in multidrug-resistant community isolates of Klebsiella spp.

Document Type : Original Article


1 Department of Microbiology, Faculty of Life Sciences and Technology, Shahid Beheshti University, Tehran, Iran

2 Department of Microbiology, Research Center for Food Hygiene and Safety, Shahid Sadoughi University of Medical Sciences, Yazd, Iran


Objective(s): Plasmid-mediated quinolone resistance (PMQR) determinants and integrons have a considerable contribution to bacterial drug resistance in Gram-negative pathogens. We studied the prevalence of PMQR genes and integron carriage in multidrug-resistant community isolates of Klebsiella spp.
Materials and Methods: Two hundred and fifty Klebsiella spp. isolates were collected from outpatient specimens between August 2015 and October 2017 in Yazd central Laboratory, Iran. Antibiotic susceptibility was determined against 17 antibiotics and minimum inhibitory concentration (MIC) of ciprofloxacin was measured by E-test. Polymerase chain reaction (PCR) was employed for detection of qnrA, qnrB, qnrS, aac(6’)-Ib-cr, oqxAB and qepA genes.
Results: Disc diffusion results showed that 17 isolates (6.8%) were multidrug resistant (MDR), two of which were Klebsiella oxytoca and 15 were Klebsiella pneumoniae. MIC measurements revealed 11 ciprofloxacin-resistant isolates (including the two K. oxytoca), three intermediately-resistant and three ciprofloxacin-susceptible isolates. All ciprofloxacin-resistant and intermediately-resistant isolates carried at least one and up to four PMQR genes. The most prevalent PMQR gene was oqxAB (93.75%) followed by aac(6’)-ib-cr (50.0%), qnrB (25.0%) and qnrS (18.75%) but qnrA and qepA were not detected. Class 1 integron was observed in 14 (82.3%) isolates including nine ciprofloxacin-resistant, two intermediately-resistant, and three susceptible isolates. Class 2 and 3 integrons were not observed.
Conclusion: Presence of MDR, multiple PMQR determinants as well as class 1 integron in community isolates of Klebsiella spp. can be an important source of transmission of these opportunistic pathogens.


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