Molecular characterization of plasmid-mediated quinolone resistance (PMQR) and ESBLs-producing Klebsiella pneumonia isolated from an Iranian teaching hospital

Abstract

Background The spread of plasmid-mediated multidrug resistance in Klebsiella pneumonia is a serious threat to the public health. We investigated the clinical characteristics and molecular epidemiology of K. pneumoniae isolated at a teaching hospital in Iran. Methods A total of 50 third-generation cephalosporins resistant K. pneumoniae strains were collected from patients’ clinical cultures. Antibiotic susceptibility testing and determination of MIC values for ceftazidime, cefotaxime and ciprofloxacin were performed. PCR and DNA sequencing were used to assess the presence of ESBL genes (blaCTX−M, blaTEM, blaSHV) and PMQR genes (qnrA, qnrB, qnrS, qepA, oqxA, oqxB and aac(6)-Ib-cr). Multilocus sequence typing (MLST) was performed on the strains to assess homology. Results Our results showed that the rates of resistance to all of antibiotics is high. All 50 K. pneumoniae strains harboured at least one of the ESBL resistance determinants. The blaCTX−M−15 gene was the major ESBLs determinant found in K. pneumoniae (88%; 44/50). PMQR was detected in 96% of the isolates and aac(6′)-Ib-cr was the most common (78% 39/50) followed by oqxA 36 (72%), oqxB 34 (68%), qnrS 20 (40%), qnrB 14 (28%) and qepA 1 (2%). MLST identified seven sequence types (STs), with the most common being ST11 (19/39). There was a strong association between PMQR genes (especially aac(6′)-Ib-cr) and ESBL genes. Conclusion The widespread detection of ESBLs-producing K. pneumoniae that co-carried PMQR determinants has become a threat to the treatment of infections in Isfahan Province of center Iran. Our findings suggest that K. pneumoniae ST11 and ST893 has a clonal distribution in our hospital. Therefore, this study highlighted the crucial need for implementing strict control measures to prevent cross transmission of these endemic clones.