High incidence of plasmid-mediated quinolone resistance genes among ciprofloxacin-resistant clinical isolates of Enterobacteriaceae at a tertiary care hospital in Puducherry, India

Background. Plasmid-mediated quinolone resistance (PMQR) has received considerable attention recently. Data analysis in Jawaharlal Institute of Postgraduate Medical Education & Research (JIPMER) revealed 75% of the Enterobacteriaceae isolates to be ciprofloxacin-resistant in 2012. Few reports regarding the prevalence of PMQR are available from India. Hence, the present study was carried out to ascertain the prevalence of PMQR genes among clinical isolates of ciprofloxacin-resistant Enterobacteriaceae in JIPMER. Methods. The study included 642 ciprofloxacin-resistant clinical Enterobacteriaceae isolates. JIPMER hospital's annual consumption data for fluoroquinolones were retrieved from the Department of Pharmacy. The test isolates were screened for the presence of qnr A, B, D, S and aac(6')-Ib-cr genes. PMQR-positive isolates alone were tested for the presence of class I (intI1) and class II (intI2) integrons. Randomly selected PCR amplicons were sequenced and analysed using MEGA software. A total of 30 PMQR strains chosen at random were assessed for the transferability of the PMQR genes. Results. A majority of the strains exhibited high MIC values with 106 strains exhibiting MIC values >256 µg/mL. The aac(6')-Ib-cr gene had the highest prevalence at 64% (414) while, qnrB and qnrS genes were present in 15% (97) and 10% (64) of the isolates respectively. None of the strains were positive for qnrA and qnrD. All PMQR-positive isolates were screened for class I (intI1) and class II (intI2) integrons. Class I integron was found to be predominant among the test isolates with a few of them carrying both the classes of integrons. Transferability of PMQR genes to transconjugants was identified. Conclusion. The incidence of PMQR genes in the tertiary-care setup of the JIPMER hospital was found to be high which could be probably due to the increased prescription of fluoroquinolones. Thus, there is a need for rational usage of fluoroquinolones.