Incidence and risk of co-transmission of plasmid-mediated quinolone resistance and extended-spectrum β-lactamase genes in fluoroquinolone-resistant uropathogenic Escherichia coli: a first study from Kolkata, India.

OBJECTIVES

Co-resistance to fluoroquinolones and β-lactams results in treatment complications for uropathogenic Escherichia coli (UPEC) infections. This study aimed to detect the coexistence and co-transmission of plasmid-mediated quinolone resistance (PMQR) and extended-spectrum β-lactamase (ESBL) genes in UPEC from Kolkata, India.

METHODS

Escherichia coli was detected biochemically from culture-positive urine samples. Antimicrobial resistance and ESBL production were confirmed by disk diffusion assay. Transfer of PMQR and ESBL genes was performed using azide-resistant E. coli J53 as recipient. PCR was conducted to identify PMQR and ESBL genes, plasmid incompatibility types, insertion sequences, integrons and ERIC-PCR patterns.

RESULTS

PMQR determinants were detected in 50.0% (35/70) of ciprofloxacin-resistant isolates, with ESBL production in 42.9% (15/35) and a β-lactamase inhibitor-resistant phenotype in 51.4% (18/35). The highest co-occurrence (37.1%; 13/35) and co-transmission of aac(6')-Ib-cr with bla, bla and bla was observed. Among the conjugal plasmids, replicon types FrepB/FrepB+F1B were predominant, with rare incidences of A/C, N, X, I1, FIIS, L/M and H1. Distribution of integrons and ISEcp1 and IS26, either alone or in combination, irrespective of PMQR and ESBL gene types was observed. Discrete ERIC-PCR profiles indicated that acquisition of PMQR and ESBLs and their dissemination may be attributed to horizontal gene transfer.

CONCLUSION

This study demonstrates for the first time the risk of co-transmission of fluoroquinolone and β-lactam resistance amongst UPEC from Kolkata, posing a major public-health threat and limiting treatment options. Monitoring at the molecular level is necessary to design appropriate prescription policies to combat the alarming rise in drug resistance amongst these uropathogens.