High prevalence of carbapenemase, AmpC β-lactamase and aminoglycoside resistance genes in extended-spectrum β-lactamase-positive uropathogens from Northern India

Objectives This study investigated the occurrence of extended-spectrum β-lactamase (ESBL) genes coexisting with carbapenemase, AmpC and aminoglycoside resistance gene in uropathogens in India. Methods Antimicrobial susceptibility testing was performed by disk diffusion. Antimicrobial resistance genes were detected by multiplex PCR. Results Of 1516 consecutive urine samples, 454 (29.9%) showed significant bacteriuria with a single micro-organism, predominantly Escherichia coli ( n = 343), followed by Klebsiella pneumoniae ( n = 92), Pseudomonas aeruginosa ( n = 10) and Proteus mirabilis ( n = 9). Among the uropathogens, 61 ESBL-producers were identified containing bla CTX-M-15 ( n = 32), bla CTX-M-15 + bla OXA-2 ( n = 15), bla CTX-M-15 + bla OXA-2 + bla TEM-1 ( n = 6), bla OXA-2 ( n = 5), bla OXA-2 + bla SHV-76 ( n = 1), bla TEM-1 + bla SHV-76 ( n = 1) and bla TEM-1 ( n = 1). All ESBL genes were located on horizontally transferable plasmids of incompatibility types HI1, I1, FIA + FIB, FIA and Y. Among the 61 ESBL-producers, 59 harboured carbapenemase genes, including bla NDM-5 ( n = 48), bla NDM-5 + bla OXA-48 ( n = 5), bla NDM-5 + bla IMP ( n = 5) and bla NDM-5 + bla IMP + bla VIM ( n = 1). ESBL-producing uropathogens also harboured 16S rRNA methylase genes, including rmtB ( n = 9), rmtA ( n = 4), rmtC ( n = 1) and armA ( n = 1). ESBL-positive isolates also contained AmpC genes, including bla CIT ( n = 8) and bla DHA-1 ( n = 1). Imipenem and gentamicin had the lowest resistance rates against the uropathogens. Conclusion This is the first report showing the high prevalence of carbapenemases in ESBL-positive isolates in this area. Regular surveillance for such resistance mechanisms will be useful for health personnel to treat infections by these multidrug-resistant pathogens.