β-lactamase and Plasmid-mediated Quinolone Resistance Determinants Among Proteus spp. Isolates at a Tertiary-care Hospital in Kolkata, India

Background: Emerging antibiotic resistance (ABR) in Proteus spp., especially to third-generation cephalosporins (3GCc), carbapenems, and fluoroquinolones, challenges the treatment outcome and infection prevention. Limited studies pose a knowledge gap between them and ABR. Methods: We investigated the in vitro efficacy of therapeutic options and prevalence of β-lactamase and plasmid-mediated quinolone resistance (PMQR) traits in 3GC- and/or fluoroquinolone- nonsusceptible Proteus (P.) spp. (n=27) in Kolkata, India, during 2021–2022. P. mirabilis was commonly isolated (>80%) from superficial and urine samples. The majority of the isolates (48-78%) remained susceptible to piperacillin-tazobactam, meropenem, amikacin, cefoperazonesulbactam, and cefepime. Results: All isolates showed >0.2 multiple-antibiotic resistance index, with >65% being multidrug and >30% being extensively drug-resistant. blaTEM (n=9), blaNDM (n=9), and qnrA (n=6) were commonly noted with the co-production of β-lactamases and PMQR in ten (37%) isolates. More than 50% of the isolates were devoid of the tested acquired genes. Conclusion: The study concludes that superbugs dominate, with limited occurrence of plasmidborne markers in this geographic location.