Antibiotic resistance, biofilm formation, and virulence gene profiling of multidrug-resistant Pseudomonas aeruginosa isolates from a multi-speciality hospital in Sikkim, India.

UNLABELLED: Effective antibiotic stewardship and monitoring of antimicrobial resistance are crucial for mitigating the emergence and spread of opportunistic nosocomial pathogens, such as Pseudomonas aeruginosa. This study aimed to identify antibiotic resistance patterns, the ability to form biofilms, and the presence of virulence-associated genes in multidrug-resistant (MDR) P. aeruginosa isolates from a multi-speciality government hospital in Sikkim, India.

METHODS

Forty clinical isolates of P. aeruginosa were characterised through antimicrobial susceptibility test (AST). MDR isolates were evaluated for biofilm formation and the presence of carbapenemase genes (blaKPC, blaGES, blaIMP, blaVIM, blaNDM, blaOXA-48), quorum sensing (lasR), efflux pump (mexAB-oprM), and various virulence-associated genes (toxA, lasA, lasB, popB, aprA, pvdA, phzM, phzS, algD) using PCR.

RESULTS

The ecfX gene specific to P. aeruginosa was detected in all isolates, confirming their identification. Among the isolates, 37.5 % were MDR, and 7.5 % were extensively drug-resistant (XDR), with a multiple antibiotic resistance (MAR) index ranging from 0.210 to 0.894. Some MDR isolates demonstrated resistance to meropenem (MIC 15.62-125 μμg/mL), indicating carbapenem resistance. All isolates showed a MIC of ≤ 2 μg/mL to colistin. These MDR isolates formed biofilms and harboured lasR, mexAB-oprM, along with the majority of virulence-related genes (toxA, lasA, popB, phzM, and algD). However, only two carbapenemase genes were detected: blaGES (66.66 %) and blaIMP (73.33 %).

CONCLUSION

This study highlights the occurrence of biofilm-forming, MDR, and carbapenem-resistant clinical isolates of P. aeruginosa. These isolates harbour several virulence-associated genes and are fully susceptible to colistin, suggesting its potential role in treating such infections. The findings emphasise the need for continued surveillance and targeted antimicrobial stewardship in hospital settings.