Beta-lactamase Profile and Biofilm Production of Pseudomonas aeruginosa Isolated from a Tertiary Care Hospital in Kolkata, India

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Introduction: Nosocomial infections caused by Multidrug Resistant (MDR) Pseudomonas aeruginosa (P. aeruginosa) have become a major clinical and public health concern. Moreover, the biofilm production protects the bacteria from antibiotics and thereby makes the drugs ineffective. Aim: To find out the β-lactamases profile of antimicrobial resistance and biofilm production of P. aeruginosa isolated from different clinical specimens of patients attending a tertiary care hospital of Kolkata, West Bengal, India. Materials and Methods: A total of 394 consecutive, non-duplicate isolates of P. aeruginosa were identified from 3559 Gram negative bacilli over a period of two years from July 2016 to June 2018. Identification of the isolates and antibiotic sensitivity testing was performed by using automated method and interpreted. Extended Spectrum β-Lactamases (ESBLs), Amp-C β-lactamase (AmpC) and Metallo-β-Lactamases (MBLs) were phenotypically detected by disk synergy test and MBL-encoding genes were detected by multiplex Polymerase Chain Reaction (PCR). Biofilm production was done by tissue culture plate assay. Laboratory data and test results were statistically analysed in counts and percentages using MS Excel 2010 version. Results: Out of 394 strains of P. aeruginosa 288 (73.10%) were isolated from male patients whereas 106 (26.90%) were isolated from female patients. Maximum number of cases (67.26%) were from adult populations. The resistance pattern showed 72.33% resistance to ticarcillin-clavulanic acid followed by ciprofloxacin (53.80%), levofloxacin (50.25%), gentamicin (51.52%), ceftazidime (CAZ) (45.93%), cefoperazone-sulbactam (40.1%), aztreonam (34.77%), imipenem (33.5%), piperacillin/tazobactum (30.96%) and Meropenem (MRP) (29.18%). Out of 394 Pseudomonas spp. isolates, 204 (51.77%) were MDR. Overall, ESBLs, AmpC and carbapenemase (MBL) production was detected in 145 (36.80%), 51 (12.94%) and 49 (12.43%) isolates by phenotypic methods. By genotypic method 53.34% were carbapenemase producing and blaNDM-1 (68.75%) was the most prevalent carbapenemase gene detected followed by blaVIM (18.75%) and co-production of blaNDM-1+ blaVIM was 12.5%. Biofilm production was observed in 158 (40.10%) isolates. Conclusion: Early detection of these β-lactamases production is crucial not only for epidemiological study and effective infection control practices to limit the spread of infection but also for planning appropriate therapy according to the resistance mechanisms of the MDR strains.