Metallo-β-lactamases producing Pseudomonas aeruginosa and the molecular mechanism of drug resistance variants

Abstract

Background

Metallo-β-lactamases (MBLs) type carbapenemases are produced by pathogenic Pseudomonas spp. and exhibit carbapenemase activity. The study will look into drug resistance and the molecular mechanisms of drug-resistant Pseudomonas aeruginosa variants.

Methods

A total of 74 P. aeruginosa strains were isolated from urine, pus, sputum, blood, throat swab, Foley’s catheter, and nasal swab. The isolates were screened for antibiotic susceptibility and the identified MDR strains were further tested for β-lactamase production. Multiplex PCR was used to identify the presence of mcr-1 and blaNDM-1 genes in MDR organisms. The minimum inhibitory concentration for ceftazidime and colistin was also determined, in addition to the biofilm inhibitor activity. Confocal microscopy was used to determine the production of biofilms.

Results

The isolated P. aeruginosa strains exhibited antibiotic resistance to aminoglycosides (amikacin and gentamicin). Fifty three percent of the isolated P. aeruginosa strains produced metallo-β-lactamase and the remaining isolates were non-metallo-β-lactamase type (46.8 %) (p < 0.0001). The MIC value of β-lactamase producers against colistin ranges from 0.5 µg/mL to 6 µg/mL. The MDR bacteria exhibited mcr-1 and blaNDM−1 genes. The MDR P. aeruginosa strain treated with colistin and ceftazidime inhibited initial biofilm formation. These combination of antibiotics effectively prevented initial biofilm development than individual antibiotics (p < 0.001).

Conclusions

The current analysis detected MDR among P. aeruginosa isolates that carried drug-resistant genes.