Epidemiology and high incidence of Metallo-β-lactamase and AmpC-β-lactamases in nosocomial Pseudomonas aeruginosa

Objective(s): Isolates producing Metallo-β-lactamase (MBL) have a significant impact on therapeutic and diagnostic layouts, plus their increased frequency has been reported globally. Determination of incidence of clinical isolates of Pseudomonas aeruginosa that are capable of producing MBL and AmpC-β-lactamases making them resistant to imipenem and cefoxitin. Materials and Methods: Out of ۱۱۵۹ collected samples of urine, wound swabs, blood, tissue, and pus, the isolation rate of P. aeruginosa in the period of March ۲۰۲۰ to February ۲۰۲۱ was ۲۲.۰% (۲۵۵/۱۱۵۹). Bacterial strains that were resistant towards imipenem were further processed for detecting the β-lactamase group of genes followed by statistical analysis of risk factors done based on clinical sample, gender, plus department of sample collection. Results: The percentage of resistance against imipenem was found to be ۵۳%. Out of ۱۳۵ strains, phenotypic tests revealed MBLs incidence to be ۶۱.۵% by combination disc test and ۸۱.۵% by Modified Hodge test (MHT). Frequencies of blaIMP-۱, blaVIM, blaSHV, blaTEM, and blaOXA genes were calculated to be ۱۳%, ۱۵%, ۳۲%, ۴۳%, and ۲۱%, respectively. Co-expressions of blaMBLs (blaVIM and blaIMP-۱) plus blaESBL (blaSHV, blaOXA, blaTEM) were detected using simplex and multiplex PCR. blaTEM, blaSHV, and blaOXA co-existed in ۷.۵% of clinical isolates. ۵.۵% of the isolates exhibited simultaneous expression of MBL/ESBL genes. ۱۵% of the isolates resistant to cefoxitin were positive for the blaAmpC gene (۱۷/۱۱۴).Conclusion: This is a pioneer report from Pakistan that concomitantly presents expression of blaVIM and blaIMP-۱ with blaTEM, blaOXA, blaSHV, and blaAmpC in isolates of P. aeruginosa.

Keywords:

Antibiotic resistance , Beta-lactamases , Infections , MDR genes , Pseudomonas aeruginosa