Detection of blavim genes in clinical isolates of carbapenem-resistant, metallo-β-lactamase producing Pseudomonas aeruginosa
Acquired metallo-β-lactamases (MBLs), associated with multidrug resistance in Gramnegative bacteria, pose serious challenges in hospitals, limiting the choice of therapeutic agents in life threatening infections such as bacteremia, lower respiratory tract and urinary tract infections. In Nigeria, there is need to prioritize research and surveillance to mitigate the impact of multidrug resistance. Ten clinical samples of Pseudomonas aeruginosa were screened for carbapenem resistance (CR) using imipenem and meropenem. Carbapenem Inactivation Method (CIM) was used to screen the CR isolates for MBL production. Polymerase chain reaction (PCR) was used to detect blaVIM genes. 60% of P. aeruginosa isolates were sensitive while 40% were resistant to carbapenems. All isolates were sensitive to colistin sulphate (control). All four CR strains showed MBL production as well as the presence of blaVIM genes. These findings reveal that MBL production is a mechanism of carbapenem-resistance in four CR isolates. The genetic basis of carbapenem-resistance found in this study is Verona integron-encoded metallo-β-lactamase (blaVIM) gene, which encodes meropenamase, an MBL. P. aeruginosa strains that produce meropenamase enzyme use this enzyme to inactivate meropenem, which makes them resistant to this drug. In Nigeria, the impact of multidrug resistance on health could be dire if urgent interventions are not put in place to stop the spread of CR-MBL pathogens. Improving healthcare, funding research efforts, surveillance, formulation and regulation of antimicrobial stewardship policies, will all contribute immensely to reduce the dissemination of MBLs.
Keywords: Carbapenem-resistance, Lagos, metallo-β-lactamase, blaVIM, Pseudomonas aeruginosa, surveillance.