DNA Sequence Analysis of BlaVEB Gene Encoding Multi-drug Resistant and Extended-spectrum β-lactamases Producer Isolates of Enterobacteriaceae and Pseudomonas Aeruginosa

Abstract

Objective: Multi-drug resistance Gram-negative bacteria possessing Extended-Spectrum β-Lactamase (ESBL) genes are of concern because of their resistance to third-generation cephalosporins. This study aims to investigate the molecular basis of resistance to modern β-lactams by ESBLs encoded by the bla VEB gene and the gene’s role in resistance. Also, gene sequencing was used to compare genetic similarities with global isolates using phylogenetic and cluster analyses. Methods: Between March and July 2018, a total of 100 Iraqi clinical isolates were examined, in this cross-sectional study, to determine their ESBL status using the double-disc synergy technique. Polymerase Chain Reactions (PCRs) were performed on extracted blaVEB genes and sequencing of the target PCR products was performed. All blaVEB sequences were compared with the available sequence data, using BLAST searches against the GenBank database. Results: A total of 35 isolates, comprising 5 Escherichia coli, 18 Klebsiella pneumoniae, and 12 Pseudomonas aeruginosa isolates were confirmed to possess ESBLs; the blaVEB gene was detected in one isolate of each species. The sequencing of these genes revealed 99% similarity with the global standard genes deposited in GenBank. Conclusions: The bla VEB gene plays an essential role in the resistance of ESBL-producing isolates to new β-lactams. Further, the sequencing and phylogenetic analyses of the genes from the P. aeruginosa, K. pneumonia, and E. coli isolates revealed 99% similarity with the GenBank global standard genes.