Beta (â)-lactamases are the most important agents that confer drug resistance among gram-negative bacteria. Continuous mutations in â-lactamases make them remarkably diverse. We carried out the transcriptome analysis of 10 â-lactamase genes of Extended-Spectrum â-lactamases (ESBL), Metallo â-lactamases (MBL), and AmpC â-lactamases (ABL) in drug-resistant and sensitive diarrheagenic E. coli (DEC) isolates obtained from children up to 5 years of age. Out of the 10 â-lactamase genes, four belonged to ESBL (TEM, SHV, CTX, and OXA); three to MBL (NDM-1, IMP, and VIM); and three to ABL (ACT, DHA and CMY) class of genes. The different categories of DEC were estimated for â-lactamases production using a set of conventional phenotypic tests, followed by detection of their messenger RNA (mRNA) expression. The study revealed a direct correlation between mRNA expression of these genes and the presence of antibiotic resistance; also corroborated by mutation analysis of the AmpC promoter region. All the 10 â-lactamase genes showed a significant increase in their expression levels in resistant isolates, compared to those of the sensitive isolates, indicating their possible role in the disease pathogenesis. Increase in mRNA expression of â-lactamase genes, and thereby virulence, may be due to multifactorial parameters causing phenotypic as well as genotypic changes. Our study highlights the necessity of instantaneous detection of â-lactamase gene expression to curb the overwhelming threat posed by emergence of drug resistance amongst the commensal E. coli strains in children from developing countries for larger public health interest.
Anti-Bacterial Agents Child, Preschool