Evolutionary relationships and genetic diversity in the BlaTEM gene among selected gram-negative bacteria

Abstract

This study investigates the genetic diversity and evolutionary relationships of the blaTEM gene, a major determinant of beta-lactam antibiotic resistance. We analyzed nucleotide sequences of 32 β-lactamase-producing strains from Klebsiella pneumoniae , Escherichia coli , Pseudomonas aeruginosa , Proteus mirabilis , and Acinetobacter baumannii obtained from public databases. Sequence analysis revealed 32 distinct sequences with 298 segregating sites and 303 mutations, indicating substantial genetic variability. A high level of haplotype diversity was observed, with 24 distinct haplotypes, reflecting evolutionary pressures and horizontal gene transfer. Phylogenetic analysis showed clear clades, suggesting the evolutionary relationships among blaTEM variants and interspecies gene transfer. The resistance profiles correlated with the genetic findings, particularly mutations. This analysis draws attention to the ongoing adaptive evolution of antibiotic resistance mechanisms, as well as the need for continued monitoring and novel therapeutic strategies. Further research with larger sample sizes and functional validation is needed to fully understand the implications of these variants in antibiotic resistance. • Genetic diversity of the blaTEM gene was analyzed in 32 β-lactamase-producing strains. • Sequence analysis revealed 32 distinct sequences with 298 segregating sites and 303 mutations. • High haplotype diversity was observed, with 24 distinct haplotypes linked to HGT. • Mutations at codons 179 and 238 confirmed in 15 strains, associated with β-lactam resistance. • HGT was observed in 8 out of 10 conjugation assays, supporting its role in resistance spread.