Coexistence of virulence and ß-lactamase genes in avian pathogenic Escherichia coli.

Emergence of multidrug resistance in E. coli and advent of newer strains is becoming serious concern which requires keen observations. This study was designed to find the ciprofloxacin resistant E. coli isolates co-existed with multi-drug resistance along with ß-lactamase production from poultry source, and finally the genome sequencing of these strains to explore genetic variations. Study constituted on isolation of n = 225 E. coli from broiler farms of central China which were further subjected to identification of resistance against ciprofloxacin followed by antibiogram of n = 26 antibiotics and identification of ß-lactamase production. Whole genome resequencing was performed using Illumina HiSeq 4000 system. PCR results revealed predominant ß-lactamase genes i.e.CTX-M, CTX-M-1, CTX-M3, TEM-1 and OXA. Furthermore, the MDR isolates were containing most of the tested virulence genes. The most prevalent virulence genes were pap-C, fim-C, fim-H, iuc-D, irp-2, tra-T, iro-N and iut-A. The single nucleotide polymorphisms (SNPs) loci mentioned in this data give valuable genetic markers to growing high-throughput techniques for fine-determination of genotyping of MDR and virulent isolates. Characterization of SNPs on functional basis shed new bits of knowledge on the evolution, disease transmission and pathogenesis of MDR E. coli isolates. In conclusion, these findings provide evidence that most of poultry E. coli are MDR, ß-lactamase producers, and virulent which could be a zoonotic threat to the humans. The whole genome resequencing data provide higher resolution of resistance and virulence characteristics in E. coli which can further be used for the development of prevention and treatment strategies.

Genetic basis of molecular mechanisms in ß-lactam resistant gram-negative bacteria.

Antibiotic-resistant bacteria are considered one of the major global threats to human and animal health. The most harmful among the resistant bacteria are ß-lactamase producing Gram-negative species (ß-lactamases). ß-lactamases constitute a paradigm shift in the evolution of antibiotic resistance. Therefore, it is imperative to present a comprehensive review of the mechanisms responsible for developing antimicrobial resistance. Resistance due to ß-lactamases develops through a variety of mechanisms, and the number of resistant genes are involved that can be transferred between bacteria, mostly via plasmids. Over time, these new molecular-based resistance mechanisms have been progressively disclosed. The present review article provides information on the recent findings regarding the molecular mechanisms of resistance to ß-lactams in Gram-negative bacteria, including CTX-M-type ESBLs with methylase activity, plasmids harbouring phages with ß-lactam resistance genes, the co-presence of ß-lactam resistant genes of unique combinations and the presence of ß-lactam and non-ß-lactam antibiotic-resistant genes in the same bacteria. Keeping in view, the molecular level resistance development, multifactorial and coordinated measures may be taken to counter the challenge of rapidly increasing ß-lactam resistance.