Molecular detection of carbapenemases and ESBLs in Gram negative bacilli isolated from broiler chickens infected with respiratory tract infections in Mosul city, Iraq

Abstract

The current study aims to detect the presence of β-lactamase enzymes in Gram-negative bacilli isolated from broiler chickens infected with respiratory tract infections in Mosul city. After cultivation on MacConkey agar, 55 isolates were obtained from 45 samples, they distributed as follows: Escherichia coli 56.36%, Klebsiella pneumoniae 14.54%, Pseudomonas aeruginosa, Proteus mirabilis and Proteus vulgaris 12.7%, 10.9%, and 5.5%, respectively. Antimicrobial susceptibility testing results showed absolute resistance to cefotaxime and nalidixic acid, high resistance to tetracycline and ciprofloxacin reached 96.4% and 94.6%, and low resistance to meropenem and imipenem with rates of 12.7% and 14.5% respectively. The results showed that all the isolates were Multiple Drug-Resistant (MDR), 96.36% of them were Extensively Drug-Resistant (XDR), while two isolates (3.63%) were Pan Drug-Resistant (PDR). Six most resistant isolates were selected and their identification was further confirmed by molecular method depending on 16s rRNA  gene. Phenotypic and molecular detection of carbapenemases and ESBLs was performed for the six isolates. Phenotypically, all isolates were ESBLs producers and five isolates out of six (83.3%) were carbapenemase producers. These detection tests were molecularly confirmed using 14 gene primers (NDM, IMP, KPC, GES, NMC-A, OXA23, OXA48, OXA58, VIM, SPM, SIM, TEM, SHV, CTX-M). The results revealed the presence of VIM and NDM carbapenemase genes at a rates of 83.3% and 33.3%, respectively. TEM and SHV ESBL genes were detected in all isolates (100%), while CTX-M detection rate was 66.6%. Negative detection rates were recorded for the rest of the genes.