Molecular study of resistance genes in Escherichia coli isolated from chronic respiratory disease cases in broilers

Chronic respiratory disease is famous in poultry farming, mainly in broiler farms. The disease is caused by Mycoplasma species in participation with E. coli. Our study was conducted on CRD of broiler chickens to isolate and determine the resistance of Escherichia coli Seventy-four swabs of the internal organs of broilers (severe respiratory signs) were collected from different areas of Mosul from September 2021 to March 2022. MacConkey agar was used with cefotaxime (1 μg/ml) to grow the isolates, and they were incubated at 37 °C for 24 hours. Colonies were identified according to standard bacteriological methods. The cefotaxime-resistant E. coli isolates underwent DNA extraction. The polymerase chain reaction of Escherichia coli isolates was used for confirmation. The results of the existing study revealed that 61 samples appeared positive for bacterial isolation from 74 (82.4%). All isolates were resistant to an arsenal of antibiotics when testing their sensitivity to antibiotics, including azithromycin, levofloxacin, gentamycin, chloramphenicol…ext. Molecular detection of resistance genes showed that all isolates contained the CTX-M gene by 100%. In comparison, the TEM gene appeared in 52 isolates (85.25%), and only 9 (14.75%) isolates showed the SHV gene. In conclusion, our results shed light on the serious problem in poultry fields, which showed that Escherichia coli isolates contain genes with high resistance to antibiotics, which are the most widely used in the treatment of bacterial infections in these farms, which means the demand for introducing more novel antibiotics in the cure of poultry health problems