Prevalence, molecular characterization and antimicrobial resistance among Escherichia coli, Salmonella spp. and Staphylococcus aureus strains isolated from Egyptian broiler chicken flocks with omphalitis

Abstract

Background: Bacterial Omphalitis has been reported as a significant cause of mortalities in newly hatched broiler chicks. Aim: This study aimed at assessment of the occurrence of omphalitis among broiler chicken in Gharbia governorate in Egypt. In addition, the bacteria associated with the occurrence of omphalitis in broiler chicken were also investigated and characterized. Methods: For this purpose, forty-three farms in that area were surveyed. The comparative levels of omphalitis caused by Escherichia coli (E. coli), Salmonella spp., and Staphylococcus aureus (S. aureus) were screened in 129 chicks. The drug resistance to eight commonly used antimicrobials in the Egyptian poultry farms was screened using the disk diffusion method. Results: The overall incidence rate of omphalitis was 37.21%. In birds with omphalitis, the co-prevalence of S. aureus, Salmonella spp., and E. coli was 87.5%. When compared to healthy flocks, broiler chicks with omphalitis caused by Salmonella spp., Escherichia coli, and S. aureus had a greater mortality rate in the first week of life. However, there were no significant differences in the mortality cases caused by these pathogens. Eighty-seven percent of the cases of omphalitis were linked to E. coli, and seventy-five percent to Salmonella spp. and S. aureus. From the yolk sac of broiler chicks with omphalitis, E. coli, Salmonella spp., and S. aureus were isolated at rates of 87.5%, 62.5%, and 45.8%, respectively. The isolates of E. coli and Salmonella spp. exhibited great sensitivity to Gentamycin and Tetracycline, however the strongest drug resistance was observed towards Cefpodoxime, Sulphamethoxazole & trimethoprim, Ampicillin, and Amoxycillin & Clavulanic acid. The recovered isolates of S. aureus showed susceptibility to chloramphenicol (72.37%), oxytetracycline (81.82%), and erythromycin (81.82%). However, every S. aureus isolate that was found resistant to amoxycillin and clavulanic acid, penicillin G and oxacillin. The existence of blaTEM, blaSHV, and blaCTX-M genes has been proposed as the genetic cause of β-lactam antibiotic resistance in Salmonella spp. and E. coli. MecA and blaZ, however, were found in every strain of S. aureus. Conclusion: The frequency of omphalitis and its-associated mortalities was comparatively high in Gharbia governorate. More efforts should be done to adopt strict hygienic standards for controlling and preventing such disease and this will consequently lead to minimizing the use of antimicrobials in poultry farms.