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 to assess the occurrence of omphalitis among broiler chickens in Gharbia governorate in Egypt. In addition, the bacteria associated with the occurrence of omphalitis in broiler chickens were also investigated and characterized.

Methods: For this purpose, 43 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 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., E. 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 75% 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 toward cefpodoxime, sulphamethoxazole and trimethoprim, ampicillin, and amoxycillin and 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. 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 made 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.

Keywords: Antimicrobial resistant.; Escherichia coli; Omphalitis; Salmonella spp; Staphylococcus aureus.

Fig. 1.. Mortality rate (%) observed in broiler chicken flocks from the screened farms in Gharbia governorate, Delta Egypt.

Fig. 2.. PCR amplification of the causative agents of Omphalitis in 1-week-old broiler chickens. (A) phoA gene-specific genomic markers for E. coli (representative). (B) invA specific marker for Salmonella (representative). (C) S. aureus 23S rRNA genes.

Fig. 3.. Antimicrobial sensitivity testing of the recovered A) E. coli, B) Salmonella spp., and C) S. aureus isolates against antimicrobials that are most commonly used in the Egyptian drug market for broiler chickens using the disk diffusion method.

Fig. 4.. Electrophoresis of β-lactamases associated with β-lactams resistance in E. coli, Salmonella spp., and S. aureus isolated from Egyptian broiler chicken farms with omphalitis. (A) PCR amplification of blaTEM gives an expected band segment at 516 bp, lane 1–7 representative for Salmonella positive strains while lane 8–14 representative for E. coli positive isolates (B) the expected band segment of bla_SHIV at 392 bp, lane 1–7 representative for Salmonella positive strains while lane 8–14 representative for E. coli positive isolates (C) the amplification of bla_CTXM gives an expected band at 593 bp lane 1–7 representative for Salmonella positive strains while lane 8–14 representative for E. coli positive isolates (D) lane 1–7 for mecA in S. aureus with expected band size 310 bp while lane 8–14 presentative for 14 for blaZ in S. aureus with expected band size 833 bp. Lane L is a 100bp DNA ladder.