Epidemiological, molecular characterization and antibiotic resistance of serovars isolated from chicken farms in Egypt.

Background: is one of major causes of foodborne outbreaks globally. This study was conducted to estimate the prevalence, typing and antibiotic susceptibilities of serovars isolated from 41 broiler chicken farms located in Kafr El-Sheikh Province in Northern Egypt during 2014-2015. The clinical signs and mortalities were observed.

Results: In total 615 clinical samples were collected from broiler flocks from different organs (liver, intestinal content and gall bladder). infection was identified in 17 (41%) broiler chicken flocks and 67 isolates were collected. Recovered isolates were serotyped as 58 (86.6%) serovar Typhimurium, 6 (9%) serovar Enteritidis and 3 (4.5%) were non-typable. The significant high mortality rate was observed only in 1-week-old chicks. E gene was detected in 92.5% of the isolates which indicating their ability to infect humans. All serovar Enteritidis isolates were susceptible to all tested antimicrobials. The phenotypically resistant serovar Typhimurium isolates against ampicillin, tetracycline, sulphamethoxazole and chloramphenicol were harbouring TEM, (A and C), (1 and 3) and (1 and R), respectively. The sensitivity rate of serovar Typhimurium to gentamycin, trimethoprim/sulphamethoxazole and streptomycin were 100, 94.8, 89.7%, respectively. The silent streptomycin antimicrobial cassettes were detected in all serovars. A class one integron (A12, F and A2) was identified in three of serovar Typhimurium strains.

Conclusions: To the best of our knowledge, this study considered first report discussing the prevalence, genotyping, antibiotic susceptibility and public health significance of serovars in broilers farms of different ages in Delta Egypt. Further studies are mandatory to verify the location of some resistance genes that are within or associated with the class one integron.