Antimicrobial resistance profiles and virulence genotyping of Salmonella enterica serovars recovered from broiler chickens and chicken carcasses in Egypt

BACKGROUND: This study aimed to survey the prevalence, antimicrobial resistance, and virulence-associated genes of Salmonella enterica recovered from broiler chickens and retail shops at El-Sharkia Province in Egypt. Salmonella virulence factors were determined using the polymerase chain reaction assays targeting the invA, csgD, hilC, bcfC, stn, avrA, mgtC, ompF, sopE1 and pefA genes. RESULTS: One hundred tweenty out of 420- samples from broiler chickens’ cloacal swabs, farm environmental samples, and freshly dressed whole chicken carcasses were positive Salmonella species. The isolates were serotyped as S. Enteritidis as the most dominant serotypes. Interestingly, none of the isolates were resistant to imipenem. The multidrug resistance was determined in 76.7% of the isolates with multidrug antibiotic resistance index of 0.2–0.6. Eight virulence genes (invA, csgD, hilC, stn, bcfC, mgtC, avrA, and ompf) were characterized among 120 S. enterica isolates with variable frequencies, while sopE1and pefA genes that were completely absent in all isolates. Based on the combination of presence and absence of virulence genes, the most common genetic profile (P7, 30%) was invA and csgD genes. CONCLUSION: S. Enteritidis and S. Typhimurium were the most common identified serotypes in the examined sources. Circulation of such strains in broiler farms required introducing special biosecurity and biocontrol measures for control of Salmonella. Such measures might limit the adverse effects of antibiotics and ensure the safety of the environment and animal-derived food. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12917-019-1867-z) contains supplementary material, which is available to authorized users.