Antibiotic resistance and virulence profiles of Salmonella serovars isolated from broiler chickens

This study investigated the antibiotic sensitivity and virulence of Salmonella serovars isolated from 86 freshly dead chicks suffered from white diarrhea. A total of 7 strains out from 334 samples of (liver, spleen, heart blood, intestinal content) were detected. The sensitivity tests examined against different eight antibiotics: ampicillin, amikacin, gentamicin, cefotaxime, vancomycin, erythromycin, ciprofloxacin, and cefepime. All Salmonella strains displayed resistance to ampicillin, gentamicin, vancomycin, and erythromycin. S. Ruiru exhibited the most extensive resistance profile, being resistant to all antibiotics except cefotaxime. ciprofloxacin was ineffective against S. Typhimurium from liver samples and S. Stanleyville. All strains except S. Ruiru were susceptible to cefepime. Virulence testing revealed that only S. Typhimurium (one strain) and S. Ruiru produced a hemolytic zone. S. Stanleyville, S. Cerro, and S. Ruiru displayed lipolytic and starch hydrolysis activity. None of the strains exhibited proteolytic or DNAse activity. Molecular analysis for the resistance genes “blaTEM , ereA , aadB , qnrA, vanA” and virulence gene “invA” gene showed presence of “invA” gene, balTEM gene, and qnrA gene in all examined salmonella serovars. While the ereA gene was found in all samples except S. Typhimurium from the intestine and the aadB gene was present in all samples except S. ruiru Although, the vanA gene was detected only in S. Typhimurium from the intestine, S. Ruiru and S. Cerro. In conclusion, the isolated Salmonella serovars exhibited varying degrees of antibiotic resistance and virulence.