Antimicrobial Resistance and Virulence Genotyping of Different Salmonella Serovars Isolated from Chickens in Egypt

Abstract

Twenty eight Salmonella strains representing 9 Salmonella serovars (S.Agama, S.Blegdam, S. Enteritidis, S.Gueuletapee, S.Infantis, S.Kentucky, S.Montevideo, S.Typhimurium and S.Virchow) were previously isolated, purified, and identified in our laboratory from freshly dead and diseased chickens suspected to infect with Salmonellosis. In the present study, antimicrobial resistance to 15 different antimicrobials and virulence genotyping to those Salmonella strains were performed. The significantly higher rate of resistance was detected against amoxicillin-clavulanic acid (AMC) and ampicillin (AMP) (85.7% and 78.5% respectively) comparing to the significantly lower rate of resistance detected against etapenem (ETP), gentamicin (GEN), ciprofloxacin (CIP), and norfloxacin (NX) (0 %, 0%, 3.5%, and 3.5% respectively). High resistance to cephalosporin antibiotics were also reported in this study. Resistance to 3 antimicrobials or more were identified in 17 out of 28 tested Salmonella strains. Interestingly, two S. Typhimurium strains were resist to 9 and 12 out of 15 antimicrobials used in this study. A multiplex Polymerase chain reaction (PCR) targeting 17 virulence genes was performed for virulence genotyping among different strains. Interestingly, all 17 virulence genes were detected in S. Infants and one strain of S. Agama. From a public health aspect, continuous resistance of Salmonella spp. to antimicrobials represent a serious public health hazard. Furthermore, Identification of virulence genes can help us to further understanding of Salmonella pathogenesis.