Antibacterial effect of different vitamin C formulations on multi-drug resistant Salmonella serovars recovered from broiler chickens.

There is a great exertion to look for the alternative therapeutic methods that assist in controlling the antibacterial resistance of Salmonellae. The aim of this study was to evaluate the antibacterial effect of vitamin C (ascorbic acid) different formulations at different concentrations. Serotyping of the isolates revealed that 10 belonged to S. Enteritidis 1,9,12:g,m, 7 S. Virchow 6,7,14:r:1,2, and 3 S. Montevideo 6,7,14:g,m[p],s :[1,2,7]. The isolates were highly resistant (100%) to amoxicillin-clavulanic acid, streptomycin, erythromycin, clindamycin, and doxycycline, and 90% of the isolates were susceptible to amikacin. PCR revealed that 10 S. Enteriditis isolates harbored 3 virulence-associated genes invA, sefA, and fimH, while 7 isolates harbored stn gene. Also, 10 S. Enteriditis isolates harbored sul1 and blaTEM genes. Biofilm formation was 100%, 50%, and 42.8% in S. Montevideo, S. Enteritidis, and S. Virchow, respectively. Vit C; (formulation1) completely inhibited the growth of all isolates at concentrations of 0.3, 0.5, and 1%, (formulation 2) inhibited the growth of the tested isolates at concentration of 0.3% while, at concentration of 0.1% inhibited only the growth of S. Virchow, (formulation 3) inhibited the growth of S. Enteritidis and S. Virchow at concentrations of 0.3 and 0.5%, (formulation 4) inhibited the growth S. Enteritidis, S. Virchow, and S. Montevideo at concentration of 1%, and (formulation 5) inhibited the growth of S. Enteritidis and S. Virchow at concentrations of 0.1, 0.5 and 1%. Formulations (4 and 1) effectively inhibited S. Enteritidis and S. Virchow biofilm-forming ability with 80%, 100% and 60% and 66.6%, respectively.