Prevalence of antibiotic resistance genes in different Salmonella enterica serovars isolated from national food outbreaks

Background Due to various reasons, outbreaks of foodborne diseases are spreading worldwide causing significant mortality and morbidity. The purpose of this study was the prevalence of antibiotic resistance genes in different Salmonella enterica serovars isolated from national food outbreaks. Materials and Methods From 360 stool swab samples, 39 Salmonella were isolated based on phenotypic tests. Then the frequency of qnr A, G test, A, qnr B, qnr S, gyr A, sul 1, sul 2, sul 3, tet A, tet B, and tet G resistance genes was assessed using PCR amplification followed by DNA electrophoresis. Also, the pattern of antibiotic susceptibility of the isolates was determined by disk diffusion method. Results Among 39 Salmonella isolates, 80% of them were resistant to at least two or more antibiotics. Out of resistant isolates, 7 isolates indicated resistance to cotrimoxazole, 5 of them had sul 2 gene and 2 carried sul 3 gene. All tetracycline-resistant isolates carried the tet A gene. Only one isolate was found as resistant to nalidixic acid, due to gyr A gene detection. Conclusion In this study an increase in antibiotic resistance was observed. Therefore, surveying the antibiotic resistance pattern in Salmonella and similar bacterial enteric pathogens should to be a priority for public health authorities.