Detection of Salmonella enterica serovar Infantis among serogroup C Salmonella isolates from poultry using PCR and determination of drug resistance patterns

Salmonellosis is an important zoonotic disease that is caused by a variety of Salmonella serovars. Our recent surveys from the Iranian poultry flocks have shown a high prevalence of serogroup C among Salmonella isolates. Because Salmonella ser. Infantis is a member of serogroup C and an important zoonotic agent as well، this study was conducted to determine the detection of Salmonella ser. Infantis among a large collection of serogroups C Salmonella isolates available in our laboratory. A total of 100 serogroup C Salmonella isolates originated from broiler chickens were selected from our bacterial collection in the Department of Avian Diseases، Faculty of Veterinary Medicine، University of Tehran. Using PCR and by application of primers specific for Salmonella ser. Infantis، the prevalence of this serovar was detected among 100 isolates. Then، using the disk diffusion procedure، the drug resistance patterns of S. ser. Infantis isolates were determined against a panel of antibacterial agents commonly used in medicine and veterinary medicine. The results showed that among 100 serogroup C Salmonella isolates، %79 isolates belonged to S. ser. Infantis. Antimicrobial susceptibility test revealed that all isolates were sensitive to florfenicol and danofloxacin. The highest antimicrobial resistance was seen for tetracycline، nalidixic acid and furazolidone. Among the resistant isolates، multidrug resistance was widespread and resistance to at least 4 and at most 11 compounds were observed. This study showed a high prevalence of S. ser. Infantis with high drug resistance among broiler flocks which is very critical due to the public health and zoonotic issues related to this serovar.