Frequency of Salmonella infection among backyard and commercial duck flocks in Iran, serotyping and drug resistance profile of Salmonella isolated from ducks

Abstract

Salmonella is one of the most important food-borne infection with worldwide distribution that infects humans and a wide range of animals. Poultry and poultry products are considered major sources of Salmonella infections for humans. Like chickens, ducks can play an important role in the transmission of Salmonella bacteria to humans. The purpose of this investigation was to obtain more knowledge about the frequency of Salmonella infection in ducks in Iran, to determine the serovar and the antimicrobial resistance pattern of Salmonella isolates. In this study, fecal samples were collected from four provinces of Iran. Each six fecal samples were pooled and 352 samples was obtained in total. In order to isolate Salmonella, all samples were cultured according to the previously described standard techniques. From a total of 352 stool samples, 20 Salmonella isolates (17.6%) were isolated and serogrouped by using slide agglutination test and then were subjected to polymerase chain reaction with Salmonella genus- specific primers and species-specific primers for serovars Enteritidis, Typhimurium and Infantis. The disc diffusion method was used to determine the sensitivity of isolates to 21 antimicrobial agents. From a total of 352 stool samples, 20 Salmonella isolates (17.6%) were isolated from which 15 and three isolates were identified as serovars Enteritidis and Typhimurium, respectively. Two isolates remained unknown.  No isolate was resistant to ceftazidime, ceftriaxone, lincospectin, fosfomycin, and colistin. The resistance to other agents was variable. There were 17 resistance patterns to 21 antimicrobial agents. Among the resistant isolates, the occurrence of multiple resistance was very significant, so that they showed resistance to at least 1 and at most 11 drugs. By comparing the findings of this study and other investigation in this field, it was shown that, like chicken flocks, Salmonella are circulating in duck flocks of Iran.