Molecular epidemiology of systemic Salmonella enterica serovar Typhimurium outbreak in canaries

In May 2007, high mortality with severe septicemia was reported in 17 flocks of canaries in different regions of Tehran province. This study was designed to follow up and study a great outbreak of salmonellosis in these canaries. Two carcasses from every flock, environment, food and water resources were examined. After isolating the bacteria, serotyping and multiplex PCR were performed to confirm the bacteria identified. The isolates within thesame serovars were investigated by R-typing using 33 antibiotics and then subjected to RAPD-PCR with three primers. The genomic DNA from these isolates were digested with XbaІ and the macro restriction fragment were separated by PFGE. S. Typhimurium was isolated from dead carcasses, visceral organs, stools and feed. Thirty-six isolated strains (35 isolates from canary carcasses and one isolate from feed) showed similar results in all of the tests, confirming the occurrenceof an outbreak. Canaries seem to be very susceptible to infection with S. Typhimurium. The clonality of isolated organisms andits characteristics is significantly important due to the severe septicemia and high mortalities in this outbreak and its public health threats. Environmental contamination within the cages, and food contaminated with stools of other canaries were the sources of infection. Inspection for food hygiene, daily cleaning of canary’s cage from stool and carrier insects and rodents are necessary to prevent such outbreaks. Combination of R-typing, RAPD-PCR and PFGE increase the differentiation power of isolates, however, they showed clonality of S. Typhimurium involved in this outbreak.