Molecular characterization of a Salmonella Typhimurium isolate from Caspian pony

Typhoid disease or salmonellosis is a common sickness in horses. In several epidemiological studies in hospitalized horses, several serotypes of Salmonella often are predominant in nosocomial infections. Transportation, overcrowding, dehydration, oral antimicrobial therapy and infections are the risk factors which may activate latent or subclinical salmonellosis. In this study, the occurrence of typhoid due to Salmonella serogroup B was considered in a Caspian ponies flock kept in a husbandry center of ponies around Tehran. During transportation of 19 ponies, two pregnant ponies aborted and four cases died because of acute septicemia. Pathological and bacteriological follow up showed salmonellosis. A multiplex polymerase chain reaction (m-PCR) assay was used for detection and identification of Salmonella to confirm pathological and bacteriological studies. Salmonella Typhimurium was isolated from bone marrow, mesenteric lymph nodes, liver and intestinal contents of died pony. Salmonella was not isolated from stools of other ponies. Pulsed Field Gel Electrophoresis (PFGE) and antibiotic susceptibility test were also performed. PFGE pattern was similar to the other collected isolates which have existed since more than 30 years ago in Iran. Because of importance of salmonellosis in ponies, using rapid methods are recommended to confirm the presence of Salmonella. Results showed that m-PCR permit to evaluate samples more rapidly than other methods and also can detect multiple genes simultaneously like virulence factors which declare virulence of the isolates and have surveillance significance.