The molecular investigation of widespread Salmonella serovars, S. typhimurium and S. enteritidis, involved in salmonellosis of cattle and sheep in farms around Tehran, Iran

Salmonellosis as an important zoonotic disease that causes food born poisoning in human through animal products and is considered as a worldwide public health hazard. Widespread studies have been conducted on different aspects of incidence, treatment and control of salmonelosis all over the world. The aim of this study was to evaluate the occurrence of widespread Salmonella serovars, S. typhimurium and S. enteritidis, isolated from an outbreak of salmonelosis in cattle herds and sheep flocks around Tehran, in summer 2009, using molecular (PCR and multiplex PCR) and conventional (bacterial culture, serology and antibiogram) tests. Tissue and faecal samples were collected from 8 calves, 5 lambs and 2 aborted cattle embryos. All involved cases were animals less than 2-month-old and the presence of Salmonella serovars were confirmed in all isolates. The infection of S. enteritidis was much more prevalent in comparison to the S. typhimurium, which was statistically meaningfull (P<0.05). Virulence gene (spv gene) of S. enteritidis was shown on 250 bp fragments in most of the organ isolates. Specifically the virulence gene was shown in all isolates of aborted fetus tissue cultures, through the molecular survey. In two calves, both S. typhimurium and S. enteritidis were detected and S. typhimurium was isolated from liver in both cases. All isolates were sensitive to streptomycin, lincospectin, enrofloxacine and trimetoprim and were resistant to doxycycline and erythromycin.