Frequency of SPI-3 among salmonella serovars: Typhi,Paratyphi B and Paratyphi C

Salmonella spp. are enteric pathogen with a worldwide distribution comprising a large number of serovars. Many virulence factors of Salmonella are encoded by located genes on Salmonella pathogenicity islands (SPIs). This study was conducted to investigate the distribution of two SPI-3 related genes in among three serotypes of Iranian salmonella: typhi, paratyphi B and paratyphi C.
A total of 25 salmonella strains were isolated from Iranian patients with clinical symptoms of salmonellosis. All isolated belong to salmonella serotypes of typhi, paratyphi B and paratyphi C. Salmonella isolates were screened for the presence of mgtC and misL genes by PCR amplification method.
Among 25 salmonella strains, 20 (80%) were positive for SPI-3 region. The presence of misL gene in these serotypes of salmonella was as follows: typhi (100%), Paratyphi C (33%), Paratyphi B (25%) and for mgtC: typhi(97%), paratyphC(33%), paratyphiB(0%).
the widely distribution of SPI-3 among Iranian salmonella isolates provide the basic information on the genetic background of virulence as well as molecular properties of three different serotypes of Salmonella. This is the first report on the distribution of SPI-3 in Salmonella isolates from Iran.