Plasmid Profile and Enterobacterial Repetitive Intergenic Consensus-PCR Characterization of Salmonella Infantis Isolates Recovered From Poultry Sources

Salmonella is known as one of the most important bacterial agents infecting both humans and animals. Salmonella Infantis has been reported as one of the 15 most prevalent serovars worldwide. Despite its clinical importance, there is little information on the molecular characteristics of S. Infantis in Iran. 

This study was conducted to characterize S. Infantis isolates collected from poultry sources in the last decade. The isolates were typified by plasmid profile and enterobacterial repetitive intergenic consensus (ERIC-PCR). 

Forty S. Infantis isolates from poultry sources were subjected to plasmid profile and ERIC-PCR characterization. We used a commercial plasmid extraction kit to extract and purify plasmid DNA which then was separated by gel electrophoresis and viewed under a UV transilluminator. For ERIC-PCR, a commercial bacterial chromosomal DNA extraction kit was used. In this study, we chose ERIC2 primer for the ERIC-PCR test. 

The plasmid profile revealed that 35% of isolates did not contain any plasmids, but the rest (65%) carried a variable number of plasmids with different molecular weights. Six plasmid profiles were found among 40 S. Infantis isolates. Using ERIC2 primer, 7 profiles were found among 40 S. Infantis isolates in ERIC-PCR. Bands with molecular weights ranging from 400 to 3000 bp were observed.

This study provided some genetic data on S. Infantis isolates recovered from poultry sources, and these data can be used for a broader epidemiological study nationwide. These findings showed that although plasmid and ERIC profiles are valuable in epidemiological studies, they have some limitations, too.