Molecular characterization of some clinical Salmonella Typhi isolates as regard to ompX gene

Background: Salmonella is known for its ability to invade and survive within host cells, which is attributed to various virulence factors it possesses. These virulence determinants enable the bacteria to adhere to and invade host cells, bypass host immune defenses, and replicate within host cells, leading to the establishment of infection. This work aims to isolate and identify S.enterica through PCR and detect the ompx gene in clinical samples from human subjects. Methods: A total of 75 blood samples were collected from patients with food poisoning and diarrhea between June 2021 and March 2022 at Al-Diwaniyah General Hospital and from some patients under internal medicine care. Identification procedures included culturing, utilizing the Vitek-2 system, and confirmation through PCR and DNA sequencing analysis. Results: The isolates were distributed as follows: 10 (33.3%) for S. typhimurium, 8 (26.6%) for S. typhi, and 12 (40%) for S. paratyphi B. The molecular detection of the outer membrane gene (ompx) for Salmonella enterica serovar was conducted using conventional PCR, revealing a high prevalence of the ompx gene in 30 (100%) isolates. The in-silico analysis identified a missense mutation in the isolates within the ompX gene, leading to the replacement of certain amino acids. This substitution encompassed both conserved and non-conserved types of amino acids. These genetic variations were further supported by the construction of a phylogenetic tree, which illustrated the evolutionary relationships among these proteins and highlighted the genetic diversity present in the ompX gene. Conclusion: It is indeed concerning that virulence genes in Salmonella strains could be enhancing their pathogenicity and potentially leading to more widespread disease outbreaks. Monitoring and understanding the presence and expression of these virulence genes are crucial in order to effectively manage and mitigate the risk of such outbreaks. The molecular detection of some outer membrane genes (ompx) for Salmonella enterica serovar was done by conventional PCR technique. It was found that high occurrence of ompx gene with 30 (100%) of isolates.