Proinflammatory Cytokines Associated with InvA and PagC Genes of Salmonella typhi Isolated from Patients Undergoing Cholecystectomy

Objective: Cholecystectomy is the surgical removal of the gallbladder. The gallbladder is often colonized by Salmonella during typhoid fever. The association between cytokine and virulence genes of Salmonella is not well known. The current study aims to identify the association between proinflammatory cytokines, TNF-α and IFN-γ, and two virulence genes, InvA and PagC, extracted from S. typhi isolates obtained from patients undergoing cholecystectomy. 
Materials and Methods: One hundred and fifty clinical specimens, including gallbladder tissues and blood, were collected from patients undergoing cholecystectomy at AL-Sadder Medical City and AL-Furat General Hospital/Iraq from December 2019 to September 2020. A Monoplex PCR technique was used to detect InvA and PagC, and an enzyme-linked immunosorbent assay was used to measure serum levels of TNF-α and IFNγ. 
Results: From a total of 66 S. typhi isolates, the prevalence of InvA and PagC was (84.8% and 69.6%) respectively. Even after adjusting for potential confounding factors, serum levels of TNF-α and INF-γ were statistically significantly higher in PagC detected in S. typhi isolates compared to PagC not detected (p-value<0.001), but there was no significant difference between InvA detected in S. typhi isolates and InvA not detected (p-value > 0.05). 
Conclusion: The virulence genes of S. typhi, especially PagC, may be considered a potent inducer of proinflammatory cytokine secretion. Further studies are needed to present the patient‘s additional clinical course according to cytokine level.