BACKGROUND: Evidence exists of a link between chronic infection by Salmonella typhi (S. typhi) and the development of gallbladder cancer (GBC), but several studies from endemic regions contradict its role in the etiopathogenesis of GBC. This study used various tools to assess the prevalence of S. typhi in patients with GBC and gallstone disease (GSD) in this region with a high incidence of GBC.
METHODS: S. typhi was detected in tissue and bile by PCR and culture and in serum by the Widal test and indirect hemagglutination assay (IHA). PCR with two pairs of S. typhi specific primers (flagellin gene H1d and SOP E gene) could detect 0.6 ng of S. typhi DNA. Fifty-four patients with GBC (cases) were matched with 54 patients with GSD (controls).
RESULTS: Of the 54 cases, 24 (44.44%) were positive on the Widal test and 12 (22.22%) on IHA, compared to 13 (24.07%) and 5 (9.26%) respectively in the controls. Eighteen (33.33%) cases showed a positive result on PCR (tissue) and 2 on PCR (bile) vs. none in the controls. Bile culture revealed no Salmonella colonies in either cases or controls. Only 3 cases were positive for Salmonella on tissue culture compared to none in the controls. The sensitivity of PCR (tissue) relative to the Widal test, IHA, culture (bile and tissue) and PCR (bile) was 100% vs. 66.67%, 11.11%, and 11.11%, and the specificity was 83.33% vs. 100%, 100%, and 100%, respectively.
CONCLUSIONS: S. typhi is significantly associated with GBC compared to GSD (33% vs. 0%). PCR appears to be the most specific diagnostic tool, the gold standard for S. typhi in tissue samples.