Introduction: Cytolethal distending toxin (Cdt) is one of the bacterial toxins that present in a variety of Gram-negative human pathogens, such as E. coli, Salmonella spp., and Campylobacter spp. CDT composed of three subunits encoded by three adjacent genes, including cdtA, cdtB and cdtC. It is approved that cdtB had toxic activity and caused DNA damage of the host cell. Despite its presence in different bacterial species, role of Cdt in acute and chronic infections, such as gastroenteritis and irritable bowel syndrome (IBS) is unclear. To analyze this correlation, we studied the prevalence of cdtB among different enteropathogenic bacteria in patients with gastroenteritis and IBS compared with healthy people.
Materials and Methods: In this cross-sectional descriptive study, 230 stool samples were collected from patients with gastroenteritis, IBS, and healthy people. The presence of Cdt-B encoding bacteria, including Escherichia coli, Campylobacter spp., Yersinia entercolitica, Providencia alkalifacience, and Salmonella enterica was examined by polymerase chain reaction using genus specific primers.
Results: Out of 230 stool samples, Cdt-B encoding Campylobacter spp. were found in 34.6% (52/150), 6.25% (5/80), and 4% (2/50) of the patients with gastroenteritis, IBS, and the control group, respectively. Carriage of Cdt-B encoding Salmonella enterica was characterized among 5.3% (8/150) of the patients with gastroenteritis and 17.5% (14/80) of the IBS patients. Although none of the patients carried cdtB of E. coli and Providencia spp., cdtB of Y. enterocolitica was detected in 1 of the patients with gastroenteritis (0.6%). Statistical analysis showed significant correlation between infection with CdtB-encoding Campylobacter spp. and IBS-D subtype. No significant correlation was found between infection with Cdt-B encoding bacteria, and other clinical and demographic data.
Conclusion: Our results confirmed relatively higher frequency of Cdt-B encoding bacteria in the intestine of IBS patients and those with gastroenteritis compared with healthy individuals. Regarding the frequency of Cdt-B encoding Salmonella and Campylobacter bacteria, it was proposed that infection with these enteropathogens could be considered as a risk factor for the development or progression of IBS among the Iranian patients. Further studies are needed to establish this involvemet.