Cytolethal Distending Toxin in Salmonella and Campylobacter spp. Isolated from Food Animals and Gastroenteritis Cases in Qatar

BACKGROUND- Campylobacter and Salmonella are two of the major foodborne pathogens that contribute to the burden of disease. The cytolethal distending toxin (CDT) has been identified as one of the virulence factors that may contribute to pathogenesis and gastroenteritis. The CDT is a trimeric subunit toxin produced by gram-negative bacteria that initiates cell-cycle arrest and causes affected cells to die by apoptosis. This study investigated the occurrence of CDT among Salmonella and Campylobacter spp. isolates recovered from animals along the food supply chain and from gastroenteritis cases in Qatar.METHODS- Samples were screened for the presence of the two pathogens using a combination of bacterial enrichment and molecular detection and positive samples were examined for the presence of CDT using a polymerase chain reaction (PCR) approach. RESULTS- C. jejuni and C. coli occurred at similar rates among non-human sources, whereas C. jejuni occurred at a higher rate compared to C. coli in human cases. Both cdtB and cdtC were detected at a higher rate among C. jejuni than C. coli recovered from human cases. Only cdtB was detected in Salmonella spp. isolates from animals and at a much lower rate.CONCLUSIONS- The presence of CDT in isolates recovered from gastroenteritis cases suggests a role in the pathogenesis of the condition. Furthermore, the detection of CDT among food animal isolates along the food supply chain highlights the potential zoonotic risk.