Cytolethal distending toxin-producing strains causing severe diarrhoea in young Mexican children.

Cytolethal distending toxins (CDTs), encoded by genes, have DNase activity leading to cellular and nuclear distension, resulting in irreversible cell cycle arrest and apoptosis of target cells. -positive strains have been isolated from children with diarrhoea. There is, however, scant information on the prevalence and clinical presentation of diarrhoeal disease caused by these strains. Furthermore, toxin production of -positive strains is rarely confirmed. We report five young children with diarrhoea caused by CDT-producing in whom stools were negative for other bacterial or enteric pathogens. On admission to hospital, all children presented watery diarrhoea with high stool output (range 7-20 stools/24 h); five had fever of 38 °C or more and four presented vomiting. Dehydration was present in four patients, one of whom had hypovolaemic shock; one child also presented hyponatraemia and hypokalaemia. In two children, -positive strains were classified as typical and atypical enteropathogenic , and the remaining three harboured -positive strains that did not belong to any diarrhoeagenic pathogroup. One -positive strain from each case was characterized by a CDT cytotoxic assay and a type-specific PCR. All strains produced the characteristic cellular intoxication due to CDT. Two strains carried the -, one -, one -, and one concurrently had and - genes. Our results suggest that CDT-producing strains are an infrequent, albeit significant, cause of severe diarrhoeal illness in children. Future research should measure the true burden of -positive diarrhoea among children.