The use of serodiagnosis in the retrospective investigation of a nursery outbreak associated with Escherichia coli O157:H7

AIMS

To use serology to investigate an outbreak of verocytotoxin (VT) producing Escherichia coli O157 in a hospital nursery, following the detection of faecal E coli O157 (phage type 49) producing VT type 2.

METHODS

ELISA and immunoblotting techniques, based on lipopolysaccharide (LPS) purified from E coli O157; diagnostic bacteriology; serotyping and phage typing; DNA probes for VT.

RESULTS

29 of 126 sera contained antibodies to the LPS of E coli O157: 10 were from children, three were from staff, and 11 were from hospital kitchen staff. Five parents of children attending the nursery were antibody positive. Sixty four sera from other hospital staff and controls did not contain antibodies to the LPS of E coli O157.

CONCLUSIONS

Serology detected evidence of infection with E coli O157 in 23% of sera examined. By bacteriology alone, only a single case of infection with E coli O157 would have been detected. Serology is valuable in providing evidence of infection with E coli O157.

Colocolic intussusception in a three-year-old child caused by a colonic polyp

Colocolic intussusception is an uncommon cause of pediatric intestinal obstruction in North America; 95% of cases are ileocolic in location, with an equal percentage in which no pathologic lead point is evident on barium enema or laparotomy. In the last 20 years less than 3% of approximately 32,500 reported cases of intussusception originated in the colon. In a significant number of these cases juvenile polyps were identified as leading points. The majority of juvenile polyps occur in the rectosigmoid colon within the reach of a standard pediatric sigmoidoscope. These tumors most often cause painless hematochezia. Occasionally, juvenile polyps may grow large and serve as lead points for colocolic intussusception when located in the proximal colon. Pediatric patients presenting with documented colocolic intussusception should suggest the possibility of a colonic polyp or other mass lesion. Careful physical examination and barium studies should provide important diagnostic clues. Treatment is aimed at removing the lead point in patients presenting with intestinal obstruction. Colonoscopic polypectomy performed by an experienced endoscopist may serve as an alternative to surgical removal of the polyp. We report a case in a three-old-child of colocolic intussusception caused by a colonic polyp, and review some of the salient features of this clinical entity.