Improper sanitation, refrigeration identified as sources of STEC outbreak

Brown JA. Pediatr Infect Dis J. 2011;doi: 10.1097/INF.0b013e3182457122.

Sanitation and disinfectant violations and improper refrigeration of potentially hazardous foods were identified as sources of the largest reported outbreak of O26:H11 infection in the United States and the largest reported non-O157 Shiga toxin-producing Escherichia coli outbreak in a US childcare center, according to results of a recent study.

In June 2010, two cases of O26:H11 infection in children aged younger than 24 months were reported at a childcare center — the children, although symptomatic, had attended different classrooms at the same center. An initial survey revealed that a diarrheal illness had been circulating at the center since May 2010, and there were symptomatic children in six rooms: the three infant rooms, the two toddler rooms and the 3-year-old room. Researchers launched an investigation to determine the cause and extent of the outbreak and prevent and control further illness among children and employees.

A cohort study was conducted among the 20 childcare center employees and 55 children distributed among the three infant rooms, the two toddler rooms and the 3-year-old rooms. Questionnaires were administered to every employee and attempted with the parents of children younger than 48 months to establish illness and exposure history.

Parents of confirmed cases — defined as a child in the infant, toddler or 3-year-old rooms at the center with laboratory-confirmed O26:H11 — were later administered a follow-up questionnaire to determine possible risk factors for illness. All childcare center employees and all children in the affected rooms were also tested for Shiga toxin-producing E. coli (STEC) and submitted stool samples for analysis, according to the findings published ahead of print in The Pediatric Infectious Disease Journal.

Forty-five cases were connected with this outbreak, including 18 confirmed (17 children and one employee) and 27 suspect cases (16 children and 11 employees), defined as a child or employee with any diarrheal illness beginning on or after May 24, 2010. Interviews were concluded for 20 of 20 staff and 50 (91%) of 55 children in the six affected rooms. The risk of being a case among children aged younger than 36 months was more than twice the risk among children aged 36 to 47 months (RR=2.10; 95% CI, 1.00-4.42).

According to the cohort study, factors that contributed to the STEC outbreak included: failure of employees to wash hands after changing a child’s diaper and before filling a child’s drink container; inappropriate disinfectant and sanitizer concentrations; absence of disinfectant in some rooms and failure to disinfect a diaper changing table after use; and potentially hazardous foods in the kitchen refrigerator held at inappropriate temperature.

Researchers said because few clinical laboratories regularly test for non-O157 STEC and pandemics spread by person-to-person transmission were not routinely reported by states to CDC until 2009, it is possible that other O26:H11 outbreaks have gone undetected in the United States.

Disclosure: The researchers report no relevant financial disclosures.

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