Outbreak of Shiga Toxin–producing Escherichia coli O157:H7 at a Child Care Center in Izumo, Japan

Background: Shiga toxin–producing Escherichia coli (STEC) is a clinically significant pathogen that causes hemorrhagic colitis and hemolytic uremic syndrome. In June 2023, an outbreak of STEC O157:H7 occurred at a child care center in Izumo, Japan. This study aimed to identify the mode of transmission of STEC O157:H7 and contributing factors to prevent future outbreaks. Methods: The child care center comprised 138 individuals (111 children and 27 staff members). Stool samples were collected from all individuals. Data regarding clinical symptoms, antimicrobial treatment, duration of bacterial shedding and possible routes of transmission were collected. Results: During the outbreak, 45 of 111 children (41%) and 1 of 27 staff members (4%) were infected with STEC O157:H7. Secondary household transmission occurred in 21 of 152 family members (14%) across 9 families. Among the 45 infected children, 7 (16%) required hospitalization, and 3 (7%) developed hemolytic uremic syndrome. No fatalities occurred. Antibiotics were administered to 30 children (67%). The median duration of bacterial shedding was 12 days (interquartile range, 8–23 days). Person-to-person transmission was identified as the most likely route of transmission within the facility. Contributing factors included inadequate hygiene practices, close contact among children during classroom activities, delayed exclusion of symptomatic individuals and delayed closure of the center. Conclusions: Person-to-person transmission played a critical role in the STEC outbreak at the child care center and within households. Early identification and prompt exclusion of infected individuals are essential to prevent further transmission in child care settings.