In the first known outbreak of Escherichia coli O26 in a U.S. child care center, neither severe illness nor a secondary household transmission was reported, according to results presented during the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy.

Data on duration of Shiga-toxin-producing E. coli serotype O26 shedding are limited, but shedding can be prolonged. However, the need for separation of infected children who have this apparently low-virulence infection remains uncertain, according to Mathieu Tourdjman, MD, MPH, CDC Epidemic Intelligence Service Officer with the Oregon Health Authority.

“The study raised more questions than it answered,” Tourdjman said during his presentation. “Child care exclusion policies vary across country. Most frequently, the policy states that children infected with O157 should be excluded until at least two consecutive stool samples are negative. Because limited data on O26 are available for O26 infection, no consensus exists on whether similar exclusion should occur.”

The outbreak of E. coli O26 occurred in an Oregon child care center in October 2010. Children who attended the child care facility were aged in range from 6 weeks to 12 years. They were separated by age into six different classrooms.

According to Tourdjman, infected staff and parents of infected children provided demographic and clinical information. Secondary transmission to household members was assessed by screening stool specimens for Shiga toxin using PCR. Positive isolates were isolated and serotyped. Cases in this particular outbreak were defined as laboratory-confirmed O26 infection among attendees or staff during October 2010.

Results of the study revealed a total of 10 cases of E. coli O26: nine children (median age: 1 year) and one staff member. Patients were in three different classrooms and not clustered. Four patients reported diarrhea, including one with bloody diarrhea, but none of the patients progressed to hemolytic uremic syndrome or required hospitalization.

The findings of the investigation also revealed that duration of shedding ranged from 12 to 46 days (median 25 days), and a lack of secondary transmission to household members.

Tourdjman M. #L1-389. Duration of Shedding and Secondary Transmission of Shiga-Toxin-Producing Escherichia coli O26 During an Outbreak in a Child Care Center:: Oregon, October 2010. Presented at: 51st ICAAC. Sept. 17-20, 2011. Chicago.