Increasing incidence of non-O157 Shiga toxin-producing Escherichia coli (STEC) in Michigan and association with clinical illness.

Infection with Shiga toxin-producing Escherichia coli (STEC) by serotypes other than O157 (non-O157) have been increasingly reported in the United States. This increase in reporting is primarily due to the improvements in diagnostic tests. We analysed 1497 STEC cases reported in Michigan from 2001 to 2012. A significant increase in the number of non-O157 STEC cases was observed over time, and similar incidence rates were observed for O157 and non-O157 STEC cases in certain time periods. The odds of hospitalization was two times higher in O157 STEC cases relative to non-O157 STEC cases when adjusted for age and gender, suggesting that O157 STEC causes more severe clinical outcomes in all age groups. The use of population-based surveillance to better define trends and associations with disease severity are critical to enhance our understanding of STEC infections and improve upon current prevention and control efforts.