Shiga toxin-producing Escherichia coli (STEC) in Tennessee: surveillance and current clinical laboratory practices

Since joining the Centers for Disease Control and Prevention's (CDC) Foodborne Diseases Active Surveillance Network (FoodNet) in 1999, Tennessee has conducted active surveillance for foodborne pathogens including Shiga toxin-producing E. coli (STEC). The number of STEC infections has increased in recent years in the United States, including Tennessee, due partly to changes in clinical laboratories practices including non-culture based testing methods. Despite increased reporting, STEC infections are likely under-recognized in Tennessee. A 2007 statewide laboratory survey indicated that less than half of clinical laboratories test for STEC on-site. Among these, only nine reported using non-culture based methods. Only one clinical laboratory reported simultaneous culture for STEC O157 and testing with an assay that detects Shiga toxins for non-O157 STEC as recommended by the CDC. Adoption of CDC recommendations coupled with timely and complete reporting will enhance public health surveillance, outbreak investigations and interventions to prevent STEC infection.