Phenotypic and genotypic characterization of enterotoxigenic Escherichia coli isolated from U.S. military personnel participating in Operation Bright Star, Egypt, from 2005 to 2009

Enterotoxigenic Escherichia coli (ETEC) is a major health problem for travelers to the Middle East. During the autumn months of 2005, 2007, and 2009, U.S. military personnel participated in Operation Bright Star (OBS) exercises in Egypt. Out of 181 military personnel enrolled in a diarrheal surveillance study, E. coli-like colonies were isolated from 170 patients. Isolates were tested for the detection of ETEC enterotoxins and colonization factors (CFs) using phenotypic and genotypic methods. Additionally, we studied the secular trends of ETEC isolates obtained from OBS studies since 1999. ETEC was isolated from 51.2% and 60.0% of the patients based on enzyme-linked immunosorbent assay and polymerase chain reaction (PCR), respectively. Heat stable (ST) was the dominant enterotoxin detected followed by heat labile (LT) and LTST. Additionally, we detected a CF in 59.7% and 67.6% of the ETEC-positive isolates using dot blot and PCR assays, respectively. The predominant CF isolated was CS6 followed by CS3.