Strain Characteristics and Antibiotic Resistance Profiles.

1All strains were isolated from human stool and were positive by PCR for stx2a, aatA and aggR. The genes for stx1, eae, and ehxA were not detected by PCR.2Determined by ELISA (Premier EHEC, Meridian Biosciences, Inc. Cincinati, OH). Titer represencents the reciprocal of the highest dilution of the sample (enrichment broth) that yielded a positive reaction according to the manufacturer’s instruction.3Interpretive criteria to categorize minimum inhibitory concentration results as susceptible, intermediate or resistant are based on current guidelines provided by the Clinical and Laboratory Standards Institute (CLSI). Interpretive criteria published in the most recent National Antimicrobial Resistance Monitoring System (NARMS) annual report (www.cdc.gov/narms) are applied for drugs that lack CLSI interpretive criteria.