Development of a DNA microarray for detection and serotyping of enterotoxigenic Escherichia coli

Enterotoxigenic Escherichia coli (ETEC) is a common pathogen worldwide causing infectious diarrhea, especially traveler's diarrhea. Traditional physiological assays, immunoassays, and PCR-based methods for the detection of ETEC target the heat-labile enterotoxin and/or the heat-stable enterotoxin. Separate serotyping methods using antisera are required to determine the ETEC serogroup. In this study, we developed a DNA microarray that can simultaneously detect enterotoxin genes and the 19 most common O serogroup genes in ETEC strains. The specificity and reproducibility of this approach were verified by hybridization to 223 strains: 50 target reference or clinical strains and 173 other strains, including those belonging to other E. coli O serogroups and closely related species. The sensitivity of detection was determined to be 50 ng of genomic DNA or 10(8) CFU per ml of organisms in pure culture. The random PCR strategy used in this study with minimal bias provides an effective alternative to multiplex PCR for the detection of pathogens using DNA microarrays. The assay holds promise for applications in the clinical diagnosis and epidemiological surveillance of pathogenic microorganisms.