Identification of Escherichia coli serotype O157:H7 by DNA probe specific for an allele of uid A gene.

Isolates of Escherichia coli serotype O157:H7 were identified by an oligonucleotide probe, PF-27, containing a unique base substitution in the allele of the uid A gene. Colony hybridization analysis of 239 bacteria, including E. coli, Shiga-like toxin-producing serogroups of pathogenic E. coli and other enteric isolates showed that the probe reacted only with isolates of serotype O157:H7. Results of genetic analyses suggest that the base substitution in the allele does not contribute to the absence of uid A gene expression in O157:H7.