Detection of Shigellae and Enteroinvasive Escherichia coli by Amplification of the Invasion Plasmid Antigen H DNA Sequence in Patients with Dysentery

Detection of Shigella organisms and enteroinvasive Escherichia coli (EIEC) by polymerase chain reaction (PCR) was evaluated in 20 patients with dysentery before and in 17 of the 20 after treatment with ciprofloxacin. DNA sequences coding for IpaH antigen, a multiple copy sequence found on the chromosome, and the invasion plasmid locus (ial) was detected after DNA amplification in 13 stools from patients from whom shigellae or EIEC were isolated but not in 21 nondysenteric stools containing other enteric bacteria. Although shigellae or EIEC were not isolated from any patient with dysentery after ciprofloxacin treatment, IpaH and ial sequences were found after PCR amplification in 7 patients after treatment with ciprofloxacin. IpaH sequences alone were detected in 4 patients; DNA augmentation ofIpaH in stools is a specific way to identify Shigella or EIEC infection in persons from whom cultures cannot be obtained promptly after the onset of diarrhea or who have received antibiotics.