A simple polymerase chain reaction technique to detect and differentiate Shigella and enteroinvasive escherichia coli in human feces

Abstract

A simple polymerase chain reaction (PCR) procedure using IS630-specific primers was developed as a general diagnostic probe to detect Shigella and enteroinvasive Escherichia coli (EIEC). However, IS630 and the other two previously reported molecular probes, ipaH and ial, cannot be used to differentiate among Shigella serotypes and EIEC strains that cause dysentery. The sensitivity of PCR protocol was determined to be 100–200 shigellae for each PCR reaction. An enrichment incubation would allow the detection of shigellae in stool samples with low bacterial concentration; i.e., <10 4 CFU/gram. Serotype-specific primers derived from the rfc genes of different Shigella strains were used in PCR reactions to differentiate among Shigella serotypes in the laboratory, such as S. sonnei, S. flexneri, and S. dysenteriae 1. It was demonstrated further that the multiplex PCR system containing rfc-specific primers can efficiently identify the most prominent Shigella serotypes in raw stool samples of acute diarrheal patients.