Development of a duplex real-time PCR for differentiation between E. coli and Shigella spp

Area of Science:

• Microbiology
• Molecular Biology
• Infectious Diseases

Background:

• Differentiating Shigella species from Escherichia coli, particularly enteroinvasive E. coli (EIEC), is crucial for diagnosing bacillary dysentery.
• Traditional biochemical and serological methods for differentiation are often complex, time-consuming, and limited in scope.
• A need exists for a rapid, reliable, and specific diagnostic tool to distinguish these closely related pathogens.

Purpose of the Study:

• To develop and validate a real-time PCR assay for the accurate differentiation between Shigella spp. and E. coli.
• To specifically distinguish EIEC from other E. coli strains and Shigella species.

Main Methods:

• A duplex real-time PCR assay was designed targeting the uidA and lacY genes.
• The assay's specificity was tested using 96 bacterial isolates, including 11 EIEC isolates and representatives of each Shigella species.

Main Results:

• All tested isolates were positive for the uidA gene, confirming its presence in both E. coli and Shigella.
• All E. coli isolates, including EIEC, were positive for the lacY gene.
• No Shigella isolate possessed the lacY gene, enabling clear differentiation from E. coli.

Conclusions:

• The developed duplex real-time PCR assay is a simple, rapid, reliable, and specific method for differentiating Shigella spp. from E. coli.
• This assay significantly simplifies the identification process compared to conventional methods, especially for distinguishing EIEC from Shigella.