Detection of diarrheagenic Escherichia coli using a two-system multiplex-PCR protocol

Area of Science:

• Molecular Biology
• Microbiology
• Infectious Diseases

Background:

• Diarrheagenic Escherichia coli (DEC) are significant contributors to diarrheal diseases.
• Conventional microbiological tests fail to differentiate DEC from commensal E. coli strains.
• Accurate identification of DEC is crucial for effective diagnosis and treatment of diarrhea.

Purpose of the Study:

• To develop and validate a two-system multiplex PCR assay for the specific detection of DEC.
• To differentiate various DEC pathotypes, including STEC, EPEC, aEPEc, ETEC, EIEC, EAEC, and DAEC.
• To establish a reliable method for clinical laboratories to identify DEC in patient samples.

Main Methods:

• A multiplex PCR assay was designed with primers targeting specific DEC virulence genes and 16S rRNA as an internal control.
• System 1 targets STEC, EPEC, aEPEc, ETEC, EIEC, and 16S rRNA.
• System 2 targets EIEC, EAEC, DAEC, and 16S rRNA, with testing on reference strains and fecal specimens.

Main Results:

• The multiplex PCR protocol accurately identified all tested DEC reference strains.
• No DEC markers were detected in negative controls, confirmed by 16S rRNA amplification.
• DEC was found in 7.6% of both patients and healthy controls; two Shigella sonnei strains were identified in the diarrhea group.

Conclusions:

• The developed multiplex PCR protocol demonstrates high specificity for DEC, including Shigella.
• The assay is suitable for routine use in clinical diagnostic laboratories.
• This method provides a valuable tool for the accurate identification of diarrheagenic E. coli.