Clonal relationships among classic enteropathogenic Escherichia coli (EPEC) belong to different O groups

Area of Science:

• Microbiology
• Bacterial genetics
• Epidemiology

Background:

• Enteropathogenic Escherichia coli (EPEC) is a significant cause of infantile diarrhea worldwide.
• Understanding the genetic relatedness and clonal structure of EPEC strains is crucial for epidemiological investigations.

Purpose of the Study:

• To investigate the genetic diversity and clonal relationships among classic EPEC strains isolated from infantile diarrhea.
• To assess the utility of O:H serotyping in conjunction with molecular and phenotypic analyses for EPEC strain characterization.

Main Methods:

• Enzyme polymorphism analysis and multilocus genotyping of 50 EPEC strains.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with silver staining for lipopolysaccharide (LPS) and outer membrane protein (OMP) profiling.
• HEp-2 cell adhesion assays to assess localized adherence patterns.

Main Results:

• A strong correlation was observed between electrophoretic types, O:H serotypes, biotypes, LPS patterns, and OMP profiles.
• EPEC strains were predominantly grouped into two genetically related clusters, with variations mainly in O antigen suggesting potential horizontal gene transfer.
• These findings indicate that distinct EPEC groups likely represent bacterial clones.

Conclusions:

• O:H serotyping is a reliable method for establishing epidemiologic linkages in EPEC diarrhea cases.
• The study supports the clonal nature of EPEC and suggests mechanisms for phenotypic diversity within clones.
• Further research into horizontal gene transfer of LPS side chains could elucidate EPEC evolution.