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Differentiation between virulent and avirulent Yersinia enterocolitica isolates by using Congo red agar
Journal of Clinical Microbiology
|September 1, 1983
Summary
The Congo red binding test differentiates virulent Yersinia enterocolitica (CR+) from non-virulent strains (CR-). CR+ strains possess plasmids and exhibit key virulence factors, unlike plasmidless CR- strains.
Area of Science:
- Microbiology
- Bacteriology
- Pathogen Identification
Background:
- Yersinia enterocolitica is a significant foodborne pathogen.
- Identifying virulent strains is crucial for public health.
- Virulence is often associated with plasmid carriage.
Purpose of the Study:
- To evaluate the Congo red binding reaction as a method for identifying virulent Yersinia enterocolitica.
- To correlate Congo red binding with plasmid presence and other virulence markers.
Main Methods:
- Clinical isolates of Yersinia enterocolitica were cultured on media containing Congo red.
- Colony types (CR+ and CR-) were identified based on Congo red binding.
- Strains were assessed for plasmid DNA and key virulence assays (autoagglutination, serum resistance, etc.).
Main Results:
- Two colony types, CR+ and CR-, were observed.
- CR+ strains possessed plasmids (40-50 Mdal) and were positive for virulence markers.
- CR- strains were plasmidless and negative in all virulence assays.
Conclusions:
- The Congo red binding assay is a simple and effective method for screening Yersinia enterocolitica virulence.
- This test efficiently identifies plasmid-bearing, virulent colonies.