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Identification and characterization of Yersinia intermedia isolated from human feces
Abstract:
Since May 1983, our laboratory has, upon request, cultured stools for Yersinia spp. by using direct plating on cefsulodin-irgasan-novobiocin agar and a 3-week cold enrichment procedure. We isolated bacteria identified as Y. intermedia from six adult patients. All isolates were recovered only by the cold enrichment procedure and misidentified as Y. enterocolitica by the API 20E system (Analytab Products, Plainview, N.Y.). Final identification was made on the basis of results obtained with conventional tube biochemical tests. The isolates were tested for the following characteristics associated with virulence in Y. enterocolitica: lack of pyrazinamidase activity, autoagglutinability, presence of a 40- to 50-megadalton plasmid, production of heat-stable enterotoxin, and mouse lethality. All isolates tested had pyrazinamidase activity, and none were autoagglutinable. However, one isolate possessed a 40-megadalton plasmid. None produced enterotoxin or were lethal for mice. Review of the medical histories of the patients revealed that four of the six had diarrhea; however, none had disease typical of that caused by Y. enterocolitica. Our data confirmed the limited pathogenic potential of Y. intermedia and suggested that its isolation was without clinical significance in our patients. Conventional biochemical tests were required for reliable identification of Y. intermedia.
Insights
Yersinia intermedia was isolated from six patients but showed limited pathogenic potential. Conventional biochemical tests are crucial for accurate Yersinia identification, distinguishing it from Yersinia enterocolitica.
Area of Science:
- Clinical microbiology
- Bacteriology
- Infectious diseases
Background:
- Yersinia enterocolitica is a significant human pathogen.
- Accurate identification of Yersinia species is crucial for clinical diagnosis.
- Standard laboratory methods may misidentify Yersinia species.
Purpose of the Study:
- To investigate the clinical significance of Yersinia intermedia isolates.
- To evaluate the pathogenicity of Yersinia intermedia.
- To assess the reliability of identification methods for Yersinia species.
Main Methods:
- Stool cultures processed using direct plating and cold enrichment.
- API 20E system and conventional tube biochemical tests for bacterial identification.
- Virulence factor analysis including pyrazinamidase activity, autoagglutinability, plasmid presence, enterotoxin production, and mouse lethality.
Main Results:
- Yersinia intermedia was isolated from six adult patients using cold enrichment.
- All Y. intermedia isolates were misidentified as Y. enterocolitica by the API 20E system.
- Y. intermedia isolates lacked typical virulence factors associated with Y. enterocolitica and showed limited pathogenicity.
- Conventional biochemical tests were necessary for correct identification.
Conclusions:
- Yersinia intermedia possesses limited pathogenic potential.
- Isolation of Y. intermedia may be clinically insignificant.
- Accurate identification of Yersinia species requires conventional biochemical testing.