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[Cytopathogenic effect of diphtheria exotoxin in cultured chick embryo fibroblasts]
E Teruel-López1, R Cárdenas-Cedeño, L Avila
1Instituto de Investigaciones Clínicas, Facultad de Medicina, Universidad de Zulia, Maracaibo, Venezuela.
Abstract:
One hundred fifty strains of Corynebacterium diphtheriae were studied from patients with symptoms of diphtheria and from healthy persons. 136 strains (90.67%) belonged to the mitis biotype, 12 (8.0%) and 2 (1.33%) to gravis and intermedius biotypes respectively. Toxigenicity was determined by traditional in vivo methods with rabbits and plaque immunodiffusion in KL-virulence medium. From the 136 mitis biotype strains studied, 130 (95.58%) showed positive toxigenicity by both methods and 11 strains (91.66%) from gravis biotype and 2 (100%) of intermedius biotype gave same results. The cellular cytotoxicity of the diphtheriae toxin was tested on culture of chicken embryo fibroblast and were positive in 132 (97.05%) strains of mitis biotype, and in all strains of gravis and intermedius biotypes. These results suggest that the cytotoxicity test seems to be a more sensitive method for detecting diphtheriae toxin production.
Insights
A study of Corynebacterium diphtheriae strains found that the mitis biotype is most common. The cellular cytotoxicity test proved more sensitive for detecting diphtheria toxin production than traditional methods.
Area of Science:
- Microbiology
- Infectious Diseases
- Bacteriology
Background:
- Corynebacterium diphtheriae causes diphtheria, a serious infectious disease.
- Understanding the distribution and toxigenicity of C. diphtheriae biotypes is crucial for disease control.
Purpose of the Study:
- To characterize the biotypes of C. diphtheriae strains.
- To compare the sensitivity of different methods for detecting diphtheria toxin production.
Main Methods:
- Studied 150 strains of Corynebacterium diphtheriae from patients and healthy individuals.
- Determined toxigenicity using in vivo rabbit methods and plaque immunodiffusion.
- Assessed cellular cytotoxicity of diphtheria toxin on chicken embryo fibroblast cultures.
Main Results:
- The mitis biotype was predominant (90.67%), followed by gravis (8.0%) and intermedius (1.33%).
- High toxigenicity rates were observed across all biotypes using both traditional and cytotoxicity methods.
- The cellular cytotoxicity test demonstrated a higher positive rate (97.05%) compared to traditional methods.
Conclusions:
- The mitis biotype is the most prevalent among studied Corynebacterium diphtheriae strains.
- The cellular cytotoxicity assay appears to be a more sensitive method for detecting diphtheria toxin production.
- This finding has implications for accurate diagnosis and surveillance of diphtheria.