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VIRULENCE AND MORPHOLOGICAL CHARACTERISTICS OF MAMMALIAN TUBERCLE BACILLI
G Middlebrook1, R J Dubos, C Pierce
1Laboratories of The Rockefeller Institute for Medical Research.
The Journal of Experimental Medicine
|October 30, 2009
Summary
Virulent mammalian tubercle bacilli form serpentine cords, aiding spread, unlike avirulent strains. Mouse infection models effectively determine virulence, correlating with guinea pig results.
Area of Science:
- Microbiology
- Pathogenesis
- Bacteriology
Background:
- Mammalian tubercle bacilli virulence is crucial for disease progression.
- Mouse models are established for assessing bacterial virulence.
- Morphological characteristics of bacterial cultures can correlate with virulence.
Purpose of the Study:
- To investigate the relationship between morphology and virulence in mammalian tubercle bacilli.
- To evaluate the utility of mouse models for virulence determination.
- To identify morphological differences between virulent and avirulent strains.
Main Methods:
- Experimental infection of mice with different tubercle bacilli cultures.
- Cultivation of virulent and avirulent variants on various media (liquid and solid).
- Microscopic examination of bacterial morphology, focusing on cord formation and acid-fastness.
Main Results:
- Virulent cultures consistently formed serpentine cords of acid-fast bacilli, facilitating surface spread.
- Avirulent variants lacked cord formation and showed reduced acid-fastness.
- Tween 80 inhibited cord formation.
- Mouse model virulence correlated with guinea pig virulence.
- Intermediate virulence strains displayed intermediate morphology.
Conclusions:
- Bacterial morphology, specifically serpentine cord formation, is a reliable indicator of mammalian tubercle bacilli virulence.
- Mouse models provide a consistent method for determining relative virulence.
- The spread of virulent tubercle bacilli on culture media is linked to cord formation, which can be modulated by Tween 80.
Keywords:
TUBERCLE BACILLI/virulence
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