All about Bacilli – Basic microbiology, parasitology, and immunology; nature, reproduction, growth, and transmission of common microorganisms and parasites in Bangladesh; prevention including universal precaution and immunization, control, sterilization, and disinfection; and specimen collections and examination. Students will have an understanding of common organisms and parasites caused human diseases and acquire knowledge about the prevention and control of those organisms.
All about Bacilli
Two genera of Gram-positive spore forming bacilli are:
➤ Bacillus: Obligate aerobes.
➤ Clostridium: Obligate anaerobes.
Classification of Bacillus:
The Classification of Bacillus are given below-
Clostridium
Morphology/Properties of Clostridium:
- Gram-positive bacilli and non-acid-fast
- Rod shaped with rounded ends
- Spore forming: possesses spherical and terminal spores. Spores are larger than the
bacillary body. - Obligate anaerobes.
- Motile with peritrichous flagella.
- Produce exotoxins.
- Non-capsulated.
- Culture anaerobically on blood agar.,
Classification of Clostridium:
The genus Clostridium can be conventionally classified on the basis of the following criteria
On the basis of position and shape of spore:
➤ Oval sub-terminal – Cl. perfringens, Cl. septicum, Cl. botulinum
➤ Oval terminal – Cl. tetani
➤ Spherical terminal – Cl. tetanomorphum
On the basis of biochemical properties:
➤ Predominantly proteolytic and mildly saccharolytic (proteolytic and saccharolytic +).
➤ Predominantly saccharolytic and mildly proteolytic (saccharolytic and proteolytic ±).
➤ Mildly proteolytic but not saccharolytic (proteolytic and saccharolytic -).
➤ Mainly saccharolytic but not proteolytic (saccharolytic ++ and proteolytic -).
➤ Neither proteolytic nor sacchrolytic (proteolytic – and saccharolytic -).
Medically Important Bacteria of Group-Clostridium:
➤ Clostridium tetani – causes tetanus,
➤ Clostridium botulinum – it causes botulism.
➤ Clostridium perfringens – it is histotoxic and causes gas gangrene.
➤ Clostridium difficile – it causes antibiotic-associated pseudomembranous colitis,
➤ Clostridium septicum – it is histotoxic and causes sepsis.
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