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Microbiology

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Gram Positive Bacilli

Question
56 out of 71
 

Regarding clostridium perfringens gas gangrene false is? (AIIMS 10)



A Clostridium perfringens is the most common cause of gas gangrene

B Naegler reaction positive

C Most important toxin is hyaluronidase

D Food poisoning strain of clostridium perfringens produces heat resistant spores.

Ans. C Most important toxin is hyaluronidase

Most important toxin is hyaluronidase

a. Clostridium perfringens (formerly known as C. welchii) is a Gram-positive, anaerobic, spore-forming bacillus. In contrast to other clostridia it is non-motile and capsulated. It is ubiquitous in nature and can be found as a normal component of decaying vegetation, soil and the intestinal tract of humans and other vertebrates.

b. Gas gangrene or clostridial myonecrosis is usually a polymicrobial condition, amongst which Clostridium perfringens is the most frequently encountered ( approx. 60%). Other clostridial spp. encountered in gas gangrene are Cl. septicum, Cl. novyi, Cl.histolyticum and Cl. sordelii.

c. The alpha toxin is the most important toxin among the 12 toxins produced by Cl. perfringens. It is lethal, dermonecrotic and hemolytic (shows hot-cold hemolysis). It is a phospholipase which splits lecithin into phosphoryl choline and diglyceride.

d. This is seen as opalescence in serum or egg yolk containing media and is specifically neutralized by its antitoxin. This specific lecithinase effect called Nagler reaction, can be seen as opacity around colonies of Cl. perfringens and is a useful test for identification of Cl. perfringens.

e. Some strains of Cl. perfringens Type A produce food poisoning due to their marked heat-resistant spores. Poorly prepared meat and poultry are the main culprits in harboring the bacterium.

Gram Positive Bacilli Flashcard List

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