1 Flashcards
What is gas gangrene?
Gas gangrene is always polymicrobial and is caused by many clostridial species.
What are the established agents of gas gangrene?
The established agents are C. perfringens (most common, 60% of total cases), C. novyi, and C. septicum (20-40%).
What are the probable agents of gas gangrene?
Probable agents include C. histolyticum, C. sporogenes, C. fallax, C. bifermentans, C. sordellii, C. aerofoetidum, and C. tertium.
What is required for the development of gas gangrene?
The development of gas gangrene requires an anaerobic environment.
What types of injuries can lead to gas gangrene?
Crushing injuries of muscles, open fractures of long bones, foreign bodies, or devitalized tissues can lead to gas gangrene.
How do anoxic muscles contribute to gas gangrene?
Anoxic muscles utilize pyruvate anaerobically to produce lactic acid.
How can wounds become contaminated with clostridial spores?
Wounds can be contaminated with clostridial spores present in soil or clothes during events like war or road traffic accidents.
What is a rare cause of non-traumatic gas gangrene?
Rarely, spontaneous non-traumatic gas gangrene occurs via hematogenous seeding of normal muscle with bowel clostridia.
What are the main toxins produced by C. perfringens?
C. perfringens produces exotoxins, chiefly a-toxin and e-toxin.
What is the principal virulence factor of C. perfringens?
The principal virulence factor is a-toxin, which has both phospholipase C and sphingomyelinase activities.
How does a-toxin affect the cardiovascular system?
a-toxin suppresses myocardial contractility, leading to reduced cardiac output and profound hypotension.
What effect does e-toxin have?
e-toxin causes marked vasodilation by activating mediators like prostacyclin and platelet-activating factor.
What toxins are produced by C. septicum?
C. septicum produces a-toxin, B-toxin (DNase), y-toxin (hyaluronidase), and other toxins.
What does C. novyi produce?
C. novyi has four subtypes (A-D), with Type-A producing bacteriophage coded alpha-toxin.
What is the incubation period for gas gangrene?
The incubation period varies: 10-48 hours for C. perfringens, 2-3 days for C. septicum, and 5-6 days for C. novyi.
