Clostridia

Clostridia bacteria are anaerobic, gram positive, spore forming bacilli (or rods). Clostridia are obligate anaerobes.

C. perfringens

• produces α-toxin, a lecithinase, which causes gas gangrene (myonecrosis) and haemolysis
• features include tender, oedematous skin with haemorrhagic blebs and bullae. Crepitus may present on palpation

C. botulinum

• typically seen in canned foods and honey
• prevents acetylcholine (ACh) release leading to flaccid paralysis

C. difficile

• causes pseudomembranous colitis, typically seen after the use of broad-spectrum antibiotics
• produces both an exotoxin and a cytotoxin
• Clostridium difficile is endogenous, it is a gut commensal.

C. tetani

• produces an exotoxin (tetanospasmin) that prevents the release of glycine from Renshaw cells in the spinal cord causing a spastic paralysis