Virulence Factors
A. Clostridium botulinum
B. Clostridioides difficile
Pathogenesis
A. Botulism
- Caused by ingestion of preformed neurotoxin (types A, B, E, F)
- Found in improperly canned foods (meat, fish, vegetables)
- Infant botulism: ingestion of spores (e.g. honey)
- Wound botulism: spores germinate in necrotic wounds
Mechanism: Botulinum toxin blocks release of acetylcholine → flaccid paralysis.
B. C. difficile Infection
- After antibiotic use (clindamycin, cephalosporins, tetracycline, ampicillin)
- Normal flora suppressed → overgrowth of C. difficile
- Spores survive gastric acid, germinate in colon
- Toxins A & B cause inflammation, apoptosis, and pseudomembrane formation
Diagnosis
C. botulinum:
- Specimen: stool, vomitus, suspected food
- Microscopy: Gram+ rods with subterminal spores
- Toxin test: mouse bioassay or ELISA
- Culture: anaerobic, proteolytic strains on RCM
C. difficile:
- Specimen: stool
- Culture: CCFA agar → yellow colonies with glassy look
- Toxin detection: ELISA for toxins A/B, PCR in some settings
Treatment
A. Botulism
- Gastric lavage, supportive care
- Antitoxin: trivalent ABE antitoxin IM
- Antibiotics: Penicillin + Metronidazole
- Ventilatory support: often essential
- Prevention: proper food canning (botulinum cook), toxoid vaccine for lab workers
B. C. difficile
- Stop causative antibiotic
- Mild/moderate: Metronidazole PO
- Severe/refractory: Vancomycin PO or Fidaxomicin
- FMT (Fecal Microbiota Transplant): for recurrence
- Infection control: patient isolation, disinfect environment