Clostridia are anaerobic, Gram-positive, spore-forming rods widely distributed in nature, particularly in soil. They form resistant spores under stress. These spores, which can survive brief heating to 100°C, and the powerful exotoxins the active bacteria produce, are central to the medical importance of the species.

Gangrena gassosa

Can be caused by various clostridia - eg, Clostridium perfringens, Clostridium septicum, Clostridium novyi e Clostridium histolyticum. See the separate Gas Gangrene articolo.

Caused by Clostridium tetani. See the separate Tetanus and Tetanus Vaccination articolo.

Caused by Clostridium difficile. See the separate Pseudomembranous Colitis articolo.

Caused by a neurotoxin of Clostridium botulinum. See the separate Botulism articolo.

Botulism and bioterrorism

• The most toxic substance known to man.² A lethal dose is <1 microgram.

• A deliberate release may involve airborne dissemination of toxin, or contamination of food or water supplies with toxin or bacteria.

• Water treatment inactivates the toxin, the toxin cannot penetrate intact skin and it loses activity within a few days.

• The most likely scenarios would therefore be:
  

  • A deliberate contamination of foodstuffs; large doses may lead directly to neurological symptoms without the gastrointestinal symptoms of nausea, vomiting and diarrhoea followed by constipation.

  • Aerosol release; most effective in an enclosed environment. After inhalation, the onset of symptoms may be as rapid as <1 hour. However, in cases of accidental inhalation symptom onset can be 3-4 days.

This is the fourth most common form of food-borne illness, after Norwalk-like viruses, Campylobacter spp. and Salmonella spp.

• Spores survive cooking, and germinate during slow cooling or unrefrigerated storage.³ They produce exotoxin, requiring a large infective dose.⁴

• It is mostly associated with meat and poultry, usually occurring in schools, hospitals, factories and catering establishments.Typically, a meat dish is stewed or boiled and allowed to stand for 4-24 hours and then served without adequate reheating.

• 6-12 hours later the patient suffers crampy abdominal pain followed by diarrhoea, which subsides 12-24 hours later.

• Clinically it appears similar to gas gangrene, now rare in UK with the legalisation of abortions.

• Formerly the leading cause of maternal death worldwide, it is still a problem in developing countries, due to illegal abortions and poor obstetric practice.

• Two major factors are involved:⁵
  

  • Infection, which is commonly caused by C. perfringens in mixed infection with non-sporing anaerobes (eg, Bacteroides spp.), Group B beta-haemolytic streptococci, staphylococci, or Escherichia coli, Neisseria gonorrhoeae, Chlamydia trachomatis e Mycoplasma spp.

  • Prodotti di concepimento trattenuti.