Bacteria: Clostridium

The Genus Clostridium

• Gram positive, spore forming rods

• Anaerobic and catalase negative

• Oval or spherical spores produced only under anaerobic conditions

• Cause wound infections, tissue infections, and food intoxications

Gas Gangrene

• Clostridium Perfringens most frequent clostridia involved in soft tissue and wound infections - myonecrosis

• Spores found in soil, human skin, intestine, and vagina

• Predisposing factors: Surgical incisions, compound fractures, diabetic ulcers, septic abortions, puncture wounds, gunshot wounds

Pathology

• Not highly invasive, requires damaged and dead tissue and anaerobic conditions

• Conditions stimulate spore germination, vegetative growth and release of exotoxins, and other virulence factors

• Fermentation of muscle carbohydrates results in the formation of gas and further destruction

Treatment and Prevention

• Immediate cleaning of dirty wounds, deep wounds, compound fracture, and infected incisions

• Debridement of disease tissue

• Large doses of Cephalosporin or penicillin

• Hyperbaric oxygen therapy

• No vaccines available

Tetanus

• Clostridium tetani

• Common resident of soil and GI tracts of animals

• Causes tetanus or lockjaw, a neuromuscular disease

• Most commonly among geriatric patients and IV drug abusers, neonates in developing countries

Pathology

• Spores usually enter through accidental puncture wounds, burns, umbilical stumps, frostbite, and crushed body parts

• Anaerobic environments is required for vegetative cells to grow and release toxin

Pathology (2)

• Tetanospasmin: Neuoroxin causes paralysis by binding to motor nerve endings, blocking the release of nerurotransmitter for muscular contraption inhibition, muscles contract uncontrollably

• Death most often due to paralysis of respiratory muscles

Neonatal Tetanus: Treatment and Prevention

• Treatment aimed at deterring degree of toxemia and infection and maintaining homeostasis

• Antitoxin therapy with human tetanus immune globulin

• Control infection with penicillin or tetracycline and muscle relaxants

• Vaccine available, booster needed every 10 years

Clostridium Difficile-Associated Disease (CDAD)

• Normal resident of colon, in low numbers

• Causes antibiotic associated colitis

• Produces enterotoxins that damage intestines

• Major cause of diarrhea in hospitals

• Increasingly common in community acquired diarrhea

Clostridial Food Poisoning

• Clostridium Botulinum: Rare but severe intoxication usually from home canned food

• Clostridium Perfringens: Mild intestinal illness, second most common form of food poisoning worldwide

Botulinum Food Poisoning

• Botulism: Intoxication associated with inadequate food preservation

• Clostridium Botulinum: Spore forming anaerobe, commonly inhabits soil and water

Pathogenesis

• Spores are present on food when gathered and processed

• If reliable temperature and pressure are not achieved air will be evacuated but spores will remain

• Anaerobic conditions favor spore germination and vegetative growth

• Potent toxin, botulin, is released

Pathogenesis (2)

• Botulin Toxin is carried to neuromuscular junctions and blocks the release of acetylcholine, necessary for muscle contraction to occur

• Double or blurred vision, difficulty swallowing, neuromuscular symptoms

Clostridial Gastroenteritis

• Clostridium Perfringens

• Spores contaminate food that has not been cooked thoroughly enough to destroy spores

• Spores germinate and multiply (especially if unrefrigerated)

• When consumed, toxin is produced in the intestine, acts on epithelial cells, acute abdominal pain, diarrhea, and nausea

• Rapid recovery

Gram Positive Regular Non-Spore-Forming Bacilli

• Regular: Stain uniformly and do not assume pleomorphic shapes

• Medically Important:

  • Listeria Monocytogenes

  • Erysipelothrix Rhusiopathiae

Listeria Monocytogenes

• Causes listeriosis

• Facultative Anaerobe

• People at Risk

  • Pregnant women

  • Newborns

  • 65 and older

  • Weak immune system