Clostridium

Clostridium

It is gram positive rod shaped bacteria. It is obligate anaerobes capable of producing endospores in most species. The spore of most species are located terminally or subterminally. Clostrdia are motile with peritrichous flagella. Their natural habitat is the soil or the intestinal tract of animals and human, where they are live as saprophytes .Clostridium contains around 100 species that include common free living bacteria, as well as important pathogens. The four main species responsible for diseases in human are:

C. botulinum causing botulism
C. tetani causing tetanus
C. perfringens causing gas gangrene
C. difficle causing pseudomembranecolitis




Clostridial that produce invasive infetions

Many different toxin- producing clostridia(C. perfringens and related clostridia) can produce invasive infection(including myonecrosis and gas gangrene)if introduced into damaged tissue. A bout 30 species of clostridia may produce such an effect, but the most common in invasive bacteria is C.perfringens (90%). C.perfringens producing enterotoxin is a common cause of food poisoning.
Pathogenesis


C.perfringens produced several toxins: - The alpha toxin of C.
- The theta toxin has hemolytic and necrotizing effects.
- DNase and hyaluronidase,
- A collagenase that digests collagen of subcutaneous tissue and muscle, are also produced
- Some strains of C. perfringens produce a powerful enterotoxin, especially when grown in meat dishes.

Clinical Findings

From a contaminated wound, the infection spreads in 1–3 days to produce crepitation in the subcutaneous tissue and muscle, foul-smelling discharge, rapidly progressing necrosis, fever, hemolysis, toxemia, shock, and death. Treatment is with early surgery (amputation) and antibiotic administration.

Diagnostic Laboratory

Specimens consist of material from wounds, pus and tissue. The presence of large gram-positive rods in Gram stained smears suggests gas gangrene clostridia; spores are not regularly present. Material is inoculated into chopped meat-glucose medium and thioglycolate medium and onto blood agar plates incubated anaerobically. The growth from one of the media is transferred into milk agar .