Clostridium is a genus that contains a large number of Gram-positive spore-forming species that cause disease in humans. Some Clostridium bacteria can be found in soil, while others naturally inhabit the intestinal tract of animals and humans. Since they are anaerobic, they cannot survive in air, but only in rotting or sealed areas. Most notable of the disease-causing bacterium are: C. tetani (tetanus), C. botulinum (botulism), C. perfringens (gas gangrene and food poisoning), and C. difficile (serious diarrhea). Several species are also able to produce bacteremia (bacteria in the bloodstream). On the other hand, C. pasteurianum is one Clostridium member that actually is helpful to humans. It causes plants to acquire nitrogen and thus is fundamental to the world’s food production.
Clostridium difficile is recognized as a cause of Pseudomembranous colitis, a potentially serious form of diarrhea, caused by taking antibiotics. No single class of antibiotics is responsible, as any one of them can cause the condition. When antibiotic treatments reduce the normal flora, C. difficile grows uninhibited, producing toxins. These toxins cause fluids to collect, damaging the cells of the bowel. The first symptoms are typical of many other diarrheal symptoms – abdominal pain and watery diarrhea. What is unusual remains unseen. Mixtures of fibrin, mucus, and white blood cells accumulate in patches on the mucosa of the colon. These patches are called pseudomembranes, or false membranes. As many as one-third of the patients with the condition will die. This type of infection, antibiotic-associated enterocolitis, has become so common that it represents the third most common nosocomial (hospital acquired) infection. About 3% of the population carry C. difficile around as part of their normal intestinal flora, passing on the bacterium in their stools.
Several forms of clostridial wound infections occur. A mixture of microbes is nearly always found in such cases, but one or more of these clostridia are always present (C. perfringes, C. novyi, C. septicum, C. histolyticum). Numerous toxins and enzymes produced by the clostridia and are able to destroy tissues, particularly muscle fibers and connective tissues. Wartime wounds and accidents often become contaminated with various clostridia which finds their way into a piece of dead tissue. As the toxins grow, the healthy tissue next to the area die as the supply of oxygenated blood is stopped. Phagocytic cells of the host are helpless against this type of infection because the bacteria remains out of reach in dead tissue.
One such wound infection is called anaerobic cellulitis. This is less severe than gas gangrene (myonecrosis) and does not involve the muscles. Instead, the infection spreads through the subcutaneous tissues in between the muscles. Gas gangrene, on the other hand, is a more severe form of the infection with destruction, involving adjacent muscle tissues surrounding the initial lesion. The swollen tissues have a dark yellowish discoloration and produce a foul-smelling, dark fluid exudate. Gas is formed by the bacteria, causing some distension of the subcutaneous tissues and considerable pain. Usually, the symptoms appear 12-72 hours after the initial injury. Along with the tissue involvment, other symptoms appear, including fever, toxemia, and shock. Without immediate treatment, death is the outcome.