Clostridia are bacteria that commonly reside in the intestine of healthy adults and newborns. Clostridia also reside in animals, soil, and decaying vegetation. These bacteria do not require oxygen to live. That is, they are anaerobes.
There are many different species of clostridia.
The most common clostridial infection is gastroenteritis (Clostridium perfringens food poisoning), a usually mild infection that typically resolves on its own. Serious clostridial infections are relatively rare but can be fatal.
Clostridia cause disease in different ways, depending on the species:
The bacteria (Clostridium botulinum) may produce a toxin in food, which is then consumed, as occurs in foodborne botulism.
The bacteria may be consumed in food, then multiply and produce a toxin in the intestine, as occurs in Clostridium perfringens food poisoning.
Clostridia spores, which are inactive (dormant) forms of the bacteria, may enter the body through a wound and become active bacteria that produce a toxin, as occurs in tetanus. Spores enable bacteria to survive when environmental conditions are difficult. When conditions are favorable, each spore germinates into an active bacterium.
Use of antibiotics may enable clostridia, which may already be present in the large intestine, to overgrow and produce two toxins, as occurs in antibiotic-associated Clostridioides (formerly, Clostridium) difficile—induced colitis.
Clostridial bacteria may enter through a wound, multiply, and produce a toxin that destroys tissue, as occurs in gas gangrene.
Clostridia can infect the gallbladder, colon, and female reproductive organs. If clostridia infect the colon of people with a low white blood cell count (such those who have leukemia or who are being treated with cancer chemotherapy), it can cause a life-threatening disease called neutropenic enterocolitis.
Rarely, one species, Clostridium sordellii, causes toxic shock syndrome in women who have an infection of the reproductive organs. Such infections may occur after a miscarriage, an abortion, childbirth, or sometimes a gynecologic procedure.
Clostridium perfringens food poisoning (a type of gastroenteritis) can develop when people eat food (usually beef) that contains clostridia. Clostridia develop from spores, which can survive the heat of cooking. If food that contains spores is not eaten soon after it is cooked, the spores develop into active clostridia bacteria, which then multiply in the food. If the food is served without adequate reheating, the clostridia are consumed. They multiply in the small intestine and produce a toxin that causes watery diarrhea and abdominal cramping.
Clostridium perfringens food poisoning is usually mild and resolves within 24 hours. But rarely, it is severe, particularly in the very young and in older people.
A doctor usually suspects the diagnosis of Clostridium perfringens food poisoning when a local outbreak of the disease has occurred. The diagnosis is confirmed by testing contaminated food or stool samples from infected people for Clostridium perfringens and its toxin.
To prevent food poisoning, people should promptly refrigerate leftover cooked meat and reheat it thoroughly before serving.
Treatment of Clostridium perfringens food poisoning includes drinking lots of fluids and resting. Antibiotics are not used.
Clostridia bacteria, usually Clostridium perfringens, are often involved in abdominal infections, usually with other bacteria (called mixed anaerobic infections).
Clostridial infections can develop when the intestine is torn. Clostridia can also infect the gallbladder and organs in the pelvis, such as the uterus, fallopian tubes, and ovaries. Clostridia usually infect the uterus after delivery of a baby or after an abortion done in conditions that are not sterile.
Clostridial infections of the abdomen and pelvis are serious and sometimes fatal. Clostridia produce large amounts of gas, which can form bubbles and blisters in the infected tissue. Often, the infection blocks small blood vessels, and the infected tissue dies, leading to gas gangrene.
Symptoms include pain and fever. The abdomen is tender to the touch. If the uterus is infected, women may have a foul-smelling, bloody discharge from the vagina.
To diagnose clostridial abdominal and pelvic infections, doctors take samples of blood or infected tissue. These samples are examined and sent to a laboratory where bacteria, if present, can be grown (cultured) and identified. Doctors may take x-rays to check for gas produced by clostridia.
Treatment of clostridial abdominal and pelvic infections involves surgery to remove the infected and dead tissue (called debridement). Antibiotics, such as penicillin, are given for at least 1 week. Sometimes penicillin is used together with another antibiotic called clindamycin. Sometimes, if an organ (such as the uterus) is badly infected, it is removed. Such treatment can be lifesaving.
Clostridial necrotizing enteritis is also called enteritis necroticans or pigbel. This infection is caused by Clostridium perfringens and typically affects the small intestine (primarily the jejunum). The infection ranges from mild to severe and can be fatal if not treated promptly. This rare infection occurs mostly in places where people consume low-protein diets, such as in the hinterlands of New Guinea and parts of Africa, Central and South America, and Asia.
Diagnosis of clostridial necrotizing enteritis is based on stool tests.
Treatment of clostridial necrotizing enteritis is with antibiotics. People who have very severe infections may need surgery.
Neutropenic enterocolitis (typhlitis) is a similar life-threatening syndrome that develops in the beginning of the large intestine (cecum) of people who have a low white blood cell count (for example, people who have leukemia or are receiving chemotherapy for cancer).
Neonatal necrotizing enterocolitis occurs mostly in premature newborns who weigh less than about 1500 grams (3 pounds). It may be caused by clostridia bacteria.
Clostridia may also spread to the blood (causing bacteremia). Widespread bacteremia (sepsis) can cause fever and serious symptoms such as low blood pressure, jaundice, and anemia. Sepsis can develop after a clostridial infection and be rapidly fatal.
To diagnose sepsis caused by clostridia, doctors take samples of blood. These samples are sent to a laboratory where bacteria, if present, can be grown (cultured) and identified.
People who have sepsis are admitted to the hospital and are given antibiotics. (See also treatment of sepsis.)