Clostridioides difficile (klos-TRID-e-oi-deez dif-uh-SEEL) is a bacterium that causes an infection of the colon, the longest part of the large intestine. Symptoms can range from diarrhea to life-threatening damage to the colon. The bacterium is often called C. difficile or C. diff.

Illness from C. difficile often occurs after using antibiotic medicines. It mostly affects older adults in hospitals or in long-term care settings. People not in care settings or hospitals also can get C. difficile infection. Some strains of the bacterium that can cause serious infections are more likely to affect younger people.

The bacterium used to be called Clostridium (klos-TRID-e-um) difficile.

Symptoms often begin within 5 to 10 days after starting an antibiotic. But symptoms can occur as soon as the first day or up to three months later.

Mild to moderate infection

The most common symptoms of mild to moderate C. difficile infection are:

• Watery diarrhea three or more times a day for more than one day.
• Mild belly cramping and tenderness.

Severe infection

People who have a severe C. difficile infection tend to lose too much bodily fluid, a condition called dehydration. They might need to be treated in a hospital for dehydration. C. difficile infection can cause the colon to become inflamed. It sometimes can form patches of raw tissue that can bleed or make pus. Symptoms of severe infection include:

• Watery diarrhea as often as 10 to 15 times a day.
• Belly cramping and pain, which may be severe.
• Fast heart rate.
• Loss of fluids, called dehydration.
• Fever.
• Nausea.
• Increased white blood cell count.
• Kidney failure.
• Loss of appetite.
• Swollen belly.
• Weight loss.
• Blood or pus in the stool.

C. difficile infection that is severe and sudden can cause the colon to become inflamed and get larger, called toxic megacolon. And it can cause a condition called sepsis where the body's response to an infection damages its own tissues. People who have toxic megacolon or sepsis are admitted to an intensive care unit in the hospital. But toxic megacolon and sepsis aren't common with a C. difficile infection.

When to see a doctor

Some people have loose stools during or shortly after antibiotic therapy. This may be caused by C. difficile infection. Make a health care appointment if you have:

• Three or more watery stools a day.
• Symptoms lasting more than two days.
• A new fever.
• Severe belly pain or cramping.
• Blood in your stool.

People who have no known risk factors have gotten sick from C. difficile. But certain factors increase the risk.

Taking antibiotics or other medicines

The intestines house a wide range of bacteria. Many of them help protect the body from infection. Antibiotics that treat an infection tend to destroy some of the helpful bacteria in the body as well as the bacteria causing the infection.

Without enough helpful bacteria to keep it in check, C. difficile can grow out of control quickly. Any antibiotic can cause C. difficile infection. But the antibiotics that most often lead to C. difficile infection include:

• Clindamycin.
• Cephalosporins.
• Penicillins.
• Fluoroquinolones.

Taking a proton pump inhibitor, a type of medicine used to cut stomach acid, also may increase the risk of C. difficile infection.

Staying in a health care setting

Most C. difficile infections occur in people who are in or have recently been in health care settings. These include hospitals, nursing homes and long-term care facilities. These are places where germs spread easily, antibiotic use is common and people's health puts them at high risk of getting an infection. In hospitals and nursing homes, C. difficile spreads on:

• Hands.
• Cart handles.
• Bedrails.
• Bedside tables.
• Toilets and sinks.
• Stethoscopes, thermometers or other medical tools.
• Telephones.
• Remote controls.

Having a serious illness or medical procedure

Certain medical conditions or procedures can up the risk of getting a C. difficile infection, including:

• Inflammatory bowel disease.
• Weakened immune system from a medical condition or treatment such as chemotherapy.
• Chronic kidney disease.
• Procedures on the digestive tract.
• Other surgery of the stomach area.

Other risk factors

Older age is a risk factor. In one study, the risk of becoming infected with C. difficile was 10 times greater for people age 65 and older compared with younger people.

Having one C. difficile infection increases the chance of having another one. The risk increases with each infection.

Complications of C. difficile infection include:

• Loss of fluids, called dehydration. Severe diarrhea can lead to a serious loss of fluids and minerals called electrolytes. This makes it hard for the body to work as it should. It can cause blood pressure to drop so low as to be dangerous.
• Kidney failure. In some cases, dehydration can occur so quickly that the kidneys stop working, called kidney failure.

• Toxic megacolon. In this rare condition, the colon can't get rid of gas and stool. This causes it to enlarge, called megacolon. Untreated, the colon can burst.

  Bacteria also may enter the bloodstream. Toxic megacolon may be fatal. It needs emergency surgery.

• A hole in the large intestine, called bowel perforation. This rare condition results from damage to the lining of the colon or occurs after toxic megacolon. Bacteria spilling from the colon into the hollow space in the middle of the body, called the abdominal cavity, can lead to a life-threatening infection called peritonitis.
• Death. Serious C. difficile infection can quickly become fatal if not treated promptly. Rarely, death can occur with mild to moderate infection.

To protect against C. difficile, don't take antibiotics unless you need them. Sometimes, you may get a prescription for antibiotics to treat conditions not caused by bacteria, such as viral illnesses. Antibiotics don't help infections caused by viruses.

If you need an antibiotic, ask if you can get a prescription for a medicine that you take for a shorter time or is a narrow-spectrum antibiotic. Narrow-spectrum antibiotics target a limited number of bacteria types. They're less likely to affect healthy bacteria.

To help prevent the spread of C. difficile, hospitals and other health care settings follow strict rules to control infections. If you have a loved one in a hospital or nursing home, follow the rules. Ask questions if you see caregivers or other people not following the rules.

Measures to prevent C. difficile include:

• Hand-washing. Health care workers should make sure their hands are clean before and after treating each person in their care. For a C. difficile outbreak, using soap and warm water is better for cleaning hands. Alcohol-based hand sanitizers don't destroy C. difficile spores.

  Visitors to health care facilities also should wash their hands with soap and warm water before and after leaving rooms or using the bathroom.

• Contact precautions. People who are hospitalized with C. difficile infection have a private room or share a room with someone who has the same illness. Hospital staff and visitors wear disposable gloves and isolation gowns while in the room.
• Thorough cleaning. In any health care setting, all surfaces should be carefully disinfected with a product that has chlorine bleach. C. difficile spores can survive cleaning products that don't have bleach.

A diagnosis of C. difficile infection is based on having:

• Diarrhea.
• Other symptoms of C. difficile infection.
• C. difficile in a stool sample.

People who have regular, formed stools should not be tested for C. difficile infection. Some people get C. difficile infection without having taken antibiotics. So recent use of antibiotics is not needed for making a diagnosis of C. difficile infection.

Stool tests

If C. difficile infection is suspected, one or more tests of a stool sample can show either the toxins or strains of the bacteria that produce toxins.

Colon exam

Rarely, to help confirm a diagnosis of C. difficile infection, a health care provider might check the inside of the colon. Tests used are either flexible sigmoidoscopy or colonoscopy. The tests involve putting a flexible tube with a small camera on one end into the colon to look for problem areas. These tests also can look for other causes of the symptoms.

Imaging tests

An X-ray of the stomach area or a CT scan can look for possible complications of C. difficile infection. These imaging tests can detect:

• Thickened colon wall.
• Enlarged bowel.
• A hole, called a perforation, in the lining of the colon.

Treatments are used only for symptoms of infection. People who carry the bacteria but aren't sick don't get treated.

Antibiotics

If C. difficile infection is related to an antibiotic, a health care provider will likely stop its use. Often, however, an antibiotic is needed to treat another infectious condition. A switch to another antibiotic might be less likely to cause diarrhea related to C. difficile infection.

Antibiotics are the main treatment for C. difficile infection. Commonly used antibiotics include:

• Vancomycin (Firvanq Kit).
• Fidaxomicin (Dificid).

Metronidazole (Flagyl) may be used with vancomycin to treat serious C. difficile infection.

Surgery

Surgery to remove the diseased part of the colon may be needed if there's:

• Severe pain.
• Organ failure.
• Toxic megacolon.
• Swelling and irritation, called inflammation, of the lining of the wall around the stomach area.

Treatment for repeat infection

About 25% of people treated for C. difficile infection get sick again. The reason might be that the first infection never went away or that bacteria cause a new infection. The risk increases with each C. difficile infection. After three or more infections, the risk of another infection is greater than 50%.

Risk of repeat infection is higher for people who:

• Are older than 65.
• Are taking other antibiotics for another condition while on antibiotics for C. difficile infection.
• Have a severe medical condition, such as chronic kidney failure, inflammatory bowel disease or chronic liver disease.

Treatment for C. difficile infection that comes back might include the following:

• Antibiotics. Treatment for repeat infections may involve one or more courses of an antibiotic. The antibiotic is often different from the one used at first. Antibiotic therapy works less well each time the infection comes back.
• Antibody-based therapy. A therapy known as bezlotoxumab (Zinplava) is a human antibody against C. difficile toxin B. It has been shown to cut the risk of repeat C. difficile infection in those at high risk of repeat episodes.

• Fecal microbiota transplant (FMT). FMT is a newer treatment for C. difficile infection that keeps coming back. FMT has been studied in clinical trials. The U.S. Food and Drug Administration has not approved FMT but allows the use of FMT for C. difficile infection as a test.

  FMT restores healthy intestinal bacteria by placing another person's (donor's) stool in your colon with specialized tubes inserted through your rectum. Donors are screened for medical conditions, their blood is tested for infections, and stools are carefully screened for parasites, viruses and other infectious bacteria before being used for FMT.

  Someone getting an FMT might need to sign consent form about the benefits and risks of the treatment. FMT also is called a stool transplant or an intestinal microbiota transplant.

  FMT restores healthy intestinal bacteria by placing another person's, called a donor's, stool in the colon with special tubes put into the rectum. Donors are screened for medical conditions, their blood is tested for infections, and stools are carefully screened for parasites, viruses and other infectious bacteria before being used for FMT.

  Research has shown that FMT done one or more times has a success rate higher than 85% for treating C. difficile infections that keep coming back.

• Probiotics. Probiotics are supplements or foods that have microorganisms to keep or improve the "good" bacteria in the body. The role of these products in C. difficile infection is not clear. Not all the research has shown that probiotics are helpful in preventing or treating infection with C. difficile.

  Researchers are studying advanced probiotics for treatment or prevention of C. difficile infection. These products aren't offered outside of research studies.

Supportive treatment for diarrhea includes:

• Plenty of fluids. Choose fluids that have water, salt and sugar, such as diluted fruit juice, soft drinks and broths.
• Good nutrition. For watery diarrhea, eat starchy foods, such as potatoes, noodles, rice, wheat and oatmeal. Other good choices are saltine crackers, bananas, soup and boiled vegetables. If you aren't hungry, you may need a liquid diet at first. After the diarrhea clears up, you might have trouble digesting milk and milk-based products for a while.