RELATED STORIES • Pseudomembranous colitis

Note: All links within content go to MayoClinic.com

Healthcare associated infections — illnesses you acquire during a stay in a hospital or longterm care facility — aren't new. But in recent years, the infections have reached epidemic proportions in hospitals and nursing homes around the world. One of the most widespread and potentially serious of these illnesses is caused by the bacterium Clostridium difficile, often simply called C. diff or C. difficile.

C. difficile bacteria are everywhere — in soil, air, water, human and animal feces, and on most surfaces. The bacteria don't create problems until they grow in abnormally large numbers in the intestinal tract of people taking antibiotics or other antimicrobial drugs. Then, C. difficile can cause symptoms ranging from diarrhea to life-threatening inflammations of the colon. According to the Centers for Disease Control and Prevention, each year in the United States C. difficile is responsible for tens of thousands of cases of diarrhea and at least 5,000 deaths. And the problem is getting worse. The number of C. difficile infections doubled between 1993 and 2003, with most of the increase coming after 2000.

C. difficile isn't confined exclusively to hospitals. It's also a growing problem among otherwise healthy people. And although the infection can usually be controlled with antibiotics, virulent strains of C. difficile are now appearing that resist treatment with common medications.

Some people who are infected with C. difficile never become sick, though they can still spread the infection. Others have bouts of watery diarrhea, often with nausea and abdominal pain and cramping. And an increasing number of people develop colitis or pseudomembranous colitis — severe inflammations of the colon. Signs and symptoms of these potentially life-threatening illnesses include:

• Profuse, watery diarrhea — 10 or more bowel movements a day
• Fever, often greater than 101 F
• Abdominal pain, which may be severe
• Blood or pus in the stool
• Nausea
• Dehydration
• Weight loss

Most people develop C. difficile infection during or shortly after a course of antibiotics, but signs and symptoms may not appear for weeks or even months after treatment has stopped.

Your intestinal tract contains hundreds of kinds of bacteria (intestinal flora). Many are essential, helping to synthesize certain vitamins and stimulating the immune system. And some play a key role in suppressing the growth of harmful organisms. But when you take an antibiotic to treat an infection, it often destroys these beneficial bacteria as well as the bacteria that's causing your illness. Without enough healthy bacteria, dangerous pathogens such as C. difficile can quickly grow out of control.

Once it takes hold, C. difficile can produce two virulent toxins that attack the lining of the intestine. The toxins destroy cells and produce pseudomembranes — telltale patches (plaques) of inflammatory cells and decaying cellular debris on the interior surface of the colon.

Almost any antibiotic can cause harmful bacteria to proliferate in the intestine, but ampicillin, amoxicillin, clindamycin, fluoroquinolones and cephalosporins are most often implicated in C. difficile infections. The use of broad-spectrum drugs that target a wide range of bacteria and the taking of antibiotics for a prolonged period increase the chance of infection. Other antimicrobials, including antiviral and antifungal drugs, and chemotherapy medications also can lead to an increased risk of infection with C. difficile.

How C. difficile spreads
Although a small number of people naturally have C. difficile in their intestinal tract, most people pick up C. difficile from the environment. The bacteria are eliminated in feces and spread to food, surfaces and objects when people who are infected don't wash their hands thoroughly. Although you can develop a C. difficile infection anywhere, the majority of cases occur in healthcare settings, where germs spread easily, antibiotics are common and people are especially vulnerable to infection.

In hospitals and nursing homes, C. difficile travels from patient to patient on the hands of caregivers and on cart handles, bedrails, bedpans, stethoscopes, thermometers — even telephones and remote controls. What's more, the bacteria produce hardy spores that can persist in a room for weeks or months.

The chance of illness increases with the length of the hospital stay. Symptoms often begin in the hospital, but they can also appear weeks or even months after discharge. In longterm care facilities, older adults may be reinfected so often that C. difficile infections become chronic.

New strains
Health experts are especially alarmed by the emergence of new, aggressive strains of C. difficile that produce far more deadly toxins than ordinary strains do. The new strains are more resistant to treatment with certain medications, and increasingly are showing up in people who haven't been in the hospital or taken antibiotics. It's not clear why or how these low-risk people become infected.

Although more people with no known risk factors — including children — are contracting C. difficile infections, your risk is greatest if you:

• Are taking or have recently taken antibiotics.
• Are 65 years of age or older. Older adults have a disproportionately high infection rate. They tend to have more health problems than younger people do and so are more likely to be hospitalized and treated with antibiotics.
• Have a serious underlying illness or weakened immune system. People with weakened immune systems are especially likely to have recurrent infections.
• Are or have recently been hospitalized, especially for an extended period. In general, larger hospitals have higher infection rates than do smaller hospitals.
• Live in a nursing home or longterm care facility. Often, the infection spreads when patients are transferred from hospitals to other facilities.
• Have had abdominal surgery.
• Have a chronic colon disease such as inflammatory bowel disease or colorectal cancer.
• Take prescription or over-the-counter antacids. By reducing stomach acid, these drugs may allow C. difficile to pass more easily into the intestine.
• Have had a previous C. difficile infection.

Many people have loose stools during or shortly after antibiotic therapy. See your doctor if your signs and symptoms last more than three days or you have severe pain or cramping, blood or pus in your stool, or more than three bowel movements a day.

Doctors often suspect C. difficile in anyone with diarrhea who has taken antibiotics in the past two months or when diarrhea develops a few days after hospitalization. In such cases, you're likely to have one or more of the following tests:

• Stool test. Toxins produced by C. difficile bacteria can usually be detected in a sample of your stool. The drawback to this test (immunoenzymatic assay) is that it isn't always reliable, occasionally producing false-negative results.
• Colon examination. To help confirm a diagnosis of C. difficile infection, you may have either a sigmoidoscopy or colonoscopy. In both procedures, your doctor uses a long, flexible tube with a camera on one end to examine the inside of your colon. A sigmoidoscopy looks only at the sigmoid colon and rectum — about the last two feet of intestine. A colonoscopy examines the entire colon. Both tests look for inflammation and pseudomembranes, which could suggest C. difficile infection.
• Imaging tests. Occasionally, you may have a computerized tomography (CT) scan, which provides detailed images of your colon. The scan can show a thickening of the wall of your colon, which is common in pseudomembranous colitis, but which is also seen in other conditions.

About a third of people with C. difficile have recurrences of their infection or are reinfected with a different strain of the C. difficile, usually within two months of the initial illness. Repeat infections tend to be more severe than the original disease and are more often fatal. Older adults and people with weakened immune systems are especially susceptible to recurring infections.

Complications of C. difficile infections include:

• Dehydration. Severe diarrhea can lead to a significant loss of fluids and electrolytes. This makes it difficult for your body to function normally and can cause blood pressure to drop to dangerously low levels (hypotension).
• Kidney failure. In some cases, dehydration can occur so quickly that the kidneys shut down (kidney failure).
• A hole in the bowel (bowel perforation). This results from extensive damage to the lining of your large intestine. A perforated bowel can spill bacteria from the intestine into your abdominal cavity, leading to a life-threatening infection (peritonitis).
• Toxic megacolon. In this condition, the colon becomes grossly distended when it is unable to expel gas and stool. Left untreated, your colon can rupture, causing bacteria from the colon to enter your abdominal cavity. A ruptured colon requires emergency surgery and in some cases may be fatal.
• Death. Even mild to moderate C. difficile infections can quickly become fatal if not treated promptly with the appropriate medication.

If possible, stopping the antibiotic that triggered the infection is the first step in treating C. difficile. For some people, this may be enough to relieve symptoms. But most people require further treatment, which may include:

• Antibiotics. In an ironic twist, the standard treatment for C. difficile is antibiotic therapy. Doctors usually prescribe oral metronidazole or vancomycin. These antibiotics eradicate C. difficile, allowing normal bacteria to flourish again in the intestine. Although metronidazole is often tried first, some recent studies suggest that it might be less effective than vancomycin in severe cases, and it cannot be used by women who are pregnant or breast-feeding. On the other hand, vancomycin is expensive and may contribute to the growth of antibiotic-resistant bacteria. Both antibiotics kill only the active form of C. difficile, not the tough, long-lived spores it produces. Because the spores persist in the body after treatment, the infection can return, requiring a second or even a third round of antibiotics. Some people have repeat bouts of C. difficile for years.
• Probiotics. Some doctors prescribe probiotics — the word means "for life." These are dietary supplements that help restore a healthy balance to the intestinal tract. A natural yeast called Saccharomyces boulardii has proved effective in treating C. difficile infections in conjunction with antibiotics.
• Surgery. For people with severe pain, organ failure or inflammation of the lining of the abdominal wall, surgery to remove the diseased portion of the bowel may be the only option.

The most important step in stopping C. difficile infections is to reserve antibiotics for times when they're really necessary. Every year in the United States, antibiotics are prescribed for viral illnesses that aren't helped by these drugs. And even some common bacterial ailments such as ear infections or bronchitis may not respond to antibiotics. Taking a wait-and-see attitude with simple ailments may often be the best course.

Other preventive measures you can take include the following:

• If you do need an antibiotic, ask your doctor to prescribe one that has a narrow range and that you take for the shortest time possible. Broad-spectrum antibiotics and those used for more than three to five days are far more likely to disrupt intestinal bacteria.
• Consider taking probiotic supplements — available at natural foods stores and many pharmacies — or eating yogurt before, during and after antibiotic treatment. This helps replace the beneficial bacteria that antibiotics destroy. Only Saccharomyces boulardii has proved effective in C. difficile infections, however.

What hospitals can do
Preventing the spread of C. difficile in healthcare settings has proved a challenging task. The Centers for Disease Control and Prevention (CDC) and various monitoring organizations have issued stringent infection control guidelines.

At a minimum, these measures are recommended:

• Hospital staff wear disposable gloves when treating people with C. difficile infections. They wash their hands thoroughly with soap and warm water before and after treating each patient, after removing gloves, and after touching surfaces that might be contaminated. Alcohol-based hand gels, which are commonly used in health care institutions, may not effectively destroy C. difficile spores.
• Visitors wash their hands with soap and warm water before entering and after leaving the room of a patient with a C. difficile infection.
• People who have a C. difficile infection have a private room or share a room with someone who has the same illness.
• All room surfaces are carefully disinfected with a product that contains chlorine bleach.
• If you have a friend or family member in a hospital or nursing home, don't be afraid to remind caregivers to follow infection control precautions. And be diligent about washing your own hands frequently with soap and warm water.