Clostridioides difficile infection is a bacterial illness that can turn an ordinary course of antibiotics into a serious health challenge, causing persistent diarrhea and potentially life-threatening inflammation of the colon.

What Is Clostridioides Difficile Infection?

Clostridioides difficile, often shortened to C. diff, is a type of bacterium that lives in many environments around us, including soil, air, water, and even on our skin. The bacterium has gone through a name change over the years. It used to be called Clostridium difficile, and you may still hear healthcare providers use that older name. Regardless of what it’s called, this germ has the ability to cause an infection of the colon, which is the longest part of the large intestine.

What makes C. diff particularly concerning is that it can exist in two different forms. When it’s outside the human body, it transforms into spores, which are like protective shells that allow the bacterium to survive for months or even years on surfaces and in the environment. These spores are incredibly tough and can withstand heat, acid, and many common cleaning products. When someone swallows these spores and they reach the intestines, they can become active again and start causing problems.

Not everyone who carries C. diff becomes sick. In fact, healthy people often have small amounts of this bacterium living in their intestines without any issues. The trouble starts when something disrupts the delicate balance of bacteria in the gut, allowing C. diff to multiply out of control and release toxins that damage the intestinal lining.

How Common Is This Infection?

C. diff infection represents a significant public health concern across the globe. In the United States alone, this bacterium causes approximately 500,000 infections every year. These infections lead to around 15,000 deaths annually, making it a serious threat that healthcare systems must address.

The infection has traditionally been thought of as something that happens mainly in hospitals and nursing homes. While it’s true that C. diff is one of the most common infections people catch in healthcare settings, the pattern has been changing. More and more cases are now occurring in the community among people who haven’t recently been hospitalized. This shift means that C. diff is no longer just a hospital problem but something that can affect anyone in their daily life.

The burden on the healthcare system is substantial. C. diff infections cost an estimated 5 billion dollars annually in the United States. Patients who develop this infection often face prolonged hospital stays, additional treatments, and a longer recovery period than they would have had without the infection.

What Causes C. Diff Infection?

The primary cause of C. diff infection is taking antibiotics. While antibiotics are powerful medicines that save lives by killing harmful bacteria, they can’t distinguish between good and bad bacteria in your body. When you take antibiotics, they wipe out many of the helpful bacteria living in your digestive tract. These good bacteria normally act as a protective barrier, keeping potentially harmful bacteria like C. diff under control.

When the good bacteria are killed off, C. diff can quickly multiply and take over. The bacterium then releases toxins called toxin A and toxin B, which damage the cells lining your intestines. This damage causes inflammation and the symptoms associated with C. diff infection. The disruption to your gut’s natural balance of bacteria, known as the microbiome (the community of microorganisms living in your digestive system), can last for several months after you finish taking antibiotics.

The effect of antibiotics on your microbiome means you remain vulnerable to C. diff infection not just while taking the medication, but for up to three months afterward. Some antibiotics are more likely to cause problems than others, with cephalosporins and clindamycin being particularly associated with C. diff infections. However, any antibiotic has the potential to disrupt your gut bacteria enough to allow C. diff to flourish.

How Does C. Diff Spread?

C. diff spreads primarily through what’s called the fecal-oral route. This means the bacteria from an infected person’s stool somehow make their way to another person’s mouth. While this might sound unlikely, it happens more easily than you might think. The spores are so small that they’re invisible to the naked eye, and they can contaminate surfaces throughout a home or healthcare facility.

When someone with C. diff uses the bathroom, spores can spread to anything they touch—toilet handles, doorknobs, medical equipment, and more. If another person touches these contaminated surfaces and then touches their mouth or handles food without washing their hands thoroughly, they can ingest the spores. The bacterium can also live on people’s skin, so direct contact with an infected person can spread the germs as well.

What makes C. diff particularly difficult to control is how resilient those spores are. Unlike many other germs, C. diff spores can’t be killed by alcohol-based hand sanitizers. They require thorough handwashing with soap and water to physically remove them from hands. In healthcare settings and homes, surfaces need to be cleaned with bleach or other disinfectants specifically designed to kill C. diff spores.

It’s worth noting that finding C. diff germs in a home environment isn’t unusual, even when no one is sick. The spores are common in our surroundings. What matters is whether conditions in your gut allow those spores to germinate and cause illness if you happen to swallow them.

Who Is at Risk?

While anyone can develop a C. diff infection, certain groups of people face significantly higher risks. The most important risk factor is recent antibiotic use. People are up to 10 times more likely to get C. diff while taking an antibiotic or during the three months after finishing a course of antibiotics. The longer you take antibiotics, the greater your risk, with extended courses potentially doubling the chance of infection.

Age plays a significant role in risk. People who are 65 years old or older are much more vulnerable to C. diff infection. In fact, among those who catch C. diff in a healthcare setting, one in 11 patients over 65 will die within a month of diagnosis. This heightened vulnerability in older adults relates to changes in the immune system that come with aging, as well as the fact that older people are more likely to be taking antibiotics, living in long-term care facilities, or spending time in hospitals.

Your immune system’s strength directly affects your risk. People with weakened immune systems—such as those who have had organ transplants and take immunosuppressive drugs, individuals with HIV/AIDS, or people undergoing cancer treatment—are more susceptible to developing C. diff infection. Their bodies are less able to fight off the bacteria even when only small numbers are present.

Recent stays in hospitals or nursing homes increase risk substantially. About 20 percent of people who are hospitalized become colonized with C. diff during their stay, and more than 30 percent of those who become colonized will develop diarrhea. These settings bring together many of the risk factors: concentrated antibiotic use, proximity to other infected people, shared equipment and spaces, and populations of people who are already ill.

Other factors that increase risk include taking proton pump inhibitors, which are medications that reduce stomach acid (such as omeprazole). Stomach acid normally helps kill bacteria that enter through the mouth, so reducing it may allow more C. diff spores to survive and reach the intestines. People who have had a previous C. diff infection are also at higher risk of getting it again. About one in six people who recover from C. diff will experience a recurrence within two to eight weeks.

Having undergone gastrointestinal surgery can make you more vulnerable as well. Additionally, people with certain chronic health conditions like diabetes or kidney failure face elevated risks. It’s important to understand, though, that you can still get C. diff even if you don’t have any of these risk factors, though your chances are lower.

What Are the Symptoms?

The hallmark symptom of C. diff infection is diarrhea. In mild to moderate cases, you might experience watery diarrhea three or more times a day for more than one day. This diarrhea is typically mushy or porridge-like in consistency, though not completely liquid. Along with the diarrhea, you may have mild cramping and tenderness in your belly.

Many people notice something distinctive about C. diff diarrhea: its smell. It often has an unusually strong and oddly sweet odor that’s different from normal diarrhea. This characteristic smell may be due to increased levels of bile acids in the stool. Sometimes the stool may have a green tint, though this can occur with other bacterial infections too. In some cases, you might see traces of blood, mucus, or pus in your stool.

Symptoms typically begin within five to 10 days after starting an antibiotic. However, the timing can vary widely. Some people develop symptoms as soon as the first day of taking antibiotics, while others don’t become ill until up to three months after finishing their antibiotic course. This delayed onset can make it difficult to connect the symptoms to the antibiotic you took weeks or months earlier.

As the infection becomes more severe, symptoms worsen considerably. Diarrhea may increase to 10 or 15 times per day. The cramping and abdominal pain can become severe and persistent. Your abdomen may become swollen and distended. You might develop a fever, experience nausea and vomiting, and lose your appetite. The rapid loss of fluids through frequent diarrhea can lead to dehydration (a dangerous loss of bodily fluids), which causes additional symptoms like rapid heart rate and feelings of extreme weakness.

At first, C. diff symptoms might resemble food poisoning or stomach flu. If you’re already taking antibiotics, you might mistake the diarrhea for a normal side effect of the medication. This is why it’s important to contact your doctor if you develop persistent diarrhea while taking or soon after taking antibiotics, rather than assuming it will resolve on its own.

In rare but serious cases, C. diff infection can cause severe complications. These include pseudomembranous colitis (a condition where patches of raw, inflamed tissue form on the colon lining that can bleed or produce pus), toxic megacolon (a life-threatening condition where the colon becomes dangerously enlarged and may rupture), and sepsis (a severe, body-wide response to infection that can lead to organ failure). These complications can be fatal if not treated urgently.

Occasionally, people can have C. diff infections without experiencing diarrhea, though this is uncommon. In such cases, other symptoms like abdominal pain and fever may be present.

How Can C. Diff Infection Be Prevented?

The single most important step in preventing C. diff infection is appropriate antibiotic use. Antibiotics should only be taken when truly necessary. If your healthcare provider recommends an antibiotic, it’s worth having a conversation about whether it’s absolutely needed and if there are alternatives. When antibiotics are required, taking them exactly as prescribed and for the full course is important, but so is avoiding unnecessary prescriptions in the first place.

If you’ve had a C. diff infection before, make sure to tell any healthcare provider—including your primary care doctor, dentists, and specialists—about your history. This important information will help them make better decisions about prescribing antibiotics in the future and taking extra precautions if antibiotics are necessary.

Hand hygiene is crucial for preventing the spread of C. diff. Washing your hands thoroughly with soap and water is the best way to remove spores from your skin. You should wash your hands every time you use the bathroom and before you eat. This is especially important if you have diarrhea or are caring for someone who does. Remember that alcohol-based hand sanitizers don’t kill C. diff spores, so soap and water are essential.

If someone in your household has C. diff infection, taking extra cleaning precautions can help protect others. Try to have the infected person use a separate bathroom if possible. If that’s not feasible, clean commonly touched surfaces in the bathroom before others use it. Focus on cleaning items that people touch frequently with their hands, including doorknobs, toilet flushers and seats, refrigerator handles, and electronics.

For surfaces, regular soap and water cleaning should be followed by disinfection with bleach-based cleaners or other products specifically designed to kill C. diff spores. Regular household disinfectants may not be effective against these resilient spores.

Laundry from someone with C. diff should be handled carefully. Wash bed linens, towels, and clothing—especially underwear—in the hottest water that’s safe for the items. Use chlorine bleach if you can do so without damaging the items. Consider wearing gloves while handling soiled laundry, and always wash your hands with soap and water afterward, even if you wore gloves. Wash items before others use them and especially if they have visible stool on them.

Taking showers and washing with soap can reduce the C. diff on your body and lessen the chance of spreading it to others or to surfaces in your home. Healthcare workers and people visiting someone with C. diff in the hospital should follow all recommended precautions, including wearing gowns and gloves when appropriate.

If you’re prescribed medications that reduce stomach acid, such as proton pump inhibitors, talk with your doctor about whether you still need them. These medications can increase your susceptibility to C. diff, so it’s worth stopping them if they’re no longer necessary for your health.

How the Body Responds: Understanding What Goes Wrong

To understand how C. diff causes illness, it helps to know what happens inside your body during an infection. Your intestines are home to trillions of bacteria, fungi, and other microorganisms that make up your gut microbiome. In a healthy person, this community of microbes lives in balance. The beneficial bacteria perform important jobs like helping digest food, producing vitamins, and protecting against harmful invaders.

When you take antibiotics, particularly broad-spectrum ones that kill many types of bacteria, these helpful microbes are destroyed along with the harmful bacteria the antibiotic is meant to target. This creates an opportunity for C. diff to flourish. The bacterium multiplies rapidly when it doesn’t have to compete with other bacteria for nutrients and space.

As C. diff multiplies, it produces two main toxins: toxin A and toxin B. These toxins are what actually cause the symptoms and damage. They attach to cells lining the intestinal wall and damage them, triggering inflammation. The inflammation causes fluid to leak into the intestines, resulting in watery diarrhea. The damaged intestinal lining becomes inflamed, a condition called colitis (inflammation of the colon).

In more severe cases, the toxins can cause such extensive damage that patches of dead tissue, inflammatory cells, and fibrin form on the intestinal wall. These patches look like membranes and give rise to the term pseudomembranous colitis. The damaged intestinal lining can bleed, which is why some people see blood in their stool.

The body’s immune response to the infection adds to the inflammation. White blood cells rush to the area to fight the infection, which can cause fever and an elevated white blood cell count. The severe inflammation and fluid loss can lead to dehydration, which strains the heart and other organs. In the most serious cases, the colon can become so inflamed and damaged that it stops working properly or even ruptures, creating a medical emergency.

The extent of damage and symptoms depends on several factors: how much toxin is produced, how virulent the particular strain of C. diff is, and how well your immune system can respond to the infection. Some strains of C. diff, like the one called ribotype 027 or NAP1, are particularly aggressive. These hypervirulent strains produce more toxins and cause more severe disease than other strains.

What makes C. diff particularly challenging is its ability to form spores. When conditions aren’t favorable for growth—such as when you’re taking antibiotics specifically targeting C. diff—the bacteria can transform into spores and essentially go dormant. These spores can survive in your intestines and later become active again after treatment stops, leading to recurrent infections. This is why some people experience multiple episodes of C. diff infection even after successful treatment.