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Infection control

Yale Medicine Magazine, 2018 - Autumn


A dangerous hospital-acquired infection, Clostridium difficile, is now increasing in the community.

In the messy world of the gastrointestinal tract, good and evil can, at least temporarily, coexist. The gut is home to trillions of bacteria, fungi, viruses, and parasites. Most are helpful in obscure ways, assisting the body in carrying out its various vital functions. But some types of bacteria, including Clostridium difficile (C. diff), are nefarious and opportunistic.

In a perfect world, beneficial bugs in the microbiome keep the bad ones in check. But when normal bacteria are wiped out (most often by antibiotics or illness), C. diff flourishes and can cause a brutal infection characterized by violent, uncontrollable diarrhea. Sometimes, especially in frail, very sick patients, this infection leads to serious complications, even death.

“If there is a window to overtake a healthy environment, C. diff will find it,” says Marianne J. Davies, DNP, APRN, an assistant professor of nursing at Yale School of Nursing. “The normal bacteria in your bowel maintain metabolism, break down food, and help with digestion. When you take antibiotics, you lower the normal flora that keep other pathogens out of the body. It’s like routine checks and balances.”

C. diff is the most common health care-associated infection in the United States, causing approximately 500,000 infections and 29,000 deaths in 2015, according to the Centers for Disease Control and Prevention (CDC).

And recently, for reasons researchers don’t understand, C. diff infections acquired in the community (versus hospitals, where the rate is actually decreasing) have been on the rise.

“There are theories as to why this is happening. Are we seeing more aggressive or resistant strains because facilities have become more efficient and are discharging patients before C. diff has had an opportunity to demonstrate itself?” Davies asks. “Typically, the onset is after you’ve been on antibiotics for five to 10 days.”

Preventive initiatives, such as limiting the use of antibiotics unless truly necessary, are imperative, Yale experts say.

Nature’s Bounty

Commonly found in the air, soil, and water, C. diff is a bacterium that occurs naturally in the gut microbiome of about 5 percent of the population. But that doesn’t make it benign.

“Healthy people with a hearty immune system may have C. diff in their intestinal tract, and they co-exist with it,” Davies says, noting, “But it’s not what we call normal flora.”

For patients in a health care setting, recent antibiotic use is the leading risk factor for contracting a C. diff infection. People on antibiotics are seven to 10 times more likely to get C. diff while on the medications and during the month after, the CDC reports. Antibiotics, which destroy and slow the growth of harmful germs, end up killing the good bugs too, explains Laura K. Andrews, PhD, APRN, an associate professor of nursing at Yale School of Nursing. This blanket effect gives C. diff room to multiply and crowd out any normal bugs that remain.

Once entrenched, C. diff releases toxins that inflame the protective lining of the large intestine. This causes C. diff colitis, which entails up to 30 watery stools a day, along with abdominal pain and fever.

“A mild case might mean taking oral antibiotics at home to treat it. For severe to life-threatening cases, you end up in the ICU and can even go into shock with multisystem organ failure,” Andrews says. “Patients can become profoundly dehydrated in less than 24 hours. They are losing liters of fluid.”

Other high-risk factors for C. diff infection include being over age 65 and/or taking immune-suppressing medications. Adding further challenges, C. diff can survive for months, is resistant to disinfectants, and can spread after contact with any contaminated surface.

“When you walk through a hospital, you see Purell and other alcohol-based sanitizers all over. These are a good reminder to staff and visitors that handwashing is important. Which is great, but these products are just an extra step. They will not kill C. diff spores. For that, she explains “diligent handwashing with hot soapy water is essential.” It takes bleach to kill the spores on surfaces and the friction of handwashing to rid hands of C. diff.

Hair of the Dog

Fortunately, many infections respond to treatment with antibiotics. Typically, it takes a 10-day course, but some people may require more time or a course of IV antibiotics in a hospital.

“If you are harboring bacteria in your bowel, there is risk of recurring infection, so it’s important to follow the prescribed course of antibiotics. Discontinuing antibiotics when symptoms decrease can contribute to antibiotic resistance,” Davies says.

Serious or resistant C. diff infections may require more aggressive strategies. In some cases, a fecal transplant procedure (transferring bacteria from a healthy person’s colon) may be necessary. For instance, surgery may be required to fix a perforated colon.

“Some strains are resistant to antibiotics, which is why we caution people not to self-medicate with antibiotics just because you have them,” Davies says. “We, as medical professionals, are making concerted efforts to be good antibiotic stewards and not overprescribe, to minimize resistance to any strain.”

Andrews agrees. “People get a cold and often go to the doctor demanding antibiotics, but a cold is a virus and antibiotics won’t work. Taking them unnecessarily is causing virulence and resistance in many classes of microbes,” she says. “By doing this, you are going to cause resistance five or 10 years down the line.”

Researchers believe a particularly virulent strain of C. diff—NAP1—that emerged in 2000 was spawned by antibiotic overuse. This strain accounts for about 30 percent of all C. diff cases. “It’s a big toxin producer. It can also be antibiotic-resistant and tends to recur,” Andrews says.

Furthermore, there has been a slow rise of community cases, including those among people who don’t fit the mold. “We are seeing it in a younger population, in those who aren’t immune-suppressed,” Davies says. “If a 19-year-old who is not on antibiotics or immune-suppressing medications comes into my office with significant diarrhea, C. diff is still something to think about.”

Yale School of Public Health is part of the Connecticut Emerging Infections Program, a collaboration between the Connecticut State Department of Public Health and the CDC. Its C. difficile surveillance program monitors all cases in New Haven County and is one of 10 sites throughout the United States monitoring C. diff infections in the population.

“One of the biggest trends we are looking at is from 2011 to 2017, when we saw the overall number of C. diff cases, as well as the hospital-acquired cases, go down. But the community-associated cases were going up,” says Danyel Olson, MS, MPH, the program’s surveillance coordinator. That trend continued until about 2015, Olson says, when the rates stabilized.

“The decrease in hospital infections could be from implementation of infection control practices, antibiotic stewardship, and new treatment guidelines,” Olson says. “We are unsure why infections increased in the community.”

Andrews, for one, is optimistic about the tide turning when it comes to the overuse of antibiotics. “I think half the battle is recognizing that this is a problem,” she says. “C. diff infection rates may get worse before they get better, but I think it goes back to getting antibiotic prescriptions under control.”

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