While MRSA has made headlines in recent months, another lesser-known organism also has infectious-disease experts worried
With all the recent media attention, most people now have heard of methicillin-resistant Staphylococcus aureus (MRSA), a bacterial strain that has emerged as one of the nation’s top threats to public health. Less well-known—but of similar concern to infectious-disease experts—is Clostridium difficile (C. difficile), a potentially deadly organism that’s spreading fast.
In the US, the number of hospital discharges in which C. difficile was listed as a diagnosis doubled between 2000 and 2003, with a disproportionate increase in cases involving elderly patients—perhaps due to their generally weakened immunity. Over a recent five-year period, it is estimated that C. difficile was responsible for about 20,000 deaths.
FUELED BY ANTIBIOTICS
C. difficile bacteria can be found in stool (animal and human) and on many surfaces. Up to 3% of healthy Americans are colonized with C. difficile—that is, they have the bacterium in their intestinal tract, but don’t get sick from it. By comparison, 20% to 40% of patients in hospitals may be colonized with C. difficile.
Main risk: The use of antibiotics. The vast majority of patients infected with C. difficile are either taking—or have recently taken—antibiotics, and most acquire the infection in the hospital. One problem with antibiotics is that they not only kill disease-causing germs but also the beneficial organisms in the intestine, which normally prevent C. difficile from proliferating.
Once C. difficile multiplies, it produces highly virulent toxins that cause inflammation and damage cells in the lining of the large intestine. The newer “superstrains” of the bacterium are thought to produce up to 20 times more of these toxins than the usual strains.
Result: Watery, often violent diarrhea…severe intestinal cramps…blood or pus in the stools…and sometimes life-threatening colitis (inflammation of the colon).
Important: If you get diarrhea that is prolonged (more than two to three days) and/or severe, do not ignore it. See a doctor immediately. You should assume that it might be caused by C. difficile if you’ve taken antibiotics in the last few months, have recently been discharged from the hospital or have cared for someone with C. difficile.
Caution: The most widely used test for C. difficile, a stool test, is about 70% to 90% sensitive—some patients who test negative for the organism are later found to be infected.
A colonoscopy (examination of the colon using a long tube with a camera attached) may be performed to check for pseudomembranes, patches of inflammatory cells that are characteristic of C. difficile infection.
DIFFICULT TO ERADICATE
Unlike many disease-causing bacteria, C. difficile produces spores. These hardy, heat-resistant forms allow the bacterium to survive in a dormant form for months or even years in the intestinal tract…and on surfaces, such as floors and doorknobs, for weeks.
People acquire C. difficile by ingesting the spores, which resist the acidity of the stomach and germinate in the small intestine. Disruption of the normal flora (bacteria) of the colon—typically through exposure to antibiotics—allows C. difficile to flourish.
Those who are exposed to the spores could get infected—and, even if they do not have symptoms, can pass the infection on to others. This is a serious problem in nursing homes and hospitals, where people tend to have weakened immune systems and often take antibiotics. In these settings, C. difficile typically is spread via the hands of contaminated health-care workers or through exposure to contaminated surfaces.
Treatment: Two antibiotics, metronidazole (Flagyl) and vancomycin (Vancocin), appear to be equally effective in treating mild-to-moderate infections caused by C. difficile.
Doctors usually start treatment with metronidazole—it’s much cheaper than vancomycin and may be less likely to lead to antibiotic-resistant organisms in the colon. For severe infections, however, vancomycin is thought to be the better choice.
BEST PREVENTION STRATEGIES
There’s some evidence that people who take antacids, including proton-pump inhibitors, such as esomeprazole (Nexium), and H2 blockers, such as ranitidine (Zantac), have a higher risk for C. difficile—possibly because antacids decrease stomach acid, thereby making it easier for the bacterium to survive and germinate in the intestine. However, antacid use alone is unlikely to increase C. difficile risk significantly unless the patient is taking antibiotics and/or is hospitalized. Effective ways to guard against C. difficile infection…
- Avoid unnecessary antibiotics. Since active C. difficile infection is almost always associated with antibiotic use, patients can reduce their risk by taking antibiotics only when they’re truly necessary. Do not ask your doctor for antibiotics when you have a viral illness, such as a cold or flu. Important: Doctors are just as likely to prescribe antibiotics unnecessarily as patients are to ask for them. If your doctor recommends that you start taking an antibiotic, ask what it’s for…if he/she is sure that you have a bacterial (rather than a viral) illness…and if it’s possible that the condition will improve on its own without antibiotics.
- Ask for a culture. If you need an antibiotic, ask your doctor to perform a culture (whenever possible) to target the drug to the infection. Virtually all antibiotics have been implicated in C. difficile infection, but the infection is more common in patients who take broad-spectrum antibiotics, such as fluoroquinolone and cephalosporin antibiotics, that have a greater tendency to disrupt the colon’s normal flora.
- Wash your hands frequently—particularly when you’re in the hospital—or if you’re caring for someone infected with C. difficile. Use warm water and regular soap, and wash for at least 15 seconds to remove spores.
- Decontaminate. If you’ve been infected with C. difficile—or you are caring for someone who has had it—disinfect surfaces daily. Hospital rooms, especially bathrooms and frequently touched surfaces, are also commonly contaminated with C. difficile.