NICHOLAS BAKALAR
Published: May 24, 2010

(NY Times) -- Health care workers and patients have yet another source of hospital-acquired infection to worry about, British researchers are reporting.

Clostridium difficile, a germ that causes deadly intestinal infections in hospital patients, has long been thought to be spread only by contact with contaminated surfaces. But a new study finds that it can also travel through the air.

The researchers emphasized that there is no evidence that C. difficile can be contracted by inhaling the germs. Rather, they float on the air, landing in places where more people can touch them.

The bug is commonly spread by contact with infected feces, and the British scientists said the new study made it even more urgent to isolate hospital patients with diarrhea as soon as possible — even before tests confirm a C. difficile infection.

“We don’t want people to wait for the confirmation,” said the study’s senior author, Dr. Mark H. Wilcox, a professor of medical microbiology at the University of Leeds. “By then, the cat’s out of the bag.”

Outbreaks of C. difficile, a bacterium resistant to many antibiotics, have been increasing in the United States since 2001, along with the evolution of more virulent strains.

People in good health are rarely infected. But broad-spectrum antibiotics can wipe out the bacteria that normally live in the intestines, allowing C. difficile to flourish. Hospitalized people on antibiotics and the elderly, even when not taking medicine, are at high risk.

Health care workers who touch contaminated feces can spread the disease by direct contact with other people or just by touching objects. The spores are resistant to disinfectants and can survive in open areas for months.

The bacterium produces toxins that can cause fever, nausea, abdominal pain, severe diarrhea — and sometimes colitis, a serious inflammation of the large intestine.

Treatment involves replacing the broad-spectrum antibiotics with other antibiotics, usually vancomycin or metronidazole.

The British researchers began with a six-month investigation of 50 patients, symptomatic and not, with confirmed infection. The air near 12 percent of them was found to be contaminated with C. difficile. The more active their diarrheal symptoms, the more likely they were to have spores in the air around them.

Then the scientists repeatedly tested 10 patients with symptomatic illness over a 10-hour period, and the air near 7 was positive for c. difficile, usually during visiting hours or when there was activity in patient rooms like food delivery, ward rounds or bedding changes. Surfaces around 9 of the 10 patients were also contaminated.

The scientists believe that the movement of people and the opening and closing of doors stir up spores on contaminated surfaces, helping them disperse and increasing the possibility of them spreading.

The finding is unlikely to change current preventive practice, said Dr. L. Clifford McDonald, an epidemiologist at the Centers for Disease Control and Prevention. He said that the study supported putting patients in a single room, “which is the norm here in the U.S.”

“There is a little bit of dispersion,” he added, “but the heavier contamination is still from direct contact.”

Dr. Wilcox agreed. “It’s important,” he said, “not to interpret the results as a justification for methods aimed at removing bacteria from the air, techniques that may be appropriate for highly immunocompromised patients, but not for those at risk for C. diff infection.”

The amounts of C. difficile found in the air were generally modest. There were no clouds of germs circulating in patients’ rooms. This may suggest a genuinely low level of airborne contamination, the researchers write, or it may be a result of methodological problems in collecting air samples: the initial location of the sampling devices, their design, or their movement to accommodate patient care or the arrival of visitors.

Dr. Wilcox said patients should protect themselves from C. difficile by the conscientious application of two substances that do not require a prescription: soap and water.

“For everyone in a hospital, staff or patients,” he said, “the chief thing is optimal hand hygiene.”

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