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Airborne Spread of Clostridium difficile

By Amesh A. Adalja, MD, May 14, 2010

Hospital-acquired Clostridium difficile infections are a growing problem in hospitals in the U.S. and many other countries. Clostridium difficile is transmitted from patient to patient, and this transmission has proven to be hard to interrupt. Patients who are infected with C. difficile can shed large amounts of spores; these spores can be found on many surfaces in the infected patient’s hospital room and can also be transmitted outside the room as fomites on healthcare providers or their equipment. A recent paper authored by British researchers, published in Clinical Infectious Diseases, demonstrates that the spores may also be spread through the air.

Routine infection control practice for C. difficile includes handwashing, donning of protective gowns and gloves, and disinfecting surfaces. In addition, infected patients commonly are isolated from uninfected patients, usually in a single occupancy hospital room. However, when single occupancy rooms are not available, patients are housed on open wards. This would create a hazard if the disease is spread through the air.

Air Sampling Used

In the British study, air was sampled adjacent to 63 C. difficile patients for 180 hours. Control air sampling was also conducted, and environmental samples were obtained from surfaces.

Positive Air Samples in 12%

In the first phase of the study, C. difficile spores were isolated in 1-hour air samples of 12% of the C. difficile patients but none of the controls. On subsequent testing, the airborne microorganisms were identical to other isolates from the patients. More intensive air sampling (10 hours) of 10 patients revealed airborne spores around 70% of the patients. Spores were found on nearby surfaces around 90% of the patients.

In later phases of the study, isolation of C. difficile from the air was associated with activities taking place near the patient (eg, rounds, food delivery, etc). The presumed mechanism is dispersal of spores that were on the patient or nearby surfaces.

Single Occupancy Rooms Should Be Employed

Because C. difficile can be recovered from the air, open-air wards—in which no barriers are present between patients—are a hazard and can foster the spread of C. difficile. The ideal environment to house C. difficile patients would keep the spores in the patient’s environment. Wearing gowns and gloves and washing hands, coupled with the use of private rooms, appear to be the best infection control practices for the prevention of C. difficile. In most U.S. hospitals, private rooms for C. difficile patients are the norm, but in the UK, where the study was conducted, they are not as common. Also, many U.S. intensive care units are like open-air wards, and the results of this study may change their C. difficile procedures.


Best EL, Fawley WN, Parnell P, et al. The potential for airborne dispersal of Clostridium difficile from symptomatic patients. Clin Infect Dis 2010;50:1450-1457.