FRIDAY, Feb. 3 (HealthDay News) -- Norovirus was the most common culprit responsible for infection outbreaks in U.S. hospitals in 2008 and 2009, new research finds.

Researchers analyzed survey results from 822 hospitals regarding their infection outbreaks. About 35 percent reported at least one infectious outbreak over the 2-year period.

Four organisms triggered nearly 60 percent of the outbreaks:

• Norovirus (18.2 percent), which causes severe gastroenteritis (abdominal cramps, vomiting, diarrhea) and is often responsible for food poisoning
• Staphylococcus aureus (17.5 percent), or staph
• Acinetobacter spp (13.7 percent)
• C. difficile (10.3 percent), which can also cause diarrhea and serious inflammation of the colon.

Nearly 23 percent of outbreak investigations led to the closure of a unit or department.

The study is published in the February issue of the American Journal of Infection Control Outbreaks.

Medical/surgical units or surgical units were the source of about 40 percent of outbreaks, while 29 percent emanated from emergency departments, rehabilitation units or long-term acute care hospitals, psychiatric units and skilled nursing facilities.

"It is clear that outbreaks of health care-associated infections occur with some frequency in hospitals as well as nonacute settings," the authors wrote in a journal news release. "An infection prevention and control program and its staff should be prepared for all aspects of an outbreak investigation through written policies and procedures as well as communication with internal and external partners."

The researchers represented insurance companies, hospitals and infection-control professionals.

More information

The U.S. Centers for Disease Control and Prevention provides more information on norovirus.