Study identifies rate of norovirus as cause of infection outbreaks in US hospitals

  • Orthopedics Today, April 2012

Norovirus was responsible for 18.2% of all infection outbreaks and 65% of ward closures in U.S. hospitals during a 2-year period, according to a study recently published in American Journal of Infection Control.

Four organisms — norovirus, Staphylococcus aureus, Acinetobactor spp and Costridium difficile — were found to be the most common culprits, according to the survey abstract.

“If we focus on the four most common organisms we found causing outbreaks, two things come to mind,” survey author Emily Rhinehart, RN, MPH, told Orthopedics Today. “One is standard precautions in hospitals should reduce the risk of any or all of them. The second this is there is a [Centers for Disease Control and Prevention] guideline — of which I was one of the principal authors — on management of multidrug resistant organisms that should prevent transmission.”

To determine how often outbreak investigations are initiated in U.S. hospitals, the triggers for these investigations and the types of organisms and control measures involved, the Rhinehart and colleagues sent a two-part electronic survey to members of the Association for Professionals in Infection Control and Epidemiology (APIC) in U.S. hospitals in January 2010. The first part of the survey focused on hospital demographics and infection prevention or control programs, while the second part looked at specific outbreak investigations.

In all, the investigators received 822 responses accounting for 386 outbreak investigations in 289 hospitals during a 24-month period. According to the study abstract, nearly 60% of the outbreaks were caused by four organisms: norovirus (18%), Staphylococcus aureus (17%), Acinetobactor spp (14%) and C. difficile (10%).

Medical/surgical units were the most common site of outbreak investigations, representing 25.7% of investigations with surgical units representing 13.9%, according to a news release from the APIC. Norovirus occurred most in behavioral health and rehabilitation/long-term acute care units, with the authors noting in the study that the other organisms occurred most often in medical/surgical units.

Noroviruses are a group of related RNA viruses that cause acute gastroenteritis in humans, the investigators told Orthopedics Today. The most common symptoms are diarrhea, vomiting and stomach pain. Noroviruses spread from person to person, through contaminated food or water, and by touching contaminated surfaces. Norovirus is recognized as the leading cause of foodborne-disease outbreaks in the United States and have been frequently reported as the cause of outbreaks on cruise ships.

“The thing about norovirus being the most common cause … was not a shock or surprise,” Rhinehart said. “This was the first study to actually quantify how frequently norovirus is causing outbreaks in hospitals. It was common knowledge it was in hospitals and outbreaks were occurring, but nobody knew how frequent it was.”

While basic practices can reduce infections and outbreaks in many cases, Rhinehart said there are specific things orthopedic surgeons must keep in mind to help reduce the occurrence of C. difficile.

“The issue with C. difficile, especially for the orthopedic surgeon, is the appropriate use of antibiotics,” Rhinehart said. “Orthopedic surgeons routinely order antibiotics as prophylaxis against [surgical site infection], so they should stay within the guidelines for administration … meaning you initiate the antibiotics within an hour of the skin incision and discontinue it 24 hours postoperatively. The overuse of antibiotics is what encourages the occurrence of C. difficile.

According to the news release, the average number of confirmed cases for all outbreaks was 10.1, with an average duration of 58.4 days. Unit closures were reported in 22.6% of cases, causing an average of 16.7 bed closures for 8.3 days.

Rhinehart said she would like to see the survey repeated every 5 years, saying “10 years ago, we would not have found norovirus as the most frequent [culprit].” – by Robert Press

Reference:
  • Rhinehart E, Walker S, Murphy D, et al. Frequency of outbreak investigations in U.S. hospitals: Results of a national survey of infection preventionists. Am J Infect Control. 2012. doi: 10.1016/j.ajic.2011.10.003
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