Hospitals were epicenters of SARS transmission in Guangzhou province and Hong Kong in 2003. In hospitals with especially severe outbreaks, the researchers looked at environmental and administrative factors that may have assisted in the transmission of the infection from one patient to another. This new study suggests that hospital beds placed too closely together, hospital staff working while having symptoms of SARS, and the use of oxygen therapy were the most significant risk factors associated with the spread of SARS in 26 hospitals in Guangzhou and Hong Kong.

These findings have implications for controlling other respiratory disease threats, including pandemic influenza, according to senior author Joseph Sung, MD, PhD, of the Chinese University of Hong Kong. "The lesson we learned during the SARS epidemic," he said, "was that the hospital can be a breeding ground for infectious disease. Nosocomial infection can amplify an infectious disease outbreak. It is very important to provide adequate space in hospital wards and implement effective infection control measures in order to avoid cross-contamination in hospitals."

Unfortunately, the authors note, it is a common practice for hospitals to increase the number of hospital beds inside a ward to meet the increasing demand, especially during an epidemic. When the distance between beds is reduced, exhaled droplets can spread from one patient to adjacent patients, spreading infection.

Healthcare staff working while sick are an obvious source of infection. This study found that hospitals could reduce the risk of outbreaks by providing staff with handwashing, showering, and changing facilities.

The use of oxygen therapy, including both the use of high flow rate oxygen masks and bi-level positive airway pressure ventilation, increased the risk of the spread of SARS. The authors hypothesize that these treatments may propel infectious air from these patients farther than without masks or ventilation. Alternatively, they may generate more infectious aerosols.

"There is a gap in the knowledge of how oxygen and ventilation therapy may promote the spread of infection. Future research should include investigating the safety of high flow rate oxygen therapy and positive pressure ventilation in medical facilities and effective ways of ventilating hospitals and clinics to avoid spreading of droplets," said Sung. "These findings are relevant not only for SARS," he concluded, "but also for other infections transmitted by droplets such as influenza."

Source: Infectious Diseases Society of America (IDSA)

Betsy McCaughey, a health-policy analyst and former lieutenant governor of New York, works to reduce infection rates by promoting changes in hospital procedures. "Almost all infections are preventable. We've worked with hospitals that have reduced infections by 90 percent," said Mrs. McCaughey, founder and chairwoman of the nonprofit Committee to Reduce Infection Deaths (RID).

CDC data on the prevalence of hospital infections -- both for the nation and for individual states -- were last published nearly a decade ago. The non-random sample of 270 hospitals showed that the infection rate climbed 36 percent between 1975 and 1996.

But it said tracking infection sites was difficult because postoperative stays were often shorter than the incubation period for Staphylococcus aureus infections.

Late last year, Pennsylvania became the first state to disclose the number of hospital-acquired infections reported by the 168 hospitals in that state. The hospitals reported 19,154 cases in which patients acquired such infections in 2005, a rate of 12.2 per 1,000 cases.

The mortality rate for patients with hospital infections was nearly 13 percent. That compared with a rate of 2.3 percent for patients without a hospital-acquired infection.

Ms. Griffin of IHI said most of the nation's hospitals are participating in initiatives the group has sponsored that are designed to prevent "unnecessary deaths and harm in hospitals."