Hospital Water Systems May Harbor Harmful Molds

SOURCE: Blood 2003;101:2542-2546.

NEW YORK (Reuters Health) - Hospital water distribution systems may serve as an important reservoir of several varieties of disease-causing molds, researchers report.

Hospital-acquired mold infections can be an important cause of illness and death in patients with weakened immune systems, according to Dr. Elias J. Anaissie, from the University of Arkansas for Medical Sciences in Little Rock, and colleagues. Such infections are thought to arise from contaminated outdoor air that infiltrates hospital ventilation systems.

Despite the widespread use of special air filters, the incidence of mold infections continues to rise, suggesting that other sources for these pathogens must exist. Previous reports have shown that water systems can be colonized with such molds.

To investigate, Anaissie's group assessed mold levels in various environmental samples from a bone marrow transplantation unit outfitted with the best air precautions.

Molds were isolated from 70 percent of the 398 water samples that were obtained, the authors report in the April 1st issue of the journal Blood. Furthermore, 22 percent of 1,311 surface swabs and 83 percent of 264 indoor air samples harbored molds.

The authors note that several findings suggest that the airborne molds probably came from water sources.

Airborne levels were highest in rooms where water was typically used, such as bathrooms, they point out. Moreover, airborne molds corresponded closely to ones present in hospital water.

"Our findings suggest that, in hospitals with adequate air precautions, airborne molds originate from hospital water and not contaminated outside air," the investigators state.

"An effective and inexpensive approach to prevent patient exposure to waterborne molds in the hospital setting is to provide high-risk patients with sterile (boiled) water for drinking and sterile sponges for bathing," the authors note. Thorough cleaning of shower room floors may also help reduce airborne levels of disease-causing molds, they add.