Electronic faucets in hospitals are intended to thwart the spread of bacteria by allowing doctors and patients to turn taps on and off without touching them. But the high-tech faucets are more likely to be contaminated with high levels of certain bacteria than traditional faucets, a new study finds.

The study analyzed water samples from taps at the Johns Hopkins Hospital in Baltimore. Half of the samples from electronic faucets grew cultures of the bacteria Legionella, while only 15 percent of samples from traditional faucets grew this bacterium. Legionella is a waterborne bacteria that can cause pneumonia in the chronically ill or people with impaired immune systems. The bacteria levels observed in the study were not high enough to be a concern for healthy people, the researchers say.

The researchers suspect the more complex valves of electronic faucets simply offer more surfaces for the bacteria to grow on. They removed all the electronic faucets from their hospital and suggest other hospitals evaluate the quality of the water coming out of their own electronic faucets.

Previous studies have suggested the water from electronic faucets tends to be "dirtier," said study researcher Dr. Emily Sydnor, of the Johns Hopkins University School of Medicine, though none have specifically looked for Legionella.

"There's a growing literature to suggest that these faucets can be a problem," Sydnor said. "It should be at least something people think about and consider a possible source of bacteria."

The research will be presented April 2 at the Society for Health Care Epidemiology of America meeting in Dallas.

Electronic faucets have been increasingly utilized in hospitals over the last decade. In addition to supposedly being more hygienic, they save water.

Sydnor and her colleagues tested water from 20 electronic faucets and 20 traditional faucets in patients' rooms.

Samples from electronic faucets had more growth on laboratory plates designed to estimate the overall number of bacteria in the water than did samples from traditional faucets. This means that, in general, water from electronic faucets was of lower quality, Sydnor said.

After the researchers disinfected the water with chlorine dioxide, samples from the manual faucets no longer grew Legionella, but some samples from the electronic faucets did. This suggests these faucets are harder to clean or disinfect, Sydnorsaid.

People usually become infected with Legionella when the bacteria become aerosolized (or airborne, as from a spray canister) and people inhale it.

The researchers plan to work with manufacturers of both types of faucets to fix their flaws and design parts that can be more easily cleaned.

Pass it on: Electronic faucets in hospitals harbor more bacteria than traditional faucets, which might pose a danger to some at-risk patients.

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This story was provided by MyHealthNewsDaily, a sister site to LiveScience.