LOS ANGELES, California (Reuters) -- Harmful bacteria can survive as long as 24 hours on computer keyboards, a study released Monday showed, highlighting what could be a growing threat as hospitals increase investment in technology.

The study carried out at Northwestern Memorial Hospital in Chicago found that keyboards can contaminate the fingers, bare or gloved, of a nurse or doctor, who could then transfer bacteria to patients.

"The emerging trend in hospitals is to have electronic health records ... some hospitals are putting computers in every patient room," said Dr. Gary Noskin, medical director of health-care epidemiology at the Chicago hospital.

His team contaminated keyboards with three types of bacteria commonly found in hospitals: vancomycin-resistant Enterococcus faecium, methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa.

Vancomycin and methicillin are common antibiotics, but some bacteria are no longer affected by the drugs.

Both of the drug-resistant bacteria strains were capable of surviving on a keyboard 24 hours after contamination, while the Pseudomonas aeruginosa lasted up to an hour, according to the study.

Staph infections, which can cause skin rashes, boils and blisters, toxic shock syndrome and other types of infections, are more likely than the others to be acquired outside of a hospital.

Enterococcus faecium can cause complicated abdominal infections, skin infections, urinary tract infections and infections of the blood stream.

Pseudomonas aeruginosa is a frequent cause of pneumonia, urinary tract infections and bloodstream infections.

The study, presented at a meeting of the Society for Healthcare Epidemiology of America, also found that touching a keyboard was enough to transmit the bacteria.

The best defense is frequent hand washing, Noskin said.

"Hands are washed before treating a patient, but hand washing prior to computer use is superfluous. Most hospitals are not aware of this," he said.