Hospital computer bugs’ take on a new twist

Nosocomial pathogens alight on keyboard, mouse

In a study that began somewhat in jest but resulted in a novel teaching tool, researchers have discovered that those increasingly ubiquitous computers used in health care may harbor "bugs" of a different stripe: nosocomial pathogens.

As more and more health care facilities implement computerized and electronic medical records, the question was bound to arise: Do the keyboard and mouse of the computer become contaminated with pathogens circulating in the facility? Felicisima Valena, RN, MSN, CIC, an infection control practitioner at the Veterans Affairs New Jersey Health System in East Orange, says the question came up when the hospital implemented a new computerized patient record system in 1999. The role of keyboards and "mice" as fomites for transmission was questioned and examined, says Valena, who presented the findings recently in Minneapolis at the 27th annual conference of the Association for Professionals on Infection Control and Epidemiology.¹

Computer study started as a joke’

"It started as a joke," Valena tells Hospital Infection Control. "If you’re not washing your hands, then [pathogens] should be there. But we thought this might be a good teaching tool, especially for hand washing. So we started to culture, and we got two infectious disease fellows interested and they helped us out."

Computer keyboards and mice were cultured in six acute-care areas, including two intensive care units, acute medicine, and surgery. Cultures were done by using pre-wet swabs. The swabs were rubbed on the keys and on the mouse until the swabs were discolored. The swabs were transported and inoculated on blood plates and into broth containing six mcg/ml of oxacillin. The broths were subcultured at 18 hours. All staphylococcal colonies were identified.

Control cultures of bed rails, bedside tables, and IV pumps showed two of 15 cultures positive for methicillin-resistant Staphylococcus aureus (MRSA). Keyboard/mouse cultures showed two of 40 cultures positive for S. aureus susceptible to oxacillin and 32 cultures positive for coagulase-negative staphylococci. Though they did not type the organisms against clinically significant strains circulating in the hospital, epidemiologic evidence in one case suggested staph was carried from a patient care area to a separate computer room designated for data entry.

"We have a residence program, and the physicians have to hunt for a computer so they can do their charts and their progress notes," she says. "So they put several computers in one big room. The physicians can go there anytime. One of the Staph aureus cultures was from one of those computers. And this was outside of the [medical] unit."

The researchers concluded that keyboards and mice are capable of maintaining staphylococcal viability and can serve as fomites for S. aureus and coagulase-negative staph. There is every expectation that this is also true for MRSA, they noted. Though the information may be useful in designing guidelines for care and use of keyboards/mice in this electronic era, the bottom line for controlling transient spread through fomites is hand washing, Valena says.

"We use it as a tool now when we are teaching hand washing," she says, adding that it also may be useful to convince administration to purchase antimicrobial hand gels for non-sink areas. The study, which included finding some positive cultures on blood pressure cuffs, also underscored the need to use designated medical items for patients in isolation, she says.

Reference

1. Valena FD, Simmons AV, Smith SM. Are computer terminal keyboards/mice a methicillin-resistant Staphylococcus aureus fomite? Presented at the Association for Professionals in Infection Control and Epidemiology. Minneapolis; June 18-22, 2000.