Touch Screens, Keyboards and Cross-Contamination Issues

Medical devices are incorporating a greater number of touch screens these days; applications for these devices include patient/visitor information kiosks, patient medical records systems, surveillance systems, med/surge monitors, as well as touch screen monitors that are quickly replacing standard keyboard applications. Infection prevention and environmental services professionals are including these touch screens on their list of high-touch surfaces that require regular cleaning, but just how contaminated are these items?

Medaris1 reports that researchers at Purdue University found that although platen glass surfaces used in biometric devices (and similar to touch screens) may look unhygienic due to visible soil and fingerprints, they harbor about the same number of bacteria as a typical doorknob.

While biometric equipment is gaining popularity in a variety of applications, Medaris reports industries are finding that many users believe the devices are unsanitary and a potential source of germs that could cause illness. The Purdue study was conducted by researcher Christine Blomeke, industrial technology professor Stephen Elliott, and biological sciences lecturer Thomas Walter. “When you look at these devices, finger moisture, dirt and oils cause the surface to appear to be dirty,” Blomeke said. “In a study we did on this last year, more than a quarter of the participants indicated that they thought the devices were somewhat unsanitary. Since the use of biometric devices is rapidly expanding in public spaces, we felt it was important to examine whether touching these surfaces would subject users to more germs than they would be exposed to by touching objects such as pens, doorknobs and elevator buttons.”

For the study, Blomeke’s team examined the bacterial recovery and transfer from three types of biometric sensors: fingerprint, hand-geometry and vein-recognition devices. Each sensor was tested separately with two kinds of bacteria: Staphylococcus aureus and Escherichia coli. To test how well the bacteria could survive on a biometric device, the surfaces were first sterilized to kill existing bacteria, then coated with a bacteria culture. Testers used sterilized gloves to touch the biometric device surface after 5, 20, 40 and 60 minutes to measure how many of the bacteria were still alive and could be transferred. Testers first touched the device surface, then a sterile plate or Petri dish containing growth media to allow any bacteria present to be more easily examined. The solution on the plate was allowed to grow for 24 hours at 99 degrees Fahrenheit. The next step was to test for bacterial transfer from the biometric device. To do this, the devices were sterilized, then testers wearing sterilized gloves touched the device surface and a sterile plate to measure how many bacteria were present before it was contaminated. Next, the device surfaces were contaminated with one species of bacteria at a time, and testers wearing sterilized gloves touched the device surface, then touched a sterile plate containing growth media 50 times. Just as in the other test, the solution was allowed to grow overnight to quantify the number of live cells recovered from touching the contaminated device. Researchers discovered that E. coli survived on the devices slightly longer than Staph bacteria, but within 20 minutes, nearly all of the bacteria had died on all three devices.

The researchers also tested a metal doorknob and found that the transfer of bacteria from the doorknob to another surface was nearly identical to that of the biometric devices. Blomeke said that on the doorknob, as well as on the three biometric devices, the majority of bacteria was transferred within the first 10 touches. “What we can take away from this is that no matter what kind of a surface it is, if it is contaminated, the more it is touched, the cleaner the surface becomes,” she said. “Of course, the bacteria are moved to the hand. But it’s important to remember that there are naturally occurring bacteria on everyone’s hands, and hundreds or even thousands of cells would have to enter the body — through a cut in the skin or from mucous tissues — to make a person sick.”

For those still unconvinced about touch screens’ role in hand carriage of pathogenic microorganisms, industry has responded by providing a number of products designed to cut down on opportunities for cross-contamination. MicroTouch Systems Inc. has introduced the CleanScreen, the first touch screen to incorporate antibacterial technology registered with the Environmental Protection Agency. To create the CleanScreen, a resistive membrane is permanently bonded to the glass surface of the company’s ClearTek 3000 touch screen, providing a surface where the growth of bacteria and viruses is retarded. The screen is designed for applications where hygiene is a concern, such as in clean-room manufacturing and hospitals. The product has several advantages over traditional touch screen cleaning procedures. CleanScreen has no effect on display optics or clarity; it is resistant to contamination and is easily cleaned. CleanScreen is also safe for the user and the environment because it contains no arsenic, heavy metals, or polychlorinated phenols. The resistive membrane does not leach into the environment, migrate to a user’s hands, or wear off when the screen is cleaned. Moreover, unlike conventional antimicrobials and disinfectants, the technology does not allow bacteria or fungi to adapt or create resistant organisms.


These frequently vilified reservoirs for pathogens are a ubiquitous part of life. A number of studies in the medical literature point to the need to clean and disinfect computer keyboards and mice regularly because they are contaminated with potentially pathogenic microorganisms

Rutala et al.2 reported on a study conducted to determine the degree of microbial contamination, the efficacy of different disinfectants, and the cosmetic and functional effects of the disinfectants on computer keyboards. The researchers assessed the effectiveness of six disinfectants — one each containing chlorine, alcohol, or phenol and three containing quaternary ammonium) against test organisms of oxacillin-resistant Staphylococcus aureus (ORSA), Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus species (VRE) inoculated onto study computer keyboards. They also assessed the computer keyboards for functional and cosmetic damage after disinfectant use. Potential pathogens cultured from more than half of the computers included coagulase-negative staphylococci, diphtheroids, Micrococcus species, and Bacillus species. Other pathogens cultured included ORSA, VRE and non-fermentative Gram-negative rods (36 percent). All disinfectants, as well as the sterile water control, were effective at removing or inactivating more than 95 percent of the test bacteria. The researchers observed no functional or cosmetic damage to the computer keyboards after 300 disinfection cycles.

Hartmann et al.3 examined the microbial contamination of computer user interfaces with potentially pathogenic microorganisms, compared with other fomites in a surgical intensive care unit of a teaching hospital. The researchers used sterile swabs to take samples from patients’ bedside computer keyboards and mice, and three other sites (infusion pumps, ventilator, ward round trolley) in patient rooms in a 14-bed surgical intensive care unit at a university hospital. At the central ward, samples from the keyboard and mouse of the physicians’ workstation, and control buttons of the ward’s intercom and telephone receiver were taken; quantitative and qualitative bacteriological sampling was conducted. A total of 1,118 samples was analyzed. Microbacterial analysis from samples in patients’ rooms yielded 26 contaminated samples from keyboard and mouse (5.9 percent) compared with 18 positive results from other fomites within patients’ rooms (3.0 percent). At the physicians’ computer terminal two samples obtained from the mouse (6.3 percent) showed positive microbial testing, whereas the ward’s intercom and telephone receiver were not contaminated.

Bures et al.4 set out to prove that computer keyboards and faucet handles are significant reservoirs of nosocomial pathogens in the intensive care unit (ICU) setting. Sterile swab samples were obtained from 10 keyboards and eight pairs of faucet handles in the medical ICU at Tripler Army Medical Center during a two-month period. MRSA obtained from the environmental and patient specimens were sent for DNA identification by using pulsed-field gel electrophoresis. A total of 144 samples were obtained (80 keyboards and 64 faucet handles), yielding 33 isolates. The colonization rate for keyboards was 24 percent for all rooms and 26 percent in occupied rooms. Rates for faucet handles in all rooms and occupied rooms were 11 percent and 15 percent, respectively. The environmental isolates and their prevalence were as follows: MRSA, 49 percent; Enterococcus, 18 percent; Enterobacter, 12 percent; and all other gram-negative rods, 21 percent. Fourteen individual patient isolates were recorded: MRSA, 43 percent; Enterobacter, 21 percent; other gram-negative rods, 36 percent; and Enterococcus, 0 percent. By using pulsed-field gel electrophoresis, an indistinguishable strain of MRSA was identified in two patients, the keyboards and faucet handles in their respective rooms, and on other keyboards throughout the ICU, including the doctors’ station. The researchers noted, “The colonization rate for keyboards and faucet handles, novel and unrecognized fomites, is greater than that of other well-studied ICU surfaces in rooms with patients positive for MRSA. Our findings suggest an associated pattern of environmental contamination and patient infection, not limited to the patient’s room. Pulsed-field gel electrophoresis results have documented an indistinguishable strain of MRSA present as an environmental contaminant on these two fomites and in two patients with clinical infections patients during the same period. We believe these findings add evidence to support the hypothesis that these particular surfaces may serve as reservoirs of nosocomial pathogens and vectors for cross-transmission in the ICU setting. New infection control policies and engineering plans were initiated on the basis of our results.”

As with touch screens, industry has provided a number of answers to keyboard contamination, including keyboards that are washable as well as keyboards imbued with antimicrobial properties.

The Medigenic keyboard and mouse addresses the growing concern of cross-contamination through its unique ability to monitor cleaning status. An indicator will flash at defined intervals to promote good infection control practices; cleaning the keyboard turns off the indicator. Excellent keyboard tactile feedback allows for high-speed data entry while the flat design enables quick cleaning with hospital-grade disinfectants. The moisture-resistant surface is comprised of a pliant silicone-based material that is designed to make it impervious to spray or liquid cleaning products.

iKey’s SlimKey-MD is a fully-sealed, easy to disinfect keyboard that is designed to improve compliance with infection control principles and practices. The SlimKey-MD keypads feature sealed, low-profile surfaces that are fast and easy to clean. Additionally, the units are engineered to be extremely compact, making them an excellent space saving solution. Since iKey’s keyboards are completely waterproof, they are able to be disinfected without ever unplugging them from the computer. Their silicone rubber keypads have no crevices where harmful bacteria can grow. A study conducted at Ball State University tested iKey’s SlimKey-MD keyboards for bacterial growth. A number of contaminates, ranging from methicillin-resistant Staphylococcus aureus (MRSA) to hepatitis C and E. coli, were applied to the keyboards. The keyboards were then disinfected with normal hospital cleaning agents. In the study, a 10 percent bleach solution was applied with a cotton swab and allowed to sit for 10 minutes. The results showed that, once wiped, the bleach had removed all bacteria from the keyboards.

Unotron’s GermStopper SpillSeal Washable Corded Keyboard S6000K features antibacterial protection incorporated into the plastic. Unotron’s SpillSeal protection allows keyboards to become fully submerged in water or antibacterial solutions for easy disinfection. “Incorporated into the plastic of our new keyboards is an inorganic silver-based biocide which allows silver ions to counteract the molecular process of microorganisms,” says Joseph Carabello, director of Unotron. “This causes the harmful organisms to die, lose their ability to infect, and prevent reproduction.”

Seal Shield Corporation has introduced its Seal Shield Medical Grade Washable Keyboard and Mouse, which are designed to be fully submersible. The products are part of a new line of infection control solutions developed specifically for the healthcare market.

No matter what technology is available on the marketplace, experts remind healthcare workers that the value of consistent hand hygiene cannot be minimized in the fight against hand carriage of pathogens from contaminated surfaces. Rutala et al.2 advise, “The risk of transmission from contaminated keyboards would be eliminated if staff performed hand hygiene after contact with inanimate objects in the patient care environment.” Absent this intervention, Rutala et al.2 advocate for routine disinfection of computer keyboards that are used in patient-care areas. They note, “Computers in these areas should be disinfected daily and when visibly soiled. In an effort to prevent contamination of computers, healthcare personnel should not touch computer keyboards with contaminated hands. If a keyboard cover is used, we suggest that it should be disinfected using these same recommendations. Additionally, mobile computers used by patients should be disinfected between patient uses. Ideally, computers used by a patient under isolation precautions should remain in the patient’s room until no longer needed and should then be disinfected before use by another person. Our data demonstrate that keyboards can be safely and successfully decontaminated with disinfectants.” ICT


1. Medaris K. Biometric sensors no dirtier than doorknobs, study finds. Oct. 10, 2007. Purdue University news accessed at:

2. Rutala WA, White MS, Gergen MF, Weber DJ. Bacterial contamination of keyboards: efficacy and functional impact of disinfectants. Infect Control Hosp Epidemiol. 2006;27:372–377.

3. Hartmann B, Benson M, Junger A, Quinzio L, Rainer R, Fengler B. Computer keyboard and mouse as a reservoir of pathogens in an intensive care unit. J Clin Monitoring and Computing. Vol. 18, No. 1. February 2004.

4. Bures S, Fishbain JT, Uyehara C, Parker JM, Berg B. Computer keyboards and faucet handles as reservoirs of nosocomial pathogens in the intensive care unit. Am J Infection Control. 28(6):465-471. December 2000.

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