The Case of the Contaminated Keyboard: Does It Compute?

Abstract & Commentary

Synopsis: Computer keyboards may serve as reservoirs for serious nosocomial pathogens.

Source: Schultz M, et al. Infect Control Hosp Epidemiol. 2003;24:302-303.

Investigators at an urban tertiary care medical center obtained microbial cultures from computer keyboards to determine whether bacterial and fungal organisms contaminated their surfaces.

One hundred samples were taken from keyboards close to patients in high-use areas of the facility. Just over half of the samples were taken from ambulatory care locations such as hemodialysis and emergency units, while the remainder were selected from acute care medical and surgical units and a long-term care facility.

The researchers found that only 5% of the cultures were negative; the other 95% contained 1 or more organisms. Coagulase-negative staphylococci and Bacillus spp. predominated (representing 128 of the total 175 isolates). Staphylococcus aureus, Gram-negative bacilli, and enterococcus—more traditional nosocomial pathogens—were isolated 11 times. Interestingly, 3 of the 5 cultures taken from operating room computer keyboards were negative.

Schultz and associates noted that routine cleaning of computer keyboards was not a standard practice in their institution. Given their observation that bacterial contamination of keyboards with potential nosocomial pathogens was common, they strongly recommended that cleaning of keyboards be routine or that other options (such as use of easily sanitized plastic keyboard covers) be considered.

Comment by Jerry D. Smilack, MD

Computers in patient care areas of hospitals and other medical facilities are now commonplace. Data entry and retrieval before, during, and after patient contact offers the possibility of transmitting microorganisms from patient A to keyboard to patient B. Does this actually happen, and if so how commonly? The answers are not yet known, but this study suggests that there is the potential.

This report is not the first to show that contamination of computer keyboards may be the rule, rather than the exception. Neely et al provided evidence that plastic covers over keyboards served as a reservoir for Acinetobacter baumannii in a pediatric burn unit.1 Bures et al found that 24% of computer keyboards in patient rooms, a nurses’ station, and a physicians’ station were contaminated with such pathogens as methicillin-resistant S aureus (MRSA), enterococci, and a variety of Gram-negative bacilli.2 They extended their findings to show that environmental and patient MRSA isolates were indistinguishable by pulsed-field gel electrophoresis, suggesting that transmission from patient to environment to patient could indeed occur. They, too, recommended policies of daily cleaning of plastic keyboard covers and intensified handwashing. Others have found similar rates of keyboard contamination as well.3, 4

What do these studies tell us? They further document evidence that bacterial contamination occurs on a variety of medical equipment and environmental surfaces and may serve as a source for nosocomial infection. Adherence to routine cleaning and disinfection practices and increased emphasis on, and compliance with, hand hygiene recommendations5 are critical elements in providing optimal patient care.


1. Neely AN, et al. Clin Infect Dis. 1999;29:1358-1360.

2. Bures S, et al. Am J Infect Control. 2000;28:465-471.

3. Devine J, et al. J Hosp Infect. 2001;48:72-75.

4. Man GS, et al. J Hosp Infect. 2002;52:314-315.

5. Centers for Disease Control and Prevention. MMWR Morb Mortal Wkly Rep. 2002;51(No. RR16):1-44.

Dr. Smilack is Infectious Disease Consultant, Mayo Clinic, Scottsdale, Scottsdale, Ariz.