Apr. 18, 2005 Some potentially harmful bacteria can survive for prolonged periods of time on the keyboards and keyboard covers of computers, a study conducted at Northwestern Memorial Hospital has found. Gary A. Noskin, MD, who is medical director of healthcare epidemiology and quality at Northwestern Memorial and who led the study, advises periodic cleaning of computer equipment and hand washing after every computer use.
"The problem is especially important in hospitals and other healthcare environments where patients are at risk of contracting bacterial infections from healthcare providers who use computers," Dr. Noskin says. He presented his findings at the 15th Annual Scientific Session of the Society for Healthcare Epidemiology of America (SHEA) in Los Angeles this week, and the study generated coverage from various news outlets including CNN, the Chicago Sun-Times and Reuters.
Noskin and his colleagues studied bacteria commonly found in the hospital environment. To determine the ability of bacteria to survive on computer keyboards, the researchers inoculated the equipment with three types of bacteria: vancomycin-resistant Enterococcus faecium (VRE), methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PSAE). VRE and MRSA are examples of bacterial strains that have developed resistance to the antibiotics (including vancomyin and methicillin) commonly used on them. Although VRE and PSAE seldom cause problems except in hospitalized patients whose immune systems are compromised by other disease or illness, recent outbreaks of MRSA skin infections in otherwise healthy persons (community-acquired MRSA) have raised concern among infectious disease experts.
"We found that VRE and MRSA were capable of prolonged survival, with growths of the bacteria evident 24 hours after contamination," said Noskin. "PSAE, on the other hand could be recovered only up to one hour on the keyboard and five minutes on the keyboard cover." The study also found that the more contact with the contaminated keyboards, the more the likelihood of transmitting bacteria to the hands.
All three bacteria are widespread in nature, inhabiting soil, water, plants, and/or animals (including humans). MRSA (staph) infection can cause skin rash, boils and blisters, toxic shock syndrome and other types of infection and is more likely than the others to be acquired outside of a hospital, often by penetrating an open wound or other skin infection. VRE infection can cause complicated abdominal infections, skin infections, urinary tract infections (UTIs) and infections of the blood stream. PSAE is a frequent cause of pneumonia, UTIs and bloodstream infections. Infections caused by these agents can be life threatening, but usually do not cause problems in healthy people.
The investigators also tested the effectiveness of disinfectants commonly used in hospitals known as "quaternary ammonium compounds' to clean the computers. The most effective disinfectant was one in which the solution remains on the cleaned surface for 10 minutes before it is wiped off. Another, with a recommend exposure to the surface of five minutes effectively disinfected keyboards, but not keyboard covers.
"While it's important to disinfect computer equipment on a regular basis, especially in a healthcare environment, the most important disease prevention strategy is to wash your hands prior to patient contact," Noskin told the Sun-Times.
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