Is Your Smart Phone Spreading Infection in the ICU?

By David J. Pierson, MD, Professor Emeritus, Pulmonary and Critical Care Medicine, University of Washington, Seattle. Dr. Pierson reports no financial relationships in this field of study.

Synopsis: Bacteria were present on the cell phones of all hospital clinicians studied, with potentially pathogenic microorganisms isolated from 29% of them. Contamination with pathogens was found more commonly with smart phones than with non-smart phones, and by multivariable analysis no other factor was associated with this difference.

Source: Lee YJ, et al. Contamination rates between smart cell phones and non-smart cell phones of healthcare workers. J Hosp Med 2013;8: 144-147.

Lee and colleagues administered questionnaires and performed bacterial cultures on the cellular phones of 203 clinicians (39% physicians, 52% nurses, 9% medical assistants) working in three university-affiliated teaching hospitals in Seoul. The questionnaire included data on participant demographics (age, gender, occupation) as well as behavior regarding cell phone use (type of cell phone, frequency and reasons for use, and cleaning of cell phones). The investigators touched the anterior and posterior surfaces of the phones onto blood agar plates and classified the recovered bacteria according to pathologic potential. Among probable pathogenic microorganisms, representative drug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus, and imipenem-resistant Acinetobacter baumannii were categorized as drug-resistant pathogens. The participants’ mean age was 29 years and 79% were women. A total of 115 (57%) were smart phone users and 88 (43%) used non-smart phones. The smart phone users were slightly younger (28 vs 29 years, P = 0.03), but this was the only significant difference between the groups. Only a minority of all cell phone users reported taking special measures to clean them.

All 203 cell phones had positive cultures: 4% had a single organism recovered, 19% had two organisms, and 76% had three or more. The most commonly cultured microorganism was coagulase-negative staphylococci, isolated from 96% of the phones. Gram-positive bacilli and Micrococcus species were also frequently recovered. Probable pathogenic bacteria were isolated from 58 cell phones (29%). S. aureus was the most common of these, and it was MRSA in 8 of the 50 instances. Acinetobacter baumannii was recovered from five phones. Probable pathogens were isolated more often from smart phones (35% vs 20% of non-smart phones, P = 0.03). The total colony count of probable pathogens from smart phones was also higher (average, 5.5 vs 5.0 from non-smart phones, P = 0.01). Among all the factors examined for possible association with phone contamination, only the phone’s being a smart phone was found to be a risk factor for contamination by bacteria with pathogenic potential (adjusted odds ratio [OR] 4.02; 95% confidence interval [CI], 1.43-11.31; P = 0.01). Using the cell phone more than 10 times during working hours appeared to be associated with pathogen contamination; however, this correlation failed to reach statistical significance (OR, 2.9; 95% CI, 0.9-9.3; P = 0.07).


This study found that health care workers’ smart phones were more frequently contaminated with potentially pathogenic bacteria than non-smart phones. The authors postulate two reasons for this — that smart phones have larger surfaces that are more often touched by the user’s fingers, and that they may be used more times during the day, since clinicians can use them for more work-related tasks than non-smart phones.

Other studies have documented frequent bacterial contamination of the cell phones of health care workers — along with their stethoscopes and various parts of their attire — as well as of the bed rails, monitors, bedside curtains, computer keypads, and other features of the patient’s immediate environment. Direct linkage between such contamination and specific cases of hospital-acquired infection has generally been lacking, although it is hard to ignore the possibility of this or measures aimed at avoiding it. Cell phones are now carried by virtually all health care workers. Today, more and more of these are smart phones, which are increasingly being integrated into clinical and administrative aspects of critical care. How concerned we should be about their contamination with potential pathogens is not entirely certain, but we should be aware of the fact that such organisms are present not only on our hands but also on the things we carry around with us in the ICU.