Use of viral DNA surrogate markers to study routes of transmission of healthcare-associated pathogens.

Background: The hands of healthcare personnel are the most important source for transmission of healthcare-associated pathogens. The role of contaminated fomites such as portable equipment, stethoscopes, and clothing of personnel in pathogen transmission is unclear.

Objective: To study routes of transmission of cauliflower mosaic virus DNA markers from 31 source patients and from environmental surfaces in their rooms.

Design: A 3-month observational cohort study.

Setting: A Veterans' Affairs hospital.

Methods: After providing care for source patients, healthcare personnel were observed during interactions with subsequent patients. Putative routes of transmission were identified based on recovery of DNA markers from sites of contact with the patient or environment. To assess plausibility of fomite-mediated transmission, we assessed the frequency of transfer of methicillin-resistant Staphylococcus aureus (MRSA) from the skin of 25 colonized patients via gloved hands versus fomites.

Results: Of 145 interactions involving contact with patients and/or the environment, 41 (28.3%) resulted in transfer of 1 or both DNA markers to the patient and/or the environment. The DNA marker applied to patients' skin and clothing was transferred most frequently by stethoscopes, hands, and portable equipment, whereas the marker applied to environmental surfaces was transferred only by hands and clothing. The percentages of MRSA transfer from the skin of colonized patients via gloved hands, stethoscope diaphragms, and clothing were 52%, 40%, and 48%, respectively.

Conclusions: Fomites such as stethoscopes, clothing, and portable equipment may be underappreciated sources of pathogen transmission. Simple interventions such as decontamination of fomites between patients could reduce the risk for transmission.