Thorough cleaning and disinfection reduce the role fomites play in the spread of disease.
Health care professionals know anything you touch can serve as a reservoir for pathogens. They also know you can transmit or contract a pathogen by coming in contact with a contaminated fomite (inanimate object). As part of our medical education, we were taught fomites can play important roles in the spread of infectious disease.1 Doorknobs and light switches are the usual suspects, but fomites also include countertops, handrails, mobile phones, and clothing.1 These items are present in most indoor environments. However, when considering health care facilities, the number and types of fomites increase dramatically, as does the presence of infectious pathogens present in those facilities.
Protocols for the proper disinfection of fomites have been in place for decades. Routine procedures for disinfecting surfaces in health care and other facilities were seriously tested when SARS-CoV-2 appeared in 2020. The spread of COVID-19 prompted questions about its mechanisms of transfer. What was more important to address: person-to-person contact, airborne transfer, or fomite transfer? Not knowing exactly how individuals became infected with COVID-19, early studies suggested the virus could survive on plastic or stainless steel for days, resulting in advice to disinfect everything.2,3
However, even though the COVID-19 virus can survive for days on surfaces, epidemiological data did not support contact with contaminated fomites as the greatest risk for spread of infection. Later studies on the importance of social distancing and mask wearing helped provide a better mechanism to avoid spread of the virus in indoor environments.4 Vaccination is now recognized as the best mechanism to avoid the spread of COVID-19.
Airborne mechanisms are more responsible for the spread of COVID-19 than contact with contaminated fomites, evidence suggests. However, the automatic reaction to disinfect surfaces opened up discussion on fomites as transmission vectors for infectious disease.
For a recent study of a neonatal intensive care unit (NICU) in a local children’s hospital, swab samples were taken from 20 sites in the unit by researchers from the University of Tennessee at Chattanooga’s Clinical Infectious Disease Control (CIDC) Research Unit (Table9). Results of this study indicated that of the 20 NICU surfaces swabbed, 12 sites (60%) had viable staphylococci and 4 of those sites (20%) had methicillin-resistant Staphylococcus aureus (MRSA) (Figure).5 However, Centers for Disease Control and Prevention (CDC) guidelines on routine environmental sampling for pathogens in hospitals deemed swab sampling not cost-effective, discouraging its use unless certain criteria (eg, ongoing bacterial infections of unknown etiology) were met.6 As a result, surface contamination of MRSA within this NICU would have gone unnoticed without the work of the CIDC.
Many outpatient clinics also have surfaces that come in contact with patients and act as vectors for infection. The CIDC also conducted studies of selected fomites in a children’s outpatient clinic and physical therapy clinics and looked at devices linked to recovery for hip replacement surgery.
In the children’s outpatient clinic, 72 of 208 (35%) swabs taken over a 6-month period found viable MRSA on the floors and toys that patients played with in the waiting room.7 In general medicine and pulmonary unit rooms of this outpatient clinic, similar levels of contamination were found, with significantly higher levels of MRSA on the general medicine floors than on the pulmonary unit floors (P < .05).8 In both the inpatient and outpatient clinics, floors are generally not off limits to children sitting or playing. Additionally, any medical instrument in clinic rooms (eg, blood pressure cuff or pen/pencil) that falls to the floor may become contaminated with pathogens present on the floors. Clinics should consider implementing protocols about contact with floors and dropped items.
For outpatient health care workers, including physical therapists (PTs) and occupational therapists (OTs), specific instruments play a critical role in patient therapy. For example, a common therapy in PT clinics is therapeutic ultrasound. This therapy involves not only the ultrasound head but also a coupling gel (usually contained in a bottle) that enhances the efficacy of the ultrasound. In a 2014 study, viable MRSA was observed on nearly 4% of the tips of gel bottles sampled.9 Although viable MRSA was not found on the ultrasound heads, other species of bacteria were found on 35% of the ultrasound heads tested. When ultrasound heads were disinfected using an approved quaternary ammonium-type disinfectant for 30 seconds, only 1 ultrasound head had any living bacteria.9 One option to reduce potential contamination from ultrasound coupling gels would be to use sterilized, single-use packets of gel for each patient.
In a study of physical therapy clinics, 16 of 81 (20%) bottles of lotion and cream used in massage therapy (soft tissue mobilization) had viable bacteria including S aureus on the threads of previously opened bottles.10 New bottles of lotion and cream did not have viable bacterial contamination. If protocols are in place to properly disinfect these bottles, risk of infection will decrease.
OTs must be careful with therapy devices that go home with patients, including those for patients recovering from hip replacement surgery. To limit the need for patients to bend over, reacher tools and sock aids help them pick up items from the floor or put their socks on. Both items, particularly during the training period in a clinic, may be shared with other patients.
In a CIDC-sanctioned study of these OT devices, a different tack was taken. By adding living bacterial cultures (S aureus, Escherichia coli, and Bacillus cereus) in known quantities to surfaces of these 2 OT devices, the CIDC researchers determined potential survival of the bacteria.11 The reacher tool handles were made of metal, and the sock aids were made of nylon plastic.
Survival of these 3 bacterial species differed on each device. For the plastic sock aids, 7.5% of S aureus survived for 48 hours. For both E coli and B cereus, survival on sock aids was less than 1% after 48 hours. However, when looking at survival of these 3 bacterial species on the metal handle of the reacher tools, the highest percentage of survival at 48 hours was for B cereus (14%). S aureus also survived on the reacher tool handle (4%), but at a lower percentage than for the sock aids. Essentially no surviving E coli was found on the reacher tool after 30 minutes.
Interestingly, results of an earlier study of S aureus survival on therapeutic ultrasound heads found close to 25% survival of these cells after 72 hours on the metal surfaces.12 Whether therapeutic devices for PT or OT act as fomites in the spread of infectious disease hinges on disinfection techniques used by the therapists or other end users. Consideration of pathogenic bacteria survival on fomite surfaces should include knowledge of the materials used to make the devices.
Research emphasizes the potential role that fomites play in the spread of infectious disease in inpatient and outpatient clinical environments. This threat is not limited to hospitals; it also spreads via facility floors and any devices patients take home. We should not only ramp up cleaning and disinfection protocols in response to rapidly spreading pathogens such as the COVID-19 virus but also be proactive by minimizing the role fomites play in the spread of infectious diseases.