Many publications report coatings that exhibit antimicrobial potency applicable to high-touch surfaces and desirable for healthcare settings to contribute to reductions in the occurrence of Hospital Acquired Infections (HAI). In this review, the importance of surface contamination and the transmission of microbes is addressed. The standard strategy to tackle fomites is to implement proper disinfection and cleaning practices and periodically monitor the environment’s cleanliness. However, the probability of recontamination of cleaned surfaces is high. Therefore, an additional first line of defense against pathogen transmission and subsequent infection is the antimicrobial surface that can eliminate or at least repel pathogens, introducing a barrier to the spread of infection. It is a simple concept, but formulating a durable, antimicrobial coating with broad-spectrum antimicrobial and antifouling activities has proven challenging. The challenges and progress made in developing such material are reviewed.
Hospital surfaces, especially high-touch surfaces, are constantly exposed to potentially infectious pathogens. Surfaces or inanimate objects that can carry and potentially transmit pathogens to humans are termed fomites. Numerous epidemiological studies exhibit the role of fomites as an essential reservoir of pathogens in transmitting microbes that cause infections in a hospital environment. Viral, bacterial, and fungal pathogen transmission is often more pronounced in hospitals and occurs through two main routes. The primary mode of transmission is direct, human-to-human transmission, where the disease-causing organism is transmitted from an infected patient or carrier to a healthy or susceptible individual. An alternate indirect route of transmission involves fomites that become contaminated with the pathogen and transmit it to others via the contact. Unfortunately, the role of surface-mediated transmission has not received much attention since being first discounted. At the beginning of the COVID-19 outbreak, surface transmission was considered the primary route, and there was substantial further interest in the application of antiviral surfaces that could interrupt transmission.
The problem of HAIs has been present for centuries and remains a persistent challenge for healthcare facilities worldwide. HAIs are conditions that patients acquire in a healthcare facility while receiving treatment. HAIs have become a common complication of hospitalization and pose a particular threat to higher-risk groups, including immunocompromised patients, children, HIV patients, patients undergoing surgery, and patients coming to the hospital with open wounds or burns. HAIs can be responsible for extended hospital stays, long-term disability, and preventable deaths, and substantially increase the expenses related to healthcare, challenging patient safety and the quality of care in all healthcare settings. The rise in the number of immunocompromised patients and our aging population makes HAIs an unavoidable public health challenge.
Nosocomial pathogens are the microbes that cause HAIs. The two important characteristics of nosocomial pathogens are (i) the capability to cause death if not treated and (ii) to survive on hospital surfaces long enough for transmission to occur. The potential for becoming a nosocomial pathogen is evaluated by the virulence exhibited by the microorganism. Unfortunately, the extensive use of antibiotics in healthcare and farming has driven the evolution of multidrug-resistant pathogens that present more troublesome HAIs to confront. So, drug-resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), further enhance the risk of HAIs, and new approaches to tackle this growing health burden and its consequences are demanded. One approach is a durable and reliable solution to interrupt fomite-mediated transmission.
Transmission of pathogens is central to the HAI chain, but understanding the mechanism and contribution of fomite-mediated transmission of nosocomial pathogens to the risk of developing HAIs requires evaluation of complex interactions and interventions within the healthcare settings. Numerous publications have highlighted the role of contaminated environments in the transmission of nosocomial pathogens, including multidrug-resistant organisms, HAI outbreaks associated with MRSA, vancomycin-resistant Enterococcus (VRE), and Clostridioides difficile. If not controlled, the HAI cycle continues until the carriers infect the healthy individuals inside the healthcare premises.
Epidemiological studies of nosocomial pathogens show that contaminated surfaces serve as a breeding hub, ultimately resulting in an outbreak. If not cleaned according to the WHO standards, fomites can give rise to biofilms, and it has been established recently that dry surface biofilms (DSB), formed on dry fomites found in a hospital environment, are more resistant to cleaning and heat. A laboratory study of DSB associated with fomites supported the proposed contribution of DSB in the nosocomial pathogen transmission. Staphylococcus aureus DSB grown on polycarbonate and glass surfaces (10 5–10 6 cfu/coupon) was effectively transferred by the ungloved forefinger, with a single touch transferring around 5% of cells from the fomite to the finger, and 20% of the cells passed on from the finger to an agar plate. In the real world, a study carried out with 61 previously clean inanimate objects from three different United Kingdom hospitals, using scanning electron microscopy (SEM), ribosomal RNA intergenic spacer analysis (RISA) polymerase chain reaction, and next-generation sequencing identified the presence of diverse dry biofilms on 95% of the samples. Therefore, the chances of nosocomial pathogens recontaminating surfaces even after cleaning and disinfection or the persistence of pathogens toward cleaning are substantial. Despite the findings of these studies, regular analysis for pathogens on surfaces is often viewed as an unnecessary burden and not usually funded.
