by Yaneer Bar-Yam
Step VI: Create Disinfection Gateways

Infections acquired in hospitals, known as HAIs or nosocomial infections, are often resistant to antibiotics and thus particularly dangerous. Each year, the estimated 1.7 million infections cause nearly 100,000 deaths in the United States. Many patients in hospitals, nursing homes and clinics become sicker from these infections than they were before they sought care. These infections also play a significant role in costs—HAI hospital costs alone were recently estimated at between $30 and $45 billion.

Current recommendations for reducing hospital-acquired infections target the patient's immediate environment and interactions with care providers. Hand washing by care providers before and after patient contact is a key part of protocols in patient-focused transmission prevention. The wide variety of other measures include identifying patients who enter the hospital with infections for additional isolation, extra care to avoid catheter-associated infections, and augmented surface sanitation—of bed rails and controls, light switches, partition screens, faucet handles, and the like.

Hand washing by care providers is a key part preventing pathogen transmission.

Collectively, recommended protocols have been shown to reduce transmission, are cost effective and could be more widely adopted. Still, the attention and effort involved are significant and progress in eliminating infections is slow.

Underlying the widespread prevalence and difficulty in addressing these infections is the large number of contacts between care providers and patients. Because there are so many contacts, the effort involved in making every contact safe is huge and this effort burdens already busy care providers.

How can we speed up progress?

We need to expand our view beyond the point of contact between patients and providers to think in terms of the overall process of transmission within a hospital and between care facilities.

Each transit across a boundary between domains should be considered as a potential “transmission” of pathogens that will infect a unit, ward, floor, building or care facility. At these boundaries, protocols of disinfection should be designed to reduce pathogen transfers from one domain to another. The boundaries between domains should be like airlocks, disinfecting people and objects that pass through them.

Disinfection gateways can prevent transmission of pathogens between distinct domains in hospitals and between hospitals.

What protocols should these boundaries have? Since there are relatively few such crossings as compared to the number of patient contacts overall, we can consider more extensive decontamination procedures than just hand washing, such as clothing sanitation and the cleaning of cell phones and other personal effects. There is evidence that lab coats, PDAs, cell phones and the like act as repositories for pathogens, and can be responsible for HAI transmission. The protocol should still be efficient, and it can be. Staging such intensive interventions at the gateways could significantly reduce the flow of pathogens between patients.

We have to consider how pathogens are transferred: from one patient to the surfaces and fabrics near that patient to the care providers and their clothing, cell phones and pagers. From there the pathogens are transferred either directly to another patient or to the fabrics and surfaces in common areas or around that patient from which they eventually reach that patient at a different contact opportunity.

Most of the possible transmission events happen because of the large number of contacts within a local ward between patients and doctors, nurses, medical technicians, food service people and cleaning staff. Each of these contacts has the potential to transfer pathogens between patients, and to contaminate objects in shared spaces, such as computer keyboards.

Bedrails, bedding, clothing, curtains, cell phones, pagers, and myriad other objects can all be locations for pathogen transfer.

If there were no virulent pathogen in the ward in the first place, none of those possible transmission events could actually transfer virulent pathogens. Using boundary protocols to reduce transmission between wards would eliminate a large number of potential transmission events among the individuals within each ward.

With the use of boundary protocols, there would be a reduction not only in the transmission of existing pathogens but also in the emergence of new resistant strains. The high number of physical contacts makes medical care facilities a uniquely fertile environment for pathogens to evolve into more virulent strains. By blocking the spread of infection between areas, we can cut down on the appearance of virulent pathogens as well as their prevalence.

Would everyone have to go through disinfection at these airlocks? Visitors and patients entering a hospital for an appointment don’t present the same level of risk (though they might be tested for infection themselves). Unlike care providers who go from patient to patient to patient, they don’t act as agents for transmission. Accordingly, the same protocols need not apply. Similarly, a caregiver who is only interacting with a single patient need not undergo this process. Furthermore, these protocols could be overridden for the sake of speed in the event of an emergency—when protocols are generally observed, a single contact is unlikely to transmit pathogens.

A mockup of a disinfection gateway for use in inhibiting the spread of infections.

The same principles of containment are behind biological membranes that prevent transmissions between parts of the body, and are the reason why the immune system is concentrated in the high-speed transport system of the body—the blood. It is the reason we have regulations about plant and animal products crossing national borders. Conversely, the absence of such boundary protections in an increasingly interconnected world has promoted the rise of highly virulent new strains of pathogens and the risks of global pandemics.

Reducing the probability of transmission at each provider-to-patient contact by hand washing and other protocols is still a good idea. At the same time, the flow of pathogens through a hospital and overall transmission between sites can be dramatically reduced. This can be done by creating additional levels of transmission-prevention at key internal boundaries in the care facility and between care facilities.

The cost of hospital-based infections is high and using high-leverage methods to eliminate them is the way to go. By instituting protocols at geographic domain boundaries, at low cost, we can dramatically reduce their transmission.

Next...Step VII: Use e-records for research.

For Further Reading

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Writing and Editing Credits

Yaneer Bar-Yam with Luci Leykum, Shlomiya Bar-Yam, Karla Z. Bertrand, and Nancy Cohen

Image Credits

Page 1: "Surgeon washing his hands in an operating room" © iStockphoto / eliandric

Page 2: "Hospital Cutaway" © iStockphoto / Peter Willems

Page 3: Photo by Susan Jensen Smith

Page 4: "Disinfection Gateway Mockup" by Alexander S. Gard-Murray and Yaneer Bar-Yam

Formatting Credits

Alexander S. Gard-Murray


This work was supported in part by the Centers for Disease Control and Prevention and by an anonymous donation to the New England Complex Systems Institute.


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