Approaches to Preventing Healthcare-Related Infections

Healthcare-related infections are a major global problem, placing a considerable burden on healthcare systems. According to data from the US Centers for Disease Control and Prevention, about 1 in 31 hospital patients has at least 1 healthcare-associated infection on any given day. Such complications result in poorer health outcomes, increased costs and overuse of antibiotics that accelerates antimicrobial resistance. Identifying the drivers of healthcare-related infections is paramount to preventing and treating them effectively while maintaining good antibiotic stewardship.

Types of healthcare-related infection

A healthcare-related infection, also called a nosocomial infection, is an infection that is acquired while receiving healthcare that was not present when the patient was admitted. There are around 20 common pathogens in healthcare settings, with one of the most concerning being methicillin-resistance Staphylococcus aureus (MRSA), which can cause severe or potentially life-threatening disease. Infections most often occur after interventions such as surgery or ventilation, or from in-dwelling medical devices such as central lines. One of the most common causes of healthcare-related infections seen in many different healthcare settings, is the use of urinary catheters.¹

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Reducing the risk from in-dwelling devices

“In the US and Europe, 40% of hospital infections are urinary tract infections (UTIs), and this is likely to underestimate the global prevalence” says Ana Flores-Mireles, Hawk assistant professor at Notre-Dame University, USA. “There are also important differences between uncomplicated UTIs and catheter-associated UTIs (CAUTIs). Uncomplicated UTIs are more common in young women and the majority of the cases are caused by one organism – Escherichia coli. By contrast, men and women of any age are equally predisposed to CAUTIs and they are caused by a range of microbes. If untreated, CAUTIs also often lead to secondary bloodstream infection with a 7-day mortality rate of more than 30%.” So, why is there such a difference in the incidence and outcomes of these types of UTI?

The answer, says Flores-Mireles, lies in the inflammatory response caused when the catheter continually scratches the bladder lining as it flexes to expand and void urine. “This constant wounding of the bladder wall causes a coagulation response where the body releases many different proteins from the blood into bladder tissue to promote wound healing,” explains Flores-Mireles. One of these proteins, fibrinogen, forms networks around wounds but also coats the catheter. Unlike the normal bladder, which is uninhabitable for non-specialist microbes, the catheter creates the perfect environment for opportunistic species to thrive. “It’s like a bed and breakfast for pathogens,” says Flores-Mireles.

Fibrinogen deposition not only allows microbes to colonize the internal portion of the catheter, it also enables microbes to use the catheter as a hoist to invade the bladder. To prevent this, Flores-Mireles and bio-engineer Caitlin Howell, associate professor at the University of Maine, USA, set out to develop a smooth, softer catheter that wouldn’t give pathogens this advantage. In a mouse model of CAUTI, a silicone oil-infused, silicone-based catheter reduced deposition of host proteins – resulting in decreased microbial colonization on the catheter itself, within the bladder and preventing further dissemination throughout the body.² Proteomics analysis also showed that the total protein abundance was significantly reduced on the catheter.

“Around 20-50% of patients in hospital or nursing homes have a catheter, often for periods up to 30 days,” says Flores-Mireles. “If the silicone-based catheter is proven to be safe and effective for longer-term use in patients, it could help to reduce CAUTIs in multiple healthcare settings.”

One of the most important advantages is that this is an antibiotic-sparing intervention. “Catheters containing antimicrobials are generally only tested in vitro, and this doesn’t reflect the host-driven infection via the inflammatory response,” says Flores-Mireles. “They will still get coated with protein causing them to release sub-therapeutic levels of antibiotics which, in turn, may drive antimicrobial resistance.” If successful, the technology could be extended to prevent infections via central lines or other in-dwelling devices.

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Preventing transmission between patients

Another important aspect of tackling healthcare-related infections is understanding the factors that influence transmission. In addition to unavoidable risks from having an open wound or an in-dwelling device, infections can also occur if a patient is in contact with contaminated equipment or if healthcare professionals (HCPs) pass on infections between patients during care. Evidence suggests that these risks increase when there is higher bed occupancy, overcrowding of patients and understaffing.^3,4 These system-level issues create a vicious cycle: one review highlights how overcrowding and understaffing leads to reduced hand hygiene and increased movement of patients and staff between wards, which increases MRSA infection rates.⁴ In turn, high MRSA incidence causes increased patient stays, resulting in further overcrowding. So how can we break this cycle?

“I think there are lots of ways to answer this question,” says Estera Mendelsohn a PhD candidate at the Global Digital Health Unit, Imperial College London, UK. “But from my perspective I think it’s important to develop systems that capture high quality and granular data on infections in different healthcare settings as a pre-requisite to good studies on infection risk.”

Rather than researchers going into a hospital to conduct a prospective study on infection risk, it’s important to use real-world, routinely collected data, says Mendelsohn: “These systems need to make it easy for HCPs to input data. It’s also important to foster good relationships with HCPs who are on the ground and understand their healthcare setting, how the data is generated and what the priorities are in that setting.”

In a recent study, Mendelsohn used electronic health records collected routinely from elderly patients during a hospital stay to examine the impact of hospital ward transfers on infection risk.⁵ From an analysis of more than 24,000 hospital stays, they found a positive association between the number of times a patient moved between wards and their odds of becoming infected. With each additional ward transfer, there was a 9% increase in the odds of infection.

“In this study we had granular detail to our data that allowed us to look at what happened to patients before they tested positive for an infection,” says Mendelsohn. “This was important because one of the first things that happens when a patient becomes infected is that they are moved into a side room, and we needed to exclude those types of transfer from our analysis.”

It’s impossible to say for sure that there is a causal relationship between ward transfers and infections, but what studies like this do is add to the evidence base that clinicians and healthcare managers can use to identify risk factors for infection. “It can help convince them that something they experience anecdotally is backed up by real data, or it can alert them to something completely new,” says Mendelsohn. “The next step is to understand if there is any way we can reduce this patient movement. Some transfers are necessary for a patient’s wellbeing, but others happen because of a shortage of beds and it’s difficult to always send patients to the most appropriate ward. Hopefully, by understanding where these situations of suboptimal patient management impact on healthcare outcomes, we might be able to prevent them. And if we can reduce the lag time between HCPs getting insights from the electronic health record data, through moving towards real-time data management and data dashboards, we might do so even faster.”

References

1. Hooton TM, Bradley SF, Cardenas DD, et al. Diagnosis, prevention, and treatment of catheter-associated urinary tract infection in adults: 2009 International Clinical Practice Guidelines from the Infectious Diseases Society of America. Clin Infect Dis. 2010;50(5):625-663. doi: 10.1086/650482

2. Andersen MJ, Fong C, La Bella AA, et al. Inhibiting host protein deposition on urinary catheters reduces associated urinary tract infections [published online ahead of print, 2022 Mar 29]. Elife. 2022;11:e75798. doi: 10.7554/eLife.75798

3. Kaier K, Mutters NT, Frank U. Bed occupancy rates and hospital-acquired infections--should beds be kept empty? Clin Microbiol Infect. 2012;18(10):941-945. doi: 10.1111/j.1469-0691.2012.03956.x

4. Clements A, Halton K, Graves N, et al. Overcrowding and understaffing in modern health-care systems: key determinants in methicillin-resistant Staphylococcus aureus transmission. Lancet Infect Dis. 2008;8(7):427-434. doi: 10.1016/S1473-3099(08)70151-8

5. Boncea EE, Expert P, Honeyford K, et al. Association between intrahospital transfer and hospital-acquired infection in the elderly: a retrospective case-control study in a UK hospital network. BMJ Qual Saf. 2021;30(6):457-466. doi: 10.1136/bmjqs-2020-012124