The ICU: Where Lethal Pathogens Lurk - Part 1

The intensive care unit —with its beeps and buzzes, IV lines and ventilators — offers stark reminders of the perils facing its vulnerable patients.

But some of the gravest threats to ICU patients are silent and invisible: the pathogens floating in the air and coating the bed rails, doorknobs, and countless other surfaces. Around the world, dangerous bacteria, fungi, and viruses abound in the ICU, with infection rates worrisome and climbing.

“Our patients are sleeping with the enemy, and we do not know when this enemy awakens,” Florian Prechter, M.D., a German infectious disease specialist, warned in Critical Care.

Dr Prechter was referring in particular to Clostridium difficile, a bacteria considered by global health authorities to have a “severe” and “alarming” impact on morbidity and mortality in the ICU. However, she could have been referring to any number of harmful microbes lurking in intensive care units — Methicillin-resistant Staphylococcus aureus (MRSA), Aspergillus, and Acinetobacter species among them. In addition, ordinary viruses such as influenza and norovirus can strike hard and spread quickly in the ICU.

Even in high-income countries, an estimated 30% of ICU patients have at least one healthcare-associated infection, such as a bloodstream infection caused by a central line or pneumonia caused by a ventilator.

Globally, the ICU infection rate is higher. In fact, data from 1,265 ICUs in 75 countries, collected on a single spring day, showed 51% of patients had acquired infections. Many proved to be deadly: The mortality rate among infected ICU patients was 25%, compared to 11% for uninfected patients.

“The last decade has witnessed a striking increase in the burden of infection in critically ill patients,” cautioned Andrew F. Shorr, M.D,. associate chief of critical care medicine at a Washington, D.C. hospital.

The financial toll is enormous as well: Infection-related costs consume an estimated 40% of total ICU expenditures.

Certainly, infectious pathogens don’t confine themselves to the ICU. They journey — via air currents and lab coats and wheelchairs — to emergency rooms, operating theatres, common corridors, and lobbies. However, given the high stakes in the ICU and the rise of antibiotic-resistant bacteria, controlling infection among critical-care patients has become a top priority, prompting hospitals to rethink their approach.

“It is time to combine existing strategies with new technology,” asserts Ojan Assadian, MD, an infectious disease consultant and president of the Austrian Society for Infection Control.

For hospitals worldwide, this means outfitting the ICU with advanced air-disinfection technology while working to improve hand hygiene and surface cleaning.

The ICU: Superbug Central

We’ve long known that hospital activity — making beds, drawing curtains, mopping floors, delivering meals — can propel large loads of bacteria into the air. It’s well documented too that airborne pathogens are frequently inhaled by patients and often settle on high-touch surfaces. However, until recently little has been known about which hospital settings harbour the most floating microbes, particularly antibiotic-resistant bacteria, aka superbugs.

Iranian researchers sought to answer that question by collecting air samples from operating theatres, surgery wards, internal medicine wards, and intensive care units at four teaching hospitals.

The “winning” ward: the ICU.

Not only is this finding a “great concern from the point of view of patients’ health,” the authors warned, but it also underscores the outsized role ICUs are playing in the emergence of antimicrobial resistance.

The high density of patients, the frequent use of antibiotics, the prolonged hospitalization of patients who harbour antibiotic-resistant bacteria — these are among the reasons ICUs are contributing to the superbug crisis.

Intensive care units are home to a wide range of superbugs, both in the air and on surfaces.

One of the more concerning is C. difficile, the most common infectious cause of diarrhoea in the ICU, with an overall incidence of about 4%.

Of course, diarrhoea of any origin is a grave threat to ICU patients, increasing their risk for dehydration, malnutrition, heart failure, electrolyte imbalance, and skin breakdown. But C. difficile infection (CDI) among ICU patients is of particular concern. Some 20% of ICU patients who develop symptomatic CDI will progress to severe chronic inflammatory bowel disease, with a mortality rate of nearly 60%.

Worldwide, strains of C. difficile are becoming more virulent, and the relapse rate is high. The worse a CDI patient’s diarrhoea, the more likely spores will cloud the surrounding air.

Another superbug wreaking havoc in the ICU is MRSA, commonly transmitted via the air and healthcare workers’ hands. MRSA infections typically seen in the ICU are pneumonia, bloodstream infections, and wound infections.

Despite heightened awareness of MRSA among critical-care personnel, an American team cautioned, MRSA infections remain a “significant challenge” in the intensive care unit.

That’s partly because MRSA is a super hardy superbug. The bacteria can survive for days, even weeks, on floors, doorknobs, sinks, mops, blood pressure cuffs, call buttons, and clothing. Adding to the challenge, infection is readily spread. The mere brush of a doctor’s lab coat against a patient’s wound can transmit MRSA.

When Scottish researchers tracked an 8-bed ICU over a five-month period, they found 16% of patients had contracted MRSA. Notably, patients were seven times more likely to acquire MRSA in the ICU during periods of nurse understaffing.

These findings highlight the need for prevention methods, such as ultra-low energy plasma technology, that do not depend on the presence or expertise of healthcare personnel.

Read part 2 here.