Tuesday, March 25, 2008

The war on hospital acquired infections, fighting on two fronts

Ok, so it's an old analogy, but it works. Imagine being at war. You're a general tasked with disrupting the enemy's supply chain. The enemy has trains, boats and trucks that carry supplies, but it also has factories where supplies are built and depots, camps and ports where large quantities of supplies are stored.

What is your bombing strategy? Do you hit the individual vessels of supplies, or do you attack where the supplies are produced and stored?

The answer is you bomb both.

And so it goes for infection control. Enforcing hand washing protocols is a good start. Hands are like the boats and trains; they're vessels that deliver supplies (infections). But if you only attack the supply carriers, some are likely to get through and new routes will open as soon as the old ones are closed.

That's why it is important to also attack the factories and staging places for supplies. For infection control, this means looking at the source of pathogens and the reservoirs in which they hide. Individually each of these tactics are good, but together, their strategic value is much greater.

I thought of this tired analogy after reading a study (1) that says previous contamination of a hospital care area is an excellent predictor of future infection. Here's an overview of the study from infectious disease dot com:
Patients may be at an increased risk for vancomycin-resistant enterococci in health care settings if they are treated in areas where contamination with vancomycin-resistant enterococci has previously occurred, according to the results of a new study, which were published in Clinical Infectious Diseases.

Prior room contamination is highly predictive of vancomycin-resistant enterococci (VRE) acquisition, according to the study’s researchers, who stressed that increased attention to environmental disinfection is warranted to help reduce the risk for VRE infection.

“Everyone on the health care team — from doctors, to nurses, to medical students, to technicians — needs to take personal responsibility for preventing infections,” Marci Drees, MD, from the Center for Outcomes Research at Christiana Care Health System in Newark, Del., and one of the study’s researchers, told Infectious Disease News. “I think for too long we’ve had the attitude that these infections ‘just happen’ and are bad luck, but we now know that many are preventable. Preventing infections comes down to the basics: universal handwashing, wearing gowns and gloves when appropriate and thorough environmental cleaning. It’s easy to cut a corner here and there when you’re busy taking care of patients, but that’s how these infections happen.”
Three of the most significant factors associated with the risk for a VRE infection included sharing a room with a VRE-colonized patient, being treated in a room where a VRE-colonized patient had been treated within the past two weeks and being treated in a room with previous positive culture results.
To put a fine point on it, infection control professionals are fighting on several fronts. Hand washing is an important tactic. We should remember, however, that hands don't produce many pathogens--although they do a fine job of transporting them.

Where are the microorganism 'factories'? Among the places in a hospital where microorganisms are produced is the Heating Ventilation and Air Conditioning (HVAC) system. Our staff members have hundreds of data points taken from microbial swabbing of hospital HVAC surfaces. We find that the same microorganisms that cause infection are found thriving on cooling coils, drain pans and water inside hospital air handlers. Pathogens that are commonly cultured on hospital cooling coils include:
  • Pseudomonas
  • Acinetobacter
  • Staphylococcus
VIGILAIR is like a carpet bomber for these pathogens. But unlike bombing, whose effects are transitory, VIGILAIR eliminates reservoirs for microbial growth and prevents them from returning.

Now, onward infection control soldier!

1. Drees M, Snydman DR, Schmid CH, et al. Prior environmental contamination increases the risk of acquisition of vancomycin-resistant enterococci. Clin Infect Dis. 2008;46:678-685.

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