Hospital Floors Linked to Pathogen Transmission

Years ago, when faced with an MDR-Acinetobacter baumannii outbreak, I recommended that our hospital implement shoe covers in the outbreak unit (along with other measures) since the floors were covered with Acinetobacter. Since then, I've been almost surprised by the continued lack of attention that floors (and even contaminated shoes) have received from my infection prevention colleagues. Fortunately, it seems, some folks are finally noticing and estimating the role that contaminated floors play in pathogen transmission in hospital settings. And by "some folks", I mean Curtis Donskey's group at the Cleveland VA.

In a study, just published in ICHE, Sreelatha Koganti and colleagues used non-pathogenic bacteriophage MS2 to measure the speed of spread from isolation room floors to patients' hands and high-touch surfaces inside (and outside!) their rooms.

First, I would like to quote from their background:

"Notably, hospital floors are often heavily contaminated but are not considered an important source for pathogen dissemination because they are rarely touched. However, floors are frequently contacted by objects that are subsequently touched by hands (eg, shoes, socks, slippers). In addition, it is not uncommon for high-touch objects such as call buttons and blood pressure cuffs to be in contact with the floor (authors’ unpublished observations). Therefore, we hypothesized that floors might be an underappreciated reservoir for pathogen transmission."

And now their results:

"MS2 was detected on multiple surfaces of all patient rooms by 1 day after inoculation... Contamination was common on high-touch surfaces in adjacent rooms, in the nursing station, and on portable equipment. Portable equipment included wheelchairs, medication carts, vital signs equipment, and pulse oximeters."

What was most surprising was that MS2 was detected on 40% of patients's hands on Day 1, 63% on Day 2 and 43% on Day 3 after the floors were inoculated. Wow.

Now, after years watching our non-responses to epidemiological data such as these, I can already foresee the responses. Most will continue to do nothing waiting for some mythical/magical cluster-randomized trial, which can't be done for economic reasons (try powering such a study). Others will ignore these results completely. And a few brave souls will soldier on with more excellent epidemiological investigations, like this study from Cleveland, hoping that people will eventually notice. Oh, and some will install copper floors.

Maybe we could start with cleaning patient-room floors daily?

image source: DailyMail.com

We need to implement shoe decontamination interventions!

You pass through places and places pass through you 

But you carry them with you on the soles of your travelers shoes

"The Littlest Birds" - The Be Good Tanyas

I know we really shouldn't be looking for other interventions to reduce pathogen transmission in hospitals since we're too busy eliminating contact precautions at the moment. But I can't resist highlighting this recent systematic review on contamination of shoe soles from Tasnuva Rashid and colleagues published in Journal of Applied Microbiology. 

The authors reviewed the published literature from 1946 through 2015 to identify studies evaluating (1) shoes as vectors for infectious pathogens and (2) evidence on possible decontamination strategies.  Their extensive review identified 13 studies (10 cross-sectional and 3 longitudinal) for inclusion. Three studies were completed in hospitals. One study found MRSA and VRE on 56% of physician shoes before rounds and 65% after rounds. Two additional studies found significant contamination of operating theater shoes with pathogens including staphylococcus, streptococcus and bacillus species. It doesn't get any better when looking at shoes worn in the community with significant contamination by C. difficile (40%), Listeria spp., Salmonella spp., and E. coli. I won't even mention the contamination found on the shoes of folks that work with animals. 

Possible interventions evaluated include placing chemical filled mats in OR and ward entry points and shoe covers. While the reviewed studies suggest possible benefits for these interventions, more studies are needed. Of course, you know where I'm heading based on my intro paragraph - we need to implement shoe covers and chemical mats immediately in all hospitals. The data is clearly just as compelling as eliminating contact precautions based on single center studies. Oh, and we can fund these new shoe-targeted interventions using the savings generated through the elimination of contact precautions. Awesome!