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uncommon for high-touch objects such as call buttons and blood pressure cuffs to be in contact with the floor (authors’ unpublished observations).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

Screening, Decolonization and Environmental Decontamination for MRSA in Nursing Homes Doesn't Work

Just in the past couple of weeks, we've written about pneumonia prevention bundles, MDRO prevention bundles, and spread of S. aureus - all in nursing homes.  It's like no one cares about acute care facilities any more! (humor) There is now more great data for those charged with managing infection control in nursing homes.

Cristina Bellini and colleagues from Lausanne University Hospital in Switzerland just published the results of cluster-randomized trial of an MRSA prevention bundle in 104 nursing homes (53 intervention, 51 control) in the April ICHE. All residents in intervention and control nursing homes (NH), who gave consent, were screened for MRSA carriage at study entry and 12 months thereafter on a single day in each NH. Newly admitted or readmitted residents were screened when admitted to the NH. Screening included nasal, groin and ulcer swabs along with urine cultures if residents had an indwelling catheter. In the intervention NHs MRSA colonized residents underwent decolonization along with environmental decontamination.

The primary decolonization bundle included 5 days of nasal mupirocin, 5 days of CHG oral rinse twice per day, 5 days of CHG showers including CHG shampoo on day 1 and 5. Environmental disinfection included daily clothing changes for 5 days, new linens on day 1 and day 5, and daily bed/table/phone/remote/wheelchair/walker disinfection with 70% alcohol. A lot of steps.

Unfortunately, the MRSA decolonization and decontamination bundle was not successful. The baseline prevalence of MRSA was 8.9% in both groups. The rate declined in intervention units to 5.8% in the intervention unit and 6.6% on the control units after 12 months (p=0.66) Full stratified results are in Table 3 below, and as you can see, no matter how they analyzed the intervention, the MRSA bundle intervention did not reduce MRSA prevalence compared to controls. This was despite the fact that the participation rate was 87%.

A limitation of this study was that they only measured prevalence and not individual level acquisition of MRSA. It is possible that by measuring prevalence they missed detecting benefits of the intervention related to reduced patient-to-patient transmission of MRSA. In any case, as I said last week about the study in CID, congratulations to the authors and journal (this time ICHE) for publishing this important negative study.

Say what?! Colonized patients (but not infected patients) contaminate the hospital environment

There is a continuous debate in infection control about whether to actively screen patients for MDRO colonization and subsequent isolation. Alternatives to active screening include passive surveillance, where only patients found to be infected through clinical cultures are isolated. Frequently, passive surveillance is justified by saying that infected patients will have a higher bio-burden compared to colonized patients, so they would be more likely to contaminate healthcare workers hands and the environment. However, is this in fact true? Are infected patients more likely to contaminate their rooms than colonized patients?

In part to answer this question, Lauren Knelson and colleagues from Duke and UNC just published a study in the July ICHE that measured the contamination of rooms after patients colonized or infected with MRSA or VRE were discharged. 48 rooms (33 from colonized patients, 15 from infected patients) were sampled using Rodac plates after patient discharge but before terminal room cleaning. Numerous sites were sampled including: sinks, toilet seats, bedside tables, bed rails, chairs, floors, TV remotes, carts, and laundry bins. This is a very small study, but even with the limited sample size they found that median CFU were higher in colonized vs infected patients' rooms (25 CFU vs 0 CFU, p=0.033). As you can see in the figure, the distribution of room contamination was greatly skewed towards higher levels of contamination at discharge from colonized patient rooms.

Some caveats: (1) More surfaces were sampled from colonized patient rooms than infected patient rooms (6.52 ± 2.47 surfaces vs 4.07 ± 2.12 surfaces; P = .02), so it's possible that surface selection could have biased these findings; and (2) Colonized patients stayed twice as long prior to discharge as infected patients (median 16 vs 7 days, p=0.28). Even though p > 0.05, this could be important since occupied rooms aren't "terminally cleaned" and "time in room" must increase contamination.

If these findings are validated, they have important implications. First, isolating infected patients (passive surveillance) would be expected to have less utility than expected. Second, the significant contamination of colonized patient rooms prior to terminal cleaning should be a reminder that we need to identify and implement environmental cleaning technologies that work continuously during the patient stay and not just focus on terminal cleaning. Finally, since infected patients would have received effective therapeutic antibiotics, these findings support the idea that effective antibiotics are important adjuvants for infection control. If true, this suggests that as the MDRO crisis expands in the absence of novel antibiotic discovery, infection control will become far more difficult (see 2011-2012 NIH KPC outbreak).

The Environment and HAI – Where does Biological Plausibility Come In?

This May's Infection Control and Hospital Epidemiology (ICHE) contained a randomized trial of copper-coated surfaces in ICU settings which reported a 50-70% reduction in several aggregate outcomes that included hospital-acquired infections and colonization with MRSA and VRE.  In this guest blog post, physician-scientists Dr. Matthias Maiwald from the KK Women’s and Children’s Hospital in Singapore and Dr. Stephan Harbarth from University of Geneva Hospitals in Geneva, Switzerland question the plausibility of these findings and put them in the larger context of what actually causes HAIs.

In 1965, Sir Austin Bradford Hill published a landmark paper, entitled “The Environment and Disease: Association or Causation?” in which he outlined what would become known as the “Bradford Hill Criteria.” The “Hill Criteria” help distinguish association from causation in epidemiological research. One of nine criteria was biological plausibility. Quoting: “It will be helpful if the causation we suspect is biologically plausible. But this is a feature I am convinced we cannot demand. What is biologically plausible depends upon the biological knowledge of the day.” As commented elsewhere, the spirit of this criterion is to check whether the proposed causation violates any of the known laws and facts of science of biology, and as Hill outlines, this depends on currently available knowledge. It is said that Hill did not intend the criteria to be applied rigidly in the sense of a checklist approach; instead, he regarded them as “viewpoints” that would merely help in the assessment.

Fast-forward to the May 2013 Special Topic Issue of ICHE concerning the role of the environment in infection prevention. In the issue’s introduction, Weber and Rutala quote figures from a 1991 article by Weinstein concerning the biologically plausible sources of healthcare-acquired infections (HAIs): “patients’ endogenous flora, 40-60%; cross infection via the hands of personnel, 20-40%; antibiotic-driven changes in flora, 20-25%; and other (including contamination of the environment), 20%.”

In the same issue, an article by Salgado and colleagues caught our attention. This clinical trial compares 614 patients randomly placed into standard ICU rooms or into rooms where 6 frequently-touched items (e.g. bed rails, overbed tables, intravenous poles, etc.) had been replaced with copper alloy surfaces. The measured primary outcomes, according to the paper’s methods, were:
   (a) any HAIs and
   (b) colonization with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE). Besides HAI and colonization, outcomes presented in the results section included the numbers of patients who had
   (c) both HAI and colonization,
   (d) HAI and/or colonization,
   (e) HAI only but no colonization (i.e. number of patients who had HAI minus the ones who had both HAI and colonization), and
   (f) colonization only but no HAI.

Are you confused? Separate data for outcomes in each trial arm were only reported for (d-f) but not (a-c).

For HAI and/or colonization (d), the article reported what amounted to a 49% reduction in the copper rooms vs. non-copper rooms (21 vs. 41 patients; p=.02), for HAI only (e) a 62% reduction in the copper rooms (10 vs. 26; p=.013), and for colonization only (f), a 67% reduction (4 vs. 12; p=.063, NS). What was was not reported were the numbers of patients with (a) HAI and (b) colonization, listed separately for each trial arm, but the article concluded – in the discussion – that copper surfaces in rooms reduced the risk of HAIs by more than half. Conventional wisdom, however, would suggest that (a) any HAIs and (b) any colonization events, would be the most biologically relevant outcomes, and that it may not be so informative to combine these two events (under d) in the same statistical calculation, because they are biologically very different from each other. So, we extracted the missing numbers from the other numbers presented and arrived at (a) HAIs 17 vs. 29, and (b) colonization, 11 vs. 15 events. Putting these into our statistics calculator, they were – non-significant.

Now, let us revisit possible transmission routes in hospitals. We have: (i) endogenous transmission, from within the patient’s own flora, (ii) exogenous transmission via direct transfer, (e.g. as in handborne without surfaces), and (iii) exogenous transmission via surfaces and secondary transmission from surfaces onto the patients. If we look at (a) HAIs and (b) colonization with MRSA or VRE, then all three pathways can lead to HAIs, while only the two exogenous pathways can lead to colonization. If there is a >50% reduction of HAIs through copper surfaces (pathway iii), this would mean that the overall proportion of transmission from pathways (i) and (ii) plus the proportion of transmission from the remaining non-copper surfaces in the copper-treated rooms among pathway (iii) among all HAIs together would contribute less than 50% to overall HAIs.

The obvious question comes to mind: is that consistent with the known proportions of the different pathways leading to HAIs? The preliminary answer, given the Weinstein data (see above), would be, “given the biological knowledge of the day, apparently not.” It is also noted that the overall numbers of HAI and colonization events in the present article are relatively small.

Finally, anyone of us engaging in research can accidentally have outcomes that are surprising or do not quite add up with existing knowledge in the field. That is, in our opinion, where the intended purpose and scope of a discussion section of an article comes in, and where the Hill Criteria provide important food for thought. As one of us has put forward (Teleclass Feb. 7, 2013) on a different occasion and concerning a different topic, we would welcome the broad application of a check for biological plausibility when findings from clinical trials – and even systematic reviews – are reported. But we are not confident that our voices will be heard.

Image of Sir Austin Bradford Hill, source: toxipedia

Larry

Reuters today has an article on Larry, a humanoid simulated vomiting system, which is used to analyze the effect of norovirus environmental contamination. I always like to add a picture to my blog posts, but today you'll be thankful I did not. Anyway, the synthetic vomitus used in the simulator, has a fluorescent marker that enables investigators to examine how widespread is the contamination after an episode of vomiting. Using Larry, they have found that droplets travel over 10 feet. This is important since the infecting dose of norovirus is very small, which makes it highly transmissible. As noted in the article, each droplet of vomitus has enough virus to infect over 100,000 people.

I have always wondered why anti-emetics are not available over-the-counter. If they were, quite a lot of misery could be avoided, ER visits averted, and maybe they would even provide norovirus source control by reducing environmental contamination.

Addendum (1/4/13):  NPR has added a video of Larry doing his job. It's quite impressive.

The ghosts of the "prior room occupant"

"Well, you know, Doc, when something happens, [it] can leave a trace of itself behind. Say like, if someone burns toast. Well, maybe things that happen leave other kinds of traces behind. Not things that anyone can notice, but things that people who "shine" can see….I think a lot of things happened right here in this particular hotel over the years. And not all of 'em was good."

-From the movie The Shining, 1980 

I’m reviewing papers for a talk I’m preparing on “control of multiple drug resistant gram negative rods (MDR-GNRs)”. So I’m looking again at a set of studies that always scare me (even more than a Stephen King novel)—those that demonstrate that a variety of bad bugs (C. difficile, MRSA, VRE, and MDR-GNRs) can be “left behind” after a patient is discharged, poised to colonize or infect the next occupant of that hospital room. It is a scandalous indictment of current hospital disinfection practices that patients must be haunted by the pathogens of the previous occupant of their hospital bed! 

There are still some practical (and financial) hurdles that must be overcome before new disinfection technologies (UV light, H2O2 vapor, antimicrobial surfaces, etc.) become standard of care. In the long run, though, I think that’s where the future lies—excellence in cleaning will remain important (organic debris will always require removal), but for microbial eradication in the environment, these technologies are going to replace our existing, more rudimentary approaches.

Q: What are Iowans doing to prevent hospital-acquired infections?

A: Quite a bit, actually. Thanks for asking!

Just last week, University of Iowa researchers Tara Smith, Marin Schweizer, and Phil Polgreen all sat down with Iowa Public Radio's Ben Kieffer (picture to the left) to discuss the latest science in HAI prevention including the epidemiology of MRSA in animal populations, the importance of environmental control in hospital settings and the latest hand-hygiene surveillance technologies.

Click on over to have a listen!

Hygiene rules

The June issue of the Journal of Infectious Diseases has an investigation of a norovirus outbreak among a soccer team (free full text here). The index case experienced nausea and vomiting in a hotel bathroom. The other cases had no contact with the index case or the bathroom after she became symptomatic. However, a reusable grocery bag with packaged cookies, chips and grapes was stored in the bathroom while the index case was ill. Even though the index case had no physical contact with the bag or its contents, it nonetheless became contaminated with norovirus, presumably via aerosolization of the virus during vomiting or defecation or via flushing of the toilet.While some media reports focused on the reusable aspect of the grocery bag, it seems likely that a disposable grocery bag would have become contaminated as well. The moral of the story is a simple one: don't store food in the bathroom!

Photo: Colorado Restaurant Consulting

Breaking...bacteria are everywhere!

As we recently found with our hospital curtain study, the media are fascinated with the fact that bacteria can survive on inanimate objects. The latest culprit, as outlined in this LA Times article, is paper. Paperless electronic medical records would seem a great solution to this problem, were it not for those germ-laden computer keyboards!

The solution is simple, fortunately. Just make sure that the last thing you touch prior to contact with a patient is an alcohol hand sanitizer.

Happy Halloween!

Maggie and Alicia

 

Nothing better than infection prevention related Halloween costumes.  I'm still trying to imagine Mike dressed as a flu vaccine, but its a bit difficult.  Anyway, here in Iowa City Maggie dressed as a collection of hospital pathogens clinging to Alicia, a contaminated textile.  Good times.

The new ICHE is here, the new ICHE is here!!!

Congrats to all of the authors who had articles published in this August's ICHE. Now that ICHE has a massive new impact score, I suspect most of them now feel like Navin when he says, "Page 73 - Johnson, Navin R.!  - I'm somebody now! Millions of people look at this book everyday! This is the kind of spontaneous publicity - your name in print - that makes people. I'm in print! Things are going to start happening to me now."  Well, I hope all the things that happen to these fine authors are a little more positive.

Highlights:

Page 737, Boyce, John M et al. looked at the impact of an automated mobile UV-C light unit on environmental contamination in 25 rooms after patient discharge. They report the unit significantly reduced aerobic colony counts and C. difficile spores.

Page 743, Rutala, William A et al. wrote an accompanying editorial that concluded that "there is now ample evidence that no-touch systems such as UV-C light or hydrogen peroxide can reduce environmental contamination...(however) only a single study using a before-after design has been published that demonstrated that such a system can reduce healthcare-associated infections." There we go again, hospital infection prevention: the queen (or king) of intermediate outcomes. Would be pretty cool if there were more independent (federal or foundation) resources to study HAI prevention interventions, such as these.

Page 791, Gupta, Kalpana et al. report the results of a cohort of all patients at the VA Boston Health Care System that had clean or clean-contaminated in 2008-2009 and a nasal MRSA PCR test less than 31 days prior to surgery. 6.6% of the patients were MRSA+ and were at significantly higher risk for postoperative MRSA infections (RR, 8.46; 95% CI, 1.70–42.04). Interestingly, vancomycin prophylaxis was associated with higher SSI risk in those negative for nasal MRSA (RR, 4.34; 95% CI, 2.19–8.57) but not in MRSA+ patients.

Page 818, Tohme, Rania A et al. reviewed hepatitis B vaccination rates and immunity among healthcare students during a 10-year period at Emory University. They report that among 4,075 students, only 60% had documented vaccination and 84% had anti-HBs concentration greater than or equal to 10 mIU/mL. It is interesting that despite CDC and ACIP (1995) recommendations of routine vaccination of children aged 11-12 years, and for all less than 18yo in 1999, the majority of students were only recently vaccinated.

If I left you off this list, sorry! You are still awesome!

Copper kills MRSA

VDB's design now only 2.5% Copper

Dr. Bill Keevil of the University of Southampton was just interviewed by the New Scientist. In the article and accompanying video, he demonstrated the MRSA-killing ability of copper. In the study, his group coated copper or stainless steel plates with 10⁷ MRSA. The copper-coated plates began to kill off the MRSA in minutes.  One caveat is that the study seems to have been supported by the Copper Development Agency. Oh, wouldn't it be great if copper killed MSSA and other bacteria too?

New Scientist, April 5, 2011
Weaver et al. Journal of Applied Microbiology, Dec 2010

No MRSA on Gym Equipment!?!

Modern Torture Devices

Some days when I'm tired, I don't feel like going to the gym. As someone who follows the IC literature, I always had a ready excuse for myself and others if I didn't want to go.  Too risky!  I don't want to catch MRSA, haven't you read the papers?

So I was depressed when I saw the headline this morning about a new study in AJIC from the University of Florida that found no MSSA and no MRSA on gym equipment surfaces before or after routine cleaning. They sampled 3 gyms (private, high school and university) on 3 separate occasions and obtained 240 samples. They swabbed gyms mats, benches, dumbells, cardio machines and weight machines. Oh well, back to the drawing board...and back to the gym.

Kathleen Ryan et al. AJIC March 2011

The Suncoast News - March 9, 2011

Kill this spore!

This month’s issue of Infection Control and Hospital Epidemiology has an interesting article from the University of Michigan group, demonstrating that having a prior room occupant with C. difficile associated disease (CDAD) is a risk factor for CDAD. Spores are hard to kill, and survive for months in the hospital environment. Meanwhile, environmental cleaning practices are highly variable….but clearly not good enough in most hospitals to eradicate C. difficile spores from the environment during terminal room cleaning. I have nothing to add to the excellent commentary on the article by David Weber and Bill Rutala. The future of environmental cleaning likely resides in touchless technologies like hydrogen peroxide vapor/mist and UV light.

Image: Transmission EM of C. difficile spore, from the Journal of Bacteriology.

VRE Forever!

Without despair we will share
And the joys of caring will not be replaced
What has been must never end
And with the strength we have won't be erased
When the truths of love are planted firm, they won't be hard to find
And the words of love I speak to you will echo in my mind

I believe when I fall in love with you
It will be forever
I believe when I fall in love this time
It will be forever

Stevie Wonder  -  I Believe (When I Fall in Love It Will Be Forever), 1972

One of the most consistent obstacles to halting the spread of MDROs in hospitals is the ability for the organisms to persist in the environment.  Nosocomial outbreak pathogens such as MDR-Acinetobacter baumannii have been shown to persist for up to a year in vitro. Vancomycin-resistant Enterococcus faecium (VREFm) has been shown to persist for up to 4 months.  Now a new letter to the editor in the March issue of Journal of Hospital Infection suggests that we may have underestimated VREFm.

Researchers at the University Medical Centre Utrecht took an outbreak CC17 VREFm strain and a non-outbreak but concurrently isolated non-CC17 VREFm strain recovered during a year 2000 outbreak and placed 1ml at 10^9 cfu/ml of each strain in 104 bottles to dry. They then tested for recovery weekly and then quarterly.  I have pasted the survival curve below.  Survival for both strains was gradual to 10^4 at 9 months and 10^2 during the next 30 months.  Out to week 170-194 between 1-7 colonies were detected. Thus, these strains survived almost 4 years!!!

Certainly gives you something to think about.  Just another reason to love the enterococcus and Stevie Wonder - the pride of Saginaw, Michigan.

Reference: Wagenvoort et al, JHI March 2011