CRE – too weak to spread!?



In the May issue of ICHE, Weber et al. published their findings of a study looking at the environmental contamination of rooms occupied  by patients colonized or infected with CRE. In addition to their observations they actively inoculated test surfaces with 102 CRE (which I find rather low). They found that the contamination in the patients’ room was infrequent (8.4%) and at low levels (5.1 CFU/120cm2). With the single exception of K. pneumoniae on formica, alle CRE had a less than 15% survival at 24 hours and a 0% survival after 72 hours.

Should we just conclude that the chance of CRE transmission from the environment is very low?

I believe that this conclusion would be too early and probably wrong. The survival of micro-organisms in the environment is clearly strain dependent and while the authors used clinical isolates they did not mention if they included a strain that has proven its ability to spread (eg. outbreak isolates). In general multi-resistant bacteria may loose some of their fitness – including the ability to survive in the environment – but survival studies like those of Kramer et al. show survival of multiple weeks for E. coli and Klebsiella spp.

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Key themes from ID Week 2013


Having somewhat dipped in towards the end of ID Week 2013 due to the overlapping Infection Prevention 2013 Conference in London, I can’t begin to provide a comprehensive overview of such a large event. Instead, I’ve tried to summarize new data on two important areas: the epidemiology and control of multidrug-resistant Gram-negative rods (MDR-GNR) and the role of the environment in transmission. You can access all of the abstracts free online here. Also, the poster abstracts that I cite below are either individually hyperlinked or can be downloaded here.


Dr Kavita Trivedi (California Department of Public Health) gave an overview of CRE in the USA, which has now been reported in virtually every state. Whilst surveillance sites, methods and definitions are problematic, CDC are coordinating some useful emerging data. For example, an NNIS prevalence survey indicates an increase in CRKP from 1% in 2001 to 10% in 2011. Also, the Multi-Site Resistant Gram-Negative Bacilli Surveillance Initiative (MuGSI) is beginning to yield some data. Early results from four states indicate that CRE is 10x less common than MRSA in the population, predominantly from urine cultures (85%) from patients with co-morbitities (93%) with a low mortality rate (4%). The CDC CRE toolkit provides a practical overview of recommended interventions. Finally, the challenges outlined by Dr Trivedi included: long-term care; variable prevalence; unknown epidemiological associations of different strains and genes; and colonization duration.

Oral presentations

A featured oral abstract by Bamburg et al. described an outbreak of NDM-producing K. pneumoniae affecting eight patients. The complex transmission map was dissected using whole genome sequencing, reminiscent of the NIH experience.

There was a useful oral session on ‘Identifying and Overcoming Challenges in Preventing Transmission of MDRO GNR’:

  • 1207, Haverkate. A Dutch group found that Klebsiella carrying OXA-48 can appear susceptible in vitro, risking ‘silent transmission’ of both the gene and the organism. The mean duration of colonization was almost one year and modeling indicated that readmission of CRE colonized patients needs to be carefully accounted for.
  • 1208, Mody. A cluster RCT in nursing home residents with urinary catheters or feeding tubes found that enhanced and preemptive isolation; ASC; and education led to a significant reduction in MDROs and CAUTI.
  • 1209, Hayden. A bundled intervention (ASC and isolation; daily CHG bathing; education; and adherence monitoring) significantly reduced CR Klebsiella in three of four LTACs included in the study. The prevalence of CR Klebsiella was remarkably high: 45% of patients at baseline. Environmental contamination was not identified, so no enhanced cleaning and disinfection was implemented, which is different to the experience of NIH.
  • 1210, Lewis. Varying the definition of ‘MDR’ made a profound impact on the proportion of patients requiring contact isolation, from 8-30%. Subsequent discussion with the authors indicated that the proposed MDR definitions developed by ECDC and CDC to be too sensitive for bacteria with less intrinsic resistance, such as E. coli. Perhaps a separate definition for the Enterobacteriaceae and non-fermenters is the way forward here?
  • 1211, Apisarnthanarak. The implementation of chlorhexidine bathing plus a switch to bleach for environmental disinfection brought an outbreak of A. bauamannii in Thailand under control. But which worked?
  • 1212, Barnes. A mathematical model indicated that hand hygiene is twice as important as environmental hygiene for interrupting A. baumannii, MRSA and VRE transmission. Whilst an awful lot of assumptions are required in this model, I can believe this 2:1 ratio in light of the following: “healthcare personnel are like small children: they touch everything and don’t always wash their hands” (Curtis Donskey) and “healthcare personnel hands are like very mobile shared surfaces” (Eric Lofgren).


  • 740, Jamal. CRE rate: 3% of 2000 Kuwaiti clinical isolate; 15.9% of CRE NDM-1 producers.
  • 746, Koper. A match made in hell between hypervirulent K2 Klebsiella and KPC; in vitro plasmid transfer demonstrated.
  • 1578, Madigan. No CRE detected in 69 international patients at Mayo Clinic; 22% carried ESBLs.
  • 1582, Johns. 50% of 66 MDR A. baumannii cases in Ohio in 2012 presented in first two days of admission, mostly admitted from extended care facilities, illustrating the ‘revolving door’ between acute and other healthcare facilities.
  • 1586, Carrilho. 26% of 157 Brazilian CRE polymyxin-resistant, though polymyxin resistance was not associated with increased mortality.
  • 1603, Drees. Remarkably, a survey from the SHEA Research Network indicates that 6% of hospitals do NOT isolate patients with CRE.
  • 1609. Decker. A study of CRE colonization patterns indicates median colonization of 216 days (range 134-376). One patient was colonized for >500.
  • 1611, Odom. CRE cultured from 12 (4.4%) of surfaces, predominantly sink drains.
  • 1612, Fitzpatrick. Selective broth enrichment added 10% sensitivity for detecting CRE. Is the resulting diagnostic delay worth the wait?
  • 1615, Lin. Chlorhexidine gluconate (CHG) daily bathing significantly reduces the number of body sites growing CRE, but several sites remain colonized.
  • 1618, Cheng. CRE identified in 1.2% of 6533 rectal screens and faecal specimens in Hong Kong, which is lower than I would expect.

Reflections from MDR-GNR research

  • We now have some intervention studies, but many include bundled interventions. We need more resolution on what works.
  • The duration of colonization with CRE seems to be long, probably around 1 year on average. Is this enough for a “once positive, always positive” approach?
  • Prevalence of CRE is variable around the USA, and in other parts of the world.
  • There is poor resolution between the epidemiology of Enterobacteriaceae and non-fermenters.
  • Most would agree that contaminated surface play an important role in the transmission of MDR non-fermenters such as A. baumannii. But is CRE an environmental issue? Some groups have found contamination and implemented enhanced disinfection, others have not.
  • Should chlorhexidine decolonization be part of the intervention for MDR-GNR?
  • Different research groups use different terminology and the meaning is sometimes obscured. International consensus is required.

Role of the environment in transmission

Dr Curtis Donskey (Cleveland) gave an excellent overview of ‘Environmental Controls for the Prevention of C. difficile Transmission’. Dr Donskey is one of the most active researchers anywhere in the world, focusing much of his attention on the role of the environment. Having established the importance of contaminated surfaces in the transmission of C. difficile, Dr Donskey explored emerging themes in addressing surfaces contaminated with spores covering conventional and automated terminal cleaning, and the impact of improving daily disinfection. The current challenges outlined included where to clean, how to validate “no-touch” automated room disinfection systems (NTD) to disentangle product claims from real-world performance, how best to engage environmental services and how to make disinfection easier in order to facilitate compliance.


  • 347, Livorsi. Patients with a higher nasal burden of MRSA are more likely to carry MRSA at other sites and contaminate their environment.
  • 348, Sitzlar. Useful stratification of MRSA/VRE room contamination rate by patient C. difficile status. Rooms of patients on precautions for CDI 3x more likely to be contaminated.
  • 1393, Deshpande. One hospital found more C. difficile contamination in the rooms of patients who were not on precautions for CDI than in rooms of patients on precautions for CDI!
  • 1394, Kundrapu. Suggests that the result would be better if those tasked with monitoring cleaning performance got their hands dirty and cleaned.
  • 1541, Sunkesula. Reduction in VRE in new unit; attributable to no shared rooms and bathrooms in the new unit?
  • 1685, Rose. A couple of carbapenem-resistant bacteria on public surfaces outside New York hospitals; I bet you it’d be higher in New Delhi!
  • 1685, Havill. Extended survival of CRE on dry surfaces; will surprise some.
  • 1690, Kirk. Almost no MRSA cultured from medication cabinets in isolation rooms. Direct plated swab lacks sensitivity?
  • 1691, Suwantarat. Quantitative assessment of HCP contact with equipment and fomites helps to define high touch (risk?) items; medication chart highest frequency of contact (1 per patient hour) yet possibly also the least cleaned item.
  • 1692, Hirsh. ipads (and other personal electronic devices) can become contaminated with pathogens; contact precautions should include an explicit instructions not to touch these items. (This was implemented at NIH during recent CRE outbreak there).
  • 1695, Williams. Pathogens identified on the clothing of HCP at the BEGINNING of their shift! (Reminds me of Hayden article where VRE commonly found on the hands of HCP BEFORE they entered patient rooms.)
  • 1697, Vassallo. Universal standard precautions didn’t stop impressive trend reductions. Time to abandon contact precautions?
  • 1698, Mann. Cleaning survey response rate of 100% (unprecedented). EVS staff have something to say, if only we’d listen.
  • 1700, Gerba. What’s for lunch in the hospital cafeteria? MRSA, enteric bacteria and spores, apparently.
  • 1701, Wiemken. Wipes are quicker and easier than bucket methods. Why wouldn’t you? (Perhaps only due to lack of wetting reducing efficacy.)
  • 1705, Boyce. The informal ‘standard’ for ‘clean’ is <2.5 cfu/cm2. This equates to 65 cfu/contact plate, which is almost 1/3 of the way to uncountable. Is this an acceptable standard for ‘clean’?
  • 1706, Power. Contaminated neonatal incubator? An hour of UVC should do the trick.
  • 1707, Horn. HPV for terminal room disinfection associated with significant reduction in CDI. Study design controlled for hand hygiene compliance, but time series analysis may have been more appropriate.
  • 1708, Anderson. Is variation in UVC cycle time for room disinfection explained entirely by variation in room size?
  • 1709, Uslan. Assessment of various Cu surfaces; I was unaware that you could apply Cu as a spray though have concerns over durability.

Other highlights

  • Decolonization has been a hot topic since several high-profile articles have been published recently. It’s a shame that universal chlorhexidine was conflated with universal mupirocin in the Huang study; the two should be considered separately in my view. The potential for resistance to mupirocin is extremely high, whereas the risk for ‘resistance’ or continued reduced susceptibility to chlorhexidine is lower. However, an interesting finding from poster 1615 was that the measured CHG skin concentration (20-1200 mg/L) was MUCH lower than the applied CHG concentration (10,000 mg/L). This brings the subtly reduced susceptibility to CHG reported in MRSA into play. Both Dr Aaron Milsone (Hopkins) and Prof Mary-Claire Roghmann (University of Maryland) highlighted the importance of the need to ‘tend the human microbiome’ and to consider the ‘host-microbiome-pathogen’ interaction rather than the ‘host-pathogen’ interaction, remembering that decolonization can cause considerable collateral damage to the host microbiome.  
  • Dr Denise Cardo (CDC) delivered the SHEA Lectureship on HAI Science and Policy. CDC are streets ahead of any other government health agency in leading HAI science through the development of common, simple goals; accountability; transparency; efficiency and strategy. HAI science alone is not sufficient to influence policy; this requires congressional briefings, senate hearings and the use of the scientific and lay press. The recently published CDC threat report outlines how the (somewhat bleak) future may look. Most poignantly, Dr Cardo could not attend the conference and delivered her lecture remotely due to the government shutdown, which signals leaner times ahead for CDC.  
  • BUGG. Dr Anthony Harris (University of Maryland) presented the results of the ‘Benefits of Universal Glove and Gown’ (BUGG) study. This RCT with impressive compliance to screening, gloving and gowning showed a significant 40% reduction in MRSA but no significant reduction in VRE. The a priori primary outcome (a composite measure of MRSA and VRE acquisition) was non-significant. I’m generally not a fan of universal approaches, since compliance in the real world is likely to tail off when the spotlight of a large study fades. Indeed, poster 1696 showing a ‘dismal’ 20% compliance rate with gowning in the field sheds a shadow on the BUGG study.   
  • Dr Brad Spellberg (UCLA) gave a wake-up call on the future of antibiotics and resistance. Reflecting on the three things guaranteed in life (death, taxes and resistance), Dr Spellberg outlined the unfair fight between humans and bacteria: we’re outnumbered to begin with, and multiply much more slowly! Dr Spellberg’s recent papers in CID and NEJM outline the radical approach required to curb and reverse antibiotic resistance including embracing technology, rekindling R&D, preserving effective agents and exploring novel therapies. Dr Spellberg gave a fascinating insight from the 1960s revealing that it’s not the first time the antibiotic pipeline has dried. We need to learn from history and rekindle R&D before the pipeline dries completely. More importantly though, exploring non-antibiotic therapies, or novel applications of existing agents, has a more realistic chance of brightening the future of antimicrobial therapy.   

SHEA 2013 environment track – conference report

When I started doing research in this area a little over 10 years ago, the role of the environment in transmission was rarely mentioned at international conferences. So, to see an entire conference dedicated to discussing the role of the environment in transmission (SHEA 2013, in Atlanta) was a mouthwatering prospect.


I’d like to congratulate the organizing committee for putting together such an engaging and entertaining programme. At times, it was true ‘edutainment’.  The slides are available here for delegates.

Stephanie Dancer – plenary

The conference began with a plenary lecture by Dr Stephanie Dancer. Irrepressible as ever, Dr Dancer made a good case for improving hospital cleaning (yes, cleaning using detergent and water – not disinfectants). She highlighted some useful older literature, like this paper from 1963 demonstrating that the role of the environment was considered important once upon a time! She also mentioned a useful initiative that she has been involved with in Scotland, mapping visually where contamination occurs in hospital rooms (amongst other things). Dr Dancer finished by covering some of the newer frontiers in the research area, for example resistance plasmids knocking around in the environment, the role of contaminated air in transmission. I enjoyed Dr Dancer’s presentation very much, although contend that detergent and water cleaning is not always enough, now more so than ever as C. difficile and resistant Gram-negatives continue to cause problems around the globe.

Daniel Morgan – fomites

Next up, Dr Daniel Morgan discussed the role of fomites in transmission. I initially thought that this would overlap with the previous and subsequent presentations, but Dr Morgan stuck carefully to his title and considered the role of individual fomites in transmission. Blood pressure cuffs, stethoscopes (or should we say “staphoscope”!), mobile devices and ties (“neck ties” in American English!) were the subject of his reviews. He performed a literature review on each fomite, identifying a surprising amount of literature. I think that contamination of mobile devices is a large and increasing problem, and regular disinfection should be recommended. Dr Morgan also mentioned the interesting looking ‘hospital microbiome’ study in Chicago. Finally, look out for women’s purses (handbags in English English!) as a potential fomite site!

Tara Palmore – water

Waterborne infections were Dr Palmore’s subject. She began by challenging audience perceptions by claiming that all hospitals have had a waterborne infection in the past 12 months. Dr Palmore described an outbreak of Legionnaires’ disease associated with a fountain in a radiology department. Speaking to staff from another hospital after the talk who have had the exact same problem recently makes me wonder how widespread this problem is! The recent problems with Pseudomonas in ICUs in the UK illustrates the potential ramifications of a contaminated water supply. However, we shouldn’t expect sterile water coming out of the taps. If you need sterile water for a patient, use sterile water!

Rekha Murthy – air

Dr Murthy was considering the role of air in the transmission of nosocomial pathogens. She began with a useful classification scheme for pathogens (inspired by this paper) as “obligate”, “preferential” or “opportunistic” in terms of airborne transmission. We know a lot about “obligate” and “preferential” airborne pathogens like TB and ‘flu. It’s the likely “opportunistic” airborne pathogens that are most interesting to me, such as norovirus, MRSA and C. difficile. Sampling indicates that you can find these pathogens in the air, but is contaminated air a vector, and intermediary between the patient and the surface or an innocent bystander?

Curtis Donskey – impact of environmental interventions

Dr Donskey evaluated the evidence that improving environmental disinfection reduces HAIs. He began by drawing a clever parallel between antimicrobial stewardship and environmental hygiene interventions: you can choose to switch product, educate or automate. Dr Donskey demonstrated ample evidence that switching product, educating and automating environmental disinfection has evidence of reducing HAIs. However, he also discussed the potential problem of publication bias, challenging that we don’t like publishing negative findings due to the perception that we’re “admitting defeat”. Publication bias is a real problem in the scientific literature (see, for example, this study showing publication bias in studies of publication bias!). Another potential problem is that, C. difficile aside, almost all studies include the acquisition of colonization rather than the development of infection due to powering issues. This has implications for the cost-benefit of interventions since infections are where most of the cost of MDROs is accrued.

John Boyce – how to culture the environment

Dr Boyce presented everything that you need to know about culturing the environment. He performed a comprehensive literature review and outlined the options: swabs, sponges, enrichment, contact plates, media and other options. My own preferred method is a swab (which can do regular or irregular objects) that is plated direct (to give a quantitative measure of contamination) and then incubated in broth (to give a qualitative but more sensitive measure). With so much heterogeneity in sampling methods, comparison between studies is almost impossible. More standardization in this area would be useful.

Silvia Munoz-Price – measuring cleaning performance

Dr Munoz-Price considered the options for measuring hospital cleaning, presenting her experience with several UV fluorescent markers and ATP bioluminescence. The experience of Dr Munoz-Price is fascinating, finding that the use of environmental cultures along with fluorescent markers was required to drive compliance with cleaning protocols in their ICU. Markers alone lacked credibility (in the eyes of some ICU staff) and cultures alone were not feasible. Also, Dr Munoz-Price’s experience indicates that one fluorescent marking system was better than another since one was more visible under normal light.

David Weber – new technology

Dr Weber covered recent work on some new disinfectant formulations and “no-touch” automated room disinfection (NTD) systems. He presented some impressive data on improved hydrogen peroxide liquid disinfectants, some of which has been published recently by his group. Then, onto NTD systems. Dr Weber began with some useful criteria for adopting NTD systems: firstly they must be demonstrably safe, secondly they must reduce bioburden, thirdly they must reduce infections and finally they must be cost-beneficial. Dr Weber considered the evidence for the four principle NTD options currently available: hydrogen peroxide vapour (HPV) or hydrogen peroxide aerosol, UVC and pulsed-xenon UV (PX-UV). There’s evidence of safety and bioburden reduction for all systems, and evidence of reduced infections (and/or colonization) for HPV. No cost-effectiveness studies published as yet. So, which NTD system to choose? All systems have their pros and cons, so it will depend on your objectives outlined in this recent review, cited by Dr Weber.

James Steinberg and Craig Zimring – the built environment

Engineering solutions to make the hospital environment more amenable to cleaning and disinfection are an attractive option. With a little planning and thought, new hospitals can be built with infection prevention and control in mind at no (or minimal) additional cost. Also, altering the built environment in existing facilities can yield infection prevention and control benefits. Unfortunately, I missed this lecture, but I suspect the content was similar to their recent review article in the ICHE special edition.

Hilary Humphreys – antimicrobial surfaces

Prof Humphreys gave an accessible overview of the various options to implement antimicrobial surfaces in hospitals. There are various options to consider: metals (principally copper and silver), chemicals or physical changes to surfaces to reduce microbial deposition and/or make them more cleanable. Prof Humphreys mentioned a European testing standard for antimicrobial surfaces that is currently in development and will supersede some (rather wacky) standards that are currently out there. Another problem is that many of the studies supporting the use of antimicrobial surfaces are in engineering journals that seem to speak a different language to the medical literature. Prof Humphreys’ talk helped in interpreting these studies, but more are required in the medical literature. The recently published copper study provides some compelling reasons to prioritize antimicrobial surfaces for further evaluation.

Bill Rutala – disinfectants and microfiber

Dr Rutala presented a convincing case that we should use disinfectants routinely, not just detergents. The main arguments for using disinfectants over detergents for ‘non-critical’ surfaces is that they are more effective at reducing contamination and may have persistent activity, and detergents can become contaminated and spread microbes. It seems that microfiber cloths are better than cotton cloths at removing microbes, but they do harbor them for longer if not disinfected appropriately. So, the evidence for the use of microfiber is somewhat equivocal.

Susan Huang – chlorhexidine bathing

Dr Huang presented three compelling randomized controlled studies evaluating chlorhexidine (CHX) bathing published recently in Lancet, New England Journal of Medicine and one of hers this is not yet published (but doubtless destined for a high-impact journal). The studies seem clear: the introduction of CHX daily patient bathing results in less acquisition, less hand contamination and less environmental contamination. I left the lecture thinking why would you not do this? The potential for reduced susceptibility to CHX is probably the only thing that will stop daily patient bathing using CHX rapidly becoming the standard of care.

Thorny issue #1 – best paths to improve the thoroughness of cleaning (Anne Matlow, Mark Rupp, Larry Nation)

Dr Matlow presented some useful social science exploring the motivations and barriers to compliance with cleaning protocols. Educational deficiencies were identified, for example, almost 40% of housekeepers didn’t think the environment harbored germs that can cause disease. Motivations were explored and it seems that achievement and recognition are more important than pay and advancement.

Dr Rupp presented on the successes and challenges of using audit and feedback to improve compliance with cleaning protocols. Dramatic gains are possible, but it is difficult to sustain the gain. Dr Rupp identified some “positive outliers” during the course of this research. Some would term this group “positive deviants”, but Dr Rupp rightly points out the connotations of this phase are all wrong! There is a potential that these “positive outliers” (if judged by fluorescent markers) are the ones who have clocked the location of the marks and simply spot clean them. Exploring this group in detail will help to confirm that they really are the effective cleaners, and, if so, learn what sets them apart.

Larry Nation is a practicing environmental services director, so was able to provide a complimentary view. His team have moved from visual assessment of cleaning efficacy to a combination of fluorescent marking, ATP and visual assessment to measure the cleaning process and its impact.

All presenters agreed that audit and feedback are essential in setting a path toward improving the thoroughness of cleaning, so Thorny Issue #1 was not all that spiky!

Thorny issue #2 – resistance to disinfectants – Wilcox v Harbarth

Dr Wilcox presented the pro case. Biocide use is gargantuan compared with antibiotic use. However, there is a lot of fear and not much data surrounding biocide resistance. Serial passage of microbes to sub-lethal doses of biocides can induce tolerance, and triclosan is most susceptible to resistance. An area with much equivocal data is the possibility of resistance or reduced susceptibly to skin antiseptics such as CHX. The widespread and most likely increasing use of CHX means that reduced susceptibility would be problematic to say the least. Dr Wilcox presented some compelling data (including some from Dr Harbarth!) that reduced susceptibility to CHX is a problem.

Dr Harbarth presented the con case, although conceded that resistance to skin antiseptics could be a major problem in the future. Dr Harbath argued that antiseptics are a major part of the solution to controlling resistant micro-organisms, not driving the development of the problem! There is very limited evidence of the interaction between antibiotic and biocide resistance and evidence of small reductions in susceptibility that are well below the in-use concentration are not relevant.

On balance, an entertaining debate, and both speakers agree that reduced susceptibility to skin antiseptics is the most likely risk. There is some evidence that small reductions in CHX susceptibility may be relevant even when well below in-use concentrations, and that this may have implications for antibiotic cross-resistance (buried deep in Table 4 of Vali et al. 2008 – look what happened to EMRSA-16 after 48 hours sub-lethal exposure to CHX).

Thorny issue #3 – sporicides for C. difficile – McDonald v Dubberke

Dr McDonald took the pro position, and presented the evidence underpinning the CDC recommendation to use an EPA-registered sporicide for disinfection of rooms potentially contaminated with C. difficile spores. Whilst removal of spores (rather than chemical inactivation) is an important part of the disinfection process, the use of sporicidal disinfectants prevents the dispersal of spores around the room on contaminated cloths. Overall, the evidence for the use of a sporicide to control the spread of C. difficile is overwhelming.

Dr Dubberke presented a rather unenviable con position, given the volume of data supporting the use of a sporicide. However, he did put together a coherent case, highlighting the academic limitations of studies supporting the use of a sporicide, reiterating the risk of publication bias and that practice is more important than product.

Both authors agree that introducing a sporicide will not solve your C. difficile problems; you need to consider all aspects of transmission for that (antimicrobial stewardship, patient susceptibility factors and others). However, the con case presented by Dr Dubberke was not persuasive enough to convince me to abandon the use of a sporicide to help control C. difficile.

Thorny issue #4 – hands v environment – Edmond v Anderson

This debate has been run at several recent conferences so I was concerned that it would be a little “old hat”. How wrong I was.

Dr Boyce (who was chairing) polled the audience at the start of the debate, finding that around 90% thought that hand hygiene is more important than environmental disinfection in preventing HAIs.

Dr Edmond began with the pro. He began by a “thought experiment”, showing that a cluster RCT to compare the impact of the two interventions is not feasible. Dr Edmond acknowledged that there is more and better evidence for environmental interventions than for hand hygiene, but argued that hand hygiene makes a larger contribution to prevention and control. He evaluated the prior room occupancy studies and concluded that the increased risk from the prior occupant only accounts for a small minority of all transmissions.

Dr Anderson’s presentation for the con was outstanding; full of thoughtful, well-constructed arguments. He began with some quotes including the classic “I got 99 problems but the [bleach] ain’t one”; I suspect it was lost on a fair proportion of the audience, but a highlight of the conference for me! Dr Anderson’s argument focused on the fact that there is more and higher quality evidence for environmental interventions than for increased hand hygiene, having scoured the lengthy hand hygiene guidance documents to find a small handful of high-quality studies. In contrast, there are now a number of high-quality studies demonstrating the impact of environmental interventions.

The post-debate vote indicated a swing towards the importance of environmental disinfection, but still the majority concluding that hand hygiene is most important. There can be little doubt that hand hygiene prior to patient contact is the single most important intervention to prevent the spread of hospital pathogens, but it seems that the contribution of the contaminated environment is considerably greater than we thought.

Some points for discussion currently on my mind, mainly prompted by meeting:

  • Should we have a standardized set of environmental sites to sample and a standardized way to sample them to make studies more comparable? (A suggestion by Prof Hilary Humphreys.) I like this idea very much. The only problem is that it may result in widespread “targeting” of these sites only by housekeepers!
  • “The ward is very big; your swab is very small” (Dr Dancer). Are we sampling a large enough surface area? The CDC sponge method will help with this.
  • Can the introduction of single rooms in multi-occupancy bays contain pathogens more effectively (prompted by this image from Dr Weber)?
  • What is the contribution of contaminated air in “opportunistic” airborne pathogens (such as norovirus, MRSA and C. difficile)?
  • How much of a problem is publication bias? Do we really all have negative environment studies that we have not got around to publishing as suggested by Dr Donskey?
  • When are NTD systems warranted, and which NTD system is suitable for the intended application?
  • Should CHX ‘source control’ be implemented universally across the hospital?
  • Are antimicrobial surfaces going to be useful in preventing transmission, and, if so, which is the most effective?

ICHE special edition on the role of the environment in transmission

Infection Control and Hospital Epidemiology have dedicated their May issue to articles investigating the role of contaminated surfaces in the transmission of pathogens. There’s an awful lot of good stuff here, but this is my take on the key findings of the studies:

  • Drs Weber and Rutala write a thoughtful introduction covering the highlights of the issue.
  • A study from the University of Maryland shows that admission to a room previously occupied by a patient with ESBL-producing Gram-negative bacteria does not increase the risk of acquisition. This is a surprise because this association has been shown for other pathogens including MRSA, VRE, C. difficile and, most interestingly, other Gram-negatives such as A. baumannii and P. aeruginosa. I suspect this difference is explained by the fact that the Enterobacteriaceae are less able to survive on dry hospitals surfaces than the lactose non-fermenting Gram-negatives such as A. baumannii.
  • Research from the Cleveland VA tells a fascinating story of sequential interventions to reduce environmental contamination with C. difficile. The introduction of fluorescent marking with feedback did not eliminate the C. difficile environmental contamination, with 50-60% of cultures remaining contaminated. Similarly, the introduction of a UVC no-touch room disinfection system for terminal disinfection did not solve the problem, with 30-40% of cultures remaining contaminated. Only when daily disinfection was performed by a dedicated team and terminal disinfection was performed by EVS supervisors and/or the infection control team was the problem finally solved and C. difficile could no longer be cultured from surfaces. This study shows firstly how a combination of interventions can be useful, and secondly, the extraordinary lengths required to eliminate C. difficile spores from the environment.
  • An in situ evaluation of a UVC room disinfection device at Duke / University of North Carolina shows that UVC decreases but does not eliminate key pathogens MRSA, VRE and C. difficilefrom the hospital environment.
  • A study from Johns Hopkins shows that the packaging of 7-9% of supply items was contaminated with MDROs, and that hydrogen peroxide vapor (HPV) is effective for the disinfection of the supply packaging. The cost of supplies discarded from six ICUs amounted to almost $400,000, not including the costs associated with waste disposal. Hence, the practice of disinfecting the packaging of supplies using HPV would generate substantial cost savings.
  • The long-awaited copper study is a multi-centre evaluation of the clinical impact of introducing 6 copper alloy high-touch sites into the rooms of patients on three ICUs. Patients were randomized to intervention copper rooms and control non-copper rooms. Patients admitted to copper rooms were significantly less likely to acquire healthcare-associated infection or colonization with MDROs. The authors also make an interesting association between the degree of contamination in patient rooms and the risk of acquisition. However, since sampling was performed weekly regardless of a patient’s infection or colonization status, it is not possible to determine whether this association is causal or simply due to the fact that infected / colonized patients are likely to shed more bacteria into the hospital environment. The scale of the difference is surprising, with a 50% difference between the groups. I am “a believer” in the role of the environment in transmission, but a 50% reduction attributable to 6 copper alloy surfaces does seem rather high. But it does seem that the introduction of copper surfaces does reduce transmission. Questions remain over the practicality and durability of the widespread adoption of copper alloy surfaces in healthcare.
  • Another University of Maryland study with a powerful cluster randomized controlled trial design shows convincingly that enhanced daily cleaning reduces MRSA and MDR A. baumanniicontamination of the gloves and gowns of healthcare personnel when they exit the rooms of patients on precautions with these pathogens. Now, in theory, healthcare personnel should discard the gowns and effectively disinfect their hands. However, since we know that this doesn’t always happen, these reductions are likely to be meaningful.
  • A study shows that N95 filters to their job and capture infectious influenza aerosols. However, in the event of an influenza pandemic, how long will the stockpile of N95 (FFP3) masks last?
  • An extensive microbiology survey from UCLH in London found that the sites closest to the patient were more likely to be contaminated regardless of ward setting. However, in ICUs, sites touched by staff were more likely to be contaminated whereas in gastrointestinal wards with mobile patients, sites touched by patients were more likely to be contaminated.
  • A short review by Carling and Huang explores evolving issues in how to tackle the contaminated healthcare environment.
  • A novel review piece by a team from Georgia, Maryland and Washington DC provides an overview of how evidence-based design can help to prevent and control the transmission of healthcare-associated pathogens.
  • A study from Florida found that 10% of rooms were contaminated with A. baumannii even when the current occupant was not known to be infected or coloinsed. This could be due to unrecognized infection or colonization, survival from a prior room occupant or important by a the patient, a visitor or healthcare personnel.
  • A study from New Haven, Connecticut found that a new activated hydrogen peroxide containing wipe was highly effective for achieving a hygiene standard of <2.5 cfu / cm2, with 75% of sites yielding no growth at all.
  • A new study from the Cleveland VA shows the value of investing time and resource in observing and supervising cleaning practices in hospitals. Direct supervision of cleaning staff was required to achieve optimal results. The concern is what happens when the direct observation becomes routine or stop all together? Will good practice continue?
  • One of the problems with UV radiation for hospital room disinfection is poor reflectivity from some hospital materials, contributing to reduced efficacy out of direct line of sight and influencing cycle times. An innovative study resulting from a collaboration between healthcare experts at the University of North Carolina and chemical engineers at the University of North Dakota found that using paint that reflects UV more effectively reduces cycle times to achieve comparative efficacy for UV room disinfection.
  • A study from South Carolina provides some further microbiological support for the clinical impact associated with copper surfaces, showing that copper alloy bedrails are associated with significantly lower bioburden than plastic bed rails.
  • A useful study from Ireland tells the story of laboratory optimization of sampling methods, which successfully recovered ESBL producing K. pneumonaiaefrom hospital surfaces.
  • A John Hopkins study provided some promising data of a mobile “UV wand” for the disinfection of hospital surfaces. The device a achieve a 1-log reduction of microbial contamination, and may provide a useful adjunctive approach to hospital disinfection.
  • Some Australian data raised some important questions about the reliability of ATP systems. The relative light unit readings for a dilution series of synthetic ATP were compared against an HPLC gold standard for three ATP systems. Substantial variation was noted for all systems, indicating that RLU values are more indicative than absolute.
  • All but one of the studies in this issue have been in the acute healthcare setting. A study from New York bucks the trend, evaluating S. aureus contamination in maximum security prisons. There did not seem to be an obvious association between S. aureus infection and contamination. If anything, the rates of contamination of inmates and their environment was surprisingly, relative to high rates of colonization with MRSA identified in other studies.
  • Yet more research from the Cleveland VA evaluates a novel disinfectant: an electrochemically activated saline solution, also known as ‘superoxidized water’. Surprisingly, the novel disinfectant performed comparably to 10% bleach for the inactivation of C. difficile in vitro, and eliminated C. difficile contamination from hospital surfaces when applied in situ. This agent should be prioritized for further evaluation.
  • Finally, a French study reports a case of catheter-related bloodstream infection related to a preoperative shower with P. aeruginosa contaminated water. Something to think about next time you have a shower.

The quality and importance of the research in this article has impressed me. However, the fact is that some of the basic questions about the role of the environment in transmission and the most cost effective interventions are yet to be answered. But we’re moving in the right direction.