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.


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