A study published in the Lancet Infectious Diseases provides further evidence that UV room decontamination reduces transmission in hospitals. The multicentre cluster-randomised study showed that introducing UV room decontamination for selected patient rooms resulted in a hospital-wide reduction in C. difficile and VRE acquisition compared with standard methods of decontamination.
This is a companion article to the BETR-D study that was published in the Lancet last year. This huge multicentre cluster-randomised study involved around 300,000 admissions to 9 hospitals over two years. The hospitals used a random sequence of terminal disinfection strategies for rooms of patients with selected target pathogens (C. difficile, MRSA, VRE, and Acinetobacter spp.). The disinfection strategies were:
- QAC disinfectant plus sodium hypochlorite for difficile (the reference method),
- QAC + UV plus sodium hypochlorite plus UV for difficile,
- Sodium hypochlorite + UV, and
- Sodium hypochlorite.
The hospital-wide rate of acquisition of the target pathogens was investigated as a combined rate and for individual pathogens.
Overall, the QAC + UV proved to be the most effective strategy, with a relative risk of acquisition for all pathogens combined of 0.89 and with an upper confidence interval that just touched 1 (see Figure). This means that this reduction for all pathogens combined was right on the borderline of what would be considered statistically significant. This was driven by a statistically significant reduction in the acquisition of VRE (relative risk 0.56, confidence interval 0.31 – 0.996; p=0.048) and C. difficile (0.89, 95% CI 0.80 – 0.99; p=0.031).
Figure 1: The relative risk of acquiring all target pathogens combined for the test methods compared with the reference method, which was QAC disinfectant for all pathogens plus sodium hypochlorite for C. difficile
These findings are curious in some ways. The original BETR-D study showed that patients coming into rooms disinfected using UV were less likely to acquire target pathogens than patients admitted to rooms disinfected using standard methods. Here, the question was whether improved terminal disinfection would have a hospital wide impact, and this was shown to be the case for VRE and C. difficile. This suggests that improving terminal disinfection not only improves patient outcomes for the next patient to occupy a single room, but has knock-on clinical benefits measurable across the entire hospital!
These findings strengthen the case for enhancing terminal disinfection strategies by adding automated room decontamination systems, such as UV.
There are few well-controlled studies investigating the impact of disinfectant wipes in a clinical setting compared with standard methods. A study from a group of researchers in Cardiff shows that one-step cleaning and disinfectant wipes are more effective than two-step detergent and chlorine solution cleaning / disinfection in removing microbial contamination from hospital surfaces.
The double cross-over study was performed on two wards with an identical layout in Cardiff, Wales. The wards received either standard cleaning / disinfection (two-step detergent cleaning followed by chlorine solution disinfection) or disinfectant wipes (one-step cleaning and disinfectant wipes that produce peracetic acid and hydrogen peroxide when activated by water). The methods were allocated to sequential 3-months blocks so that each ward crossed over between the two cleaning / disinfection approaches, along with a baseline period and washout periods. A training programme for all staff involved with cleaning was delivered before both the standing cleaning / disinfection and disinfectant wipe phases. Weekly samples were collected from 11 surfaces over the course of the study, and ATP was used to measure surface cleanliness.
The introduction of training alone improved the efficacy of standard cleaning and disinfection, resulting in a reduction in colony counts, ATP score, and the presence of indicator organisms. The introduction of wipes demonstrated an incremental benefit over training and standard methods, resulting in a significant reduction in total aerobic count, total anaerobic count, and ATP score compared with baseline; the overall reduction in aerobic count was significantly greater for wipes compared with detergent and chlorine solution. Furthermore, the reintroduction of standard cleaning and disinfection was associated with the counts increasing significantly on many of the items.
The incremental benefit of wipes over training and standard methods is best illustrated by trends in indicator organisms (see Figure). Here, the number of indicator organisms decreased as a result of training and standard methods, but decreased following the implementation of disinfectant wipes. The reduction of antibiotic-resistant Gram-negative bacteria (including ESBLs and CRE) was the most marked.
This paper illustrates both the value of training to improve the standards of conventional cleaning and disinfection, and the incremental value of introducing disinfectant wipes. The disinfectant wipes provided a one-step cleaning and disinfection process that was easier and more effective that a two-step cleaning then disinfection process involving detergent and chorine solution. Although the study was not designed to evaluate any clinical outcomes, the reduction in microbial contamination associated with the introduction of disinfectant wipes, especially contamination with multidrug-resistant Gram-negative bacteria, reduces risk in the clinical setting.
A new study from Jordan has reinforced that cross-resistance between biocides and antibiotics doesn’t seem to be a problem. The study found that although multidrug-resistant E. coli were commonly identified from the environment in both hospital and community settings, there was no evidence of cross-resistance between antibiotics and biocides, and all E. coli were susceptible to in-use concentrations of biocides.
21 of 430 environmental samples from two hospitals and 10 homes grew E. coli. Almost half of the isolates were multidrug-resistant, and two thirds were ESBL-producers by phenotype. Surprisingly, there was no difference in the rate of ESBL-producers between hospital and community isolates. Also, the MIC of biocides (including ethanol, chloroxylenol, cetrimide and iodine) were all below in-use concentrations, and similar between community and hospital isolates. Perhaps most importantly, there was no association between antibiotic and biocide susceptibility.
The potential association between biocide and antibiotic resistance has been reviewed in detail before. The European Union produced a report in 2009 concluding that there was limited evidence of biocide and antibiotic cross-resistance. This is because the mechanisms of action of antibiotics and biocides are fundamentally different. Antibiotics tend to have a very specific target, in interrupting the metabolism of bacterial cells, whereas biocides tend to have multiple physical targets and do not rely on interrupting metabolism to be effective. We need to keep an eye on the potential for cross-resistance between biocides and antibiotics – but for now, it is not a problem.
Our clinical team spent some time at ECCMID in Madrid last week, and have summarised some of the key updates from our point of view.
We hope you find this summary useful – please feel free to get in touch if you have any questions!
It is clear that sharing a room or multi-occupancy bay with a patient infected or colonised with an HCAI-related pathogen is a risk factor for acquisition. Indeed, the physical segregation of patients has been a key intervention to prevent the spread of infectious diseases since the advent of germ theory! The risk of acquiring pathogens from contamination left behind by a previous occupant of the same room or bed-space is less obvious, but one that is now widely recognised. However, which is greater? The risk from a current roommate, or the risk from a previous occupant of the same bed-space? Whilst you may think it would be the current roommate, a new study suggests that the risk from the previous room occupant may be greater!
The American research team performed a large case-control study, in a population of 760,000 patients across four hospitals in New York between 2006 and 2012. More that 10,000 patients developed an HCAI during this period, and these cases were matched with uninfected controls based on time, location, and length of stay. The key finding was that both exposure to a roommate or a previous room occupant with the same pathogen that caused the HCAI were risk factors for HCAI. Interestingly, exposure to a current room occupant increased the risk of HCAI 5-fold, whereas exposure to a previous room occupant increased the risk of acquisition 6-fold! Whilst the study was not designed to compare directly the increased risk from current roommates with previous room occupants, this finding suggests that exposure to a previous room occupant could be a greater risk for HCAI than exposure to a current roommate. One possible reason for this is that a current roommate with an HCAI is a more obvious, tangible risk for transmission, and so basic IPC practice and cleaning standards are higher. In contrast, a previous room occupant is an unseen risk, so cleaning standards are lower.
These findings reinforce the need to improve cleaning and disinfection of the clinical environment both during the stay of patients, and at the time of discharge to minimise the risk of HCAI.