Disinfectant wipes mop the floor with chlorine solution

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.

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Cross-resistance between biocides and antibiotics doesn’t seem to be a problem

e-coliA 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.

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Updates from ECCMID 2018

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.

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  • Loreen Herwaldt gave an overview on the state of the art in IPC, focussing on the need for continuous innovation. We agree – and GAMA continues to explore innovative technology and solutions to address HCAI and AMR.
  • Jon Otter discussed the emergence of multidrug resistant Gram-negative bacteria, arming hospitals with a strategy to deal with these challenging bacteria when they first arrive. Jon ‘asked the audience’ whether hand hygiene or contaminated surfaces are most important in preventing the spread of CPE in hospitals. Whilst the majority of the audience chose hand hygiene, we beg to differ. As one tweeter put it, there’s no point in practicing good hand hygiene is the environment is heavily contaminated with pathogens!
  • Ben Cooper talked about the utility of mathematical modelling in informing IPC strategy. Whilst it’s not reasonable to expect a model to do the thinking for you, it can give us some answers to questions that we can’t answer with physical experiments. And Ben highlighted a couple review articles about how mathematical modelling can help to understand the transmission of infectious diseases and could be hypothesis-generating for IPC (here and here).
  • Marc Bonten outlined the knowledge base for IPC; whilst limited, it’s improving with high-quality (albeit pragmatic) randomised controlled trials of IPC interventions coming through (for example, the BETR-D trial showing that UVC room disinfection reduces the acquisition of MDROs).
  • Several presenters, including Gili Regev-Yochay from Israel, highlighted the importance of addressing sink and drain contamination in order to prevention the transmission of CPE. Exactly how to do this is still an open question! Do we replace them? Bleach them? Or even remove them altogether?!
  • Several presentations highlighted the importance of addressing the contaminated environment when trying to control Candida auris (for example Oxford and Spain).
  • A study from Taiwan found that improving environmental cleaning through education reduced the incidence of MDRO acquisition.
  • And finally, a brave set of Brazilian researchers (in full PPE!) deliberately contaminated a mocked up hospital room with live norovirus and demonstrated that normal cleaning activities result in aerosolisation of live virus. So, PPF3 masks for cleaners then!
  • We hope you find this summary useful – please feel free to get in touch if you have any questions!

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    The unseen risk from the previous room occupant

    hospital-room

    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.

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    Multi-occupancy bays as a risk factor for norovirus spread

    norovirus-1

    Norovirus is a common cause of gastrointestinal diseases in hospitals and other ‘semi-closed’ environments (like cruise ships, prisons, and schools). A new study suggests that wards whether patients share multi-occupancy bays are more likely to experience norovirus outbreaks, and that the risk of norovirus transmission increases as more patients share a bay.

    The factors driving norovirus transmission are poorly understood. This is because designing studies in norovirus transmission is difficult. Norovirus usually spreads in outbreak clusters, which are often contained using bundled interventions. So, it’s very difficult to understand which part of the bundle was effective in containing an outbreak – or, indeed, whether an outbreak would have stopped without any intervention at all! A new Swedish study reviewed outbreaks and a large number of sporadic norovirus cases in almost 200 wards across southern Sweden to understand risk factors for norovirus spread.

    The study found that risk factors for norovirus transmission were: sharing a multi-occupancy with a norovirus case, vomiting, older age (>80 years), comorbidity, and hospital onset of symptoms. These factors remained significantly associated with norovirus transmission even when accounting for all variables together in a multivariable model. The more patients who shared a multi-occupancy bay, the greater the risk of norovirus spread: in fact, the risk doubled for each extra patient in the bay!

    These findings suggest that improving the segregation of patients who become symptomatic with norovirus-like symptoms will help to prevent the spread of norovirus in hospitals.

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