Further intel on disinfectants and antiseptics for Candida auris

We posted a week or two ago about a study evaluating the efficacy of various antiseptics and disinfectants for addressing Candida auris. A similar study published recently presents similar findings: chlorine-based disinfectants, and iodine-based and chlorhexidine-based antiseptics all have a role to play in tacking C. auris.

The lab study collected a range of C. auris isolates, including some multidrug-resistant strains, and performed a quantitative suspension test (EN 13624:2013) using a chlorine-based disinfectant, 10% povidone-iodine, 2% chlorhexidine in 70% alcohol, and 2% chlorhexidine gluconate. In clean and dirty conditions, all but the 2% chlorhexidine gluconate resulted in a >4.5 log reduction in the amount of C. auris present in the suspension. Interestingly, the povidone-iodine was not as effective against C. albicans, achieving only a ~3-log reduction. Also, it is worth noting that the chlorine-based disinfectant was tested with a longer 5 minute contact time, to reflect the use of this product as a surface disinfectant rather than skin or hand antiseptic. It would have been good to see the impact of the chlorine-based disinfectant with a shorter (and more realistic!) contact time; a 5 minute contact time is very difficult to achieve in practice, so this is not realistic of the use of disinfectants in practice.

The 2% chlorhexidine gluconate achieved a 1-3 log reduction on all strains of C. auris, within the 2 minute contact time. The testing methodology is important here: 4% chlorhexidine washcloths were shown to inhibit the growth of C. auris when tested using an experimental methodology in a recent study, which involved placing swatches of the cloths onto culture media to observe whether zones of clearing occurred. This experimental methodology is probably a better model for in-use efficacy, because it accounts for extended exposure to chlorhexidine due to residual activity. Also, it's important to note that 4% chlorhexidine gluconate was diluted to 2% to match the concentration of chlorhexidine in the 2% chlorhexidine in 70% alcohol suspension.

These findings support the use of a range of disinfectants and antiseptics including chlorine-based disinfectants, and iodine-based and chlorhexidine- based antiseptics in the prevention and control of C. auris.

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More single rooms = less MDR Gram-negatives in the ICU

An 11 year Dutch study provides compelling evidence that a move to single rooms from multi-occupancy bays dramatically reduced the burden of multidrug-resistant (MDR) Gram-negative bacteria in the ICU.

The study was centred in a 16 bed ICU in The Netherlands. From 2002-2009, the ICU was composed of a mixture of multi-occupancy bays and single rooms. Then, from 2009-2013 (the end of the study), a new ICU was opened with 100% single rooms. During the period before the move to the new ICU, there were frequent and sustained clusters of clonally related MDR Gram-negative bacteria including Klebsiella, Enterobacter, Serratia, Pseudomonas and Acinetobacter species. After the move to the new ICU, there was a significant reduction in the burden of these bacteria on the ICU, with the total number of MDR Gram-negative bacteria cases falling from around 120 to 20 per 12 month surveillance period.

The authors carefully evaluated the situation to rule out other factors that may have explained this reduction, showing that there were no significant changes in bed occupancy and the number of admissions. However, it is important to note that some important factors that may have explained the reduction could not be measured, for example, compliance with hand hygiene and other basic IPC practices. Also, selective digestive decontamination (SDD) was in use before the more to the new ICU and ceased shortly before the move. Stopping SDD would have reduced the selective pressure for antibiotic resistant bacteria, so could well have contributed to the reduction. Finally, there was no control group to measure the impact of other interventions.

Despite these limitations, this study along with several others, provides evidence that moving to single rooms reduces the transmission of antibiotic resistant bacteria.

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Antiseptics and disinfectants to support the prevention and control of Candida auris

Candida auris is an important emerging pathogen, which caused a large outbreak in a London hospital and has been reported from around the world. It shows a high level of resistance to antibiotics and appears to spread rapidly in hospitals. A new study evaluates the efficacy of various antiseptics and disinfectants that could support the prevention and control of C. auris.

The authors evaluates the efficacy of two commonly used disinfectants (chlorine and hydrogen peroxide vapour) and antiseptics (chlorhexidine gluconate and povidone iodine) against 34 Candida species, including 28 C. auris isolates. HPV was tested in the gas phase, whereas two chlorine-based products and the antiseptics (chlorhexidine gluconate and povidone iodine) were tested in the liquid phase, to represent the uses of these disinfectants / antiseptics in practice. Also, a novel methodology was used to test the efficacy of two brands of pre-impregnated 2% chlorhexidine gluconate washcloths (including the Clinell Wash Cloths). These were tested by adding a cut piece of the wash cloths onto the surface of an agar plate and performing measuring the diameter of the zone of clearing.

Gas phase HPV inactivated most of the C. auris isolates tested, and was considered to be 96.6%-100% effective. This suggests that longer HPV exposure may be necessary to fully inactive C. auris. All Candida species were inactivated fully by in-use concentrations of the disinfectants and antiseptics tested. In the experimental procedure to test the antimicrobial activity of the pre-impregnated wash cloths, the C. auris isolates tested appeared to be less susceptible than the non-C. auris isolates tested, suggesting that C. auris is less susceptible to chlorhexidine than non-C. auris isolates, as seems to be the case for most other disinfectants and antiseptics. Both types of pre-impregnated wash cloths performed similarly.

These results suggest that antiseptics such as chlorhexidine gluconate and povidone iodine, and disinfectants such as chlorine and hydrogen peroxide vapour are suitable for preventing the transmission of C. auris, and that current in-use concentrations are adequate.

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