A randomised multicentre trial in Italy published this month in the Journal of Hospital Infection has examined the effectiveness of automated hydrogen peroxide (AHP) supplemented with silver ions, and 5,000 ppm sodium hypochlorite (bleach) on Clostridium difficile (CD). Twenty-eight rooms previously occupied by patients with C. difficile infection (CDI) at four health facilities were randomised to either AHP or sodium hypochlorite disinfection. Prior to disinfection both rooms underwent a standard operating cleaning procedure to remove visible soil. Eight high-touch locations in each room were swabbed before and after disinfection to look for the presence of CD bacteria. Prior to the disinfection phase, CD was detected in 18 of the 28 rooms (64%) sampled, the most commonly contaminated sites being the light switch, nursing call device and the bedside table. This agrees with several other studies which have highlighted the presence of CD in the environment following discharge of CD positive patients.
Both disinfection methods were shown to significantly reduce CD contamination in the rooms, 50% contamination pre and 0% post decontamination in the HP arm and 79% contamination pre and 14% post decontamination in the bleach arm, although there was no statistically significant difference, probably because of the small sample size. The unblinded nature of the study means that housekeeping staff were aware that sampling was taking place and may have changed the way they approached the disinfection procedure in the bleach arm in order to compete with the automated system. We presume also that researchers carrying out the sampling were also aware of the disinfection methods as blinding is not referred to in the paper. Another interesting finding was that the average total time from a patient leaving a room to it being available for the next occupant was slightly longer with sodium hypochlorite in comparison to HP procedure, again possibly due to thoroughness of the staff cleaning with Chlorine as the average disinfection process for a room with Chlorine was 119 minutes.
The study highlights that both methods were effective at reducing CD contamination to a point, however it is interesting that even after a decontamination process that took nearly two hours, a significant number of rooms (14% in this case) remained positive post decontamination in the Chlorine arm, thus continuing to pose a risk to the next occupant. Additionally, a more detailed description of the bleach-based disinfection method used in the study would help the reader to interpret the results in the context of routine practice in the UK NHS. In addition, presenting clinical infection rates alongside these laboratory results would provide a valuable association with important clinical effectiveness outcomes.
An interesting study published a couple of years ago showed that transmission of bacteriophage used as a surrogate for respiratory viruses was reduced significantly by introducing a once-per-day hand wipe in the home environment. Could this suggest that hand wipes have a role in reducing viral illness at home?
Five households, each containing two adults and three children, were included in the study. A female adult’s hands were inoculated with a high concentration of a non-pathogenic marker of virus spread: a common bacteriophage. The hands of all household members and surfaces in the house were then sampled 8 hours later to see how far the virus had spread. The process was then repeated, but this time with each household member asked to wipe their hands at least once per day with a sanitising wipe, in addition to normal hand washing with soap and water. The wipe intervention was associated with a significant reduction in contamination of the hands of the inoculated individual, and surfaces in the house. There was a non-significant reduction in contamination of non-inoculated hands.
The group then applied these findings to the potential transmission of key viruses, rhinovirus and rotavirus, concluding that there would be a 30-90% reduction in transmission risk of these viruses through a hand wipe intervention.
This study certainly supports the benefit of an increased frequency of hand cleansing in the home environment. The intervention could just as easily have been at least one extra hand wash per day using soap and water. However, a hand wipe provides convenience and accessibility that will almost certainly result in more hand cleansing being done!
Whilst the transmission of a bacteriophage may not follow the same dynamics as the transmission of a pathogenic virus, this study certainly provides compelling data in line with other studies that a hand wipe intervention in the home environment could help to prevent viral illness.
A Dutch laboratory evaluation of four different disinfectant applied by either spraying or wiping has found that most are effective against key hospital pathogens. However, the hydrogen peroxide spray was ineffective against VRE, suggesting a problem with hydrogen peroxide stability.
The study tested the ability of a hydrogen peroxide solution (branded a sporicidal), QAC, alcohol, and glucoprotamin to inactivate clinical isolates of VRE, K. pneumoniae, and A. baumannii. The products were applied as either a spray or wipe following a 1 hour contact time.
All disinfectants achieved a >5 log reduction on the organisms tested, with the exception of hydrogen peroxide sprayed onto VRE. Now, hydrogen peroxide is very effective against enterococci, so I suspect that this illustrates a problem with instability of the hydrogen peroxide in the disinfecant formulation.
It is also worth noting that the long contact time (1 hour) is not representative of the real world application of these products, where a 1 minute contact time would be more appropriate!
This study provides further evidence that QACs (the key active ingredient of Clinell Universal wipes) can be used to provide stable and effective disinfectant wipes.
A helpful US study tracked the non-emergence of phenotypic or genotypic chlorhexidine resistance associated with hospital-wide use of chlorhexidine gluconate (CHG) antisepsis.
The 700 bed hospital introduced hospital wide CHG bathing in 2010, removed it in 2011, and reinstated it in 2015. They evaluated a collection of S. aureus isolates that were considered hospital-acquired and found that there was no reduction in CHG susceptibility during the two periods of CHG use, and found no evidence of qacA or qacB genes, which have been linked with reduced susceptibility to CHG. The study is one of the few that evaluated hospital-wide use of CHG, so there was certainly a pretty strong selective pressure for reduced susceptibility to emerge!
Whilst this study does not prove that CHG is somehow ‘resistance-resistant’ – indeed, other studies have found evidence of reduced susceptibility associated with CHG use – it does reinforce that CHG is a well-tolerated antiseptic that does not readily promote reduced susceptibility.
A number of key studies were published at ECCMID 2017, providing further evidence of the utility of chlorhexidine for reducing the risk of HCAI.
A study from South Korea evaluated the impact of universal skin antisepsis using 2% chlorhexidine gluconate (CHG) washcloths in reducing MRSA acquisitions and bloodstream infections. Following a 12 month baseline period, a 2 year intervention using CHG was following by a 1 year intervention using CHG plus mupirocin. The study showed a significant impact of CHG bathing in reducing MRSA acquisition, and also an incremental benefit of adding nasal mupirocin to the decolonisatoin regieme. Whilst it is useful to have more data that mupirocin and CHG combined reduces the risk of MRSA, it may be that a ‘screen and treat’ approach is the most balanced way forward for mupirocin treatment, because of the risk of resistance, which seems to be less of a risk for CHG.
A bundle of interventions was tested in reducing the spread of CRE and ESBL Gram-negative bacteria in an Italian organ transplant unit. The bundle included screening, isolation, CHG bathing for known carriers, hand hygiene, and staff education. Screening and isolation was performed for CRE and ESBL, whereas the other interventions were implemented for CRE only. A sharply increasing rate of CRE was reversed, and returned below baseline levels following the intervention. The ESBL rate was static before the intervention, but decreased significantly in response. This shows that a intervention bundle aimed primarily at CRE also had some impact on ESBL, which was a bonus!
Finally, a large randomised controlled trial of 2% CHG / alcohol vs. 5% povidone-iodine / alcohol showed that there was no significant difference in the blood culture contamination rate following blood culture collection. This reinforces findings from other studies.
So, some evidence that chlorhexidine represents a versatile and effective antiseptic biocide!