Commodes, Disinfection, and CDI
A study of the efficacy of peracetic acid based disinfectants on the removal of clostrodiodes difficile from commodes in a clinical environment.
Abstract
Clostrodiodes difficile is a bacteria that lives in the digestive system of some people. In a healthy individual the bacteria are kept in check by other ‘gut flora’ that prevent C. Diff multiplying. However, antibiotics and numerous health conditions allow C. Diff to multiply. Depending on the strain in question this can lead to unpleasant, and potentially life threatening C. Diff infections. Once infected a patient will shed the bacteria, primarily in faeces, and the bacteria forms very hardy spores that can survive for a long time outside of the body. These spores are very infectious and, if not contained, can lead to large outbreaks of C. Diff in healthcare settings.
Introduction
Clostrodiodes difficile bacteria are found in the gut (digestive system) of around 1 in 30 (~3%) adults1,2,3,4, and about 2 in 3 infants2. Under normal circumstances a healthy individual will not suffer ill effects from the presence of C. diff bacteria as the range of ‘good’ bacteria that live in the gut prevent it from growing and reaching levels that would cause issues.1,2,3 The problem comes when an individual’s health has been affected in some way. Antibiotics affect the gut flora and can allow C. Diff to multiply, immunosuppressants and immune compromised patients are susceptible, and other groups such as the elderly, or those in long-term healthcare are at risk1,3,4,5. If C. Diff manages to multiply, some strains release toxins which cause inflammation, leading to a C. Diff Infection (CDI) with symptoms such as diarrhoea, painful stomach cramps, dehydration, and fever1,4. CDI is a serious infection and has an all cause 30-day mortality of 15% or greater6. Once a patient has had a C. Diff infection the chance of recurrence increases, having a 20% chance of recurrence after one infection, climbing to 50% or more after a second infection4. Once a patient has become infected C. Diff can spread easily, and bacteria are shed via an infected person’s diarrhoea1,3. Outside of the body the C. Diff bacteria will become spores, a highly resistant form of the bacteria that are less susceptible to disinfectants and environmental changes such as heat and dehydration1,3. An infected patient can excrete up to 1 x 107 spores per gram of faeces6. Due to the long-lived nature of spores, any contaminated surface can be a source of infection for other at risk patients. Shared facilities such as commodes, toilets, and any communal equipment will become a primary route of infection, and unwashed hands, clothing, bedding, and any personal items can result in spreading of spores to other areas. Any occurrence of CDI emphasises the need for high level sporicidal disinfection for outbreaks, and the importance of preventative cleaning to avoid such outbreaks in the first place. This study aims to determine the effectiveness of Peracide in-situ peracetic acid, and peracetic acid wipes, at commode cleaning and disinfection.
Method
A spinal rehabilitation ward was used as the location for swabbing and cleaning of commodes. Two commodes were designated, and after use they were set aside in a shower room across from a patient bay. They were then left untouched until the cleaning started.
For the cleaning tests, the cleaning products were prepared as follows:
The Peracide solution was generated using 2 x 3g Peracide tablets dissolved in 500mL lukewarm water (~40°C) using a standard Peracide dilution bottle. The tablets were allowed 10 minutes to dissolve and activate, with occasional agitation.
The instructions for the wipes state, “To activate, wet the wipe with cold water under a tap or dip into a bucket. Squeeze out the wipe to remove excess water”. To allow fair comparison 4 peracetic acid wipes were wetted with lukewarm water and allowed 10 minutes for generation of peracetic acid.
While the two disinfectants were generating their biocide, both commodes were swabbed at 3 points to test the initial Colony Forming Unit (CFU) count before being disinfected. Table 1 (below) shows the locations and numbers of swabs taken. After the swabbing was complete, the Peracide solution had turned from purple to pink, showing that the solution is ready for use. The PAA wipes had also been wetted for a period of ten minutes.
The Lead IPC Nurse for the hospital, who is clinically trained to clean commodes, began the process of cleaning and disinfection. Starting with the Peracide solution, the lead IPC Nurse identified it would be easier to transfer the solution from the 500ml bottle to a bowl and submerge the cloths as needed. The seat of the commode was cleaned first on top and then flipped to clean the underside of the seat. When the seat was cleaned it was moved out of the way, then the back of the chair was cleaned, then the arm rests, legs, and wheels of the commode. For the whole cleaning process 8 cloths were used in conjunction with the Peracide solution. This process was replicated with the 4 PAA wipes.
When the commodes had been cleaned, both were confirmed to be visibly wet, and were left to air dry. This took approximately 10 minutes for both cleaning tests. While waiting for the commodes to dry the next round of swabs were prepared and labelled. The same processes / locations as the pre-clean swabs were used, as shown in table 1, to ensure the pre-clean and post-clean swabs can be compared for the number of micro-organisms present.
All of the swabs were sent to MSL Solution Providers to analyse the swabs for the CFU count of micro-organisms present. A guaranteed delivery service was used to ensure the swabs were no more than 24 hours old at time of analysis.
| PAA Wipes | Peracide ISPAA Solution | ||||
|---|---|---|---|---|---|
| Pre-clean | Post-clean | Location | Pre-clean | Post-clean | Location |
| C1 | C4 | Around the hole on the seat | P1 | P4 | Around the hole on the seat |
| C2 | C5 | Across the back-rest | P2 | P5 | Across the back-rest |
| C3 | C6 | Along the arm-rests | P3 | P6 | Along the arm-rests |
Table 1 – Sample ID and location for each swab pre and post clean.
Results
| PAA Wipes | Peracide ISPAA Solution | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| CFU Count - Aerobic Mesophilic Bacteria | CFU Count - Aerobic Mesophilic Bacteria | ||||||||
| Sample Point | Pre-clean | Sample Point | Post-clean | Reduction | Sample Point | Pre-clean | Sample Point | Post-clean | Reduction |
| C1 | >3000 | C4 | 1 | 3000 | P1 | >3000 | P4 | 1 | 3000 |
| C2 | 280 | C5 | 10 | 270 | P2 | 310 | P5 | 1 | 300 |
| C3 | 1230 | C6 | >3000 | -1770 | P3 | 1060 | P6 | 150 | 910 |
| Average Reduction: | 500 | Average Reduction: | 1400 | ||||||
| CFU Count - Yeast and Mould | CFU Count - Yeast and Mould | ||||||||
| Sample Point | Pre-clean | Sample Point | Post-clean | Reduction | Sample Point | Pre-clean | Sample Point | Post-clean | Reduction |
| C1 | 1 | C4 | 1 | 0 | P1 | 1 | P4 | 1 | 0 |
| C2 | 1 | C5 | 1 | 0 | P2 | 1 | P5 | 1 | 0 |
| C3 | 1 | C6 | >3000 | -3000 | P3 | 1 | P6 | 1 | 0 |
| Average Reduction: | -1000 | Average Reduction: | 0 | ||||||
Table 2 - Results of swab tests for all sample points expressed in number of Colony Forming Units (CFU)
Discussion
The results show the effectiveness of peracetic acid in reducing the number of colony forming units. Initial (pre-clean) levels of bacteria are as would be expected for a used commode, and the overall reduction in CFU for Peracide and peracetic acid wipes is comparable, although the reduction factor for Peracide is, on average, about 3 times more effective.
The result for sample location C3 is indicative of recontamination during cleaning. This emphasises both the need for cleaning methods that do not lead to recontamination, as well as a disinfectant that destroys the bacteria collected on the cleaning wipes after they have been used.
Yeasts and moulds were present in such low levels that all the tests are essentially at their limit of detection, and show no measurable reduction due to the initial low levels. Again, sample C3 shows the importance of avoiding cross-contamination during cleaning, as well as using disinfectants that can negate pathogens after they have been removed from surfaces.
Costs Comparison
PAA Wipes come in a pack of 25 wipes costing £7 per pack on the NHS Supply Chain.
Using 4 of these wipes per commode will cost £1.12.
Peracide was used at 2000 ppm as recommended by the manufacturer for use on commodes.
So 2 x 3g tablets were used in 500mL of water at a cost of £0.16 (£0.08 per tablet).
Additionally 8 cloths were used at £0.05 per cloth, adding £0.40 to the cost of cleaning the commode.
The overall cost of cleaning a commode with Peracide is £0.56.
Around 100mL of Peracide solution was used in the process of cleaning the commode, so 400ml was still available for further cleaning. The remaining solution is viable for over 12 hours and is already active so it can be used on a further 4 commodes without preparation of more solution.
This reduces the cost of solution used per commode to £0.03, and including the wipes would be £0.43 per commode.
The cost of cleaning 5 commodes with 1x 500ml bottle of 2000ppm solution of Peracide and 8 cloths per commode, would be a total of £2.15. The cost of cleaning 5 commodes with PAA Wipes would be £5.60.
Therefore, the overall saving for just 5 commodes would be £3.45.
The number of commodes cleaned throughout the hospital per day would be significantly higher, for example if 30 commodes were cleaned per day at the hospital, the savings by using Peracide instead of PAA wipes would be £20.70 per day and £7555.50 per year.
Method of Cleaning
It was noticed that the underside of the seat on both commodes were visibly soiled, and looked like both hadn’t been cleaned properly in these areas for some time.
Conclusion
Peracetic acid based disinfectants are highly effective in a short time. With the exception of the re-contaminated sample point, both products reduce the number of CFUs dramatically. With diligent cleaning the presence of bacteria, and other pathogens, can be reduced to such a level that infection spreading becomes extremely unlikely to impossible.
The results show the importance of good cleaning practices as recontamination of equipment can negate the best efforts in other areas. It also shows the importance of using a disinfectant that is capable of destroying pathogens after they have been removed. Good cleaning practices should prevent recontamination, but knowing that pathogens that have been removed are being destroyed is an extra level of security to prevent spread of infections.
References
1. NHS Inform. Clostridium difficile. https://www.nhsinform.scot/illnesses-and-conditions/infections-and-poisoning/clostridium-difficile May 2023
2. King’s College Hospital. Clostridium difficile, Information for patients and visitors. https://www.kch.nhs.uk/wp-content/uploads/2023/01/pl-262.5-clostridioides-difficile.pdf April 2022
3. Leeds Community Healthcare. Clostridium difficile. https://www.leedsccg.nhs.uk/content/uploads/2017/09/CDI-leaflet-completed.pdf
4. Community IPC Policy for Domiciliary Care staff. https://www.infectionpreventioncontrol.co.uk/content/uploads/2021/05/DC-02-C.-difficile-April-2021-Version-2.00.pdf April 2021
5. Uwamahoro MC, Massicotte R, Hurtubise Y, Gagné-Bourque F, Mafu AA and Yahia L (2018) Evaluating the Sporicidal Activity of Disinfectants against Clostridium difficile and Bacillus amyloliquefaciens Spores by Using the Improved Methods Based on ASTM E2197-11. Front. Public Health 6:18. doi: https://doi.org/10.3389/fpubh.2018.00018
6. Kenters, N., Huijskens, E., de Wit, S. et al. Effectiveness of various cleaning and disinfectant products on Clostridium difficile spores of PCR ribotypes 010, 014 and 027. Antimicrob Resist Infect Control 6, 54 (2017). https://doi.org/10.1186/s13756-017-0210-3