Detergents and disinfectants
Tuladhar, E: et al. 2012. Residual Viral and Bacterial Contamination of Surfaces after Cleaning and Disinfection.
Objective
- To investigate the efficacy of cleaning and disinfection procedures for reducing contamination
• by noroviruses, rotavirus, poliovirus, parechovirus, adenovirus, influenza virus, Staphylococcus aureus, and Salmonella enterica
• from artificially contaminated stainless-steel surfaces.
Results
- After a single wipe with water, liquid soap, or 250-ppm free chlorine solution,
• the numbers of infective viruses and bacteria were reduced by 1 log10 for poliovirus and close to 4 log10 for influenza virus.
• There was no significant difference in residual contamination levels after wiping with water, liquid soap, or 250-ppm chlorine solution.
• When a single wipe with liquid soap was followed by a second wipe using 250- or 1,000-ppm chlorine, an extra 1- to 3-log10 reduction was achieved, and
• except for rotavirus and norovirus genogroup I (extra reduction 1-3 log10), no significant additional effect of 1,000 ppm compared to 250 ppm was found.
• A reduced correlation between reduction in PCR units (PCRU) and reduction in infectious particles suggests that at least part of the reduction achieved in the second step is due to inactivation instead of removal alone. - They used data on infectious doses and transfer efficiencies to estimate a target level to which the residual contamination should be reduced and found that
• a single wipe with liquid soap followed by a wipe with 250 ppm free chlorine solution was sufficient to reduce the residual contamination to below the target level for most of the pathogens tested.
Cleaning methods
- wet wiping (surface was dried in 3 minutes)
- only cleaning
- cleaning + disinfection.
Conclusions
- The enveloped respiratory influenza A virus has higher sensitivity to disinfection than the nonenveloped enteric viruses.
- The two-step procedure consisting of a single wipe with liquid soap followed by a disinfection step using 250-ppm chlorine solution is likely to be a good intervention strategy in cases of viral respiratory disease outbreaks.
El-Azizi, M. et al. 2016. Efficacy of selected biocides in the decontamination of common nosocomial bacterial pathogens in biofilm and planktonic forms.
Objective
- Tested how efficiently
• glutaraldehyde (GLA)
• hydrogen peroxide (HPO)
• peracetic acid (PAA)
• sodium hypochlorite (SHC)
remove bacteria in planktonic and biofilm forms. - Bacteria in the study: Acinetobacter baumannii, Burkholderia cepacia, Enterococcus faecalis, Enterococcus faecium, methicillin resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and one reference strain of Escherichia coli.
Evaluation of the killing activity of the biocides
• Against the planktonic phase of bacteria, the minimum bactericidal concentrations of the biocides required to kill all bacteria (MBC100) were determined
• Against the biofilms of bacteria using an in vitro biofilm device the minimum concentrations of biocide required to kill 85% of bacteria in the biofilms (MBC85) were determined
• Scanning electron microscopy (SEM) was used to visualize the effect of S. epidermidis pre-exposure to sublethal concentrations of PAA on biofilm formation.
Results
- All biocides completely killed all nine types of bacteria in the planktonic phases at all concentrations and at all exposure times, but there was a big variation of the biocide concentration needed.
- The biofilms were significantly less susceptible to the biocides than were planktonic cells of the same microorganism.
- Note: No products, according to the guideline, are CDC-recommended, EPA-registered, or FDA-cleared for the eradication of microorganisms from biofilms. This means that all listed chemicals are only recommended for combating micro-organisms in the planktonic form.
Russel, A. D. 2003. Similarities and differences in the responses of microorganisms to biocides. (Article)
From the article
- Unlike antibiotics, biocides are multi-targeted antimicrobial agents.
- There is considerable variation in the response of different microorganisms to biocides.
- Reasons for these varied responses are poorly understood at present.
- Few biocides are bactericidal (including mycobactericidal), sporicidal, virucidal and fungicidal.
- Most are bactericidal (with or without being mycobactericidal), virucidal and fungicidal but do not inactivate spores.
- Some biocides show activity against protozoa and algae.
- Factors that affect antimicrobial activity are well documented
• period of contact
• concentration
• temperature
• pH
• presence of organic soiling matter, and
• type of organism. - Article presents the mechanisms how different disinfectant agents kill microbes
• aldehydes, cationic biocides, alcohols, chlorine compounds, iodine and iodophors, peroxygens, phenols, phenylether (triclosan), organic acids and esters, metal ions, alkylating agents.
Kampf, G. et al. 2020. Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents.
Review article, collecting data of HCoV, MERS-CoV, SARS-CoV, MVH, TGEV
Persistence of coronavirus on inanimate surfaces
- Most data were described with the endemic human coronavirus strain (HCoV-) 229E.
• On different types of materials, it can remain infectious for from 2 hours up to 9 days. - A higher temperature such as 30°C or 40°C reduced the duration of persistence of highly pathogenic MERS-CoV, TGEV and MHV.
- However, at 4°C persistence of TGEV and MHV can be increased to 28 days.
Inactivation of coronaviruses by biocidal agents in suspension tests
- Few comparative data obtained with SARS-CoV indicate that persistence was longer with higher inocula.
- In addition, it was shown at room temperature that HCoV-229E persists better at 50 % compared to 30 % relative humidity.
Inactivation of coronaviruses by biocidal agents in carrier tests
- Ethanol at concentrations between 62 % and 71 % reduced coronavirus infectivity within 1 min exposure time by 2.0-4.0 log10.
- Concentrations of 0.1-0.5 % sodium hypochlorite and 2 % glutardialdehyde were also quite effective with > 3.0 log10 reduction in viral titre.