Doi:10.1016/j.jhin.2006.07.019

Journal of Hospital Infection (2006) 64, 386e390 Efficacy of super-oxidized water foggingin environmental decontamination J. Clark , S.P. Barrett M. Rogers , R. Stapleton a Department of Microbiology, Charing Cross Hospital, London, UKb Sterilox Technologies International ltd, Beaconside, Stafford, UK Received 5 September 2005; accepted 2 July 2006Available online 14 October 2006 The efficacy of decontamination using Sterilox fog was assessed against meticillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii. Ceramic tiles were inoculated with the test organisms and, once dried, were subjected to Sterilox fogging using a stationary vaporizing ma- chine sited at a distance of 3 m for 10 min and then left for a further hour.
In a second experiment using the same organisms, the first 10-min foggingperiod was followed by a directed fogging period of 30 s at a distance of1 m. Organisms were cultured from the tiles, plated on to tryptone soya agarand incubated for 48 h. Initial counts of approximately 109 colony-formingunits/mL for both organisms were reduced approximately 104 fold for MRSAand 105.8 fold for A. baumannii when using a single fogging. The second fog-ging resulted in 106.8-fold reductions for both organisms. Sterilox fog is safeand simple to use, and can reduce levels of nosocomial pathogens by a factorof almost 107. It is worthy of clinical evaluation in clinical settings to deter-mine whether it maintains its microbicidal effects against a variety of organ-isms on different surfaces.
ª 2006 The Hospital Infection Society. Published by Elsevier Ltd. All rightsreserved.
The use of disinfectants to decontaminate hospi-tals has mixed success in eliminating organisms Meticillin-resistant Staphylococcus aureus (MRSA), from the environment, and novel methods of and the means of controlling it, continue to be of cleaning have been explored previously.Various major interest to the healthcare community methods of transmission of these organisms havebeen identified, and many infection control mea-sures have been tried with different degrees of * Corresponding author. Address: Department of Microbiology, West Middlesex University Hospital NHS Trust, Isleworth TW7 Decontaminating the clinical environment after a patient has been infected with MRSA, or with 0195-6701/$ - see front matter ª 2006 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.jhin.2006.07.019 a multi-resistant Gram-negative bacterium, is made in maximum recovery diluent [MRD, (peptone thought to be a sensible precaution in stopping nosocomial transmission of these organisms. French dilutions were plated on to TSA, incubated for et al. reported the use of a vaporized disinfectant 48 h, colonies were counted and the initial bacterial system that reduced environmental MRSA contami- concentration was calculated. Ceramic tiles measur- nation, although further work is required to deter- ing 10 cm  10 cm were cleaned using detergent fol- mine the effect of environmental decontamination lowed by 70% isopropyl alcohol, wrapped in on MRSA infection rates.However, work performed aluminium foil and autoclaved at 121 C for 15 min.
by Wilcox et al. indicated that using specific dis- Ten drops (100 mL/drop) of bacterial suspension infectants when decontaminating hospital wards [109 colony-forming units (CFU)/mL] were evenly reduced the incidence of Clostridium difficile in- distributed on to 13 tiles (‘positive tiles’), and 10 fection.Whilst the interest of the popular press drops (100 mL/drop) of sterile MRD were evenly dis- has focused on MRSA, multi-resistant Gram-negative tributed on to two tiles (‘negative tiles’) as controls.
bacilli have attracted far less interest. Acineto- They were left to dry at room temperature for 2 h.
bacter baumannii is a Gram-negative coccobacillus A Dyna-Fogâ Model 2739 Hurricane ‘Cold Fog’ that is frequently resistant to virtually all anti- ULV/Mister (Dynafog, Indianapolis, USA) fogging biotics.It has been found resident on intensive machine was used for this experiment (capacity care units, with reservoirs such as curtains being 3.8 L, maximum output 19 L/h). The Sterilox solu- identified, and can be a particular problem to treat tion contained 180 parts per million of available due to its broad antibiotic resistance profile.The free chlorine at pH 5.2. Five positive tiles were po- financial impact of healthcare-associated infec- sitioned horizontally on a laboratory workbench tions is well recognized with an increase of inpatient and five tiles were positioned vertically. Addition- stay and morbidity and mortality, and an estimated ally, three positive tiles and the two negative tiles cost to the UK National Health Service in the region were sealed inside a laminar flow cabinet in the laboratory, which was not in use, to create positive Steriloxâ is an established disinfectant for heat- and negative controls inside a sealed environment.
labile flexible endoscopes, and has a broad The fogging machine was positioned 3 m away with spectrum of activity against mycobacteria, fungi, an unobstructed path to the tiles, and was run for viruses, bacterial endospores, and Gram-positive 10 min on maximum output. Afterwards, the labo- and Gram-negative bacteriSterilox is some- ratory was left for 1 h to allow time for the fog to times termed ‘super-oxidized water’ and its princi- settle and act upon the exposed tiles. In the pal ingredient is hypochlorous acid, which is safe second modified procedure, tile preparation and to use and not harmful to the environment. The fogging were performed as above, but at the end present study examined the decontamination effi- of the 10-min initial fogging, the fogging machine cacy of Sterilox fog against MRSA and acineto- was held approximately 1 m from the tiles and bacter dried on to environmental surfaces.
a further 30-s fogging was performed. The tilesreceived no physical cleaning action, i.e. the tilesurface was not wiped in any way during the fogging process. After this stage, it was necessaryto dry the laboratory using a mop due to the accu- This study was carried out using two strains of MRSA mulation of liquid caused by the fogging process.
and two strains of A. baumannii. The MRSA strains Each tile was placed in a plastic bag containing comprised a clinical isolate (sensitive to fusidic 100 mL MRD with 1% sodium thiosulphate for Steri- acid, vancomycin, teicoplanin, linezolid, rifampicin lox neutralization. The tiles were then agitated and mupirocin, and resistant to erythromycin, tri- manually within the bag for 1 min, and serial methoprim and tetracycline) and a type strain (Na- 10-fold dilutions were made in MRD. Since each tional Collection of Industrial and Marine Bacteria, tile was eluted into 100 mL MRD, and 1 mL (i.e.
NCIMB 50143). The acinetobacter strains comprised 2 Â 0.5 mL aliquots) of this was plated neat on to a clinical isolate (resistant to all commonly used an- TSA, the limit of detection was 100 organisms/ tibiotics except colistin) and a type strain (NCIMB tile, i.e. 1 CFU/mL neat eluate. This process was re- 12457). Two days prior to the study, a pure culture peated for the positive controls, and the negative of bacteria was plated on to tryptone soya agar controls were plated using 0.5 mL of neat dilution aliquots alone. The plates were then incubated at at 30e35 C. A bacterial suspension to 5 McFarland 35 C for two days and colonies were counted units (equivalent to 109 organisms/mL) was pre- (with no growth being equivalent to <100 colonies pared and a serial 10-fold dilution to 10À7 was on the tile; the limit of sensitivity). A neutralization validation was performed to determine the ability type strain of acinetobacter (NCIMB 12457) gave of sodium thiosulphate to neutralize Sterilox resi- a mean colony count of 4.6 Â 102 CFU/tile from due. This involved adding either 10 mL fogging solu- the horizontal tiles and 1.1 Â 104 CFU/tile from tion (test) or 10 mL MRD (control) to 100 mL MRD the vertical tiles on the first fogging run. The sec- containing 1% sodium thiosulphate, and inoculating ond fogging run gave counts of 1.0 Â 102 CFU/tile both solutions with 1 mL of the 104 dilution of each for both horizontal and vertical tiles. The clinical test organism, plating after 1 min and incubating isolate of acinetobacter showed a mean count of for 48 h to ensure complete microbial recovery.
3.4 Â 102 CFU/tile for the horizontal tiles and1.7 Â 103 CFU/tile for the vertical tiles on the firstrun. The second fogging run yielded mean counts of 3.8 Â 102 CFU/tile from the vertical tiles and3.2 Â 102 CFU/tile from the horizontal tiles. The The experiment was conducted twice, with the standard method used on the first run and the Pooling the results for horizontal and vertical modified method involving the second hand-held tiles, the type strain of MRSA gave log10 reduction fogging on the second run. After each run, the tile factors of 4.05 and 6.64 for the first and second elutes were plated on to TSA. Recovery of the fogging experiments, respectively. For the clinical organisms from the positive controls demonstrated isolate of MRSA, the corresponding figures were that the organism remained viable once dried on to 3.75 and 6.99. The acinetobacter type strain the ceramic tiles. Mean recovery from the MRSA gave log10 reduction factors of 5.65 and 6.99 for controls was 1.0 Â 109 CFU/tile on the first fogging the first and second fogging runs, respectively, run and 1.6 Â 109 CFU/tile on the second run for and for the acinetobacter clinical isolate, the cor- the type strain, and 2.1 Â 109 CFU/tile on the first responding figures were 5.85 and 6.57.
run and 1.37 Â 109 CFU/tile on the second run forthe clinical isolate. Mean recovery from the acine-tobacter 8.5 Â 108 CFU/tile for the first and second runs,and the type strain yielded 4.8 Â 108 CFU/tile and The use of Sterilox in the fogging studies resulted 1.4 Â 109 CFU/tile for the clinical isolate on its re- in a 104-fold decrease of the MRSA type strain and spective fogging runs. The negative controls for all a 103.75-fold reduction of the MRSA clinical isolate after a single treatment, and a 106.64-fold de- On the first fogging run, the MRSA type strain crease and a 106.69-fold decrease of the type strain (NCIMB 50143) yielded a mean colony count of and the clinical isolate after the two-stage treat- 3.8 Â 104 CFU/tile from the horizontal tiles and ment. Acinetobacter strains showed greater reduc- 1.8 Â 105 CFU/tile from the vertical tiles. The tions after one fogging compared with MRSA second fogging run showed horizontal and vertical (106.65-fold and 105.85-fold reductions for the mean yields of 5.2 Â 102 CFU/tile and 2.6 Â type and clinical strain, respectively). After a sec- 102 CFU/tile, respectively. The clinical isolate of ond fogging, reductions similar to the MRSA results MRSA gave mean counts of 2.52 Â 105 CFU/tile for the horizontal tiles and 5.64 Â 105 CFU/tile for ded two-stage fogging treatment, whilst improving the vertical tiles on the first fogging run, and efficacy, does involve more user interaction in mean counts of 1.4 Â 102 CFU/tile for both hori- a clinical setting, which may restrict its clinical zontal and vertical tiles on the second run. The Log10 mean colony counts of the four fogging experiments Note: 100 colony-forming units/mL was the limit of sensitivity and a result of 2 signifies that no organisms were recovered. Figuresin parentheses are log10 reduction factors achieved by fogging. MRSA, meticillin-resistant Staphylococcus aureus.
Exner et al. showed that spread of S. aureus diminished.As yet, there has been no work exam- within the environment could result from inade- ining the impact of organic matter contamination quate cleanThese authors used a suspension on a fogging system. The manufacturers recom- of S. aureus of 0.05 mL (3  107 CFU/mL) inocu- mend that the system should only be utilized at lated on to a 5 cm  5 cm square of floor and then the end of a cleaning process, and in such circum- mopped in a U-shape using a variety of cleaning stances, any organic contamination should have agents. After drying, swabs were taken from the ini- been removed. However, further work needs to be tial square of floor and three adjacent squares of carried out to investigate any role of organic con- identical size, 7 cm apart, and plated to determine tamination of surfaces on the efficacy of Sterilox the presence of S. aureus. Mops soaked in water, in these situations. Work is also needed on the use quaternary ammonium compounds or alkylamines of Sterilox fog in the clinical setting to discover showed incomplete killing of the S. aureus and any potential problems of using the fog in a func- caused dissemination throughout the non-inocu- tioning clinical area with respect to the technical lated tiles. Only aldehydes and peroxides showed aspect of using the system, as well as the resultant complete killing of the S. aureus with no dissemina- liquid residue interfering with clinical appliances.
tion. Environmental contamination with A. bau- With the UK Government publishing ‘Winning mannii in an intensive care setting suggested that ways’, it is clear that infection control is a major poor cleaning was associated with increased pa- public concern, and the cleaning and cleanliness of tient coloniIn view of the environment be- hospitals remains high on the political agenda.
ing a potential source of patient contamination, The reductions observed in this study compare and since the conventional ‘mop and bucket’ tech- favourably with the use of alkylamine compounds, nique appears to risk leaving residual contamina- and the safety profile of Sterilox means that it is tion of surfaces, the use of a fogging treatment a good candidate for decontaminating the hospital that may be able to permeate into the various re- cesses that can be found within most clinical set-tings (such as behind drawers, within the bed This study found that Sterilox is able to reduce The authors would like to thank Sterilox UK for the the burden of MRSA and acinetobacter on environ- kind provision of consumables used in this study.
mental surfaces when fogged. It would clearly be of Laboratory work was performed at Charing Cross interest to investigate the activity of Sterilox against other nosocomial pathogens that can per-sist on surfaces in the clinical environment such asclostridia and enterococci. Organic contamination of the environment is an important consideration ofany decontamination process, and the manufac- 1. Barrett SP, Simmons NA. Controlling MRSA: what is the way turers of Sterilox emphasize that a thorough clean- forward? J Hosp Infect 2005;59:170e171.
ing of contaminated areas should be carried out 2. Cooper BS, Stone SP, Kibbler CC, et al. Isolation measures in the hospital management of methicillin resistant Staphylo- prior to the 60-min disinfectant fogging treatment coccus aureus (MRSA): systematic review of the literature.
as part of a biohazard decontamination protocol.
The microbiocidal activity of Sterilox in the pres- 3. Farrington M, Redpath C, Trundle C, Brown N. Controlling ence of organic load has been demonstrated in MRSA. J Hosp Infect 1999;41:251e254.
previous work. Selkon et al. reported that Sterilox, 4. French GL, Otter JA, Shannon KP, Adams NMT, Watling D, Parks MJ. Tackling contamination of the hospital environment in a suspension test, was rapidly effective in the by methicillin-resistant Staphylococcus aureus (MRSA): a compar- presence of 1% horse serum against a variety of or- ison between conventional terminal cleaning and hydrogen per- ganisms including Escherichia coli, Pseudomonas oxide vapour decontamination. J Hosp Infect 2004;57:31e37.
aeruginosa and MRSA with kill rates comparable to 5. Johnston MD, Lawson S, Otter JA. Evaluation of hydrogen 2% glutaraldehydeBoth agents required a longer peroxide vapour as a method for the decontamination ofsurfaces contaminated with Clostridium botulinum spores.
contact time in the presence of high organic loading J Microbiol Methods 2005;60:403e411.
(5% calf serum). Shetty et al. reported Sterilox to be 6. Ribner BS, Landry MN, Gholson GL. Strict versus modified equally effective under high and low soil conditions isolation for prevention of nosocomial transmission of (1% and 5% horse serum, respectively) against four methicillin-resistant Staphylococcus aureus. Infect Control Mycobacteria spp. and strains of Helicobacter py- 7. Rayner D. MRSA: an infection control overview. Nurs Stand lori, vancomycin-resistant enterococci and Candida albicans.However, activity against C. difficile 8. Wilcox MH, Fawley WN, Wigglesworth N, Parnell P, Verity P, spores in the presence of 5% horse serum was Freeman J. Comparison of the effect of detergent versus hypochlorite cleaning on environmental contamination and 13. Exner M, Vacata V, Hornei B, Dietlein E, Gebel J. Household incidence of Clostridium difficile infection. J Hosp Infect cleaning and surface disinfection: new insights and strate- gies. J Hosp Infect 2004;56(Suppl. 2):S70eS75.
9. Livermore DM. The threat from the pink corner. Ann Med 14. Denton M, Wilcox MH, Parnell P, et al. Role of environmen- tal cleaning in controlling an outbreak of Acinetobacter 10. Das I, Lambert P, Hill D, Noy M, Bion J, Elliott T. Carbape- baumannii on a neurosurgical intensive care unit. J Hosp nem-resistant acinetobacter and role of curtains in an outbreak in intensive care units. J Hosp Infect 2002;50: 15. Shetty N, Srinivasan S, Holton J, Ridgway G. Evaluation of mi- crobicidal activity of a new disinfectant: Steriloxâ 2500 against 11. Plowman R, Graves N, Griffin M, et al. The socio-economic Clostridium difficile spores, Helicobacter pylori, vancomycin burden of hospital acquired infection: executive summary.
resistant Enterococcus species, Candida albicans and several Mycobacterium species. J Hosp Infect 1999;41:101e105.
12. Selkon JB, Babb JR, Morris R. Evaluation of the antimicrobial 16. Chief Medical Officer. Winning ways: working together to activity of a new super-oxidized water, Steriloxâ, for the reduce healthcare associated infection in England. London: disinfection of endoscopes. J Hosp Infect 1999;41:59e70.

Source: http://www.faithgroup.co.in/pdf/sterigen/select_sterigen_references/SOW%20efficacy%20fogging.pdf