Fumigation of high-containment microbiology facilities is an international requirement and in the UnitedKingdom this process is still commonly undertaken using formaldehyde vaporization. Formaldehyde usage is simple and inexpensive, but concerns exist over its toxicity and carcinogenicity. Alternative fumigants exist, although independent, parallel comparison of these substances is limited. This study determined the level of biocidal efficacy achievable with formaldehyde and compared this with other commonly used fumigants. Three different hydrogen peroxide-based fumigation systems were evaluated (two vapor and one dry-mist methods), along with true gas systems employing ozone and chlorine dioxide. A range of challenge microorganisms was used at different room locations to assess the efficacy, usability, and safety of the fumigation equipment. These microorganisms included Geobacillus stearothermophilus, Clostridium difficile, Mycobacterium fortuitum, and Vaccinia virus. Only chlorine dioxide and formaldehyde fumigants gave consistently high levels of antimicrobial efficacy across all bacterial challenge tests (typically greater than a 5-log reduction). All systems performed similarly against Vaccinia virus, but variable results were noted for Geobacillus, C. difficile, and M. fortuitum for the hydrogen peroxide-and ozone-based systems. The study also revealed inconsistencies in system reliability and reproducibility, with all fumigant systems aborting midcycle on at least one occasion. In contrast, formaldehyde fumigation was confirmed as extremely reliable, largely because of its simplicity (liquid plus hot plate). All the fumigants tested have UK workplace exposure limits of 2 ppm or less, yet residual fumigant was detected for the formaldehyde and hydrogen peroxide systems following cycle completion, even after room aeration. Articles

When transferring highly infective patients to specialist hospitals, safe systems of work minimise the risk to healthcare staff. The EpiShuttle is a patient transport system that was developed to fit into an air ambulance. A validated decontamination procedure is required before the system can be adopted in the UK. Hydrogen peroxide (H2O2) vapour fumigation may offer better penetration of the inaccessible parts than the liquid disinfectant wiping that is currently suggested. To validate this, an EpiShuttle was fumigated in a sealed test chamber. Commercial bacterial spore indicators (BIs), alongside organic liquid suspensions and dried surface samples of MS2 bacteriophage (a safe virus surrogate), were placed in and around the EpiShuttle, for the purpose of evaluation. The complete kill of all of the BIs in the five test runs demonstrated the efficacy of the fumigation cycle. The log reduction of the MS2 that was dried on the coupons ranged from 2.66 to 4.50, but the log reduction of the MS2 that was in the organic liquids only ranged from 0.07 to 1.90, confirming the results of previous work. Fumigation with H2O2 alone may offer insufficient inactivation of viruses in liquid droplets, therefore a combination of fumigation and disinfectant surface wiping was proposed. Initial fumigation reducing contamination with minimal intervention allows disinfectant wipe cleaning to be completed more safely, with a second fumigation step inactivating the residual pathogens.

Introduction: The performance of 2 disinfectant chemicals, peracetic acid (PAA) and hypochlorous acid (HOCl), was evaluated using a Venturi-nozzle-based light decontamination system (LDS) for delivery. The atomization equipment combined low-pressure air and disinfectant via a handheld lance, producing a fine, dense aerosol. A range of microorganisms, including Bacillus cereus and Bacillus anthracis ( Vollum) spores, were used as test challenges to evaluate chemicals and equipment. Methods: The tests undertaken included assessments over fixed and variable exposure times, use of multiple surface materials, and a live agent challenge. Results: Over a fixed-time exposure of 60 minutes, aerosolized PAA gave 7- to 8-log reductions of all test challenges, but HOCl was less effective. Material tests showed extensive kill on most surfaces using PAA (≥6-log kill), but HOCl showed more variation (4- to 6-log). Testing using B. anthracis showed measurable PAA induced spore kill inside 5 minutes and >6-log kill at 5 minutes or over. HOCl was less effective. Discussion: The results demonstrate the importance of testing decontamination systems against a range of relevant microbiological challenges. Disinfectant efficacy may vary depending on product choice, types of challenge microorganisms, and their position in a treated area. The most effective disinfectants demonstrate biocidal efficacy despite these factors. Conclusion: The data confirmed PAA as an effective disinfectant capable of rapidly killing a range of microorganisms, including spores. HOCl was less effective. The LDS system successfully delivered PAA and HOCl over a wide area and could be suitable for a range of frontline biosecurity applications.

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