![]() The spore suspension was heat-treated at 65☌ for 30 min before use. The suspension was washed three times in cold sterile water by repeated centrifugations (9 300 g for 30 min) to remove cell debris and media co-contaminants. When the sporulation reached ≥95%, the spores were harvested from the plates using cold sterile water. The plates were daily monitored microscopically for sporulation progression for a period of 7–9 days. Briefly, an overnight tryptic soy broth culture was seeded on Lab Lemko agar plates and incubated at 37 ± 2☌. anthracis Ames spores were prepared as detailed in Rastogi et al. ![]() Each inoculation event consisted of one actuation from the MDI. 1 × 10 7 spores over a 18 mm diameter coupon surface. atrophaeus spores via a metered dose inhaler (MDI) according to the aerosol deposition-based inoculation methods described previously ( Lee et al. The surfaces of the materials were inoculated with B. This spore product was then blended with silicon dioxide particles. atrophaeus was cultivated, then allowed to sporulate, centrifuged, then spray dried. niger and Bacillus globigii) were obtained from the US Army Dugway Proving Ground Life Science Division, and were prepared as described previously ( Brown et al. atrophaeus (ATCC 9372 formerly Bacillus subtilis var. Test organisms and inoculation proceduresĭried spores of B. In addition, the tests in the pilot-scale chamber allowed us to assess the effect of location within the chamber on decontamination efficacy, while the bench-scale tests allowed us to compare the degree of inactivation between the two species. Tests were conducted to assess the effect of operational variables such as the type of humidifier quantity and concentration of the aqueous H 2O 2 solution and contact time, on decontamination efficacy. Laboratory (bench-scale) tests were also conducted at the Edgewood Chemical and Biological Center (ECBC) facility in Edgewood, MD, with spores of both B. 2007), led to the present study, which investigated the sporicidal effects of relatively long durations of low concentration HPV generated with simple, readily available commercial off-the-shelf (COTS) humidifiers.ĭecontamination tests were conducted at EPA’s Research Triangle Park (NC) laboratories using Bacillus atrophaeus spores, with the HPV disseminated using COTS humidifiers in a pilot-scale chamber. These results, and reports of other HPV outgassing research ( Baron et al. In addition, high concentrations were found to pose a risk of material incompatibility and resulted in off-gassing of HPV for extended periods in lined ventilation duct ( Meyer et al. It is also difficult to attain and maintain high concentrations of HPV in a building without large generating equipment (this is actually a problem for any fumigant), and isolation of the fumigant poses a safety challenge. ![]() While this approach may be appropriate for routine decontamination of facilities in regular use, implementation on a large scale and in a field setting would be problematic. Laboratory testing of HPV as a sterilant has typically focused on exposure of relatively short durations (2–4 h) at high concentration (>200 ppm) using specialized equipment and concentrated liquid feedstock, for example, 35% concentration of H 2O 2 in aqueous solution. HPV has also been shown to inactivate prions ( Fichet et al. 1997), and bacterial spores ( Johnston et al. Effective decontamination using HPV has been demonstrated against a wide range of micro-organisms, including vegetative bacteria ( French et al. HPV has been widely used for decontamination of healthcare, pharmaceutical, animal and food industry facilities ( Klapes and Vesley 1990 McDonnell and Russell 1999 Krause et al. complete removal of all interior materials and equipment to reduce demand for the HPV fumigant, subdividing the building into 10 separate decontamination zones to reduce needed capacity to generate the HPV, the use of several modified HPV generators), and difficulties were encountered, in order to reach and maintain the target HPV concentration. For one of the contaminated buildings (Department of State SA-32), it was decided to fumigate using a target HPV concentration of 216 parts per million (ppm) for 4 h, with temperature held above 21 ☌ ( US EPA 2005). anthracis spores in a building were unknown. ![]() At that time, the optimal application conditions (concentration, contact time, temperature and relative humidity (RH)) for use of HPV to inactivate B. Hydrogen peroxide vapour (HPV) was used to decontaminate two of the affected buildings ( Canter 2005). Deliberate dissemination of Bacillus anthracis (Ames strain) endospores (referred to as spores for the rest of this manuscript) through letters processed by the US Postal Service in the fall of 2001 led to the contamination of numerous offices, buildings and residences across Florida, New Jersey, New York and Washington DC.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |