Bio-decontamination of a Mouse Parvovirus infected 7,000m³ bio-medical research building 

Following extensive contamination with both Mouse Parvovirus (MPV) and continued attempts to clear using traditional cleaning regimes, a large (approximately 7000m³) bio-medical research facility had a requirement for being fumigated before the building could be re-occupied. The key criteria used to select the method employed were: (i) Efficacy against MPV; (ii) capability for large-scale deployment in order to complete the simultaneous fogging of rooms, corridors, and other inter-connected areas; (iii) ability to overcome challenging topology, such as lifts and lift shafts; (iv) residue-free technology to leave the building ready for immediate re-occupation; and (v) documented verification of the biological efficacy of the fumigation process.

Solution

BIOQUELL’s Room Bio-Decontamination Service (“RBDS”) was selected to treat the area. The two floor building was divided into four discrete zones, which were fogged sequentially. Up to 17 Clarus™ ‘R’ hydrogen peroxide vapour generators were strategically placed in the zones to ensure even vapour distribution; 29 Clarus™ R2 aeration units were also included to remove the H2O2 vapour at the end of the cycle; and instrumentation modules were located in each zone to monitor the key parameters. Each zone was then sealed before fumigation commenced and remained sealed until the H2O2 vapour had been removed at the end of the process via catalytic conversion to water vapour and oxygen. The entire process was monitored and controlled from outside the room via the control computer. The perimeter of each zone was monitored for leakage using hand-held hydrogen peroxide vapour sensors.

Gassing Cycle Verification

Geobacillus stearothermophilus spores dried onto metal discs and sealed in Tyvek pouches were used as biological indicators (BIs) to verify the efficacy of the fumigation procedure. Two different inocula were used: BIs inoculated at >1.0x10⁶ for standard locations and BIs inoculated at >1.0x10⁴ for challenge locations. Standard BIs were distributed around the building according to BIOQUELL’s protocols. Challenge BI locations were established prior to the decontamination of each zone and included sites around and within intricate equipment.
 
Results

Post RBDS there have been no acquisition of MPV within the facility for a period of 12 months.
The BIs were retrieved after aeration and incubated for seven days at 60^oC. Positive control BIs that were not exposed to the fumigation process showed signs of growth. 600/600 BIs that were exposed to the decontamination process were negative (following remedial fumigation¹ in two small rooms). BI challenge sites included inside computer equipment, lift shafts, anaesthetic equipment and cage racks.

None of the sensitive electronic equipment that was exposed to the hydrogen peroxide vapour was affected, demonstrating the excellent materials compatibility of the RBDS process.

Conclusion
 
The target of a 6-log reduction in Tyvek pouched G.stearothermophilus spores in standard locations and a 4-log reduction in challenge locations was achieved throughout the building. The entire decontamination project was completed in six working days. Hence, the RBDS system provides a very rapid and effective fumigation system, which combined with the rapid aeration method produces a minimal cycle time.

This system is used frequently in many other applications such as the fumigation of specific problem-causing micro-organisms or for general decontamination of laboratories, including CL3 facilities, cleanrooms, pharmaceutical manufacturing plants and hospitals. The RBDS system is infinitely scalable so that very large areas and entire buildings (as in this case) can be rapidly and effectively fumigated.

¹ Two standard BI's were positive, indicating a <6-log reduction at these sites. These rooms were isolated and remedially bio-decontaminated to ensure that the full 6-log bio-deactivation target was acheived.

For further details of H2O2 bio-decontamination solutions including equipment and room services, please contact BIOQUELL.