Whole-building decontamination of Bacillus anthracis Sterne spores by methyl bromide fumigation

Abstract

Aims: To evaluate the field inactivation of Bacillus anthracis Sterne spores with methyl bromide (MB) using commercial fumigation techniques.

Methods and results: Eighty-seven wood and 87 glass coupons each containing ca. 1 × 10(6) B. anthracis Sterne spores, were placed in 22 locations inside a 1444 m(3) conference building. Four additional 12-coupon sets (six wood, six glass) were removed from the building at 16, 24, 32 and 40 h during fumigation. The building was sealed under two tarpaulins and fumigated with MB at ≥225 g m(-3) mean concentration for 48 h at 28°C and 83% RH. All B. anthracis spores fumigated for more than 16 h were inactivated. A single wood coupon from the 16-h set yielded ca. 2 × 10(3) CFU. No damage to the building or its contents was observed.

Conclusions: MB fumigation is a rapid, economical and effective whole-structure decontamination method for B. anthracis spores.

Significance and impact of the study: MB fumigation offers a method of whole-structure B. anthracis decontamination without removal of materials, damage to sensitive electronics, costly indoor retrofitting.

Keywords: antibacterial; commercial fumigation; non-corrosive; sensitive materials; sporicide.

Figure 1

(a) Inner ethylene vinyl alcohol tarp (black) with skirt around the building perimeter; (b) clamping seams of the outer vinyl tarp; (c) fully tarped building.

Figure 2

Contents of test building. (a) Large central room; (b) projection equipment; (c) computer routing station; (d) personal computer.

Figure 3

Room arrangement and locations of Bacillus anthracis coupons in the fumigated building.

Figure 4

Concentration (g m⁻³), accumulated dosage (g h m⁻³), and additions (kg) of methyl bromide at four data logged locations during the study fumigation. Locations (Fig. 3): N (○), D (□), K (▵) and Q (×).