Virulent spores of Bacillus anthracis and other Bacillus species deposited on solid surfaces have similar sensitivity to chemical decontaminants

Abstract

Aims: To compare the relative sensitivity of Bacillus anthracis and spores of other Bacillus spp. deposited on different solid surfaces to inactivation by liquid chemical disinfecting agents. Methods and Results: We prepared under similar conditions spores from five different virulent and three attenuated strains of B. anthracis, as well as spores of Bacillus subtilis, Bacillus atrophaeus (previously known as Bacillus globigii), Bacillus cereus, Bacillus thuringiensis and Bacillus megaterium. As spore‐surface interactions may bias inactivation experiments, we evaluated the relative binding of different spores to carrier materials. The survival of spores deposited on glass, metallic or polymeric surfaces were quantitatively measured by ASTM standard method E‐2414‐05 which recovers spores from surfaces by increasing stringency. The number of spores inactivated by each decontaminant was similar and generally within 1 log among the 12 different Bacillus strains tested. This similarity among Bacillus strains and species was observed through a range of sporicidal efficacy on spores deposited on painted metal, polymeric rubber or glass. Conclusions: The data obtained indicate that the sensitivity of common simulants (B. atrophaeus and B. subtilis), as well as spores of B. cereus, B. thuringiensis, and B. megaterium, to inactivation by products that contain either: peroxide, chlorine or oxidants is similar to that shown by spores from all eight B. anthracis strains studied. Significance and Impact of the Study: The comparative results of the present study suggest that decontamination and sterilization data obtained with simulants can be safely extrapolated to virulent spores of B. anthracis. Thus, valid conclusions on sporicidal efficacy could be drawn from safer and less costly experiments employing non‐pathogenic spore simulants.

Inactivation of Bacillus anthracis Spores by Liquid Biocides in the Presence of Food Residue

“…The high potency of sodium hypochlorite as a sporicide under clean conditions at room temperature has been described previously (2,16,17). The sporicidal efficacy of sodium hypochlorite in this study may have been greater if the working solutions had been adjusted closer to neutral pH (5,16).…”

“…The safety challenges in working with Bacillus anthracis spores have led many researchers to conduct research using surrogate organisms. Some of the surrogates used include nonvirulent strains of B. anthracis and other Bacillus species: Bacillus subtilis, Bacillus atrophaeus, Bacillus cereus, Bacillus thuringiensis, Geobacillus stearothermophilus, and Bacillus megaterium (13,17,27).…”

Identification by Quantitative Carrier Test of Surrogate Spore-Forming Bacteria To Assess Sporicidal Chemicals for Use against Bacillus anthracis

“…The use of suspension test protocols for this purpose (4) also makes it difficult to extrapolate the findings to the inactivation of the spores on environmental surfaces. A recent study used a carrier test for this purpose (13). However, certain manipulations in the test method could inadvertently lead to the wash-off of viable spores and thus give erroneously higher levels of spore kills.…”

“…The AHP-based formulation was neutralized with a solution of Letheen broth (Difco) with 0.1% (wt/vol) sodium thiosulfate (Na 2 S 2 O 3 ) and 0.1% (vol/vol) Tween 80 in sterile normal saline (13). Chlorine-based formulations (bleach and ClO 2 ,) and PAA were neutralized with a solution of 0.1% sodium thiosulfate and 0.1% Tween 80 in saline (9).…”

Germicidal UV Sensitivity of Bacteria in Aerosols and on Contaminated Surfaces

“…Even fewer data is available for human pathogens and still even fewer for microbes of interest in biodefense. Previous efforts in ours and other laboratories have focused on spores of B. anthracis and other Bacillus species Sagripanti et al 2007), particularly on B. subtilis spores whose sensitivity has been studied in all UV regions, including UVC (Coohill and Sagripanti 2008). In contrast, less data is available on the sensitivity of Bacillus cells in the vegetative state, before sporulation or after germination.…”