Test method development to evaluate hot, humid air decontamination of materials contaminated with Bacillus anthracis ∆Sterne and B. thuringiensis Al Hakam spores.
OBJECTIVE
To develop test methods and evaluate the survival of Bacillus anthracis ∆Sterne and Bacillus thuringiensis Al Hakam spores after exposure to hot, humid air.


RESULTS
Spores (>7 logs) of both strains were dried on six different test materials. Response surface methodology was employed to identify the limits of spore survival at optimal test combinations of temperature (60, 68, 77°C), relative humidity (60, 75, 90%) and time (1, 4, 7 days). No spores survived the harshest test run (77°C, 90% r.h., 7 days), while > 6·5 logs of spores survived the mildest test run (60°C, 60% r.h., 1 day). Spores of both strains inoculated on nylon webbing and polypropylene had greater survival rates at 68°C, 75% r.h., 4 days than spores on other materials. Electron microscopy showed no obvious physical damage to spores using hot, humid air, which contrasted with pH-adjusted bleach decontamination.


CONCLUSIONS
Test methods were developed to show that hot, humid air effectively inactivates B. anthracis ∆Sterne and B. thuringiensis Al Hakam spores with similar kinetics.


CONCLUSIONS
Hot, humid air is a potential alternative to conventional chemical decontamination.
Dahlgren Division, CBR Concepts and Experimentation Branch (Z21) and Sensor Technology Branch (Q31), Naval Surface Warfare Center, Dahlgren, VA, USA. DLGR_NSWC_Z20@navy.mil
T L
TL
Buhr
A A
AA
Young
Z A
ZA
Minter
C M
CM
Wells
D C
DC
McPherson
C L
CL
Hooban
C A
CA
Johnson
E J
EJ
Prokop
J R
JR
Crigler
D000388:Air; D001408:Bacillus anthracis / Q000302:isolation & purification*; D001413:Bacillus thuringiensis / Q000302:isolation & purification*; D003666:Decontamination / Q000379:methods*; D006358:Hot Temperature; D006813:Humidity; D046529:Microscopy, Electron, Transmission; D013171:Spores, Bacterial / Q000302:isolation & purification / Q000648:ultrastructure; D013223:Statistics as Topic