Inactivation of Bacillus piliformis spores by heat and certain chemical disinfectants.

The inactivation of Tyzzer's organism (Bacillus piliformis) spore isolated from rats by heat and various chemical disinfectants was studied. The spores were from B. piliformis-infected rat liver tissues. The spore suspension (10(4) 50% of rat liver lesion producing dose with prednisolone treatment/ml) was treated with heart or disinfectants. Inactivation of the spores was examined in experimentally infected rats. Rats were inoculated perorally with a treated spore suspension and injected subcutaneously with prednisolone. On the sixth day after inoculation, rats were examined grossly for liver lesions. Spores were inactivated at 80 degrees C for 15 min but not at 60 degrees C for 30 min. Spores were inactivated by 0.4% peracetic acid, 0.015% sodium hypochrolite, 1% iodophol, 5% phenol. Alcide and 0.37% formaldehyde solution, but not by 0.037% formaldehyde solution, 70% ethanol, 0.3% benzethonium chloride solution, 3% cresol and soap solution, or 4% chlorhexidine digluconate. These findings suggest that B. piliformis spores are relatively sensitive to heat and certain chemical disinfectants.