Sporicidal activity of chemical and physical tissue fixation methods.
OBJECTIVE
The effects of alcohol based fixation and microwave stimulated alcohol fixation were investigated on spores of Bacillus stearothermophilus and Bacillus subtilis (var. niger).


METHODS
Spores were exposed to 10% formalin, or different concentrations of various alcohol containing fixatives (Kryofix/Spuitfix). Adequate controls were also set up in conjunction with the test solutions. The spores were immersed with and without adjunctive microwave stimulation in the various solutions tested. Possible surviving spores were recovered in revival broth and after incubation, and Gram staining viable counts were performed.


RESULTS
Alcohol based fixatives did not have a sporicidal effect on B stearothermophilus or B subtilis (var. niger) spores, and microwave stimulated alcohol fixation at 450 W and up to 75 degrees C did not have a sporicidal effect.


CONCLUSIONS
When alcohol based fixatives are used for fixation, precautions should be taken with the material thus treated, as it may contain viable spores or other pathogens, which are destroyed after 24 hours of formalin treatment. Of the physicochemical methods tested involving microwaving, none was successful in eliminating viable spores from the test material.
Vardaxis
N J
NJ
Department of Medical Laboratory Science, Royal Melbourne Institute of Technology, Bundoora, Australia. vardaxis@rmit.edu.au
Hoogeveen
M M
MM
Boon
M E
ME
Hair
C G
CG
D001407:Bacillus / Q000187:drug effects*; D000431:Ethanol / Q000494:pharmacology; D005404:Fixatives / Q000494:pharmacology*; D005557:Formaldehyde / Q000494:pharmacology; D006801:Humans; D008872:Microwaves; D016272:Occupational Health; D013242:Sterilization / Q000379:methods*; D013997:Time Factors; D016707:Tissue Fixation / Q000379:methods*
D005404:Fixatives; D005557:Formaldehyde; D000431:Ethanol