The sterilizing capacity of propylene oxide and chlorhexidine diacetate solutions upon pre-injection swabs saturated...

The sporicidal activity of two solutions which have been used in the production of 'sterile' pre-injection swabs has been investigated. Propylene oxide (3.4% w/w) and chlorhexidine diacetate (0.6% w/w), both made up in approximately 65% w/w propan-2-ol, were artificially contaminated with spores of Bacillus subtilis var. niger and swabs were impregnated with these; surviving spores were enumerated at various temperatures and times of storage. Chlorhexidine diacetate had no sporicidal activity, whereas the activity of propylene oxide was dependent on temperature. The former should not be considered a sterilant and the latter can only be considered such if a controlled incubation period at an elevated temperature is employed.