COMPARATIVE SPORICIDAL EFFECTS OF LIQUID CHEMICAL-AGENTS

We compared the effectiveness of glutaraldehyde, formaldehyde, hydroge n peroxide, peracetic acid, cupric ascorbate (plus a sublethal amount of hydrogen peroxide), sodium hypochlorite, and phenol to inactivate B acillus subtilis spores under various conditions, Each chemical agent was distinctly affected by pH, storage time after activation, dilution , and temperature, Only three of the preparations (hypochlorite, perac etic acid, and cupric ascorbate) studied here inactivated more than 99 .9% of the spore load after a 30-min incubation at 20 degrees C at con centrations generally used to decontaminate medical devices, Under sim ilar conditions, glutaraldehyde inactivated approximately 90%, and hyd rogen peroxide, formaldehyde, and phenol produced little killing of sp ores in suspension, By kinetic analysis at different temperatures, we calculated the rate of spore inactivation (k) and the activation energ y of spore killing (Delta E) for each chemical agent. Rates of spore i nactivation had a similar Delta E value of approximately 20 kcal/mol ( ca, 83.68 kJ/mol) for every substance tested, The variation among k va lues allowed a quantitative comparison of liquid germicidal agents.