COMPARATIVE SPORICIDAL EFFECT OF LIQUID CHEMICAL GERMICIDES ON 3 MEDICAL DEVICES CONTAMINATED WITH SPORES OF BACILLUS-SUBTILIS

Background: The relatively limited variety of sur faces and geometries challenged in current sporicidal resting reduces the predictive value of these analyses when extrapolated to the wide variety of medical de vices. The unknown spore load being challenged and the qualitative nat ure (growth/no growth) of those tests further prevent precise comparis on among liquid chemical disinfectants. Hence, the relative activity o f different chemical substances has not been clearly established, hind ering selection of the best agent for each clinical situation. Methods : A micromethod was developed io assess sporicidal activity against Ba cillus subtilis spores deposited on three different medical devices: c arbon-steel dental burs, silicone-rubber medical catheters, and titani um-alloy dental abutmeat screws. The spore load on each device and the recovery after three analytical steps were quantitatively assessed wi th spores radiolabeled with carbon 14 methionine. Results: The killing of 2 to 7 x 10(6) spores loaded on three different devices and expose d to glutaraldehyde, formaldehyde, copper ascorbate, hydrogen peroxide , peracetic acid, sodium hypochlorite, or phenol for 30 minutes at 20 degrees C ranged from a 10(3)-fold decrease For 10% hydrogen peroxide to zero decrease for 5% phenol. Our results suggest that the nature of the surface being challenged may affect the sporicidal activity of so me chemical agents. Conclusion: The quantitative data presented allow comparison of the sporicidal effect of different liquid chemical agent s. These findings may help prevent an overestimation of sporicidal act ivity and possible transmission of pathogens from the surface of impro perly decontaminated medical devices.