EFFICACY OF STANDARD DISINFECTANT TEST METHODS FOR CONTACT LENS-CARE SOLUTIONS

Two disinfection systems based on hydrogen peroxide (0.5, 1.5 and 3%) and chlorhexidine gluconate (0.004%) were challenged in suspension tes ts using a modification of a standard method, with inocula containing 10(6) ol 10(8) cfu/ml of the standard organisms Serratia marcescens, P seudomonas aeruginosa and Staphylococcus warneri. The effect of an org anic load on the shapes of microbial inactivation curves was also inve stigated. Although ther-e were rapid declines in viability of 1-2log u nits (cfu/ml) within the first minute of challenge in all cases, decli nes in viability subsequently levelled out vapidly, and with hydrogen peroxide viable counts increased slightly thereafter. These increases are unexplained, but may in part be attributable to disruption of cell clumps during challenge. Copyright (C) 1996 Elsevier Science Ltd