Efficacy of disinfectants containing accelerated hydrogen peroxide against conidial arthrospores and isolated infective spores of Microsporum canis and Trichophyton sp.

BACKGROUND: Accelerated hydrogen peroxide is a proprietary disinfectant formulation that is available for both commercial and home use and is labelled as antifungal. HYPOTHESIS/
OBJECTIVES: To determine the antifungal efficacy of accelerated hydrogen peroxide disinfectants against Microsporum and Trichophyton spp.
METHODS: Three products formulated as ready to use and three concentrates were used. Concentrates were tested at dilutions of 1:8, 1:16 (recommended dilution) and 1:32. One product was a surgical instrument disinfectant. Sterile water, sodium hypochlorite (1:32 dilution) and over-the-counter 3% hydrogen peroxide were used as controls. Conidial suspensions contained ~9.6 × 10(5) /mL Microsporum canis, ~1.0 × 10(7) /mL M. gypseum or ~2.0 × 10(7) /mL Trichophyton sp. and were tested at 1:10 dilution. Isolated infective spore suspensions of M. canis from an untreated cat and T. erinacei from an untreated hedgehog were tested at 1:10, 1:5 and 1:1 spore-to-disinfectant dilutions.
RESULTS: Too many colonies to count were present on untreated control plates. Accelerated hydrogen peroxide and household hydrogen peroxide inhibited growth of both pathogens in conidial (1:10 dilution) and spore suspensions (1:10, 1:5 and 1:10 dilution). There was no lack of efficacy of products that were >12 months old. CONCLUSIONS AND CLINICAL IMPORTANCE: Accelerated hydrogen peroxide products are an option for environmental disinfection of surfaces exposed to M. canis and Trichophyton sp. after appropriate gross decontamination and mechanical cleaning with a detergent. The results from conidial testing were identical to those of isolated infected spore testing, which suggests that accelerated hydrogen peroxide products with label claim as antifungal against Trichophyton mentagrophytes may be suitable as an alternative disinfectant to sodium hypochlorite.