Diluting the efficacy of hydrogen peroxide room decontamination?

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A somewhat perplexing new study has just been published in the Journal of Hospital Infection comparing the effectiveness of two hydrogen peroxide based automated room decontamination systems: a low-concentration (5%) hydrogen peroxide system (Deprox) and a high-concentration (30%) hydrogen peroxide system (Bioquell).

The study evaluated the impact of the two systems each run in 10 single rooms containing seeded metal discs placed in five locations, with a 6-log load of MRSA, K. pneumoniae, and C. difficile spores. The MRSA and K. pneumoniae were either low soiling (0.03% BSA) or heavy soiling (10% BSA), and the C. difficile spores was either low soiling (0.03% BSA) or in body fluid. In addition, surface samples were taken from 22 surfaces in each room before and after decon using contact plates. The bottom line is that both systems achieved a >5-log reduction on all of the discs (including those with heavy soiling), and there were no real differences in the levels of surface contamination remaining. All this understandably moved the authors to conclude that ‘The starting concentration and mode of delivery of hydrogen peroxide may not improve the efficacy of decontamination in practice.’

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