The Presterilization Microbial Load on Used Medical Devices and the Effectiveness of Hydrogen Peroxide Gas Plasma AgainstBacillus SubtilisSpores

Abstract

Objectives: To determine the microbial load found on used critical medical devices (5 spinal anesthesia needles, 21 catheters, and 28 sheaths) prior to sterilization and to evaluate the effectiveness of hydrogen peroxide gas plasma against inoculatedBacillus subtilisvargiobigii(American Type Culture Collection 9372) spores.Methods: Membrane filter and pour-plate methods were applied to estimate total microbial loads (aerobic and anaerobic, mesophilic and thermophilic, vegetative and spore forms). Spinal anesthesia needles (102 units) and sheath components (61 units) were inoculated with a suspension ofB subtilisspores. After drying, the devices were sterilized with hydrogen peroxide gas plasma.Results: Higher counts of aerobic, mesophilic, and fungal organisms were recovered when the drying period was insufficient. Anaerobic spores were not found in any analyzed presterilization items. The hydrogen peroxide gas plasma effected a 5 to 7 log₁₀-fold reduction inB subtilisspore counts in well-dried needles and sheath components.Conclusions: The success of hydrogen peroxide gas plasma sterilization depends mostly on educating the staff to assure well-cleaned and dried reusable medical devices, allowing penetration of the hydrogen peroxide gas plasma into the critical points of the items and providing a reduction in organisms.