The presterilization microbial load on used medical devices and the effectiveness of hydrogen peroxide gas plasma against Bacillus subtilis spores

OBJECTIVES: To determine the microbial load found on used critical medical devices (5 spinal anesthesia needles, 21 catheters, and 28 sheaths) prior t o sterilization and to evaluate the effectiveness of hydrogen peroxide gas plasma against inoculated Bacillus subtilis var globigii (American Type Cul ture Collection 9372) spores. METHODS: Membrane filter and pour-plate methods were applied to estimate to tal microbial loads (aerobic and anaerobic, mesophilic and thermophilic, ve getative and spore forms). Spinal anesthesia needles (102 units) and sheath components (61 units) were inoculated with a suspension of B subtilis spor es. After drying, the devices were sterilized with hydrogen peroxide gas pl asma. RESULTS: Higher counts of aerobic, mesophilic, and fungal organisms were re covered when the drying period was insufficient. Anaerobic spores were not found in any analyzed presterilization items. The hydrogen peroxide gas pla sma effected a 5 to 7 log(10)-fold reduction in B subtilis spore counts in well-dried needles and sheath components. CONCLUSIONS: The success of hydrogen peroxide gas plasma sterilization depe nds 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 organism s.