Abstract
Aims
To evaluate the efficacy of hydrogen peroxide gas plasma (HPGP) in sterilising biologically contaminated nerve-stimulating needles for reuse, which could contribute to sustainability and reduce medical waste.
Methods
Nine sterile, 21-gauge x 4-inch Stimuplex nerve-stimulating needles were inoculated by passing Geobacillus stearothermophilus spore suspension through the lumen and tubing, as an indicator for the efficacy of sterilisation. One additional nerve-stimulating needle was not inoculated as a negative control. All 10 needles were packaged in individual sterilisation pouches with an HPGP-specific biological and chemical indicator. Eight samples were sterilised with HPGP. The remaining inoculated sample was not sterilised as a positive control. Tryptic soy broth (TSB) was aspirated through all 10 needles into individual TSB tubes that were then incubated at 60°C for 48 hours and inspected for a colour change indicating bacterial growth. An aliquot from each TSB tube was plated on agar plates and incubated at 60°C for 24 hours. All colonies grown were speciated by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry.
Results
All chemical and biological indicators confirmed a successful sterilisation cycle. However, in contrast to the indicators, the TSB cultures from all eight inoculated needles post-sterilisation and the untreated positive control, underwent a colour change indicating bacterial growth, and bacterial colonies, confirmed as G. stearothermophilus, were observed on nutrient agar plates from these nine cultures. No bacterial growth was observed on the negative control plate.
Conclusions
HPGP autoclaving, though appropriate for temperature-sensitive equipment, is ineffective for nerve localiser needles.
Clinical relevance
While reducing medical waste is important, it must not compromise patient safety. Not all medical materials can be reliably sterilised. Stimuplex nerve-stimulating needles should remain single-use only and are not suitable for re-sterilisation with HPGP.
