Comparison between visual analysis and microscope assessment of surgical instrument cleanliness from sterile service departments
ABSTRACT Modern hospital sterile service departments (SSDs) routinely inspect instruments visually to assess the degree of contamination present after the washer/disinfector cycle. We aimed to test the effectiveness and reliability of this method. Surgical instrument sets were obtained from nine anonymous National Health Service (NHS) Primary Care Trust SSDs to investigate the efficacy of 'in-place' cleaning procedures. The instruments were first inspected visually, followed by a novel technique called episcopic differential interference contrast microscopy. This was combined with a sensitive fluorescent reagent, SYPRO Ruby, to rapidly visualise and assess contamination levels on the medical devices. The application of a Contamination Index (0-4) for both proteinaceous and non-proteinaceous deposits on the surface allowed quantitative assessment. Close correlation was seen for simple instruments between visual assessment and microscopic analysis. For more complex instruments, however, there was a marked difference between the two assessment techniques and the microscopy procedure showed areas of proteinaceous and non-proteinaceous crystalline soiling that was difficult or impossible to see by eye. Visual assessment of cleaning is fraught with possible error. This survey shows how large amounts of contamination could pass undetected using such antiquated methods. The new methodology applied in the assessment of surface contamination is rapid and generally applicable and could be used more widely for routine monitoring of instrument cleanliness.
- SourceAvailable from: Mukhtar H. Ahmed
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- "The prion-causing agent is highly robust and has been shown to remain infectious even after modern cleaning and inactivation regimes such as autoclaving (121 °C, 30 min) or chemical methods, e.g. formaldehyde gas, have been implemented . β-Amyloid (Aβ) with ~4 kDa is the major component of the amyloid plaques found in prion diseases . "
ABSTRACT: TiO2 thin films are of great interest as biocompatible coatings and also as photocatalytic self-cleaning and antimicrobial coatings. In this work we used β-amyloid as a model for infectious protein to investigate the attachment and photocatalytic degradation. TiO2 films were prepared on stainless steel substrates using magnetron sputtering. The films were characterised before and after exposure to β-amyloid (1–42), using XRD, Raman spectroscopy, XPS and AFM. The TiO2 film was mostly composed of the anatase phase with a relatively high surface roughness. The presence of Raman peaks at 1668 cm− 1 and 1263 cm− 1, with the XPS spectral feature for nitrogen at 400 eV, confirmed the adsorption of amyloid on surface. Following exposure of the β-amyloid contaminated TiO2 to UV-B irradiation a slight shift of amide modes was observed. Furthermore, the amide I spectra show an overall decrease in α-helix content with presence of a minor peak around 1591 cm− 1, which is related to tryptophanyl and tyrosinyl radicals, which can lead to conformational change of β-amyloid. The C1s band at 292.2 eV suggests the formation of free carboxylic acid. The loss in the crucial structure of β-amyloid leads to reduce the fibril formation, thought to be induced through a photocatalytic process.Materials Science and Engineering C 06/2014; 39:227–234. DOI:10.1016/j.msec.2014.03.011 · 3.09 Impact Factor