Instruments chemical disinfection

Ayliffe G.A.J., Coates D. Hofifinan P.N. (1993) Chemical Disinfection in Hospitals. London PHLS. British Medical Association (1989) Code of Practice for Sterilization of Instruments and Control of Cross Infection. London BMA (Board of Science and Education). 

However, the development of microbicidally active phenol derivatives started from phenol itself, from carbolic acid, the antiseptic properties of whidh were detected in 1860 and first used by Lister in 1867 to kill bacteria on medical instruments, surgical dressings and wounds. The development of chemical disinfection revolutionized progress in hospitals, particularly in surgery. It was possible to successfully employ and develop surgical techniques which in the past had been feasible but unpractical because of the associated unavoidable massive and generally fatal infections. 

Gebel, J., Bansemir, K.-P., Exner, M., Goroncy-Bermes, P., Kirsch, A., von Rheinbaben, F. and Werner, H.-P., 2000. Evaluating the Efficacy of Chemical Disinfectants for Medical Instruments Quantitative carrier test. Hyg. Med. 25, 443-457. 

The most convenient way to disinfect work areas and materials, equipment, and instruments is through the use of chemical agents. Use of chemical disinfection is often necessary because pressurized steam, the most reliable method of sterilization, is not feasible for disinfecting large spaces, surfaces, and large items of equipment. Moreover, high temperatures and moisture can damage delicate instruments, particularly those with optical and electronic components. 

In disinfection of instruments, the chemicals used must not adversely affect the instruments, e.g. cause corrosion of metals, affect clarity or integrity of lenses, or change texture of synthetic polymers. Many materials such as fabrics, rubber, plastics are capable of adsorbing certain disinfectants, e.g. quaternary ammonium compounds (QACs), are adsorbed by fabrics, while phenolics are adsorbed by rubber, the consequence ofthis being a reduction in concentration of active compound. A disinfectant can only exert its effect ifit is in contact with the item being treated. Therefore access to all parts of an instrument or piece of equipment is essential. For small items, total immersion in the disinfectant must also be ensured. 

Formaldehyde and glutaraldehyde are used for disinfection or sterilization of instruments such as fiberoptic endoscopes, respiratory therapy equipment, hemodialyzers, and dental handpieces that cannot withstand exposure to the high temperatures of steam sterilization. They are not corrosive for metal, plastic, or rubber. These agents have a broad spectrum of activity against microorganisms and viruses. They act by alkylation of chemical groups in proteins and nucleic acids. Failures of disinfection or steri... 

The Food Standards Code [10] is the main regulatory instrument which controls the quality of food, contaminant levels, approved additives, processing aids, sanitisers and disinfectants and these standards are performance based. If a chemical or a group of chemicals is covered by a food standard then they must only be used in food in accordance with the standard. However, if a chemical is not mentioned in a standard, then this does not preclude its use in food. For a new chemical not previously used in food production, it would be necessary for the supplier to undertake a detailed risk analysis of the product to demonstrate its safety and suitability. The assessment would need to consider both the toxicological profile of the chemical and the levels of human exposure that are likely to arise from residues in food. 

Field test C was an example of application to surface waters used for human consumption. Such waters were essentially uncontaminated by chemicals and needed only a conventional disinfection. Nevertheless, this plant was monitored in consideration of the fact that accidental pollution by gasoline and oil had been recorded in the past due to the proximity of an adjacent highway with heavy traffic. Figure 16.8c shows a typical mass spectrum of this instance, with no significant ions. This instrument was monitored over 547 days (12,240 analyses, 1020 hours) during which the days off were 37, that is 7% of the period (Table 16.2). 

Glutaraldehyde is also used for high-level disinfection of biopsy forceps [301], peak flow meters [302] and, as an alternative to formaldehyde, of hae-modialyzers [303-305], though there is continued criticism of the latter practice due to an increased risk of infection and chronic exposure of patients to aldehydes [303, 306]. Glutaraldehyde is the only chemical found to be effective in the disinfection of composite polishing instruments in dentistry [307],... 

---