Aerosol Surface Disinfectant

Fogging with aerosol mists should not be used but fumigation with humidified formaldehyde vapour may be employed to reduce microbiological contamination in places inaccessible to surface disinfection. 

CDS of clean room walls, floors and accessible surfaces of clean room equipment is routinely undertaken between production runs. The final CDS step often entails fogging the room. This is achieved by placing some of the disinfectant in an aerosol-generating device (a fogging machine ). This generates a fine disinfectant mist, or fog, within the clean room, capable of penetrating areas difficult to reach in any other manner. 

The primary purpose of the Sterilamp tube in air-conditioning systems has been to destroy microorganisms (22). Tests on the effect of 1 to 2 p.p.m. by voliune of ozone on E. coli sprayed into an air duct revealed that the organisms were not destroyed. This would confirm the data of Elford and Van den Ende ( ) that ozone is a poor disinfectant of air at low relative humidity. At high relative humidity these authors found that as low as 0.04 p.p.m. by volume destroyed bacteria dispersed in an aerosol. This would also agree with the results reported here, that organisms on surfaces and seeded on Petri plates can be destroyed by minute amounts of ozone. 

Small Areas Fumigate with disinfectant gas or aerosol (e.g., formaldehyde). Follow fumigation with a wash of all surfaces employing a disinfectant such as household bleach. Rinse with water. 

Equipment glassware, the external surfaces of product containers and other such materials must be disinfected before transfer from a contained area using a validated method (see 47 above). Batch documentation can be a particular problem. Only the absolute minimum required to allow operations to GMP standards should enter and leave the area If obviously contaminated, such as by spills or aerosols, or if the organism involved is an exotic, the paperwork must be adequately disinfected through an equipment pass, or the information transferred out by such means as photocopy or fax. 

The use of aerosol disinfectant preparations when collecting specimens may contaminate the sample if an aerosol propellant is used. Contamination of blood samples with ethanol or 2-propanol may also occur if an alcohol-soaked swab is used to cleanse skin prior to venepuncture. Gross contamination with technical xylene (a mixture of o-, m-, and p-xylene together with ethylbenzene) has been found in blood collected into Sarstedt Monovette Serum Gel blood collection tubes contamination with toluene (up to 22 mg 1 ), 1-butanol, ethylbenzene, and xylene has been found in batches of these same tubes. Contamination with 1-butanol or 2-methyl-2-prop-anol occurs commonly in blood collected into tubes coated with EDTA. Care should be taken when handling frozen tissue prior to analysis as any compounds present in ambient air may condense on the cold surface and give rise to false positives. Processing blank frozen tissue can control for this possibility. 

Because microorganisms are airborne, laboratory surfaces should be sterilized prior to beginning work. To do this, there are many aerosol disinfectants available that are simply sprayed onto the area and wiped away. Some laboratories rely on solutions of chlorine (bleach) to assist in maintaining a sterile environment. Although ultraviolet light can be used as a surface sterilant, most laboratories rely on wiping down the area with a liquid disinfectant (Table 13.3). Several disinfectants that find application in the winery (Chapter 9) can also be used in a laboratory such as iodine or QUATS. Other laboratory disinfectants are the phenol-based formulations like o-phenylphenol (Lysol ) and hexachlorophene (PhisoHex ). 

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