Disinfectants microbial contamination

Maximum Residual Disinfectant Level (MRDL) - The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants. 

Particulate, as well as microbial, contamination must be guarded against when sterile products are being manufactured. Thus, walls, ceilings and floors should possess smooth, impervious surfaces which will (i) prevent the accumulation of dust or other particulate matter and (ii) allow for easy and repeated cleaning and disinfection. For the same reasons, where walls and floors or ceilings meet, covings should be used. 

The theoretical basis of light-induced antimicrobial treatment is described, followed by examples of its application for the cleaning and disinfection of surfaces. All available information supports the idea that PDT could offer a very efficient and cost-effective way to combat microbial contamination of foods. The advantages and pit-falls of the technique are discussed. Directions of future research needed for bringing the technology to commercial reality are identified. 

Furthermore, a microbial survey should be performed on all packaging materials that come in contact with the product to ensure the absence of microbial contamination. Attention must also be given to details during packaging operations. For example, on small-volume orders, bottle closures, or tips for plastic squeeze-spray containers are often placed on the product by hand. This procedure can be a source of microbial contamination unless operators use gloves that are sterilized and disinfected periodically during use. 

Municipal water plants provide limited treatment, mostly intended to make the water safe to drink. A lot of contaminants, such as salts, dissolved gases, and organic materials contained in natural sources, remain in the municipal water supply. In addition, chlorine or other disinfectants are often added as part of the treatment process to control microbial contamination. For many critical applications required in pharmaceutical plants, such water quality is not sufficient, and further treatment is necessary. 

EPA (2001b). Controlling Disinfection By-Products and Microbial Contaminants in Drinking Water, Clark, R. M., and Boutin, B. K., eds., Office of Research and Development, US Environmental Protection Agency, Cincinnati, Ohio, EPA/600/R-01/110, December 2001. Accessed at http //www. epa.gOv/nrmrl/pubs/600r0 111 0/600r01110.pdf. 

As more restrictions on product preservatives have been set in the last 10 years, more instances of microbial contamination have appeared and liquid detergent process equipment and operations have approached those used in the food and pharmaceutical industries. Process equipment is being installed to a more sanitary level, which means easier to clean and disinfect. Predominantly the equipment is designed for cleaning in place (CIP) without the need to disassemble. This chiefly means that surfaces are polished, circulation dead spaces are avoided, and drainage is virtually perfect. Usually the equipment is washed with alkaline and acid solutions, and then with a disinfectant solution. Additional equipment to handle and recirculate disinfectant solutions becomes part of the system design. 

Validation of disinfectants should be concentrated on two aspects of their potential to create problems in aseptic manufacture. First, they may themselves be sources of microbiological contamination second, they may not be effective against microbial contaminants. 

Disinfectants and detergents should be monitored for microbial contamination dilutions should be kept in previously cleaned containers and should not be stored for long periods unless sterilized. Partly emptied containers should not be topped up. 

Interior surfaces (walls, floors and ceilings) shall be smooth and free from cracks they shall not shed matter and shall permit easy cleaning and disinfection. Drains should be avoided wherever possible and, unless essential, should be excluded from aseptic areas. Where installed they should be fitted with effective, easily cleanable traps and with breaks to prevent back-flow. The traps may contain electrically operated heating devices or other means for disinfection. Any floor channels should be open, shallow and easily cleanable and be connected to drains outside the area in a manner that prevents ingress of microbial contaminants. 

Sterilized and disinfected materials required for the preparation of sterile products in a clean room must be introduced into the latter in such a manner that microbial contamination will be prevented as far as possible. 

Microbial contamination should be controlled by air filtration, effective cleaning, disinfection and ensuring only the minimum number of personnel required enter the area The area must at all times be neat and tidy to prevent accumulation of materials that could promote microbial growth. Insects, animals and birds must be totally excluded. 

Coagulase-negative Staphylococcus species, particularly S. epidermidis, are the most common causes of catheter-related bacteremia [25], Heavy colonization of the skin-insertion site has been shown to be strongly correlated with catheter-related bacteremia. In hemodialysis patients, the risk of S. aureus bacteremia is six times greater than in nonhemodialysis patients. And numerous incidents of intravascular infection have been traced to microbially contaminated topical disinfectants. 

Sanitisation means disinfection for reducing microbial contamination down to an acceptable level, whereas sterilisation implies the inactivation of all microorganisms. Cleaning always precedes sanitisation. When a membrane system (membrane elements, pressure vessels and piping) has been infected by bacteria or mould, the system requires chemical sanitisation. Hot water sanitisation is used in pharmaceutical membrane systems. 

Soil in itself is not a cause of cross-infection. But soils serve as a refuge for disease-causing bacteria. Detergents are needed to break down the soils and permit the disinfectants to contact and kill the organisms. When a disinfectant is combined with a detergent, it is the role of the detergent to disperse and remove soil from a surface, and thereby enable the detergent to reach and destroy any microbial contamination that may lie beneath the dirt barrier. 

Microbially contaminated liquid effluent can be made safe in one of three ways sterile filtration, chemical disinfection or heat treatment. 

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