Surface microbial growth

Physical instability of liquid formulations involves the formation of precipitates, less-soluble polymorphs, adsorption of the drug substances onto container surfaces, microbial growth, and changes in product appearance. Evaluation of product acceptability is subjective and includes properties such as color, odor, taste, and clarity. Dye stability depends on the... 

On exterior surfaces, microbial growth can result in wide ranging problems. 

Rating on a scale from 0 to 10, where 10 corresponds to complete coverage by surface microbial growth [14]. The biocides are listed from the least efficient to the most efficient (Folpet) in an outdoor test. 

Condensation will wash contaminating organisms onto the surface of the bulk phase where, especially if the vessel remains unstirred for some time, dilution of the surface layer, and hence the biocide in it, can allow profuse microbial growth to occur. When mixing recommences, such a high microbial loading will enter the bulk phase and may overwhelm a biocide. 

Beyond physical barrier protection, several natural processes lead to skin surface conditions unfavorable to microbial growth. Both sebaceous and eccrine secretions are acidic, lowering the surface pH of the skin below that welcomed by most pathogens. This acid mantle (pH 5) [16] is moderately bacteriostatic. Sebum also contains a number of short-chain fungistatic and bacteriostatic fatty acids, including propanoic, butanoic, hexanoic, and heptanoic acids [17]. That the skin s surface is dry also offers a level of protection. It comes as no surprise that fungal infections and other skin infections are more prevalent in the skin s folds... 

Deodorants are also targeted to the skin surface to keep microbial growth in check. They slow or prevent rancidification of the secretions of apocrine glands found in and around the axillae (armpits) and the anogenital regions. Medicated soaps also belong in this family. 

Microbial activity can also be stimulated by mineral colloids through their ability to sorb metabolites that would otherwise have an adverse effect on microbial growth (Filip et al. 1972 Filip and Hattori 1984) This may be due to the toxicity of metabolites, and their feed back repression and, encouraging competitors. Predictably, montmorillonite (CEC —100 cmol kg-1 and specific surface of 800 m g 1) is more effective than kaolinite and finely ground quarts. Other substances, such as antibiotics and pesticides that are toxic to some microorganisms, can also be adsorbed by the surfaces of mineral colloids (Theng and Orchard 1995 Dec et al. 2002). 

Examine all plates/strips for microbial growth under a strong light. Wipe their outer surfaces with disinfectant. 

In the guide to inspections of topical products [28], it is indicated that water deionizers are usually excellent breeding areas for microorganisms, where flow rates, temperature, surface area of resin beds, and microbial quality of the feed water all influence microbial growth. Since topical products (e.g., creams, ointments)... 

Masonry products have been widely used in the construction industry and include building materials such as cementious materials, concrete, brick, tile, stone, grout, and like substances. Driveways, garage flooring, concrete block, brick fronts, fireplaces, fireplace hearths, as well as tiled floor, wall and counter top surfaces are exemplary applications. Masonry surfaces are porous and if left unprotected can deteriorate from exposure to water and they can become discolored. For example, water penetration can cause spalling or lead to discoloration via microbial growth. Tiles and grouts employed in homes come in contact with various foods and liquids, e.g., fruit juice, coffee, oils, ketchup, mustard, etc. that can cause discoloration. 

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