Microbiological contaminants bacteria

For all humidifiers, full consideration should be given to the possibility of the growth of fungi, algae, bacteria, and in particular Legionella pneumophila, the microbiological contamination that causes humidifier fever, etc. 

Biofluids are very prone to microbiological contamination, especially fluids sudh as urine, which are difficult to collect under sterile conditions. Samples should be stored deep frozen to minimize the effects of such contamination but evidence of bacterial growth will be seen in a time-dependent pattern of metabolites if NMR spectra are measured over a period of time or if the sample is kept at room temperature for extended periods. It has been noticed that bacteria can incorporate a atom from D2O into metabolites and the presence of isotopically labelled acetate (CH2D.COOH and CD2H.COOH observable in the H NMR spectrum) for example is a good indication of bacterial contamination. °... 

The microbiological contamination of products (bioburden) is minimal prior to sterilization. There is a working limit on contamination immediately before sterilization that is related to the efficiency of the method to be used and the risk of pyrogens. All solutions, in particular large-volume parenterals, are passed through a bacteria retentive filter, if possible immediately before the filling process. Where aqueous solutions are held in sealed vessels, any pressure-release outlets are protected, e.g., by hydrophobic microbial air filters. 

Nonwoven materials are used extensively for drapes and cover cloths and are composed of films backed on either one side or both sides with nonwoven fabrics. The film is completely impermeable to bacteria while the nonwoven backing is highly absorbent to both body perspiration and secretions from the wound. Hydrophobic finishes may also be applied to the material in order to achieve the required bacteria barrier characteristics. The developments in surgical drapes have led to the use of loop-raised, warp-knitted polyester fabrics that are laminated back to back and contain micropo-rous PTFE films in the middle for permeability, comfort, and resistance to microbiological contaminants. 

Microbiological contaminants—Microbes used as indicators that other, potentially harmful bacteria may be present. 

In addition, a number of other components will have a marked effect on the susceptibility of polymer dispersions to microbiological contamination. Jakubowski et al. (1992) studied the influence of raw materials on their susceptibility. By adding various of these to water at in-use concentrations, followed by inoculation with a variety of bacteria, yeasts and moulds isolated from contaminated products, they were able to show that many surfactants, defoamers and other additives were highly susceptible (Table 7). 

One of the reasons why it is important to remove suspended solids in water is that the particles can act as a source of food and housing for bacteria. Not only does this make microbiological control much harder but, high bacteria levels increase the fouling of distribution lines and especially heat transfer equipment that receive processed waters (for example, in one s household hot water heater). The removal of suspended contaminants enables chemical treatments to be at their primary jobs of scale and corrosion prevention and microbial control. 

In order to achieve complete destruction of biological contaminants in water through sonication very high ultrasonic intensities are necessary. Unfortunately this makes the technique expensive to use for general microbiological decontamination. However over the last two decades some conventional disinfection techniques involving chemicals, ultraviolet light and heat treatment have become less effective as some bacteria become more resistant. Such processes have become a focus for the use of sonication as an adjunct to other techniques. 

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