Microbiological testing practices

Samples for laboratory microbiological testing normally need to be received either early in the workweek (for observation before the end of the week) or on the last work day of the week (for observation on the first day of the following week). Laboratory practices vary, so check first. 

A common practice in microbiological testing is that pharmaceutical ingredients and products are tested without full consideration of their significance. Sometimes, all raw materials purchased and product manufactured are submitted to the microbiology laboratory... 

Gas niters may be evaluated prior to use by the same methods used for liquid filters (see Section 111 below), allowing that they can be effectively dried out and sterilized without loss of the qualities being tested. Alternatively they may be evaluated by exposure to particles in a gas stream, for instance by the sodium name test, which is also used for HEPA filters. Microbiological tests have to be considered in a somewhat different light. Leahy and Gabler 71 describe an aerosol challenge test of 10 Ps. diminuta bacteria per mL over a four-day period as an appropriate manufacturer s validation test. It would not be practical for routine use. 

Waterside problems that lead to decreases in efficiency and material deterioration can be caused by a variety of mechanisms, such as electrochemical corrosion and deposition of foulants. These problems can be exacerbated by low flow, poor operational practice, process contamination, or specific stresses. It is also important to try to determine cause and effect relationships in order to provide a logical and practical water treatment solution. Such a solution will usually involve some form of cleaning, plus a combined engineering and chemical action plan. Inspection may be made easier by the use of a Boroscope or similar optical/video recording device. The color, texture, and quantity of all deposits should be noted, measurements of pits taken, and microbiological contaminants analyzed. It may be useful to conduct biocide efficiency tests on bacterial slimes. The period when a heat exchanger is open for inspection may be an opportune time for the permanent installation of ports for corrosion-monitoring probes. 

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