Microbiological test organization

As with many of the vitamins, biological assays have an important historical role and are widely used. For example, microbiological assays use l ctobacillusplantarum ATCC No. 8014 (57,59) or l ctobacillus arabinosus (60). These methods are appropriate for both nicotinamide and nicotinic acid. Selective detection of nictonic acid is possible if l euconostoc mesenteroides ATCC No. 9135 is used as the test organism (61). The use of microbiological assays have been reviewed (62). 

For most assays, the incorporated pantothenic acid has to be Hberated en2ymatically. Usually, a combination of pantotheinase and alkaline phosphatase is used to hberate the bound pantothenic acid. The official method for pantothenic acid of the Association of Official Analytical Chemists (AOAC) is the microbiological assay that uses U. Plantarium (A.TCC 8014) as the test organism (71). Samples are extracted at 121°C at pH 5.6—5.7, proteins are precipitated at pH 4.5, and the resulting clear extracts are adjusted to pH 6.8 prior to assay. This procedure is only suitable to determine calcium pantothenate or other free forms of pantothenic acid. 

The first study was performed by Venturini [97, 98] in both rats and dogs by using a microbiological assay (i.e. agar diffusion test and S. aureus 209 P FDA as test organism). Conversely from rifampicin, whose serum levels were already detectable 30 min after the administration and still measurable after 48 h, only trace amounts (i.e. 0.2 pg/ml) of rifaximin were detected in serum of fed rats 4 h later (fig. 6). The amount of detectable antibiotic was reduced by 50% in fasted animals. Similar results have been obtained in dogs after oral administration of 25 mg/ kg of both rifamycin derivatives [97, 98], No detectable amount of rifaximin was found in serum at any time. 

The evaluation of patients treated for IE includes assessment of signs and symptoms, blood cultures, microbiologic tests (e.g., MIC, minimum bactericidal concentration [MBC], or serum bactericidal titers), serum drug concentrations, and other tests to evaluate organ function. 

Organization of the Pharmaceutical Quality Assurance Microbiological Testing Laboratory... 

Although microbiological in vitro assays are the currently accepted international detection methods, many problems surround their usefulness. Test strains of microorganisms differ widely, as also does their susceptibility to antimicrobial inhibition. A negative result generated from one particular assay technique may yield a positive result when a different test organism is used. 

Investigations into performance characteristics have shown that various factors affect the efficiency of the microbiological assays tlieir relative influence depends upon the kind of antibacterials assayed and, especially, tlie test organism (7). Agar composition and pH, type of test strain, incubation temperature, depth of the agar, and the manner of incubation are all parameters of critical importance (7-9). 

Prior to 1941, mj/o-inositol was often determined by isolation, as such or as the hexaacetate.87 The isolated inositol was weighed, or was oxidized to carbon dioxide (which was measured in a gas buret).92 In 1941, Woolley98 published his microbiological method, in which the yeast Saccharomyces cerevisiae was used as a test organism. Soon afterward, there appeared an improved procedure, using Saccharomyces carlsbergensis,9i 96 and an additional method based on the discovery of an inositol-less mutant of the common bread-mold, Neurospora crassa.96-98 Plundreds of types of foods,... 

The fermentation batches are incubated aerobically under stirring at 28°-30°C. At intervals the antibiotic activity is assayed microbiologically by the agar diffusion method using Sarcina lutea as the test organism. The maximum activity is reached after 96-120 h of fermentation. 

In certain health food literature, Spirulina, a blue-green algae, has been claimed to be a source of vitamin B12. It appears that this was based on the results obtained from the United States Pharmacopeia microbiological assay for vitamin B12. This assay uses Lactobacillus leichmannii as the test organism and it is known that this organism responds to some vitamin B12 analogs. Herbert and Drivas (H7) found that analogs of the vitamin accounted for more than 80% of what appeared to be vitamin B12. ... 

Pantothenic add levels in foods and body fluids can easily be measured by microbiological assays. Lactic acid bacteria are used as the test organism. Where measurement of ihe vitamin occurring as coenzyme A is desired, the coenzyme must first be treated virlth hydrolytic enzymes to liberate the pantothenic acid prior to the microbiological assay... 

ORGANIZATION OF THE PHARMACEUTICAL QUALITY ASSURANCE MICROBIOLOGICAL TESTING LABORATORY... 

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