Microbiological and immunoassay

It may be important to consider the variability of the matrix due to the physiological nature of the sample. In the case of LC-M/MS-based procedures, appropriate steps should be taken to ensure the lack of matrix effects throughout application of the method, especially if the nature of the matrix changes from the matrix used during method validation. For Microbiological and immunoassay, if separation is used prior to assay for study samples but not for standards, it is important to establish recovery and use it in determining results. In this case, possible approaches to assess efficiency and reproducibility of recovery are ... 

Immunoassay is a method that identifies and quantifies unknown analytes usiag antibody—antigen reactions. Techniques are based ia immunochemistry, analytical chemistry, and biochemistry, with a history of development paralleling advances ia microbiology and immunology (see also Immunotherapeutic agents). 

As mentioned earlier, the immunoassay can be done with a number of procedural modifications and in this instance one must substitute the isotope with another molecule (fluorescent dye, magnetic particle, enzyme) which can be measured and therefore serve as the source of tracer. For our initial studies we have chosen to use the enzyme immunoassay (EIA) system. At the present time the EIA is still in its infancy and although a number of successful EIA s have been developed the method cannot be considered a panacea (34). The future of this assay appears to be very bright and exciting, and there is considerable interest in the application of the EIA to problems in both microbiology and clinical medicine (34). Many of the procedures and protocols are derived from RIA procedures and the EIA, like the RIA, has the potential to be performed in a multitude of procedural variations but, for the purpose of this manuscript we will describe only the system we have chosen for our use. 

The FSIS Test Review System was developed to encourage the development of new tests by making the testing requirements known to test developers, and by expediting and standardizing the review process. All methods designed to measure the same analyte will be evaluated by the same standard, e.g., HPIC methods, microbiological inhibition tests, and immunoassays for the same analyte would all be evaluated from the perspective of limit of detection, accuracy, and precision. 

P. A. Cunniff, ed.. Official Methods of Analysis of AO AC International, 16th ed., Vols. I and II, AO AC International, Arlington, Va., 1995. Vol. I includes Pesticide Formulations and Pesticide Residues. Over 2100 coUabotatively tested, approved methods for chemical and microbiological analyses, with 149 new methods, 103 revised/updated methods, methods using anibody-based test kits, enzyme immunoassay, and annual supplements containing new and revised methods chemical and common names of all dmgs and pesticides easy-to-locate references. 

Although some European countries still accept the results of the four plate test as confirming the presence of antibiotic residues in samples ( ), other work indicates that FPT test is not necessarily reliable. The occurrence of natural microbial inhibitors in tissues has frequently been noted (4,9,49,82), It has also been frequently observed that the results obtained by microbial and physicochemical procedures sometimes differ considerably (9,10,45,82,86), Results obtained in our laboratory suggest that even inactivation by penicillinase may not be totally specific for B-lactam antibiotics (W), The specificity of immunoassay procedures depends on the specificity of the antibody used in the test (95), Specific antisera are not widely available at present. Physicochemical procedures are therefore essential for identification and confirmation of suspect residues detected by microbiological tests. 

Salmonella and Listeria are a source of numerous food borne illness. As a result, a lot of attention has been focused on these microorganisms. The effort in the Salmonella area focused on obtaining antibodies which can detect several serotypes (14-16, 61,64, 90) and shortening the assay time from 3-4 days to 1-2 days by use of more sensitive formats and enrichment protocols (74, 75, 91,92). Numerous immunoassay kits for Salmonella were developed, such as the Salmonella-Tek (74, 75), Tecra Salmonella (93) and Bio-Enza Bead (94), to name a few. More information on kits is given in section 2.9. Additional information is available for Salmonella, Listeria and other microbiological contaminants and toxins (see Table 1) in review articles and books (5, 7,11-13, 88,95-99). 

Howanitz, J. H. (1992). Overview of Nonisotopic Immunoassay Labels in Immunochemical Assays and Biosensor Technology for the 1990s, Yasushi Kasahara Robert M. Nakamura, Garry A. Rechnitz (Ed.), Amer Society for Microbiology, pp. 22-35. 

Fluorescence polarization immunoassay determination of serum vancomycin concentrations can result in falsely high vancomycin concentrations in excess of 30-80% in patients with renal dysfunction. This is due to the formation of a non-toxic, non-microbiologically active pseudometabolite, the vancomycin crystalline degradation product (132). A report on a 48-year-old man underlies the significance of resulting underdosing and eventually suboptimal clinical response (133). 

The applications are succinctly described and include applications of luminescence in antioxidant research, phagocytosis, microbiology, ecology, food and environmental testing, immunoassay, enzyme assays, DNA probe assays, and reporter gene and gene expression assays. 

Hierholzer, J.C., Johansson, K.H., Anderson, L.J., Tsou, C.J., and Halonen, P.E. (1987) Comparison of monoclonal time resolved fhioroimmunoassay with monoclonal capture biotinylated detector enzyme immunoassay for adenovirus antigen detection. Journal of Clinical Microbiology, 25, 1662 1667. 

Listeria, after a preliminary enrichment step, a quick immunoassay step is used to establish possible positives, in which the presence of Listeria will be confirmed through microbiological tests. In the case of Salmonella, a preliminary enrichment step is followed by growth of the bacteria in a medium capable of stimulating production of the somatic and flagellar proteins that represent the specific reactive antigens detectable in subsequent immunoassay. 

Although vitamins can be determined, both qualitatively and quantitatively, by MS, routine analysis is usually best conducted by other means (e.g., HPLC with ultraviolet (UV) or fluorescence detection, immunoassay methods, or microbiological methods). Analytically, MS does have an important role as a reference technique, especially when used in isotope... 

Major vitamin Bi2-dependent metabolic processes include the formation of methionine from homocysteine, and the formation of succinyl coenzyme A from methylmalonyl coenzyme A. Thus, apart from directly determining vitamin B12 concentration in serum, elevated levels of both methylmalonic acid and homocysteine may indicate a vitamin B12 deficiency. Serum cobalamine concentration is often determined by automated immunoassays using an intrinsic factor as binding agent. These assays have mainly replaced the microbiological methods. Literature data about vitamin B12 concentration in serum varies. Values <110-150pmoll are considered to reflect deficiency, whereas values >150-200pmoll represents an adequate status. 

See also Bioassays Overview Microbial Tests Bioautography. Blood and Plasma. Fluorescence Clinical and Drug Applications Food Applications. Food and Nutritional Analysis Dairy Products. Gas Chromatography Mass Spectrometry. Immunoassays, Techniques Enzyme Immunoassays. Liquid Chromatography Normal Phase Reversed Phase Food Applications. Microbiological Techniques. Radiochemical Methods Food and Environmental Applications. Vitamins Fat-Soluble. 

HoloTC RIA and holoTC enzyme immunoassay (EIA) were evaluated in a multicentre study involving four European laboratories (Nexo and Hoffmann-Lucke 2011) with similar results calibration curve 1.36-24.5 pmol/L, imprecision 6% for EIA and 10% for RIA. Moreover, RIA results were also similar to those of the microbiological assay (calibration curve 1.36-24.5 pmol/L imprecision 4-7%) (Refsum et al. 2006). 

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