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A latex fixation test, also called a latex agglutination assay or test (LA assay or test), is an assay used clinically in the identification and typing of many important microorganisms. These tests use the patient's antigen - antibody immune response.
Rapid diagnostic methods to detect cryptococcal antigen include latex agglutination testing, lateral flow immunochromatographic assay (LFA), or enzyme immunoassay (EIA). Polymerase chain reaction (PCR) has been used on tissue specimens, with PCR having a sensitivity of 82% and a specificity of 98% for cryptococcal infection.
Illustration of the effects of excess antigen and blocking antibodies on immunoassays. In an agglutination test, a person's serum (which contains antibodies) is added to a test tube, which contains a particular antigen. If the antibodies interact with the antigen to form immune complexes, called agglutination, then the test is interpreted as ...
Quellung is the German word for "swelling" and describes the microscopic appearance of pneumococcal or other bacterial capsules after their polysaccharide antigen has combined with a specific antibody. The antibody usually comes from serum taken from an immunized laboratory animal. As a result of this combination, and precipitation of the large ...
The test is usually performed using commercially available test kits which detect the reaction of heterophile antibodies in a person's blood sample with horse or cow red blood cell antigens. These test kits work on the principles of latex agglutination or immunochromatography. Using this method, the test can be performed by individuals without ...
A latex agglutination test may be positive in meningitis caused by Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Escherichia coli and group B streptococci; its routine use is not encouraged as it rarely leads to changes in treatment, but it may be used if other tests are not diagnostic.
As a result, the blood of a host applied to a diagnostic kit causes the aggregation of the pathogenic particles due to the antigen-agglutinin interaction. Conversely, agglutination can also be used to identify new bacteria or cells with a specific antigen by exposing them to serum containing known agglutinins. [3]
The complement fixation test is an immunological medical test that can be used to detect the presence of either specific antibody or specific antigen in a patient's serum, based on whether complement fixation occurs. It was widely used to diagnose infections, particularly with microbes that are not easily detected by culture methods, and in ...