Y

Patient antibodies specific antigen

RBCs

No complement Hemolysin (all bound up in Ag-Ab reaction)

No lysis

Figure 10-5 Complement fixation test.

the CF test. At this time, CF tests are performed chiefly for diagnosis of unusual infections and are done primarily in reference laboratories. This test is still probably the most common method for diagnosing infection caused by fungi, respiratory viruses, and arboviruses, as well as to diagnose Q fever. Laboratories without experience in performing these tests should not adopt complement fixation tests for routine diagnostic testing when other less demanding procedures are available.

Enzyme-Linked Immunosorbent Assays

BLISA technology for antibodies to infectious agents are sensitive and specific. As described more thoroughly in Chapter 9, the presence of specific antibody is detected by the ability of a second antibody conjugated to a colored or fluorescent marker to bind to the target antibody, which is bound to its homologous antigen. Various enzyme-substrate systems, including the use of avidin-biodn to bind marker substances, are also discussed in Chapter 9. The antigen to which the antibodies bind, if these antibodies are present in the patient's sera, is either attached to the inside of the wells of a microtiter plate, adherent to a filter matrix, or bound to the surface of beads or plastic paddles. Advantages of ELISA tests are that they can be performed easily on many serum samples at the same time and that the colored or fluorescent end products are easily detected by instruments, removing the element of subjectivity inherent in so many serologic procedures that rely on a technologist's interpretation of a reaction. Disadvantages include the need for special equipment, the fairly long reaction times (often hours instead of minutes for particle agglutination tests), the relative end point of the test (which relies on measuring the amount of a visible end product that is not dependent on the original antigen-antibody reaction itself but on a second enzymatic reaction as compared with a directly quantitative result), and the requirement for batch processing to ensure that performance of the test is cost effective.

Commercial microdilution or solid-phase matrix systems are available to detect antibody specific for hepatitis virus antigens, herpes simplex viruses 1 and 2, respiratory syncytial virus (RSV), cytomegalovirus,

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Bacterial Vaginosis Facts

Bacterial Vaginosis Facts

This fact sheet is designed to provide you with information on Bacterial Vaginosis. Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina.

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