Exam 17: Diagnosing Infections

Mycobacterium tuberculosis has traditionally been identified in patient samples using biochemical tests,and more recently through DNA probe analysis.In vivo testing can also be completed using the tuberculin skin test. A more recent test that seems to be surpassing the others is the QuantiFERON-TB gold test.Blood samples are mixed with protein antigens of M.tuberculosis.After 16 to 24 hours of incubation,the amount of the cytokine interferon produced by the patientt's cells is measured.If the patient is infected with M.tuberculosis,their WBCs will release interferon in response to contact with the tuberculosis protein antigens.This test falls under which category of identification tests?

Which of these tests is an in vivo test?

Nucleic acid testing is appropriate as a testing method when one is not sure what microorganisms are present in the specimen.

Which test compares the percentage of cytosine and guanine bases to adenine and thymine bases?

It is necessary to do lab tests to diagnose all diseases.

Which sample is not collected by sterile needle aspiration?

The testing method involving the separation of serum proteins by electrophoresis,their subsequent transfer to special filters,and then probing with patient sera is the:

Which test is used to identify antigens on red blood cells for blood typing?

Viruses can be used to identify bacteria because of viral specificity for a host cell.This identification method is called:

In your microbiology lab,your class is identifying bacteria.You are using dichotomous keys to aid in the identification process using the data from a variety of biochemical tests.What problems do you foresee in this procedure,using the key?

Biochemical tests include all of the following except

When minute samples of DNA need to be genetically analyzed for identification purposes,which test can be effectively used?

The ELISA is commonly used for diagnosing salmonellosis.

ELISA tests use a fluorescent dye as a label to trace antigen-antibody reactions.

What type of test affixes an antigen to an inert particle such as a latex bead?

Which test is the confirming test for people who initially tested antibody-positive in the screening ELISA test?

Urine and fecal specimens require

Both pulse-field gel electrophoresis and Western blotting utilize electrophoresis in their procedures.When comparing the two procedures,which statement is true?

Which test is especially good for bacteria that are not readily cultivated in the lab?

The ELISA test has been used as the most common,rapid screening test for HIV infection.Its sensitivity is very high but its specificity is rather low (for an important identification test).Which statement describes this accurately?