Foundations in Microbiology
10th Edition
ISBN: 9781259705212
Author: Kathleen Park Talaro, Barry Chess Instructor
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 17.L2, Problem 3CT
Why do some tests for antibody in serum (such as for HIV and syphilis) require backup verification with additional tests at a later date?
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Serial dilutions are made in order to determine the level of the antibody in the sample.
True or False ?
Suppose you were instructed to make two antiserum solutions: The first is identical to what you used in the lab exercise. The other is a 10:6 dilution of the antiserum. After incubation with the antigen, the full-strength antiserum produces a precipitous ring, but the diluted antiserum does not. Explain these results. Is this due to poor specificity or sensitivity of the test?
Enzyme immunoassay tests are used to screen blood specimens for the presence of antibodies to HIV, the virus that causes AIDS. Antibodies indicate the presence of the virus. The test is quite accurate but is not always correct. Approximate probabilities of positive and negative test results when the blood tested does and does not actually contain antibodies to HIV are given in the table.
Test Result
Positive
Negative
Antibodies present
0.9985
0.0015
Antibodies absent
0.0060
0.9940
Suppose that 1%1% of a large population carries antibodies to HIV in their blood.
Probabilities from trials with 2897 people known to be free of HIV antibodies and 673 people known to be infected, reported in J. Richard George, "Alternative specimen sources: methods for confirming positives," 1998 Conference on the Laboratory Science of HIV, found online at the Centers for Disease Control and Prevention, www.cdc.gov.
(b) What is the probability that the test is positive for a…
Chapter 17 Solutions
Foundations in Microbiology
Ch. 17.1 - Describe what is involved in the main categories...Ch. 17.1 - Explain several techniques in specimen collection...Ch. 17.1 - Summarize the main procedures in isolation,...Ch. 17.1 - Summarize the major techniques in identifying and...Ch. 17.1 - Describe the general principles in specimen...Ch. 17.1 - Explain why it is important to prevent microbes...Ch. 17.1 - Summarize the kinds of tests that are used to...Ch. 17.2 - Describe some direct methods of testing a...Ch. 17.2 - Summarize the aims in selection of culture...Ch. 17.2 - Prob. 6ELO
Ch. 17.2 - Describe how flowcharts and comparison tables are...Ch. 17.3 - Explain the different variations on genetic...Ch. 17.3 - Describe what is involved in direct specimen...Ch. 17.3 - Prob. 6CYPCh. 17.3 - Describe the applications of PCR in identification...Ch. 17.4 - Describe the background aims of immunologic...Ch. 17.4 - Identify how antigen-antibody reactions are...Ch. 17.4 - Prob. 11ELOCh. 17.4 - Explain the basic methods behind the Western blot...Ch. 17.4 - Prob. 13ELOCh. 17.4 - What is the basis of serology and serological...Ch. 17.4 - Differentiate between specificity and sensitivity.Ch. 17.4 - Prob. 10CYPCh. 17.4 - Prob. 11CYPCh. 17.4 - Prob. 12CYPCh. 17.4 - Prob. 13CYPCh. 17.4 - Give examples of several tests that employ...Ch. 17.4 - What is meant by complement fixation? What are...Ch. 17.4 - Prob. 16CYPCh. 17.5 - Describe the concepts behind the main types of...Ch. 17.5 - Prob. 15ELOCh. 17.6 - Prob. 16ELOCh. 17.6 - Prob. 17CYPCh. 17.6 - Prob. 18CYPCh. 17.6 - Prob. 19CYPCh. 17.6 - Prob. 20CYPCh. 17.6 - Observing figure 17.17, indicate whether each...Ch. 17.L1 - Multiple Matching. Match each of the following...Ch. 17.L1 - Prob. 2MCQCh. 17.L1 - Prob. 3MCQCh. 17.L1 - Prob. 4MCQCh. 17.L1 - A patient with a _____ titer of antibodies to an...Ch. 17.L1 - Prob. 6MCQCh. 17.L1 - Prob. 7MCQCh. 17.L1 - An example of an in vivo serological test is a....Ch. 17.L1 - Which of the following specimens must be removed...Ch. 17.L1 - Prob. 1CSRCh. 17.L1 - Prob. 2CSRCh. 17.L1 - Prob. 3CSRCh. 17.L1 - Prob. 1WCCh. 17.L1 - Prob. 2WCCh. 17.L1 - Briefly describe the principles and give an...Ch. 17.L1 - Prob. 4WCCh. 17.L1 - Prob. 5WCCh. 17.L1 - Prob. 6WCCh. 17.L2 - Prob. 1CTCh. 17.L2 - Prob. 2CTCh. 17.L2 - Why do some tests for antibody in serum (such as...Ch. 17.L2 - Prob. 4CTCh. 17.L2 - Prob. 5CTCh. 17.L2 - Prob. 6CTCh. 17.L2 - From chapter 3, fig 3.17a (reproduced on the...Ch. 17.L2 - Prob. 2VC
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