Textbook of Diagnostic Microbiology 4th Edition - Test Bank

Textbook of Diagnostic Microbiology 4th Edition – Test Bank

 

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Sample Questions Are Posted Below

 

Mahon: Textbook of Diagnostic Microbiology, 4^th Edition

 

Chapter 05: Performance Improvement in the Microbiology Laboratory

 

Test Bank

 

MULTIPLE CHOICE

 

1. Quality control is designed to:

a.	Ensure the medical reliability of lab data
b.	Check media
c.	Check reagents
d.	Monitor incubator and refrigerator temperatures

 

 

ANS:   A

Checking media, checking reagents, and monitoring incubator and refrigerator temperatures are all included in quality control. Each of these answers represents only a part of quality control, whereas the first answer encompasses all the activities one would do in a quality control program.

 

REF:    page 94           OBJ:    Level 1 – Recall

 

2. Actual laboratory testing is called a(n):

a.	Preanalytic activity
b.	Analytic activity
c.	Postanalytic activity
d.	Research activity

 

 

ANS:   B

Preanalytic activity is what happens before a lab test is run. Postanalytic activity is what happens after a lab test is run. The analytic activity is the actual running of the laboratory test. Research is a term that applies to a series of focused experiments conducted to test a hypothesis.

 

REF:    page 94           OBJ:    Level 1 – Recall

 

3. All of the following activities will directly affect the quality of a laboratory test EXCEPT:

a.	Preanalytic
b.	Analytic
c.	Accreditation
d.	Postanalytic

 

 

ANS:   C

Laboratory professionals have found that the preanalytic, analytic, and postanalytic activities directly affect the quality of a laboratory test. Accreditation is a peer review of the policies and procedures of a laboratory that may indirectly affect the quality of a laboratory test.

 

REF:    page 94           OBJ:    Level 1 – Recall

 

4. In January 2004, The Joint Commission (TJC) implemented performance measurements for organizational systems that are critical to patient safety, quality of care, treatment, and services. This new initiative is called:

a.	Performance improvement
b.	Quality control
c.	Quality assurance
d.	Shared visions-new pathway

 

 

ANS:   D

Quality control consists of processes pertaining to the quality of analytic testing. Performance improvement is a process that consists of setting performance standards, measuring the standards again some criteria, then improving processes that fall short of the standards. Quality assurance is a comprehensive system that takes the preanalytic, analytic, and postanalytic processes into consideration when determining the quality of laboratory data. The new TJC initiative, Shared visions-new pathway, focuses on performance measurement of organizational systems that are critical to patient safety, quality of care, treatment, and services.

 

REF:    page 94           OBJ:    Level 1 – Recall

 

5. All of the following activities are included in a laboratory quality control program EXCEPT:

a.	Air quality
b.	Temperatures
c.	Media
d.	Antimicrobial susceptibility testing

 

 

ANS:   A

The air quality in a laboratory is not routinely tested. A quality control program focuses on procedures, equipment, and policies that affect how well laboratory tests are performed, the quality of submitted specimens, and test results.

 

REF:    pages 95-100                                      OBJ:    Level 1 – Recall

 

6. The morning tech arrives at the microbiology laboratory and goes around checking daily temperatures. This person will check temperatures daily on all of the following temperature-dependent equipment EXCEPT:

a.	Centrifuges
b.	Incubators
c.	Heating blocks
d.	Refrigerators

 

 

ANS:   A

A centrifuge is not typically a temperature-dependent piece of equipment.

 

REF:    page 95           OBJ:    Level 2 – Interpretation

 

7. Thermometers used in the laboratory must be calibrated before they are put into use. This is accomplished by:

a.	Sending to the National Institute of Standards and Technology (NIST) to determine its accuracy
b.	Checking against an NIST thermometer
c.	Measuring the grades to make sure they are the standard size and accuracy
d.	Using a colored dye

 

 

ANS:   B

A thermometer calibration is conducted by comparison of the NIST thermometer reading to the laboratory thermometer’s reading. Any variation is noted on the certificate of calibration.

 

REF:    page 95           OBJ:    Level 1 – Recall

 

8. Preventive maintenance on an instrument includes all the following EXCEPT:

a.	Disinfecting the surface of the instrument
b.	Oiling and cleaning the instrument
c.	Replacing filters
d.	Recalibrating instruments

 

 

ANS:   A

Disinfecting the surface of an instrument is usually done as a daily activity and is generally not considered preventive maintenance. All the other choices are preventive maintenance activities that will keep an instrument in top shape and functioning at the proper level so as to increase its lifetime and keep it producing quality results.

 

REF:    page 95           OBJ:    Level 1 – Recall

 

9. Commercial media must have quality control testing performed by the manufacturer. Because of high failure rates, all of the following media must be retested by the hospital laboratory EXCEPT:

a.	Campylobacter media
b.	Selective media for pathogenic Neisseria
c.	Trypticase soy agar with 5% sheep blood
d.	Chocolate

 

 

ANS:   C

Trypticase soy agar with 5% sheep blood does not have a high failure rate, so the hospital laboratory need not retest it.

 

REF:    pages 96-97     OBJ:    Level 1 – Recall

 

10. Media that do not need to be retested by the hospital laboratory must still undergo observation for all of the following EXCEPT:

a.	Moisture
b.	Sterility
c.	Breakage
d.	Organism colony characteristics

 

 

ANS:   D

When a laboratory is not required to retest prepared media, it still must observe media for moisture, sterility, breakage, and appearance. Results of media observation must be recorded and must include lot numbers.

 

REF:    page 97           OBJ:    Level 1 – Recall

 

11. When a medium needs to be quality controlled because it was prepared in-house or because it is complex, all the following rules must be followed EXCEPT:

a.	Only media not specified in Clinical and Laboratory Standards Institute (CLSI) guidelines should be tested.
b.	The medium should be tested for sterility and pH.
c.	The organism selected for quality control testing should represent most fastidious organisms for which the medium is designed.
d.	Testing techniques should be different for primary plating media than for biochemical or subculturing media.

 

 

ANS:   A

All in-house media must be tested for pH, sterility, and positive and negative reacting organisms—that is, if a medium should inhibit a specific organism or group of organisms, it should be tested with those organisms to ensure it “works.” CLSI guidelines give specific guidance as to what type of quality control testing should be performed on media prepared in-house.

 

REF:    page 97           OBJ:    Level 1 – Recall

 

12. Reagents that should undergo quality control in the microbiology laboratory include all the following EXCEPT:

a.	Optochin
b.	Immersion Oil
c.	b-Lactamase
d.	Nitrate

 

 

ANS:   B

All stains performed in a microbiology laboratory along with Optochin, b-lactamase, nitrate, bacitracin, catalase, coagulation, gelatin, germ tube, hippurate, Kovac’s, oxidase, PYR, typing sera, Voges-Proskauer, and X & V strips should undergo quality control testing in a microbiology laboratory. Immersion oil does not need QC testing.

 

REF:    pages 97-98     OBJ:    Level 1 – Recall

 

13. Antimicrobial susceptibility is hard to control because many of the same species of organisms have a varied susceptibility to particular antibiotics. To reduce this variation, Clinical and Laboratory Standards Institute (CLSI) guidelines recommend the following:

a.	Use in-house organisms isolated from past patients
b.	Share strains between hospital laboratories
c.	Use specific strains from American Type Culture Collection (ATCC)
d.	Obtain test strains from Centers for Disease Control and Prevention (CDC)

 

 

ANS:   C

Specific ATCC strains of control organisms are recommended by CLSI. There is too much variation in organisms isolated from patients to use as quality control organisms. Hospital laboratories trying to share strains would find this a cumbersome process for routine quality control. CDC does not store routine strains of microbes for quality control testing.

 

REF:    page 98           OBJ:    Level 1 – Recall

 

14. In any susceptibility system, variables that can affect the results include the following:
15. Antibiotic potency
16. Inoculum concentration
17. Bactericidal level
18. pH
19. Anion content

a.	1, 2, and 3 are correct
b.	1, 3, 4, and 5 are correct
c.	1, 2, 3, 4, and 5 are correct
d.	1, 2, and 4 are correct

 

 

ANS:   D

The factors affecting results include antibiotic potency, inoculum, concentration, and pH. The bactericidal level of antibiotic and anion content does not affect susceptibility results. Other factors affecting results include agar depth, evaporation, cation content, thymidine content, instrument failure, temperature, moisture, and difficulty in determining endpoints.

 

REF:    pages 98,100                                      OBJ:    Level 2 – Interpretation

 

15. Susceptibility testing of control organisms is usually conducted daily until precision can be demonstrated with _____ or _____ _____ days of susceptibility testing using Clinical and Laboratory Standards Institute (CLSI) guidelines.

a.	20, 30, consecutive
b.	15, 20, consecutive
c.	30, 40, nonconsecutive
d.	5, 10, consistent

 

 

ANS:   A

Once the 20- or 30-day evaluation has been accomplished, quality control organisms may be tested weekly instead of daily. All results should be kept as long as the antimicrobial agent is used or at least 2 years after discontinuing the agent.

 

REF:    page 100         OBJ:    Level 1 – Recall

 

16. How can personnel competency be determined?

a.	Asking an employee to explain how to do a test
b.	Proficiency testing
c.	Asking another employee to comment on someone’s competency
d.	Assuming competency from one’s credentials

 

 

ANS:   B

Proficiency testing consists of carefully designing samples and giving them to techs as unknowns for the purpose of identifying them. This will show how competent a tech is at performing job tasks. Asking an employee how to do a test is not the same as having someone perform the test. Doing a test involves motor skills and coordination that cannot be measured by asking a person about how to do a test. Two things that are never done to evaluate a person’s competency are asking another employee to comment on someone’s competency and assuming one is competent from his or her credentials.

 

REF:    page 100         OBJ:    Level 1 – Recall

 

17. The following are provisions of CLIA 88 EXCEPT:

a.	Verify employee competency upon employment.
b.	Determine an employee’s competency.
c.	Reverify the employee’s competency monthly.
d.	Reverify the employee’s competency annually.

 

 

ANS:   C

To maintain quality in the laboratory, CLIA 88 mandated that an employee’s competency must be verified upon employment, an employer must determine an employee’s competency, and the employee’s competency must be reverified annually. It did not mandate reverifying an employee’s competency monthly because this would be an impossible task—the time frame is too short.

 

REF:    page 100         OBJ:    Level 1 – Recall

 

18. Quality control stock cultures are available from all of the following EXCEPT:

a.	American Type Culture Collection (ATCC)
b.	Commercial sources
c.	Proficiency testing isolates
d.	Centers for Disease Control and Prevention (CDC)

 

 

ANS:   D

CDC is a clearinghouse for knowledge concerning infectious diseases, but CDC does not provide stock cultures to hospital laboratories.

 

REF:    page 100         OBJ:    Level 1 – Recall

 

19. Popular media choices for maintaining stock cultures include:

a.	TSA deeps
b.	Cornmeal
c.	Sabouraud dextrose
d.	CTA with glucose

 

 

ANS:   A

For best results, a stock culture should be grown in a large volume of broth, then divided among enough small freezer vials to last a year. Media selection for freezing is at the discretion of individual laboratory, but it should not contain sugars. If organisms use sugars while being maintained, acid by-products could kill the organism over time. CTA, Sabouraud dextrose, and cornmeal all have sugar. TSA deeps is the only choice that is sugar-free.

 

REF:    page 100         OBJ:    Level 1 – Recall

 

20. Which of the following is an example of a mission statement for an institution?

a.	“The AFMS Flagship—Comprehensive Healthcare…On Time…On Target”
b.	“Working Together for a Healthy America”
c.	“Your Total eLearning Solution”
d.	“Will Answer Questions Correctly 95% of the Time”

 

 

ANS:   B

An organization’s vision and mission statements must be clearly emphasized so that all employees become involved and understand that each one of them has a role in the mission, and that they must strive to make performance improvement part of their everyday life to achieve the organization’s mission. Answers a and c are vision statements, whereas d is an objective.

 

REF:    page 102         OBJ:    Level 2 – Interpretation

 

21. All the following are components of JCAHO recommendations for establishing performance monitors EXCEPT:

a.	Plan
b.	Design
c.	Do
d.	Assess

 

 

ANS:   C

The components of the recommendations are plan, design, measure, and assess.

 

REF:    page 102         OBJ:    Level 1 – Recall

 

22. Customers of a laboratory include all the following EXCEPT:

a.	Patients
b.	Insurers
c.	Doctors
d.	Accrediting organizations

 

 

ANS:   D

Anyone who looks to the laboratory for service is a customer. Doctors, nurses, insurers, and patients are all customers. Accrediting organizations are not expecting services from a laboratory, so they cannot be considered a customer.

 

REF:    page 102         OBJ:    Level 1 – Recall

 

23. An unlabeled specimen is sent from the intensive care unit to the laboratory. When the specimen arrives in the laboratory, the laboratory manager decides that correct action needs to occur. What can be constructed to evaluate and correct the problem?

a.	Find fault with the nurse causing the problem.
b.	Provide training for the nurse responsible for the problem.
c.	Empower a facilitator.
d.	Make a cross-functional team.

 

 

ANS:   D

When patient outcome is less than desirable, the process must be evaluated and corrected. The focus is on the process, not the individual. The primary rule to follow is to refrain from finger pointing or fault finding. Preanalytic and postanalytic activities usually take place outside the laboratory and require a cross-functional team to evaluate and correct the problem.

 

REF:    page 103         OBJ:    Level 3 – Synthesis

 

24. When is a broken process fixed?

a.	When the problem is prevented from happening again.
b.	When everyone is happy with the process.
c.	When the process becomes seamless.
d.	When the hospital administrator determines that the cross-functional team is no longer needed.

 

 

ANS:   A

A process is not fixed just because the reason something went wrong is explained. It is fixed only when the problem is prevented from happening again.

 

REF:    page 103         OBJ:    Level 1 – Recall

 

25. What is benchmarking?

a.	Identifying a problem to be fixed
b.	Seeking an industry’s or profession’s best practices to imitate and improve
c.	Explaining why a problem occurred
d.	Asking the CEO’s opinion and going with his or her idea

 

 

ANS:   B

Benchmarking is seeking an industry’s or profession’s best practice to imitate and improve. Benchmarking was initially practiced in business and industry, but it has now become an important part of the hospital quality management program.

 

REF:    page 103         OBJ:    Level 1 – Recall

 

26. When performing tests in the microbiology laboratory, the detection limit of a test refers to the _____ of that test.

a.	Analytic specificity
b.	Analytic sensitivity
c.	Clinical sensitivity
d.	Clinical specificity

 

 

ANS:   B

The analytic sensitivity of a test refers to its ability to detect a particular analyte or a small change in its concentration. Analytic sensitivity is usually defined as the 0.95 confidence level (+/– 2 SD) and may be referred to as the detection limit. Analytic specificity is a test’s ability not to react with substances other than the one of interest. Clinical sensitivity is the proportion of specimens that test positive from people who are known to have the disease. Clinical specificity is the population of specimens that test negative from people who are known to be disease free.

 

REF:    page 105         OBJ:    Level 1 – Recall

 

27. A technician is performing a chemistry test on a control sample. The technician gets the following values for the control: 4.3, 4.3, 4.3, 4.2, 4.4, 4.3, 4.2, and 4.4. The actual value is 4.3. These results are said to be:

a.	Systematically inaccurate
b.	Sensitive
c.	Accurate
d.	Bias

 

 

ANS:   C

The degree of conformity of a measurement to a standard or true value is accuracy. Bias is the mean difference of test results from an accepted reference method caused by systematic errors.

 

REF:    pages 105-106                                    OBJ:    Level 3 – Synthesis

 

28. A test is performed on a group of 10 patients. Six patients have a disease, and four are free of the disease. If six patients (all known to have the disease) of this group test positive for the disease, we say that the clinical sensitivity of this test is:

a.	60%
b.	40%
c.	50%
d.	100%

 

 

ANS:   D

Clinical sensitivity is the proportion of positive test results obtained when a test is applied to patients known to have the disease. Thus it is the frequency of positive test results in patients with the disease. If six patients in our group are known to have the disease and all six test positive, then the clinical sensitivity of the test is 100%.

 

REF:    page 106         OBJ:    Level 3 – Synthesis

 

29. A group of 10 patients are to be tested: six are known to have a disease and four are disease free. If the four disease-free patients tested negative for this disease, what would the clinical specificity of this test be?

a.	100%
b.	60%
c.	40%
d.	50%

 

 

ANS:   A

Clinical specificity is the proportion of negative results obtained when a test is applied to patients known to be free of disease. Thus it is the frequency of negative test results in patients without the disease. So if there are four patients in this group and they all test negative with this test, then the clinical specificity is 100%—all negative individuals tested negative with this test.

 

REF:    page 106         OBJ:    Level 3 – Synthesis

 

30. Incidence is:

a.	The frequency of a disease at a designated single point in time in the population being tested
b.	The number of new cases of disease over a period of time
c.	Proportion of negative test results in a population known to be free of disease
d.	Positive results in patients with the disease

 

 

ANS:   B

Incidence is defined as the number of new cases of disease over a period of time. Prevalence is the frequency of a disease at a designated single point in time in the population being tested. Clinical specificity is the proportion of negative test results in a population known to be free of the disease. Clinical sensitivity is the positive results in patients with the disease.

 

REF:    page 106         OBJ:    Level 1 – Recall

 

31. A test can have both a positive and negative predictive value. All the following elements are needed to compute the positive and negative predictive value of a test EXCEPT:

a.	Sensitivity of a test
b.	Specificity of a test
c.	Incidence of the disease being tested
d.	Prevalence of the disease being tested

 

 

ANS:   C

The predictive value of a test is the probability that a positive result (positive predictive value) accurately indicates the presence of an analyte or a specific disease. The formula is:

where PPV = positive predictive value

P = prevalence of disease being tested

Se = sensitivity of test

Sp = specificity of test

 

REF:    page 107         OBJ:    Level 1 – Recall

 

32. Assume that a certain test for group A Streptococcus has reported sensitivity and specificity of 90% and 98%, respectively, and the estimated prevalence for group A Streptococcus infection in acute pharyngitis is 5%. What is the positive predictive value of this test?

a.	99.5%
b.	30%
c.	90%
d.	70.3%

 

 

ANS:   D

where PPV = positive predictive value

P = prevalence of disease being tested

Se = sensitivity of test

Sp = specificity of test

 

REF:    page 107         OBJ:    Level 3 – Synthesis

 

33. Usually, negative test results are more reliable in predicting:

a.	The absence of disease
b.	The presence of disease
c.	The sensitivity of a test
d.	The specificity of a test

 

 

ANS:   A

Usually, with tests, the negative predictive value (NPV) is higher than the positive predictive value (PPV). This shows that tests can more accurately predict the absence of disease. The sensitivity and specificity of a test do not predict the presence or absence of a disease.

 

REF:    page 107         OBJ:    Level 1 – Recall

 

34. The efficiency of a test indicates:

a.	The percentage of patients who test positive for the disease
b.	The percentage of patients who are correctly identified as having or not having the disease
c.	The percentage of patients who test negative for the disease
d.	The number of patients tested for a disease

 

 

ANS:   B

Test efficiency =

TP = number of patients with true positive

TN = number of patients with true negative

FP = number of patients with false positive

FN = number of patients with false negative

 

REF:    page 108         OBJ:    Level 1 – Recall

 

35. Screening is:

a.	Used for only particular test analytes
b.	Not practical in a hospital laboratory
c.	Used for testing large populations of patients
d.	When a high incidence of a disease is found in a population

 

 

ANS:   C

Screening is used for testing large populations of patients. Generally, screening tests have high clinical sensitivity and negative predictive value. Positive results with such tests generally require confirmation with a more specific test.

 

REF:    page 108         OBJ:    Level 1 – Recall

 

36. Confirmation is used after:

a.	Careful consideration by the doctor to do the test
b.	A test that has a low predictive value
c.	A test that has a low specificity
d.	Obtaining a positive screening result

 

 

ANS:   D

Confirmation is the process of repeating a screening test using a test that is more sensitive and specific to ensure accuracy for the initial screening result. Confirmatory tests help seek out false-positive screening tests.

 

REF:    page 108         OBJ:    Level 1 – Recall

 

37. When choosing a test to perform in your laboratory, an in-house verification is always performed. Verification of a test:

a.	Serves to establish that the performance parameters of the test are satisfactory
b.	Lets techs actually perform the test
c.	Lets physicians perform the test
d.	Allows laboratory management to view positive results

 

 

ANS:   A

A test must be verified by a laboratory to ensure that it will work as described on the package. A test must perform up to specifications in a lab or it is not worth using. Although having techs perform the test in-house shortens the turnaround time for results, the test is evaluated for its performance. Physicians are not allowed to perform tests in a clinical laboratory. Laboratory management does not need to see positive test results. Laboratory management will evaluate the test on its in-house performance.

 

REF:    page 109         OBJ:    Level 1 – Recall

 

38. Test validation is the ongoing process providing information that a test is performing correctly. The components of validation include all the following EXCEPT:

a.	Quality control
b.	Specimen requirements
c.	Proficiency testing
d.	Instrument calibration

 

 

ANS:   B

Specimen requirements do not assess the functioning of a test. Quality control, proficiency testing, and instrument calibration evaluate test functioning on a continual basis.

 

REF:    pages 109-110                                    OBJ:    Level 1 – Recall

 

39. All of the following provide guidelines to ensure the continual correct performance of tests EXCEPT:

a.	Accrediting agencies
b.	Regulatory agencies
c.	Centers for Disease Control and Prevention (CDC)
d.	Manufacturers

 

 

ANS:   C

CDC does not publish recommendations in regard to continual test validation. CDC is a clearinghouse for infectious disease knowledge.

 

REF:    pages 109-110                                    OBJ:    Level 1 – Recall