Textbook of Diagnostic Microbiology 4th Edition – Test Bank

Complete Test Bank With Answers

 

 

Sample Questions Posted Below

 

1. 2. 3. Mahon: Textbook of Diagnostic Microbiology, 4th Edition

Chapter 05: Performance Improvement in the Microbiology Laboratory

Test Bank

MULTIPLE CHOICE

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

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

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 – Recall4. 5. 6. 7. 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

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

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

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

accomplished by:8. 9. 10. a. Sending to the National Institute of Standards and Technology (NIST) to determine

its accuracy

b. c. Checking against an NIST thermometer

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

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

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

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: D11. 12. 13. 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

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. c. The medium should be tested for sterility and pH.

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

Reagents that should undergo quality control in the microbiology laboratory include all the

following EXCEPT:

a. Optochin

b. Immersion Oil

c. -Lactamase

d. Nitrate

ANS: B

All stains performed in a microbiology laboratory along with Optochin, -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

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. b. c. d. Use in-house organisms isolated from past patients

Share strains between hospital laboratories

Use specific strains from American Type Culture Collection (ATCC)

Obtain test strains from Centers for Disease Control and Prevention (CDC)

ANS: C14. 15. 16. 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

In any susceptibility system, variables that can affect the results include the following:

1. Antibiotic potency

2. Inoculum concentration

3. Bactericidal level

4. pH

5. 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

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

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: B17. 18. 19. 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

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

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

Popular media choices for maintaining stock cultures include:

a. TSA deeps

b. Cornmeal

c. Sabouraud dextrose

d. CTA with glucose

ANS: A20. 21. 22. 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

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

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

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 – Recall23. 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. b. c. d. When the problem is prevented from happening again.

When everyone is happy with the process.

When the process becomes seamless.

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 specificity27. 28. 29. 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

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

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

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. c. d. The number of new cases of disease over a period of time

Proportion of negative test results in a population known to be free of disease

Positive results in patients with the disease

31. 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

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:

32. 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

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

33. 34. 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

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

The efficiency of a test indicates:

a. b. The percentage of patients who test positive for the disease

The percentage of patients who are correctly identified as having or not having the

disease

c. d. The percentage of patients who test negative for the disease

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 analytesb. c. d. Not practical in a hospital laboratory

Used for testing large populations of patients

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

37. 38. 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

When choosing a test to perform in your laboratory, an in-house verification is always

performed. Verification of a test:

a. b. c. d. Serves to establish that the performance parameters of the test are satisfactory

Lets techs actually perform the test

Lets physicians perform the test

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

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 calibration39. 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

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