Question 1

A drug will generally inhibit multiplication of the bacteria so that the patient's immune defense mechanisms are no longer overwhelmed when:

Accepted Answer

A) all the debris and necrotic cells are removed. 
B) the drug concentration exceeds the MIC for the microbe. 
C) the patient is not infected with a gram-negative rod. 
D) two synergistic drugs are used to kill the bacteria. 
A) all the debris and necrotic cells are removed. 
B) the drug concentration exceeds the MIC for the microbe. 
C) the patient is not infected with a gram-negative rod. 
D) two synergistic drugs are used to kill the bacteria.

Question 2

What principle do most current automated antimicrobial susceptibility instruments use to read growth?

Accepted Answer

A) Turbidimetric detection 
B) Turbidity suppression 
C) Hydrolysis of a fluorogenic growth substrate 
D) Carbon dioxide concentration 
A) Turbidimetric detection 
B) Turbidity suppression 
C) Hydrolysis of a fluorogenic growth substrate 
D) Carbon dioxide concentration

Question 3

A microbiology technologist is performing a b-lactamase test on a staphylococci isolated from a hospitalized patient.The test was negative, so the technologist reported out in vitro antimicrobial susceptibility test results for b-lactam antibiotics.After 2 days, the patient was not improving and the physician changed the patient's antibiotic to an aminoglycoside.The patient showed improvement immediately.Why was the b-lactamase test on the staphylococci negative, when the organism produced b-lactamase?

Accepted Answer

A) The test was a false negative-the organism really did produce b-lactamase, but it did not react with the test. 
B) Staphylococci must be exposed to the b-lactam agent before it will produce a positive test result. 
C) The test was a false positive-the organism reacted with the test, but it did not produce a b-lactamase. 
D) The staphylococci on the plate were more than 24 hours old and false-negative test results can occur when an "old" organism is used. 
A) The test was a false negative-the organism really did produce b-lactamase, but it did not react with the test. 
B) Staphylococci must be exposed to the b-lactam agent before it will produce a positive test result. 
C) The test was a false positive-the organism reacted with the test, but it did not produce a b-lactamase. 
D) The staphylococci on the plate were more than 24 hours old and false-negative test results can occur when an "old" organism is used.

Question 4

All of the following steps are taken to verify the results from an atypical antibiogram except:

Accepted Answer

A) reexamining the disk diffusion plate, or minimal inhibitory concentration (MI
C)  tray, to ensure that results were properly interpreted. 
B) checking earlier reports to see whether the particular patient previously had an isolate with an atypical antibiogram. 
C) calling around to other hospitals to see if they are encountering the same organism with that same antibiogram. 
D) repeating the test, if necessary. 
A) reexamining the disk diffusion plate, or minimal inhibitory concentration (MI
C)  tray, to ensure that results were properly interpreted. 
B) checking earlier reports to see whether the particular patient previously had an isolate with an atypical antibiogram. 
C) calling around to other hospitals to see if they are encountering the same organism with that same antibiogram. 
D) repeating the test, if necessary.

Question 5

What McFarland standard provides turbidity comparable to that of a bacterial suspension containing approximately 1.5 ´ 10⁸ CFU/mL?

Accepted Answer

A) 1.0 
B) 1.5 
C) 0.5 
D) 2.0 
A) 1.0 
B) 1.5 
C) 0.5 
D) 2.0

Question 6

In this method of antimicrobial susceptibility testing, specific volumes of various concentrations of antimicrobial solutions are dispensed into premeasured volumes of molten and cooled agar, which is subsequently poured into standard Petri dishes.Organisms are inoculated onto the plate.What type of antimicrobial susceptibility testing is this?

Accepted Answer

A) Macrodilution 
B) Broth dilution 
C) Disk diffusion 
D) Agar dilution 
A) Macrodilution 
B) Broth dilution 
C) Disk diffusion 
D) Agar dilution

Question 7

A 12-year-old girl goes to the doctor complaining of a sore throat, fever, headache, and general malaise.The doctor does a quick strep test that is positive for group A b-hemolytic Streptococcus.No antibiotic testing is needed because Streptococcus is:

Accepted Answer

A) universally susceptible to penicillin. 
B) universally susceptible to erythromycin. 
C) not treated in throat cultures. 
D) not considered a pathogen in the throat. 
A) universally susceptible to penicillin. 
B) universally susceptible to erythromycin. 
C) not treated in throat cultures. 
D) not considered a pathogen in the throat.

Question 8

When would it be appropriate for an institution to routinely test group C agents?

Accepted Answer

A) For urinary tract infections 
B) If a particular institution routinely encounters large numbers of isolates resistant to group A and group B agents 
C) For blood cultures 
D) If a particular institution routinely encounters large numbers of isolates susceptible to group A and group B agents 
A) For urinary tract infections 
B) If a particular institution routinely encounters large numbers of isolates resistant to group A and group B agents 
C) For blood cultures 
D) If a particular institution routinely encounters large numbers of isolates susceptible to group A and group B agents

Question 9

In this type of antimicrobial susceptibility test, a McFarland 0.5 standardized suspension of bacteria is swabbed over the surface of a Mueller-Hinton agar plate, and paper disks containing single concentrations of each antimicrobial agent are placed onto the inoculated surface.What is the name of this test?

Accepted Answer

A) Kirby-Bauer 
B) MIC 
C) Breakpoint 
D) Agar dilution 
A) Kirby-Bauer 
B) MIC 
C) Breakpoint 
D) Agar dilution

Question 10

What is a mechanism for ensuring the testing personnel are proficient in their tasks?

Accepted Answer

A) Supervisory review of reported results 
B) Self-assessment checklists 
C) Periodic competency testing through proficiency surveys 
D) All of the above 
A) Supervisory review of reported results 
B) Self-assessment checklists 
C) Periodic competency testing through proficiency surveys 
D) All of the above

Question 11

How many hours of incubation are necessary for the antimicrobial susceptibility test run on the BD Phoenix?

Accepted Answer

A) 6 to 8 hours 
B) 8 to 12 hours 
C) 12 to 18 hours 
D) 24 hours 
A) 6 to 8 hours 
B) 8 to 12 hours 
C) 12 to 18 hours 
D) 24 hours

Question 12

What is the principle of the Etest?

Accepted Answer

A) Turbidimetry 
B) Establishing an antimicrobial density gradient in agar 
C) Carbon dioxide concentration 
D) Redox indicator system 
A) Turbidimetry 
B) Establishing an antimicrobial density gradient in agar 
C) Carbon dioxide concentration 
D) Redox indicator system

Question 13

What broth is recommended in the tube dilution minimal inhibitory concentration (MIC) tests?

Accepted Answer

A) Trypticase soy 
B) Mueller-Hinton 
C) Columbia 
D) Cooked meat 
A) Trypticase soy 
B) Mueller-Hinton 
C) Columbia 
D) Cooked meat

Question 14

What is the storage temperature for frozen panels?

Accepted Answer

A) 0° C 
B) -20° to -70° C 
C) -75° to -100° C 
D) 273 K 
A) 0° C 
B) -20° to -70° C 
C) -75° to -100° C 
D) 273 K

Question 15

All of the following techniques are used to measure the amount of antimicrobial agent in the serum except:

Accepted Answer

A) biologic assays. 
B) immunoassays. 
C) chromatographic assays. 
D) bioluminescence assays. 
A) biologic assays. 
B) immunoassays. 
C) chromatographic assays. 
D) bioluminescence assays.

Question 16

What is generated by analysis of individual susceptibility results on isolates from a particular institution in a defined period and represents the percentage of isolates of a given species that is susceptible to the antimicrobial agents commonly tested against the species?

Accepted Answer

A) Historical antibiogram 
B) Laboratory workload report 
C) Infection control committee report 
D) Cumulative antibiogram 
A) Historical antibiogram 
B) Laboratory workload report 
C) Infection control committee report 
D) Cumulative antibiogram

Question 17

On a breakpoint panel, when two concentrations are tested and no growth is present in either well, the isolate is:

Accepted Answer

A) susceptible. 
B) resistant. 
C) intermediate. 
D) none of the above. 
A) susceptible. 
B) resistant. 
C) intermediate. 
D) none of the above.

Question 18

Because the identity of the bacterial isolate is often unknown at the time the susceptibility testing is performed, it may include drugs that are inappropriate for reporting.What does the microbiologist do when this occurs?

Accepted Answer

A) A drug should not be indiscriminately reported because results may be misleading. 
B) If the drug is tested, the results are reported because the microbiologist does not know what antibiotic was prescribed to the patient. 
C) The microbiologist reports this immediately to the microbiology supervisor because this is a wasteful practice. 
D) The microbiologist only reports on the drugs to which the bacteria are sensitive. 
A) A drug should not be indiscriminately reported because results may be misleading. 
B) If the drug is tested, the results are reported because the microbiologist does not know what antibiotic was prescribed to the patient. 
C) The microbiologist reports this immediately to the microbiology supervisor because this is a wasteful practice. 
D) The microbiologist only reports on the drugs to which the bacteria are sensitive.

Question 19

What is the most widely used supplementary quality control measure for antimicrobial susceptibility testing?

Accepted Answer

A) b-Lactamase testing 
B) Use of antibiograms to verify results generated on patient isolates 
C) Correlation of clinical outcomes with laboratory findings 
D) None of the above 
A) b-Lactamase testing 
B) Use of antibiograms to verify results generated on patient isolates 
C) Correlation of clinical outcomes with laboratory findings 
D) None of the above

Question 20

Quality control of antimicrobial susceptibility tests involves:

Accepted Answer

A) performing antimicrobial susceptibility tests on organisms using the Clinical and Laboratory Standards Institute (CLSI) charts to interpret the results. 
B) using organisms grown from patient cultures to test the reactivity of the antimicrobial drugs. 
C) testing standard reference strains that have defined antimicrobial susceptibility (or resistance) to the drugs tested. 
D) none of the above. 
A) performing antimicrobial susceptibility tests on organisms using the Clinical and Laboratory Standards Institute (CLSI) charts to interpret the results. 
B) using organisms grown from patient cultures to test the reactivity of the antimicrobial drugs. 
C) testing standard reference strains that have defined antimicrobial susceptibility (or resistance) to the drugs tested. 
D) none of the above.

Exam 13: Antimicrobial Susceptibility Testing

A drug will generally inhibit multiplication of the bacteria so that the patient's immune defense mechanisms are no longer overwhelmed when:

What principle do most current automated antimicrobial susceptibility instruments use to read growth?

All of the following steps are taken to verify the results from an atypical antibiogram except:

What McFarland standard provides turbidity comparable to that of a bacterial suspension containing approximately 1.5 ´ 10⁸ CFU/mL?

A 12-year-old girl goes to the doctor complaining of a sore throat, fever, headache, and general malaise.The doctor does a quick strep test that is positive for group A b-hemolytic Streptococcus.No antibiotic testing is needed because Streptococcus is:

When would it be appropriate for an institution to routinely test group C agents?

What is a mechanism for ensuring the testing personnel are proficient in their tasks?

How many hours of incubation are necessary for the antimicrobial susceptibility test run on the BD Phoenix?

What is the principle of the Etest?

What broth is recommended in the tube dilution minimal inhibitory concentration (MIC) tests?

What is the storage temperature for frozen panels?

All of the following techniques are used to measure the amount of antimicrobial agent in the serum except:

What is generated by analysis of individual susceptibility results on isolates from a particular institution in a defined period and represents the percentage of isolates of a given species that is susceptible to the antimicrobial agents commonly tested against the species?

On a breakpoint panel, when two concentrations are tested and no growth is present in either well, the isolate is:

Because the identity of the bacterial isolate is often unknown at the time the susceptibility testing is performed, it may include drugs that are inappropriate for reporting.What does the microbiologist do when this occurs?

What is the most widely used supplementary quality control measure for antimicrobial susceptibility testing?

Quality control of antimicrobial susceptibility tests involves:

Bacterial Cell Structure, Physiology, Metabolism, and Genetics

Host-Parasite Interaction

The Laboratory Role in Infection Control

Control of Microorganisms

Performance Improvement in the Microbiology Laboratory

Specimen Collection and Processing

Microscopic Examination of Materials From Infected Sites

Use of Colony Morphology for the Presumptive Identification of Microorganisms

Biochemical Identification of Gram-Negative Bacteria

Immunodiagnosis of Infectious Diseases

Applications of Molecular Diagnostics

Antimicrobial Agent Mechanisms of Action and Resistance

Staphylococci

Streptococcus, Enterococcus, and Other Catalase-Negative, Gram-Positive Cocci

Aerobic Gram-Positive Bacilli

Neisseria Species and Moraxella Catarrhalis

Haemophilus and Other Fastidious Gram-Negative Bacilli

Enterobacteriaceae

Vibrio, Aeromonas, Plesiomonas, and Campylobacter Species

Nonfermenting and Miscellaneous Gram-Negative Bacilli

Anaerobes of Clinical Importance

The Spirochetes

Chlamydia, Rickettsia and Similar Organisms

Mycoplasma and Ureaplasma

Mycobacterium Tuberculosis and Nontuberculous Mycobacteria

Medically Significant Fungi

Diagnostic Parasitology

Clinical Virology

Agents of Bioterror and Forensic Microbiology

Biofilms: Architects of Disease

Upper and Lower Respiratory Tract Infections

Skin and Soft Tissue Infections

Gastrointestinal Infections and Food Poisoning

Infections of the Central Nervous System

Bacteremia and Sepsis

Urinary Tract Infections

Genital Infections and Sexually Transmitted Diseases

Infections in Special Populations

Zoonotic Diseases

Ocular Infections

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