Deck 11: Susceptibility Testing

Question 1

Which of the following criteria is considered the most important when selecting an antibiotic for treating meningitis?

A) Potential for allergic reactions
B) Ability to cross blood-brain barrier
C) Cost
D) Dosage intervals

Answer 1

Ability to cross blood-brain barrier

Question 2

An individual who exhibits rash and hives on starting treatment with penicillin may also exhibit these same symptoms with

A) cephalosporins.
B) carbapenems.
C) monobactams.
D) vancomycin.

Answer 2

cephalosporins.

Question 3

Which of the following antibiotic classes acts on the organism's protein synthesis?

A) Beta-lactams
B) Glycopeptides
C) Carbapenems
D) Aminoglycosides

Answer 3

Aminoglycosides

Question 4

The key to the successful use of bacteriostatic antibiotic in treating an infection is

A) the compliance of the patient.
B) an immunocompetent state.
C) its spectrum of activity.
D) its mode of administration.

Question 5

Which of the following antibiotics is considered bactericidal?

A) Tetracycline
B) Erythromycin
C) Vancomycin
D) Clindamycin

Question 6

Aerobes are intrinsically resistant to metronidazole because

A) the antibiotic must be reduced to be active.
B) they are able to actively pump out the antibiotic.
C) the antibiotics cannot cross their cell wall.
D) they produce destructive enzymes.

Question 7

Which of the following acquired resistance mechanisms is demonstrated by methicillin-resistant Staphylococcus aureus against oxacillin?

A) Modification of organism target
B) Enzymatic inactivation of the antimicrobial agent
C) Decreased uptake or ability to pump out the antibiotic
D) Both a and b
E) All of the above

Question 8

An antibiotic that inhibits an organism on susceptibility testing and generates a susceptible result

A) will be effective in-vivo.
B) cannot be used for treatment.
C) means no known resistance mechanisms are detected.
D) means the organism will not develop resistance in the future.

Question 9

Which of the following organizations or health care personnel develops guidelines for

A) Infection control team
B) Hospital pharmacists
C) Centers for Disease Control and Prevention
D) Clinical and Laboratory Standards Institute

Question 10

The microbiology department received a notice that its last susceptibility media shipment is being recalled due to increased levels of thymine. If any of the medium was used for susceptibility testing, what antibiotic(s) would be affected?

A) Aminoglycosides
B) Macrolides
C) Trimethoprim-sulfamethoxazole
D) Quinolones

Question 11

The results obtained from a disk diffusion susceptibility test are

A) quantitative.
B) qualitative.
C) measured in centimeters.
D) categorized as either susceptible or resistant.

Question 12

The susceptibility results obtained using broth dilution are

A) obtained using a final inoculum equal to 1.5 X 10⁸ CFU.
B) the highest concentration of an antimicrobial agent that inhibits growth.
C) qualitative.
D) quantitative.

Question 13

An alpha-hemolytic, catalase-negative, gram-positive diplococcus was isolated from the expectorated sputum of a 79-year-old female admitted with pneumonia. The

A) be reported as a penicillin-resistant Streptococcus pneumoniae.
B) be reported as a penicillin-susceptible Streptococcus pneumoniae.
C) not be reported because it is a viridans Streptococcus.
D) be retested against penicillin using an MIC method.

Question 14

What is the MIC of the organism on the image provided?

A) Azithromycin-0.38 µg/mL
B) Erythromycin-27 mm
C) Tetracycline-30 µg/ml
D) All results are qualitative, not quantitative.

Question 15

Which of the following antibiotics is a strong inducer for the expression of the mecA gene in MRSA?

A) Oxacillin
B) Cefoxitin
C) A beta-lactam
D) Methicillin

Question 16

Which of the following vancomycin-resistant genes is not considered an infection control issue because it cannot be passed to other organisms via a plasmid?

A) vanA
B) vanB
C) vanC
D) vanD

Question 17

A gram-negative rod that displays resistance to ertapenem should also be tested using the

A) Hodge test.
B) ESBL screen.
C) AmpC induction screen.
D) chromogenic nitrocefin test.

Question 18

Which of the following antibiotic results must be edited if a gram-negative rod produces AmpC enzymes?

A) All carbapenems
B) All beta-lactams
C) Aztreonam
D) No changes are made to susceptibility results.

Question 19

Which of the following procedures tests the patient's own infectious organism against serial dilutions of his or her peak and trough antibiotic blood levels to determine the 99.9% kill level?

A) Serum bactericidal test
B) Minimum inhibitory concentration
C) Minimum bactericidal concentration
D) Antibiotic level assay

Question 20

A microbiologist reviews the susceptibility results of Proteus mirabilis isolated from catheterized urine of a 57-year-old male in a coma. The organism test results included:
Based on these results, the microbiologist should

A) report the results as tested.
B) test the organism for ESBL production.
C) test the organism for AmpC production.
D) perform a Hodge test.

Question 21

Validation of a new susceptibility method requires testing organisms

A) with known susceptibility patterns.
B) for at least two consecutive months.
C) in parallel with both the new and current methods.
D) both a and c.

Question 22

Using an assay to determine the exact level of antibiotic present in a blood sample is done to

A) determine the appropriate level for therapy.
B) ensure the current level of antibiotic is not present in the toxic range.
C) establish the dosing pattern for the most effective antibiotic level.
D) ensure the patient is compliant in taking the antibiotic as directed.