Question 1

What is the approximate final concentration of organisms in each well of a microdilution tray?

Accepted Answer

A) 3 ´ 105 colony-forming units (CFU)/mL 
B) 1 ´ 105 CFU/mL 
C) 4 ´ 105 CFU/mL 
D) 5 ´ 105 CFU/mL 
A) 3 ´ 105 colony-forming units (CFU)/mL 
B) 1 ´ 105 CFU/mL 
C) 4 ´ 105 CFU/mL 
D) 5 ´ 105 CFU/mL

Question 2

Why are aminoglycosides not an effective treatment for meningitis?

Accepted Answer

A) They do not cross the blood-brain barrier. 
B) They are nephrotoxic and will harm the patient's kidneys. 
C) They are ototoxic and will harm the patient's ears. 
D) They are not effective against Neisseria, Streptococcus, or Haemophilus. 
A) They do not cross the blood-brain barrier. 
B) They are nephrotoxic and will harm the patient's kidneys. 
C) They are ototoxic and will harm the patient's ears. 
D) They are not effective against Neisseria, Streptococcus, or Haemophilus.

Question 3

On a breakpoint panel, when there is growth in the low concentration but no growth in the high concentration, 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 4

When performing disk diffusion testing with Haemophilus influenzae and H.parainfluenzae, what type of medium is used?

Accepted Answer

A) Mueller-Hinton with 5% sheep blood 
B) Mueller-Hinton with hematin and nicotinamide adenine dinucleotide (NA
D)  
C) Mueller-Hinton with 5% lysed horse blood 
D) Mueller-Hinton 
A) Mueller-Hinton with 5% sheep blood 
B) Mueller-Hinton with hematin and nicotinamide adenine dinucleotide (NA
D)  
C) Mueller-Hinton with 5% lysed horse blood 
D) Mueller-Hinton

Question 5

Oxacillin-resistant staphylococci can appear susceptible in vitro to other b-lactam agents such as:

Accepted Answer

A) quinolones. 
B) tetracyclines. 
C) cephalosporins. 
D) aminoglycosides. 
A) quinolones. 
B) tetracyclines. 
C) cephalosporins. 
D) aminoglycosides.

Question 6

Once zone measurements have been made, the millimeter reading for each antimicrobial agent is:

Accepted Answer

A) sent to the physician to determine the appropriateness of antibiotic therapy for his patient. 
B) converted into minimal inhibitory concentration (MI
C)  units. 
C) interpreted as susceptible, intermediate, or resistant. 
D) none of the above. 
A) sent to the physician to determine the appropriateness of antibiotic therapy for his patient. 
B) converted into minimal inhibitory concentration (MI
C)  units. 
C) interpreted as susceptible, intermediate, or resistant. 
D) none of the above.

Question 7

What principle does the VITEK series use to determine antimicrobial susceptibility?

Accepted Answer

A) Turbidimetry 
B) Redox indicator system 
C) Hydrolysis of a fluorogenic substrate 
D) Carbon dioxide concentration 
A) Turbidimetry 
B) Redox indicator system 
C) Hydrolysis of a fluorogenic substrate 
D) Carbon dioxide concentration

Question 8

Why should antimicrobial susceptibility testing of normal flora isolates or isolates likely to represent contamination or colonization not be performed?

Accepted Answer

A) This may encourage a physician to treat a normal condition. 
B) This will expose normal flora to various antibiotics and cause resistance to develop. 
C) The amount of antibiotic needed to kill all of the normal flora in a site can cause toxic effects to the patient. 
D) Antimicrobial susceptibility testing should be performed on all bacteria isolated from the patient. 
A) This may encourage a physician to treat a normal condition. 
B) This will expose normal flora to various antibiotics and cause resistance to develop. 
C) The amount of antibiotic needed to kill all of the normal flora in a site can cause toxic effects to the patient. 
D) Antimicrobial susceptibility testing should be performed on all bacteria isolated from the patient.

Question 9

What does the broth microdilution minimal inhibitory concentration (MIC) test use for testing?

Accepted Answer

A) Test tubes 
B) Plastic strips 
C) Multiwell microdilution trays 
D) Multiwell macrodilution trays 
A) Test tubes 
B) Plastic strips 
C) Multiwell microdilution trays 
D) Multiwell macrodilution trays

Question 10

What is the principle of the most commonly used test to detect b-lactamase production?

Accepted Answer

A) Chromogenic cephalosporin nitrocefin 
B) Redox reaction 
C) Hydrolysis of fluorogenic substrate 
D) Reduction of acetoin 
A) Chromogenic cephalosporin nitrocefin 
B) Redox reaction 
C) Hydrolysis of fluorogenic substrate 
D) Reduction of acetoin

Question 11

What principle does the TREK ARIS 2X System use to determine antimicrobial susceptibility?

Accepted Answer

A) Redox indicator system 
B) Turbidimetry 
C) Hydrolysis of a fluorogenic substrate 
D) Carbon dioxide concentration 
A) Redox indicator system 
B) Turbidimetry 
C) Hydrolysis of a fluorogenic substrate 
D) Carbon dioxide concentration

Question 12

To obtain a bactericidal effect in enterococci, ampicillin or penicillin must be given in combination with:

Accepted Answer

A) macrolides. 
B) peptidoglycans. 
C) cephalosporins. 
D) aminoglycosides. 
A) macrolides. 
B) peptidoglycans. 
C) cephalosporins. 
D) aminoglycosides.

Question 13

After the plate is incubated in the Kirby-Bauer test, what occurs?

Accepted Answer

A) The plate is tested to make sure an isolated organism grew on the plate. 
B) The diameter of each inhibition zone for each antibiotic is measured using a ruler or caliper. 
C) The amount of carbon dioxide in the plate is measured to ensure confluent organism growth. 
D) None of the above occurs. 
A) The plate is tested to make sure an isolated organism grew on the plate. 
B) The diameter of each inhibition zone for each antibiotic is measured using a ruler or caliper. 
C) The amount of carbon dioxide in the plate is measured to ensure confluent organism growth. 
D) None of the above occurs.

Question 14

What type of antimicrobial susceptibility testing method does Clinical and Laboratory Standards Institute (CLSI) recommend for anaerobes?

Accepted Answer

A) Microdilution 
B) Agar dilution 
C) Tube broth macrodilution 
D) Disk diffusion 
A) Microdilution 
B) Agar dilution 
C) Tube broth macrodilution 
D) Disk diffusion

Question 15

What principle does the MicroScan Walkaway SI use to determine antimicrobial susceptibility?

Accepted Answer

A) Redox indicator system 
B) Turbidimetry 
C) Hydrolysis of a bioluminescent substrate 
D) Carbon dioxide concentration 
A) Redox indicator system 
B) Turbidimetry 
C) Hydrolysis of a bioluminescent substrate 
D) Carbon dioxide concentration

Question 16

Why would normal flora isolates from immunosuppressed patients undergo antimicrobial susceptibility testing?

Accepted Answer

A) These are not normal flora; they are other potential pathogens that have the same colonial morphology as normal flora. 
B) Species usually viewed as normal flora may be responsible for an infection in an immunosuppressed patient. 
C) All bacteria isolated from immunosuppressed patients must have antimicrobial susceptibility tests performed. 
D) Cultures from immunosuppressed patients only grow pathogenic organisms that must undergo antimicrobial susceptibility testing. 
A) These are not normal flora; they are other potential pathogens that have the same colonial morphology as normal flora. 
B) Species usually viewed as normal flora may be responsible for an infection in an immunosuppressed patient. 
C) All bacteria isolated from immunosuppressed patients must have antimicrobial susceptibility tests performed. 
D) Cultures from immunosuppressed patients only grow pathogenic organisms that must undergo antimicrobial susceptibility testing.

Question 17

Note that for some antimicrobial agents, different minimal inhibitory concentration (MIC) interpretive criteria exist for:

Accepted Answer

A) organisms or organism groups. 
B) anatomic sites. 
C) age groups. 
D) immune status. 
A) organisms or organism groups. 
B) anatomic sites. 
C) age groups. 
D) immune status.

Question 18

What antibiotics are active against extended-spectrum b-lactamases (ESBL)-producing strains of bacteria?

Accepted Answer

A) Cephalosporins 
B) Penicillins 
C) Carbapenems 
D) Aztreonam 
A) Cephalosporins 
B) Penicillins 
C) Carbapenems 
D) Aztreonam

Question 19

When should antimicrobial susceptibility testing be performed on a bacterial isolate from a clinical specimen?

Accepted Answer

A) When the isolate is determined to be a probable cause of the patient's infection 
B) When the susceptibility of the isolate to particular antimicrobial agents cannot be reliably predicted 
C) Both a and b 
D) None of the above 
A) When the isolate is determined to be a probable cause of the patient's infection 
B) When the susceptibility of the isolate to particular antimicrobial agents cannot be reliably predicted 
C) Both a and b 
D) None of the above

Question 20

In vitro testing conditions that can be modified to enhance the expression of oxacillin resistance include all the following except:

Accepted Answer

A) using Mueller-Hinton media. 
B) making final test readings after a full 24 hours of incubation. 
C) incubating tests at temperatures no greater than 35° C. 
D) preparing inocula using the direct inoculum suspension procedure. 
A) using Mueller-Hinton media. 
B) making final test readings after a full 24 hours of incubation. 
C) incubating tests at temperatures no greater than 35° C. 
D) preparing inocula using the direct inoculum suspension procedure.

Exam 13: Antimicrobial Susceptibility Testing

What is the approximate final concentration of organisms in each well of a microdilution tray?

Why are aminoglycosides not an effective treatment for meningitis?

On a breakpoint panel, when there is growth in the low concentration but no growth in the high concentration, the isolate is:

When performing disk diffusion testing with Haemophilus influenzae and H.parainfluenzae, what type of medium is used?

Oxacillin-resistant staphylococci can appear susceptible in vitro to other b-lactam agents such as:

Once zone measurements have been made, the millimeter reading for each antimicrobial agent is:

What principle does the VITEK series use to determine antimicrobial susceptibility?

Why should antimicrobial susceptibility testing of normal flora isolates or isolates likely to represent contamination or colonization not be performed?

What does the broth microdilution minimal inhibitory concentration (MIC) test use for testing?

What is the principle of the most commonly used test to detect b-lactamase production?

What principle does the TREK ARIS 2X System use to determine antimicrobial susceptibility?

To obtain a bactericidal effect in enterococci, ampicillin or penicillin must be given in combination with:

After the plate is incubated in the Kirby-Bauer test, what occurs?

What type of antimicrobial susceptibility testing method does Clinical and Laboratory Standards Institute (CLSI) recommend for anaerobes?

What principle does the MicroScan Walkaway SI use to determine antimicrobial susceptibility?

Why would normal flora isolates from immunosuppressed patients undergo antimicrobial susceptibility testing?

Note that for some antimicrobial agents, different minimal inhibitory concentration (MIC) interpretive criteria exist for:

What antibiotics are active against extended-spectrum b-lactamases (ESBL)-producing strains of bacteria?

When should antimicrobial susceptibility testing be performed on a bacterial isolate from a clinical specimen?

In vitro testing conditions that can be modified to enhance the expression of oxacillin resistance include all the following except:

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

Filters