Exam 13: Antimicrobial Susceptibility Testing

A microbiology technologist is performing a β-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 β-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 β-lactamase test on the staphylococci negative,when the organism produced b-lactamase?

If the minimal inhibitory concentration (MIC)or zone size is interpreted as intermediate using the latest Clinical and Laboratory Standards Institute (CLSI)tables:

On what media is Kirby-Bauer testing for Neisseria gonorrhoeae performed?

What is the most critical step in any susceptibility test?

Two antibiotics are contraindicated in pediatric patients.They are:

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

How should quality control testing occur?

How are antibiotics chosen for inclusion into laboratory antimicrobial testing protocols?

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

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

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

What test uses the patient's serum,and the bacterial isolate responsible for the patient's infection,to determine the dilution of patient's serum that inhibits the bacteria?

What automated system was originally designed for use in space?

The inhibition zone size and minimal inhibitory concentration (MIC)interpretive criteria published by the Clinical and Laboratory Standards Institute (CLSI)are established by careful analysis of all of the following EXCEPT:

In the Kirby-Bauer test,what is used to grow streptococci that do not grow adequately on unsupplemented Mueller-Hinton agar?

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

A man goes to his doctor because he has a cloudy substance dripping from his penis.A Gram stain is performed and gram-negative intracellular diplococci are observed.What is the drug of choice to treat this infection?

What is the storage temperature for frozen panels?

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

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