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AST
AST
65 terms
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Answers
1
Beta-lactamase test, cefinase test, acidometric test are all the same test.
False
True
2
Antibiotics work by targeting all of the following except:
Bacterial plasmid DNA
DNA replication
Bacterial cell wall
RNA transcription
3
Vancomycin is bacteriostatic.
False
True
4
Streptococcus pyogenes
is considered universally susceptible to penicillin.
True
False
5
Cefoxitin-resistant
Staphylococcus aureus
is called:
Methicillin-resistant S. aureus
Erythromycin-resistant S. aureus
Penicillin-resistant S. aureus
Oxacillin-resistant S. aureus
6
Define "antagonism"
Variable effectiveness when drugs are combined
Decreased effectiveness when drugs are combined
Effectiveness is not changed when drugs are combined
Increased effectiveness when drugs are combined
7
Which of the following accurately describes the mode of action of beta-lactamase inhibitors
Reversibly changes beta-lactase conformation
Irreversibly denatures beta-lactamase enzyme
Reversibly denatures beta-lactamase enzyme
Binds to the active site of beta-lactamase enzyme
8
Define the AST outcome "resistant".
Futile
The antibiotic would not be effective
The antibiotic would be effective
The antibiotic would be effective at a higher than usual dose
9
Which of the following organisms require HTM instead of MH agar for disk diffusion AST?
Proteus
Proteus mirabilis
Streptococcus pneumonia
Haemophilus influenzae
10
SXT disk diffusion results should be interpreted:
Via automation only
By measuring from peak to peak
From the point where growth was reduced by 80%
Only when erythromycin and clindamycin are also present
11
Which of the following organisms require modified disk diffusion methods?
Streptococcus pneumonia
Proteus
Proteus mirabilis
Haemophilus influenzae
12
A D-zone test is used to demonstrate clindamycin induced antagonism with erythromycin
True
False
13
This beta-lactamase test is:
Inconclusive
Negative
Invalid
Positive
14
What does ESBL stand for?
Endocarditis susceptible bacterial ligand
Enterobacteriaceae bulusconii biovar litigious
Extended Spectrum Beta-Lactamase
Effective and Susceptible Beta-lactams
15
ESBL inactivates one or more antibiotics in which of the following:
Quinolones
Penicillin
Aztreonam
Cephalosporins
16
What is wrong with this disk diffusion AST?
Too many disks were used
Growth is confluent
The wrong agar was used
Inoculum is too light
17
Bacitracin is the A disk.
False
True
18
Beta-lactamases can be transported out of the cell and act extracellularly in some organisms.
True
False
19
Define "synergy"
Effectiveness is not changed when drugs are combined
Variable effectiveness when drugs are combined
Decreased effectiveness when drugs are combined
Increased effectiveness when drugs are combined
20
This
Proteus
inoculum has swarmed up to the disk. How should this be interpreted?
The growth was not confluent and the test is inconclusive
It should be measured around the 80% reduction of growth
Zone of inhibition is zero and should be reported as resistant
The swarm should be ignored and measured as normal
21
Define "indifference"
Increased effectiveness when drugs are combined
Effectiveness is not changed when drugs are combined
Variable effectiveness when drugs are combined
Decreased effectiveness when drugs are combined
22
The concentration which will kill >99.9% of organisms is:
Maximum bacteriocidal concentration
Minimum bacteriostatic concentration
Minimum bacteriocidal concentration
Maximum bacteriostatic concentration
23
Define Bacteriostatic
Stimulates organisms
Surprises organisms
Kills organisms
Inhibition of microbial growth
24
Define the AST outcome "susceptible".
The antibiotic is effective at higher-than-normal doses
The effectiveness could not be assessed
The antibiotic would be effective
The antibiotic would not be effective
25
Which of the following are required for performing a Kirby-Bauer AST?
Incubation at 40C
16 to 18 hours of incubation before interpretation
Disks must be applied within 15 minutes after inoculation
Confluent inoculum on MH
26
Vancomycin is typically used to target which organisms?
MRSA
Streptococcus spp.
Clostridium difficile
Enterococcus spp.
27
Define "Bactericidal".
Inhibits organisms
Depresses organisms
Kills organisms
Stimulates organisms
28
Define empiric
To treat existing disease
Therapy based on traditional treatment methods
Therapy preventing infection
Therapy based on observation and experience of clinician
29
In microdilution, how is MIC determined?
By the last well showing growth
By the first well showing growthing
By the first well showing no growth
By the last well showing no growth
30
Describe the mechanism of beta-lactams.
Blocks metabolite formation
Binds to transpeptidase enzymes, preventing the formation of peptide bonds
Blocks gyrase binding
Blocks final stages of peptidoglycan synthesis
31
Define the AST outcome "intermediate".
The antibiotic would not be effective
The antibiotic would be effective
The effectiveness could not be assesed
The antibiotic would be effective at higher than normal doses
32
Vancomycin works on:
Gram positive organisms only
On GNR when given orally
All types of bacteria
Gram negative organisms only
33
Bacteriostatic drugs slow microbe growth to give the body time to kill it.
True
False
34
Which of the following are types of antibiotics?
Semisynthetic
Synthetic
Natural
Hormonal
35
Antibiotic gradient is also known as:
E test
Disk diffusion
Automated instrumentation
Broth dilution
36
Group B drugs are screened during an AST only upon physician request.
True
False
37
Beta-lactamase can be produced at low levels, causing organisms to initially test as susceptible and become resistant.
False
True
38
What are considerations when deciding to perform an AST?
Isolate is probably the cause of patient's infection
Body site from which the organism was isolated
Standardized testing methods are available for the isolate
Susceptibility of the isolate to a particular antimicrobial is uncertain
39
What is VRSA?
Vancomycin susceptible Staphylococcus aureus
Viridans strain Staphylocuccus adenii
Vanrhoden resistant Staphylococcus aureus
Vancomycin Resistant Staphylococcus aureus
40
Which of the following organisms require CO2 for disk diffusion AST?
Proteus mirabilis
Streptococcus pneumonia
Proteus
Haemophilus influenzae
41
Define therapeutic
To treat existing disease
Therapy preventing infection
Therapy based on traditional treatments
Therapy based on observation and experience of clinician
42
Which of the following antibiotics should you interpret where there is an 80% reduction of growth?
Vancomycin
Trimethoprim-sulfamethoxazole
Erythromycin
Tetracycline
43
What two antibiotics are contraindicated in pediatric patients?
Tetracycline and fluoroquinolones
Tetracycline and ceclor
Augmentin and erythromycin
Cleocin and zithromax
44
What is VISA?
Vancomycin Intermediate Staphylococcus aureus
Zinacef intermediate Staphylococcus aureus
Vallium induced Streptococcus aureus
Vancomycin Resistant Staphylococcus aureus
45
This beta-lactamase test is:
Negative
Positive
Invalid
Inconclusive
46
Vancomyocin is always given intravenously,
EXCEPT
for which of the following?
Clostridium difficile infections
Enterococcus spp.
Streptococcus spp.
MRSA infections
47
Which of the following are targets of antibiotics?
Interruption of cell wall or membranes
Interruption of protein synthesis
Interruption of conjugation
nucleic acid metabolism
48
Bacitracin is used to identify:
Enterobacter spp.
Group A Streptococcus (GAS)
Staphylococcus aureus
Giardia
49
Disk diffusion is the most established and best proven AST method.
True
False
50
Which of the following are beta-lactamase inhibitors?
Sulbactam
Clavulanic acid
Tazobactam
Naladixic acid
51
Group C drugs are screened during an AST only upon physician request.
True
False
52
Which of the following are used to screen for ESBL?
Cefazolin (CZ)
Ceftazidime (CAZ)
Ceftriaxone (CRO)
Amoxicillin (AmC)
53
Which of the following cause penicillin resistence?
Candidiasis
Altered PBPs
Beta-lactamase
Golgi apparatus
54
What is PRSP?
Primary resistance or susceptibility program
Penicillin resistent Streptococuspneumoniae
Providence registry of served prescriptions
PMP recording service and publication
55
How are Disk Diffusion ASTs interpreted?
Diameter of inhibition zones are measured in micrometers
Diameter of inhibition zones are measured in millimeters
Radii of inhibition zones are measured in millimeters and multiplied by two
Radii of inhibition zones are measured in centimeters and multiplied by two
56
Which of the following organisms require MH with 5% sheep blood instead of plain MH agar for disk diffusion AST?
Streptococcus pneumonia
Haemophilus influenzae
Proteus mirabilis
Proteus
57
Which of the following is a beta-lactamase inhibitor?
Nitrocefin
Cefinase
Sulfanilic acid
Clavulanic acid
58
How can antibiotic resistance be mitigated?
Improving patient compliance
Prescribing newer, more powerful agents
Preventing over prescription
Correctly prescribing for the correct organism
59
What type of organisms does vancomycin (Va) target?
Gram negative bacteria
Gram positive bacteria
Giardia
Mycobacteria
60
Which of the following are required for performing a Kirby-Bauer AST?
Inoculum 0.5 McFarland made with fresh 16-24 hour colonies
pH 7.2 to 7.4 at room temperature
MH agar at least 4mm thick
E test strips
61
Which of the following are
not
considered when choosing antimicrobials for an AST?
Physical limitations of the plate
CLSI standards
Toxicity
Age of the patient
Doctor's familiarity with the drug
Cost
62
How should this be interpreted?
The results are inconclusive and should not be measured
It should be measured from peak to peak
CAZ is never used for AST, so the test is invalid
It should be measured from where growth is inhibited by 80%
63
Define prophylactic.
Therapy preventing infection
Therapy based on traditional treatment methods
To treat existing disease
Therapy based on observation and experience of clinician
64
Cefoxitin (FOX) is used to screen for MRSA
True
False
65
Age is
not
a factor when determine which antimicrobials are tested during an AST.
False
True
