Antimicrobial Resistance and Susceptibility Flashcards Preview

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Flashcards in Antimicrobial Resistance and Susceptibility Deck (43):
1

Which is the most important superbug associated with hospitals?

Carbapenem- resistant K. pneumoniae

2

Which of the following are most common in hospitals and the community, including livestock and companion animals?

a. Methicillin-resistant S. aureus (MRSA)
b. ESBL-producing E. coli
c. Multidrug resistant S. pneumoniae
d. A and C
e. A and B
f. B and C

e. A and B

3

True/ False. Antibiotic therapy is only recommended for invasive infections.

True.

4

Which drugs have a resistance to Salmonella?

Cephalosporins or fluoroquinolones

5

Which drugs have a resistance to Campylobacter?

Macrolides or fluoroquinolones

6

True/ False. MDR (multi drug resistant) bacteria are usually resistant to all drugs except cephalosporins.

False. They are resistant to cephalosporins

7

Which of the following are beta-lactam resistant?

a. MRSA
b. MRSP
c. ESBL
d. All the above

d. All the above

8

What does MRSA stand for?

Methicillin Resistant Staphylococcus Aureus

9

True/False. MRSA and MRSP have the lowest affinity to penicillins and cephalosporins.

True.

10

Which of the following MRSA is associated with livestock?

a. CC8
b. CC22
c. CC398
d. CC9

c. CC398

11

What does MRSP stand for?

Methicillin Resistant Staphylococcus Pseudintermedius

12

True/False. Approximately 70% of MRSP cases are skin and wound postsurgical infections acquired in the clinic.

True.

13

What does ESBL stand for?

Extended Spectrum Beta Lactamase

14

What is ESBL?

It is an enzyme hydrolyzing/inactivating most Beta lactams produced by gram-negative bacteria

15

What is the only beta lactam ESBL does not hydrolyze/inactivate?

Carbapenems

16

True ESBLs are susceptible to B- lactamase inhibitors such as _____.

Clavulanic acid

17

What are the three main ESBL classes?

CTX-M
SHV
TEM

18

Which is the most common type of ESBL in animals?

a. CMY-2
b. CTX-M-2
c. CTX-M-1
d. CMY-1

c. CTX-M-1

19

A false ESBL (resistant to Beta-lactamase inhibitors) is widespread in small animals and limited to poultry

CMY-2

20

Which ESBL type can be transferred horizontally from E.coli livestock to E.coli in humans?

CTX-M-1

21

How do bacteria acquire resistance?

Mutation
Horizontal gene transfer by transformation, transduction, and conjugation

22

What is transduction?

A transfer mediated by phage delivery

23

True/False. Antimicrobial resistance is a qualitative property.

False. Its a quantitative property

24

What are the two dilution methods for AST?

Broth dilution tests
Agar dilution tests

25

What are the two agar diffusion methods for AST?

Disk/tablet diffusion test (semi-quantitative)
Gradient diffusion E test (quantitative)

26

___ is the lowest concentration that inhibits completely growth of the test strain.

MIC (minimum inhibitory concentration)

27

What is MBC (Minimum bactericidal concentration)

The lowest concentration that kills the test strain

28

True/False. Diffusion method has a high reproducibility and robustness, whereas dilution method has a medium reproducibility and robustness.

False. Diffusion method has a MEDIUM reproducibility and robustness, whereas dilution method has a HIGH reproducibility and robustness.

29

Is the dilution method more expensive or cheaper than the diffusion method?

More expensive than diffusion

30

True/False. Standardization and quality control are required for reproducibility of AST.

True.

31

How is quality control done?

-Reference strains of different species are routinely included in the testing (every day, or every week)
-MIC of the reference strain has to fall within a given range
-If not within a range the test will not be valid and should be repeated

32

What is the incubation period for the AST laboratory test?

35 Degrees C for 16-20 hours

33

What is a breakpoint?

A drug-specific value to interpret the results of susceptibility testing and determine if an antibacterial is potentially useful in the treatment of a bacterial infection.

34

A strain is defined as ___ by a level of antimicrobial activity associated with a high likelihood of therapeutic success.

Susceptible

35

A strain is defined as ___ by a level of antimicrobial activity associated with a high likelihood of therapeutic failure.

Resistant

36

What is the standard range of a susceptible MIC? Resistant MIC?

less than or equal to 4 = susceptible
greater than or equal to 32 = resistant

37

What data is needed for setting breakpoints?

1. MIC distribution to determine MIC value that separates the WT population from resistant populations
2. PD/PK index
3. Clinical and bacteriological outcome data from clinical trials

38

When is a strain defined as wild type (WT) for a species?

By the absence of any acquired resistance genes and/or mutations increasing the MIC of the antimicrobial agent

39

If a strain is ___ for AST, it is inhibited at blood concentrations achieved by standard dosage of the drug.

Susceptible

40

Clinical efficacy is possible if the strain infects body sites where the drug concentrates or if the dosage can be increased compared to standard dosage.

Intermediate

41

Resistant for AST

The strain is NOT inhibited at blood concentrations achieved by standard dosage of the drug.

42

What are the two drugs used for detection of MRSA/MRSP?

Oxacillin
Cefoxitin

43

True/False. Strains resistant to oxacillin/cefoxitin should be regarded as susceptible to all beta lactams.

False. They are resistant to Beta lactams