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Pharmacology > L29: Misc Antimicrobials > Flashcards

L29: Misc Antimicrobials Flashcards

1
Q

Which of the following is a Nitroimidazole?
A. Metronidazole
B. Nitrofuratoin
C. Rifaximin
D. Fidaxomicin

A

A. Metronidazole

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2
Q

Which class do Fidaxomicin, Rifaximin, Nitrofurantoin, and Metroidazole belong to?
A. Ribosome Agents
B. DNA/RNA Agents

A

B. DNA/RNA Agents

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3
Q

Linezolid, Chloramphenicol, and Clindamycin are ___ agents
A. Ribosome
B. DNA/RNA

A

A. Ribosome

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4
Q

What is an example of a Lincomycin?

What is an example of a Oxazolidinone?

A

Lincomycin
- Clindamycin

Oxazolidinones
- Linezolid

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5
Q

_____ damages DNA and is bactericidal (concentration dependent and rapid)
A. Metronidazole
B. Nitrofuratoin
C. Rifaximin
D. Fidaxomicin

A

A. Metronidazole

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6
Q

How does Metronidazole damage DNA?

A

Intracellular accumulation, then redox reactions w/ferredoxin (low O2 tension required!)

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7
Q

True or False: Metronidazole is active against aerobic microbes (amoeba, protozoa, gram - bacteria)

A

False - anaerobic

Note: There is low O2 tension found in anaerobes

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8
Q

Which of the following is curative for Trichomoniasis?
A. Metronidazole
B. Nitrofuratoin
C. Rifaximin
D. Fidaxomicin

A

A. Metronidazole

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9
Q

True or False: Resistance to metronidazole is limited

A

True

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10
Q

3 AE’s associated with Metronidazole?

A

1) Metallic taste, headache
2) Peripheral neuro, seizures, ataxia
3) BBW - carcinogen

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11
Q

True or False: Metronidazole should be avoided in 1st trimester of pregnancy

A

True

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12
Q

Which drug is the choice for gram (-) anaerobic infections?
A. Metronidazole
B. Nitrofuratoin
C. Rifaximin
D. Fidaxomicin

A

A. Metronidazole

  • less effective against gram (+) anaerobes and facultatives
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13
Q

____ is a urinary antiseptic that inhibits DNA/RNA/Proteins and is only used to treat lower UTI’s (not pyelo)
A. Metronidazole
B. Nitrofuratoin
C. Rifaximin
D. Fidaxomicin

A

B. Nitrofuratoin

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14
Q

Nitrofurantoin MOA involves bacterial reduction to high reactive ___

A

intermediates

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15
Q

Can patients w/bad kidneys use Nitrofurantoin?

A

no - contraindicated

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16
Q

AE associated w Nitrofurantoin?

A

1) Appetite suppression
2) Neuropathy, C. dif, Pulm tox

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17
Q

True or False: While acquired resistance is uncommon w/Nitrofurntoin use (and there is no cross resistance) – Pseudomonas and Proteus are innately resistant

A

True

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18
Q

Where do both Rifaximin and Fidaxomicin accumulate when given orally?

A

Gut/Feces

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19
Q

Both Rifaximin and Fidaxomicin bind and inhibit bacterial ____
A. RNA
B. DNA
C. DNAP
D. RNAP

A

D. RNAP

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20
Q

____ is a rifamycin, like rifampin. It treats gram (+) (-) and aerobes/anaerobes

____ is good for gram (+) and anaerobes, but NOT gram (-)

A

Rifaximin; Fidaxomicin

21
Q

Two clinical uses of Rifaximin?
A. Acne/C. Dif
B. Traveler’s Diarrhea and C. diff
C. Only C. dif

A

B. Traveler’s Diarrhea and C. diff

22
Q

Clinical use of Fidaxomicin?
A. Acne/C. Dif
B. Traveler’s Diarrhea and C. diff
C. Only C. dif

A

C. Only C. dif

23
Q

____ belongs to the lincosamide class (note: only 1 drug belongs to this class) and has identical binding site to macrolides on 50S ribosomal rubunit. It is BACTERIOSTATIC !!
A. Clindamycin
B. Chloramphenicol
C. Linezolid

A

A. Clindamycin

24
Q

Which drug is good against anaerobes and non-bacterial infections and can be used to treat skin/soft tissue infections caused by strep/staph in patients allergic to penicillin or community acquired MRSA/ORSA?
A. Clindamycin
B. Chloramphenicol
C. Linezolid

A

A. Clindamycin

25
Q

Which two agents are resistant to clindamycin?

A

Enterococci and gram (-) anaerobes

26
Q

True or False: Clindamycin distributes to abscesses and is concentrated in phagocytic cells

A

True

27
Q

Which drug is among the worst antimicrobial for promoting C. dif?

A

Clindamycin

28
Q

Mutation / methylation of binding site on ribosome (MLS-Type B) is associated with use of which drug?

A

Clindamycin

29
Q

Why do strains that are resistant to macrolides due to efflux respond to clindamycin?

A

Clindamycin is not a substrate for efflux pumps

30
Q

True or False: Clindamycin induces methylase expression, so cross resistance with macrolides from methylation relies on constituitively active enzyme

A

False - clindamycin does NOT induces methylase expression, so cross resistance with macrolides from methylation relies on constituitively active enzyme (D Test)

31
Q

What does a positive D test mean, in the case of Clindamycin?

A

Methylase is present that may mutate to become constitutive

32
Q

______, a streptogramins B that has same binding site and mechanism as macrolides (50S)
A. Dalfopristin
B. Quinupristin

A

B. Quinupristin

33
Q

True or False: Both Qunupristin and Dalfopristin are rapidly bactericidal

A

True

34
Q

What is the function of Dalfopristin in Qunupristin-Dalfopristin?

A

Changes ribosome shape, making it easier for Qunupristin to bind (blocks PP formation)

35
Q

Two uses of Qunupristin-Dalfopristin?

A

1) Gram (+) infections
2) Infective endocarditis

36
Q

Both Qunupristin-Dalfopristin inhibit which CYP enzyme?

A

CYP3A4

37
Q

What are three ways by which drug resistance develops in Qunupristin-Dalfopristin?

A

1) Increased drug efflux of dalfopristin
2) MLS-Type B
- Modified ribosomal drug binding site via chromosomal mutation, ribosome methylation
3) Enzymatic inactivation

38
Q

How do Oxazolidinones work?
A. Binds to A site
B. Binds to P site

A

B. Binds to P site, prevents formation of translation initiation complex by binding 23S on 50S

39
Q

True or False: Oxazolidinones are bacteriostatic and have no cross resistance w/other 50S drugs

A

True

40
Q

Four uses of Oxazolidinones?

A
  1. Gram (+) anaerobe
  2. Strep/Staph MRSA
  3. Infections caused by E. faecium
  4. VRE, gram (+) anaerobes
41
Q

Which drug class is associated with headaches, thrombocytopenia, mitochondrial toxicity?

A

Oxazolidinones

42
Q

What causes drug resistance in Oxazolidinones?

A

Point mutation in 23S rRNA of the 50S ribosomal subunit

43
Q

____ reversibly binds to 50S subunit (site close to macrolides and clindamycine) and prevents peptide bond formation. It is BACTERIOSTATIC.

A

Chloramphenicol

44
Q

True or False: Chloramphenicol can bind to 80S ribosome and mitochondrial 70S ribosome

A

False - it can bind to mitochondrial 70S but not 80S

45
Q

Four uses of Chloramphenicol?

A
  1. Broad spec against gram +/-
  2. Ricettsiae
  3. Anaerobes
  4. Bacterial meningitis tx with severe B-lactam allergy
46
Q

Gray Baby Syndrome (due to poor glucuronic acid conjugation) and Aplastic Anemia are AE associated with use of _____

A

Chloramphenicol

47
Q

What causes drug resistance in Chloramphenicol?

A

Increased expression of inactivating enzyme Chloramphenicol Acetyltransferase

48
Q

ok

A

Pharmacology (53 decks)

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