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Lindsey's D&D Unit 3 > Antibacterial Agents IV: DNA Function Inhibitors > Flashcards

Antibacterial Agents IV: DNA Function Inhibitors Flashcards

1
Q

What drugs interact with Metronidazole?

A

inhibitors and inducers of CYP450

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2
Q

Tx for Giardia lamblia giardiasis?

A

Metronidazole

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2
Q

Give an example of resistance due to escape.

A

Sulfonamides are noncompetitively antagonized by methionine, homocysteine, serine, purines, and thymine

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3
Q

What are the adverse rxns for Nitrofurantoin use?

A

GI upset, occasionally hypersensitivity rxns, neuropathy, birth defects

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3
Q

Tx of Pseudomonas aeruginosa burn infections?

A

topical silver sulfadiazine

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4
Q

Why are Sulfonamides selectively toxic?

A

humans don’t synthesize their own folic acid

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5
Q

Tx of Plasmodium (resistant) malaria?

A

sulfadoxine + pyrimethamime

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6
Q

How do the Sulfonamides work?

A

they’re analogs of PABA that competitively inhibit dihydropteroate synthetase (enzyme used to synthesize folic acid)

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6
Q

What drug can predispose neonates to kernicterus? Why?

A

Sulfonamides; its protein binding displaces bilirubin

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6
Q

Tx of MRSA skin infections?

A

TMP/SMX

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7
Q

Name the Abx that inhibit DNA function (4).

A
  1. fluoroquinolones (-floxacin) 2. Nitrofurantoin 3. Metronidazole 4. Sulfonamides (Sulfa-)
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7
Q

Sulfonamides have synergy with _____, which inhibits dihydrofolate reductase (DHFR).

A

trimethoprim (TMP)

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8
Q

What is the tx for Staph. aureus (MSSA) skin infections?

A

levofloxacin, moxifloxacin, gemifloxacin (respiratory quinolones)

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8
Q

Inhibitors of _____ have increased potential for human toxicity.

A

dihydrofolic acid reductase

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9
Q

Tx for Entamoeba histolytica amebiasis?

A

Metronidazole

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10
Q

Tx for C. diff diarrhea, pseudomembranous colitis?

A

Metronidazole

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10
Q

Sulfonamides have synergy with trimethoprim (TMP), which inhibits _____.

A

dihydrofolate reductase (DHFR)

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11
Q

Name the 4 fluoroquinolones.

A
  1. ciprofloxacin 2. levofloxacin 3. gemifloxacin 4. moxifloxacin
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11
Q

Name 3 methods of resistance that Sulfonamides use?

A
  1. acquired (increased PABA or altered DHPS) 2. escape (end products from pus) 3. natural (no folic acid req = not susceptible)
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12
Q

Tx for Clost. perfringens gas gangrene, food poisoning?

A

Metronidazole

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13
Q

Tx for Trichomonas vaginalis trichomoniasis?

A

Metronidazole

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15
Q

What is the mechanism of action of the fluoroquinolones?

A

inhibits DNA gyrase and topo IV

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16
Q

Tx for Helicobacter pylori gastritis, peptic ulcers?

A

Metronidazole

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16
Q

Tx of U.C.?

A

sulfasalazine

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17
Q

Tx of Moraxella catarrhalis otitis media?

A

TMP/SMX

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19
Q

What are the adverse rxns for the fluoroquinolones?

A

GI upset, CNS issues, QT elongation, skin rashes, abn glucose, tendon rupture, arthropathies

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19
Q

What is TMX/SMX?

A

trimethoprim/sulfamethoxazole combo drug (sulfonamide class)

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20
Q

Tx of Norcardia nocardiosis?

A

sulfisoxazole, sulfadiazine

21
Q

What is the tx for Moraxella catarrhalis sinusitis, bronchitis?

A

levofloxacin

21
Q

What is the tx for Chlamydia trachoma, C.A. pneumonia, urethritis?

A

moxifloxacin, gemifloxacin

22
Q

Why do antacids negatively affect fluoroquinolones?

A

they reduce oral absorption of cipro

23
Q

What is the tx for Myco. pneumoniae C.A. pneumonia?

A

moxifloxacin, gemifloxacin

24
Q

Why do Sulfonamides have a delayed onset of action?

A

the folate stores have to be depleted

25
Q

How is Metronidazole absorbed, distributed, and metabolized?

A

GI not affected by food; good dist including CSF and bone; hepatic metabolism

27
Q

What is the tx for Bacilllis anthracis anthrax?

A

ciprofloxacin

28
Q

Sulfonamides are ____ spectrum Abx.

A

broad

30
Q

How are fluoroquinolones absorbed, distributed, metabolized, and excreted?

A

A: orally or parenterally D: into most tissues, including bone, fat, muscle, prostate, repro organs, and urine M: minimal E: kidney

31
Q

____ should cease until 24-48 hours post Metronidazole therapy because _____.

A

Breast feeding; it can be carcinogenic

32
Q

Is Metronidazole bactericidal or bacteriostatic?

A

bactericidal

33
Q

Combination use of Sulfonamides + trimethoprim (TMP) is BACTERIOSTATIC/BACTERICIDAL.

A

BACTERICIDAL

34
Q

Trimethoprim (TMP), used with sulfonamides, is also used in combination with _____.

A

sulfamethoxazole

36
Q

What is Nitrofurantoin used for?

A

URIs

36
Q

Are Sulfonamides bacteriostatic or bactericidal?

A

bacteriostatic

38
Q

What is the tx for Strep. pneumoniae pneumonia, chronic bronchitis, acute sinusitis?

A

levofloxacin, moxifloxacin, gemifloxacin (respiratory quinolones)

40
Q

Which drug is contraindicated in pregnancy and in children under 18yo?

A

fluoroquinolones

42
Q

Why is Nitrofurantoin selectively toxic?

A

mammalian enzymes don’t reduce Nitrofurantoin as rapidly

44
Q

What are the adverse rxns for Metronidazole?

A

nausea, dry mouth, headache, metallic taste, candida superinfections

45
Q

Where do bacteria obtain methionine, homocysteine, serine, purines, and thymine used to escape (resistance)?

A

from pus

46
Q

How does resistance to fluoroquinolones occur, and how often?

A

point mutations in the binding site on DNA gyrase, or a change in drug permeability- plasma mediated; 10^7-10^9 organisms

47
Q

What is the absorption, distribution, metabolism, and excretion of the sulfonamides?

A

well absorbed from the GI tract on an empty stomach but with plenty of fluids; distributed widely in body water including pleural, ocular, synovial fluid, and CSF- crosses placenta; N-acetylated to inactive compound; excreted by kidney with increasing pH and in breast milk

48
Q

Which drugs interact with the fluoroquinolones?

A

theophylline (esp with ciprofloxacin), antacids (with cipro)

49
Q

Tx of Shigella diarrhea?

A

TMP/SMX (preferred over quinolones in children)

51
Q

What is the mechanism of action for Metronidazole?

A

transformed into a reactive nitro radical anion that breaks DNA and inhibits replication

52
Q

What happens to the urine in Nitrofurantoin use?

A

it turns brown

53
Q

Tx of Klebsiella, Proteus, Enterobacter UTIs?

A

TMP/SMX

54
Q

What is the tx for Pseudomonas aeruginosa, E. coli, Klebsiella, Serratia, Proteus, Enterobacter, Shigella, Salmonella UTIs and traveler’s diarrhea?

A

ciprofloxacin, levofloxacin

55
Q

How does Nitrofurantoin work?

A

reduced by bacterial enzymes to intermediates that damage bacterial DNA

57
Q

Is Nitrofurantoin bacteriostatic or bactericidal?

A

both, depending on the conc

58
Q

What is the tx for Richettsia rocky mountain spotted fever, Q fever?

A

moxifloxacin, gemifloxacin

59
Q

What are the 6 adverse rxns with Sulfonamides?

A
  1. sensitization rxns 2. renal damage 3. hemolytic anemia in G6PD pts 4. GI upset 5. category C in pregnancy 6. drug interactions (bilirubin, oral anticoagulants, sulfonylurea hypoglycemic agents)
60
Q

______ have synergy with trimethoprim (TMP), which inhibits dihydrofolate reductase (DHFR).

A

Sulfonamides

61
Q

Tx for Bacteriodes fragilis intraabd and brain abscesses?

A

Metronidazole

62
Q

How is Nitrofurantoin absorbed and excreted?

A

complete from GI tract; into urine via filtration and excretion

64
Q

What is the tx for H. influenzae lower RI, pneumonia?

A

moxifloxacin, levofloxacin

64
Q

Tx of Staph. aureus conjunctivitis?

A

sulfacetamide

65
Q

What should be avoided during Metronidazole therapy?

A

alcohol, pregnancy, breast-feeding

67
Q

Tx of Chlamydia trachoma, C.A. pneumonia, urethritis?

A

TMP/SMX

68
Q

Choose: Fluoroquinolones are BACTERICIDAL/BACTERIOSTATIC.

A

bactericidal

69
Q

Tx of Pneumocystis carinii pneumonia?

A

TMP/SMX

Lindsey's D&D Unit 3 (12 decks)

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