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Immunity, Infection and Disease > Antifolate Drugs and DNA Gyrase Inhibitors > Flashcards

Antifolate Drugs and DNA Gyrase Inhibitors Flashcards

1
Q

What type of drugs are sulfonamides?

A

Antifolate drugs

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2
Q

What molecule are sulfonamides structural analogs of and what is the use of this molecule?

A

PABA, it is needed by organisms to form Dihydrofolic acid to produce purines

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3
Q

What enzyme do sulfonamides inhibit and do they do it competitively or non-competitively?

A

Competitively inhibit dihydropteroate synthase (thus reversibly blocking folic acid synthesis)

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4
Q

Are sulfonamides bacteriocidal or bacteriostatic?

A

Bacteriostatic

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5
Q

Why are mammalian cells not affected by sulfonamides?

A

We lack the enzymes for folate synthesis (instead we use exogenous folate)

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6
Q

Two gram-positive organisms that are susceptible to sulfonamides

A

Staphylococcus aureus, and Listeria

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7
Q

5 gram-negative organisms that are susceptible to sulfonamides

A

Escherichia coli, Klebsiella, Salmonella, Shigella, Enterobacter

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8
Q

Two protozoa that are susceptible to sulfonamides

A

Pneumocystis jiroveci (carinii), toxoplasma

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9
Q

Two atypical bacteria that are suscpetible to sulfonamides

A

Nocardia, chlamydia

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10
Q

Sulfonamides are not active against what type of bacteria?

A

Pseudomonas

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11
Q

Three mechanisms of sulfonamide resistance

A

1) Overproduction of PABA, 2) Production of folic acid-synthesizing enzyme with low sulfonamide affinity, 3) Loss of permeability to sulfonamides

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12
Q

Which sulfonamides are oral, absorbable (include the indication for each)

A

Sulfasoxazole and sulfamethoxazole (UTIs), Sulfadiazine (toxoplasmosis), sulfadoxine (malaria 2nd line)

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13
Q

Which sulfonamides are oral, nonabsorbable (include the indication for each)

A

Sulfasalazine - ulcerative colitis, enteritis, other inflammatory bowel diseases

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14
Q

Which sulfonamides are topical (include the indication for each)

A

Sodium sulfacetamide (ophthalmic) - conjuctivitis, Mafenide acetate - burn wounds, Silver sulfadiazine - burn wounds (less toxic than mafenide)

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15
Q

Which sulfonamides are IV (include indications for each)

A

Sulfamethoxazole (in combination with trimethoprim) - pneumocystis pneumonia, shgellosis, salmonella, stenotrophomas, UTIs, prostatitis, tyhpoid

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16
Q

How do sulfonamides cause hypoglycemia?

A

They can augment insulin release

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17
Q

How do sulfonamides cause renal tubular acidosis?

A

They inhibit carbonic anhydrase

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18
Q

Hematologic AEs of sulfonamides

A

Hemolytic or aplastic anemia, granulocytopenia, thrombocytopenia, hemolytic rxns in pts with G6PD deficiency

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19
Q

Sulfonamides given in the third trimester might have what effect on the newborn?

A

Kernicterus

20
Q

Allergic rxns to sulfonamides

A

Type I (IgE), Serum sickness, Skin eruptions

21
Q

Idiosyncratic rxns to sulfonamides

A

Hepatitis, Stevens-Johnson, toxic epidermal necrolysis

22
Q

Sulfonamide antibiotics are cross-allergenic with what classes of drugs?

A

Carbonic anhydrase inhibitors, thiazides, furosemide, bumetanide, torsemide, diazoxide, sulfonylurea

23
Q

What enzyme does trimethoprim inhibit and what does this enzyme do?

A

Inhibits bacterial dihydrofolic acid reductase (converts dihydrofolic acid to tetrahydrofolic acid for folic acid synthesis)

24
Q

Indications for trimethoprim

A

UTIs

25
Q

What enzyme does pyrimethamine inhibit and what does this enzyme do

A

Inhibits dihydrofolic acid reductase in PROTOZOA. This is necessary for folic acid synthesis

26
Q

Indications for pyrimethamine

A

Toxoplasmosis, malaria, pneumocystis jiroveci pneumonia (2nd line)

27
Q

What is the effect of giving trimetoprim or pyrimethamine together with a sulfa drug?

A

Blocks sequential steps in purine synthesis, has bacteriCIDAL effect

28
Q

Mechanisms of trimethoprim/pyrimethamine resistance

A

1) Reduced cell wall permeability, 2) Overproduction of dihydrofolate reductase, 3) Production of altered dihydrofolate reductase (OFF: Resistance is often plasma encoded)

29
Q

AEs of trimethoprim and pyrimethamine

A

Megaoloblastic anemia, leukopenia, granulocytopenia (also nausea, vomiting, drug fever, vasculitis, diarrhea, elevations of hepatic aminotransferases, hyperkalemia, hyponatremia) |S S p600

30
Q

What is used as prophylaxis to prevent hematologic side effects of trimethoprim and pyrimethamine?

A

Folinic acid (but dont use when treating pneumocystis pneumonia in AIDS pts)

31
Q

What is the trimethoprim-sulfamethoxazole combination not used much in URI or penumonia?

A

Increased resistance amongst pneumococci, also its not active against pseudomonas species

32
Q

In severe infections, the dosing of TMP-sulfametoxazole is based on which component?

A

The TMP component

33
Q

What is the mechanism of fluoroquinolones?

A

Inhibit bacterial topoisomerase II (DNA gyrase) and topoisomerase IV

34
Q

Which fluorquinolone is least affected by bacterial efflux pumps and why?

A

Moxifloxacin, has a bulky side chain

35
Q

Which tends to be more susceptible to fluoroquinolones, enterococci or staphylococci?

A

Staphylococci

36
Q

Which fluoroquinolones are active against atypical organisms (eg Chlamydia), intracellular pathogens (eg Legionella) and Tb and M. Avium complex?

A

All fluoroquinolones

37
Q

What type of drug is nalidixic acid and what is it used for?

A

A first generation fluoroquinolone, UTIs

38
Q

List second generation fluoroquinolones (six total, two important)

A

Cirpofloxacin (Cipro) and Levofloxacin (Levaquin). Also enoxacin, lomefloxacin, ofloxacin, pefloxacin

39
Q

Is ciprofloxacin most active against Gram-negative or Gram-positive organisms?

A

Gram-negative

40
Q

Which is better against Gram-positive organisms, ciprofloxacin or levofloxacin?

A

Levofloxacin

41
Q

List third generation fluoroquinolones (six total, two important)

A

Moxifloxacin (Avelox) and Gemifloxacin (Factive). Also clinafloxacin, gatifloxacin (tequin), sparfloxacin, and trovafloxacin (trovan)

42
Q

What is the main improvement from second to third generation fluoroquinolones?

A

Better activity against gram-positive organisms

43
Q

Which is better against gram-negative organisms, a 2nd or a 3rd generation fluoroquinolone?

A

Cipro (a 2nd gen) is better than the 3rd gens

44
Q

Which fluoroquinolone has the best anti-anaerobic activity?

A

Moxifloxacin (a 3rd generation)

45
Q

What type of medication should not be given within 2 hours of fluoroquinolone administration and why?

A

Antacids, they impair fluoroquinolone bioavailability

46
Q

Which fluoroquinolone does not require renal dose adjustment?

A

Moxifloxacin

47
Q

AEs of fluoroquinolones

A

Most minor. GI distress, headache, dizziness, insomnia, skin rash, abnormal LFTs, arthropathy, tendonitis, torsades de pointes, allergic rxns

Immunity, Infection and Disease (86 decks)

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