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Flashcards in Macrolides and Fluoroquinones Deck (67):
1

Macrolides are what general antibiotic type and for what are they named?

Protein synthesis inhibitors
Named for large macrolide ring structure

2

What is a prototype macrolide?

Erythromycin

3

What drug does Erythromycin act like in its antibacterial activity?

Penicillin, which is a cell wall inhibitor.

4

What are the 2 new macrolides that are semisynthetic with an extended spectrum and improved pharmacokinetics?

Azithromycin
Clarithromycin

5

What are the 2 new macrolides, Azithromycin and Clarithromycin used for?

Alternatives to penicillins for prophylaxis of bacterial endocarditis

6

What structure in the Macrolide makes it easily hydrolyzed in the stomach and thereby inactivating a large part of the drug?

The lactone ring

7

What is the erythromycin spectrum of activity (bacteriostatic/cidal), what bacteria is it active against?

Narrow spectrum
Bacteriostatic
Gram Positive Cocci

8

What is the spectrum of activity for Azithromycin and Clarithromycin?

somewhat broader, to include activity against gram negatives like H. influenza

9

What is the macrolide mechanism of action?

bind to 50S bacterial ribosome subunit to inhibit ribosomal translocase activity

10

What does inhibiting translocase activity of the 50S subunit mean?

It stops transfer of nascent peptide from A site to P site which stop the next amino acid from being added

11

Can Erythromycin be bacteriocidal?

Yes, depending on concentration of developing bacterial resistance

12

What is good about narrow spectrum in antibiotics?

It reduces the risk of developing bacterial resistance

13

What is the drawback of erythromycin's method of delivery and how is it avoided?

Destroyed by stomach acid so give w/ enteric coating or as ester salt (estolate, state)

14

What is the major difference in Azithromycin and Clarithromycin from Erythromycin?

Azithromycin and Clarithromycin are not sensitive to stomach acid

15

If bacteria are resistant to Erythromycin, Azithromycin, Clarithromycin, what does that mean for other drugs that bind the 50S subunit?

Bacteria are most likely resistant to those as well

16

What are the other two 50S subunit binding protein synthesis inhibitor antibiotics?

Clindomycin
Chloramphenicol

17

Of Erythromycin, Azithromycin, and Clarithromycin: which has the longest half-life?

Azithromycin (60-70 hrs)

18

What cells do Azithromycin and Clarithromycin concentrate in?

Macrophages

19

Azithromycin and Clarithromycin, due to their concentration in Macrophages, are useful against what opportunistic infection commonly found in HIV and immunocompromised patients?

Mycobacterium avium intracellulaire

20

Where is erythromycin metabolized?

Liver

21

What is the positive with the longer half-lives of Azithromycin and Clarithromycin?

Require dosing only 1-2 times/day

22

Most common side effects of Macrolides (erythromycin, azithromycin, clarithromycin)?

Gi disturbances

23

What metabolism do macrolides mess with leading to their drug interactions?

Inhibit cytochrome P450 drug metabolism by liver

24

How is Azithromycin metabolized?

In urine and bile, so it is safe for a person with liver disease.

25

What is the most common mechanism for resistance to Macrolides in bacteria?

Plasmids encoding erythromycin efflux transporters or methylation enzymes

26

What is Macrolide dosing for endocarditis prophylaxis that Dr. Ritter gave?

500 mg, 30-60 mins before surgery

27

What is a rare risk factor associated with erythromycin?

Cholestatic jaundice from ester salts of erythromycin interrupting bile flow

28

What Penicillin Class is Erythromycin similar to?

Penicillin G

29

When would a macrolide be indicated?

Patient with penicillin allergy
Bacteria is penicillin resistant

30

What are 2 infections macrolides are commonly used to treat?

Respiratory (pneumonia, mycoplasm, Legionella) Skin

31

What is a prototype Fluoroquinolone?

Ciprofloxacin

32

What are 3 major advantages of Fluoroquinolones?

Oral effectiveness
Activity toward gram positive and gram negative
Safe

33

Is Ciprofloxacin (fluoroquinolone) bacteriocidal or bacteriostatic? What bacteria is it effective against?

Bacteriocidal
Gram Positive and Gram Negative

34

What is the method of action of Fluoroquinolone?

Inhibit DNA replication by inhibiting bacterial enzyme DNA gyrase

35

Bacterial DNA gyrase is related to what in humans and what are their purposes?

Human DNA topoisomerases
Relieve buildup of torsional strain during DNA replication

36

What is an administration consideration with fluoroquinolones?

don’t take with dairy or antacids because they bind divalent and trivalent metal cations(like tetracyclines do as well)

37

Which fluoroquinolone is useful for the treatment of UTIs because it does not have as good tissue penetration as Ciprofloxacin and Ofloxacin?

Norfloxacin

38

What can block the excretion of fluoroquinolones?

Probenecid (used in war to prolong supplies of penicillin [internet])

39

What is huge contraindiction for using fluoroquinolones?

Do not use in pregnant/nursing women or children under 18 due to potential to damage growing cartilage (Achilles tendon rupture)

40

What is a notable drug interaction for fluoroquinolones?

They increase plasma levels of warfarin

41

Which quinolone (older group) is used only for UTIs?

Nalidixic Acid

42

Large Glycopeptide druge whose most important use is treatment of Methicillin Resistant Staphylococcus infections (MRSA)

Vancomycin

43

Is vancomycin bactericidal or static?

bactericidal

44

What is vancomycin's method of action?

inhibit cell wall synthesis but by different mechanism than penicillin

45

What is vancomycin the DOC for?

Treating pseudomembranous colitis from clindamycin

46

What are 2 methods of administration for vancomycin and is it absorbed systemically?

Intravenous (IV)
Orally (125 mg 4/day)
No systemic absorption

47

How is vancomycin excreted?

Kidney

48

What are 2 side effect risks from vancomycin?

Ototoxicity
Nephrotoxicity

49

What is the mechanism of action for bacitracin?

Inhibit transport of building blocks of cell wall to outside cell membrane

50

What is the clinical use of bacitracin?

Topical treatment of skin & eye bacterial infections

51

With what drugs is bacitracin used in combination?

Polymyxin B and Neomycin

52

Clindamycin is an alternative drug for what?

Alternative to amoxicillin for endocarditis prophylaxis

53

What is the dosing of Clindamycin before surgery for endocarditis prophylaxis?

600 mg 30-60 min before surgery

54

Given how good it is against anaerobes, when should Clindamycinbe be used?

Late phase dental infections (bacteroides, prevotella, porphyromonas, fusobacterium)

55

For what is Clindamycin the DOC?

Anaerobic infections (e.g. B. fragilis)

56

What are 3 protein synthesis inhibitor drugs that are alternatives to amoxicillin for prophylaxis of endocarditis?

Azithromycin
Clarithromycin
Clindamycin

57

What is the major risk with Clindamycin?

Enterocolitis due to C. diff overgrowth (superinfection)

58

What is the drug used to treat the superinfection caused by Clindamycin?

Vancomycin (vancomycin vanquishes the turds)

59

What are two drugs other than Nalidixic acid and Norfloxacin that are used for UTIs?

Nitrofurantoin
Methenamine

60

Which five drugs are used to treat M. tuberculosum?

1. Isoniazid
2. Ethambutol
3. Rifampin/Rifampicin
4. Pyrazinamide
5. Streptomycin

61

Which are the three major agents used to treat M. tuberculosum?

1. Isoniazid
2. Ethambutol
3. Rifampin

62

What is THE major agent used for M. tuberculosum

Isoniazid

63

Isoniazid has hepatotoxicity when paired with what other Tb drug?

Rifampin/Rifampicin

64

What is the mechanism of action for methambutol?

inhibits synthesis of tubercle bacilli cell wall component

65

What is the mechanism of action for Rifampin?

inhibits DNA-dependent RNA polymerase

66

What is the tuberculosis drug that is an inducer of hepatic microsomal drug-metabolizing enzymes leading to many drug-drug interactions?

Rifampin

67

Why should you use a drug cocktail to treat tuberculosis?

Tuberculosis is slow growing with high mutation and resistant rates.