Macrolides, Fluroquinolones, Aminoglycosides

Question 1

Macrolides include which antibiotics?

Answer 1

Erythromycin
Azithromycin
Clarithromycin
Telithroycin (ketolide)
Fidaxomicin

Question 2

The MOA of Macrolides:

Answer 2

Inhibition of protein synthesis via the 50S ribosomal subunit
Bacteriostatic

Question 3

Which two drugs should you not use macrolides with and why?

Answer 3

Clindamycin and chloramphenicol

Overlaps with binding site creating competition and no benefit

Question 4

What types of organisms are macrolides effective agains?

Answer 4

Gram + and intracellular bac
Atypical org: Chlamydia, Mycoplasma, Legionella
CAP, acute bac sinusitis, acute exacerbation of chronic bronchitis
MAC (azithro, clarithro)
H.pylori (clarithro)

Question 5

Which macrolide has the longest half-life and what does this mean about treatment?

Answer 5

Azithromycin

Can give a 3-5day course and intracellular levels can continues for days (Z-pak)

Question 6

What is different about the macrolide fidaxomicin (Dificid) and how is it used?

Answer 6

Bacteriocidal against Gram + anaerobes/aerobes

Used in the treatment of C.diff (minimal systemic absorption, excreted in the feces)

Question 7

AE of macrolides include:

Answer 7

GI distress
Hepatotoxicity, esp telithromycin (ex-don’t use to treat sinusitis)
Dose-dependent ototoxicity (prolonged, high doses)

Question 8

DI of erythromycin, clarithromycin, telithromycin:

Answer 8

Inhibition of CYP3A4

Telithromycin is also a substrate of CYP3A4

Question 9

Which macrolide produces the least amount of DI and can be considered your ‘safest’?

Answer 9

Azithromycin

Question 10

Quinolones include which drugs?

Answer 10

Norfloxacin
Ciprofloxacin
Ofloxcin (topical)
Levofloxacin
Sparfloxacin
Lomefloxacin
Moxifloxacin
Trovafloxacin

Question 11

What is the MOA of quinolones?

Answer 11

Inhibit DNA gyrase

Bacteriocidal

Question 12

How may resistance to quinolones occur?

Answer 12

Mutation change in DNA gyrase

Question 13

Quinolones cover which organisms and how is this related to the treatment of CAP?

Answer 13

Gram +, -, and atypicals, M. Tb
(poor anaerobic coverage)

To cover a patient for CAP you can prescribe ceftriaxone and azithromycin (Gram+ and atypical coverage) or prescribe quinolone alone which has broader spectrum coverage and drop to just one more narrow spectrum once pneumonia isolated

Question 14

What is true of the IV and oral forms of quinolones?

Answer 14

They share bioequivalence

Question 15

What patient populations are quinolones CI in?

Answer 15

Children, pregnancy, breastfeeding

Question 16

Quinolones can cause what serious AE?

Answer 16

Erosion of cartilage that can lead to tendinitis and tendon rupture

Question 17

Other AE of Quinolones include:

Answer 17

QTc prolongation
Photosensitivity/phototoxicity
Hepatic damage (trovafloxacin)

Question 18

How are quinolones cleared from the body?

Answer 18

Renally

Question 19

DI with quinolones include:

Answer 19

Antacids and other products containing cations significantly decrease absorption (bind and prevent absorption)

Question 20

Which quinolone is good for the treatment of Pseudomonas, UTIs, and intra-abdominal infections?

Answer 20

Ciprofloxacin

Question 21

Which quinolone is broad spectrum and good for the treatment of Pseudomonas, UTIs, URIs, and is the L isomer of ofloxacin?

Answer 21

Levofloxacin

Question 22

Which quinolone is used for BMT prophylaxis?

Answer 22

Norfloxacin

Question 23

Aminoglycosides include:

Answer 23

Amikacin
Gentamicin 
Tobramycin (IV, IM)
Neomycin (oral, topical, 
Streptomycin (IM)

Question 24

How is streptomycin’s MOA different from other aminoglycosides?

Answer 24

MOA: Inhibits initiation of bacterial protein synthesis

Only 1st line AG for TB

Question 25

What is the MOA for most aminoglycosides?

Answer 25

Irreversible binding to the 30S ribosomal unit

Produces misreading of bacterial mRNA resulting in faulty bacterial protein synthesis

Question 26

Aminoglycosides are bacteriocidal and demonstrate _____ dependent killing.

Answer 26

concentration

Peak levels are important = need high enough concentrations for drug to be bacteriocidal

Question 27

What type of organisms do aminoglycosides cover?

Answer 27

Gram - , including Pseudomonas

Question 28

Which drug class do aminoglycosides have synergy with?

Answer 28

Beta-lactams

often for treatment with Gram + endocarditis

Question 29

What is the post antibiotic effect associated with aminoglycosides?

Answer 29

The drug levels in plasma have subsided yet the antibiotic continues to have effect d/t the irreversible binding to the 30S subunit. Trough monitoring to monitor for toxicity and prevent accumulation of drug

Question 30

Are aminoglycosides hydrophilic or lipophilic and how does that affect them?

Answer 30

Hydrophilic
Poor oral absorption
Not significantly metabolized (renally excreted)
Lack CNS penetration

Question 31

AE of aminoglycosides include:

Answer 31

Ototoxicity (highest risk from streptomycin)
Nephrotoxicity (others more than streptomycin)
Neuromuscular blockade with high doses

Question 32

What should be monitored in a patient taking aminoglycosides?

Answer 32

Serum Cr
Peak and trough levels if pt: unstable renal func, unstable volume status, poor clinical response, change in aminoglycoside dose

Question 33

When are peak levels not necessary for an aminoglycoside?

Answer 33

When using gentamicin for Gram + synergy

Question 34

In treatment with aminoglycosides peaks are drawn for _______ and troughs are drawn for ______.

Answer 34

Efficacy

Toxicity

Question 35

Aminoglycoside peak and trough parameters:

Answer 35

Peak: 10-20mg/L (3-5mg/L for synergy)
Trough: <1mg/L

Question 36

What is often prescribed for traveller’s diarrhea?

Answer 36

Cipro