Updated: 2/27/2019

Aminoglycosides

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Topic
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N/A
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Questions
4
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Evidence
6
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Topic
Snapshot
  • A 24-year-old woman presents to the emergency room for abdominal pain and foul-smelling discharge from her vagina. About 4 days ago, she gave birth to twins via C-section and was sent home without complications. Yesterday, she developed a fever as well as abdominal pain. On physical exam, there is significant tenderness to palpation. She is started on intravenous antibiotic therapy with 2 agents, covering both anaerobes and aerobic gram-negative organisms. (Postpartum endometritis)
Introduction
  • Drugs
    • amikacin
    • gentamicin
    • neomycin
    • streptomycin
    • tobramycin
  • Mechanism of action
    • irreversibly binds to 30S subunit of bacterial ribosomes
      • prevents initiation complex from forming
      • causes misreading of genetic code
    • requires oxygen for uptake and is effective only against aerobes
    • works synergistically with beta-lactams
    • bactericidal
  • Mechanism of resistance
    • bacterial enzymes inactivate the drug by modifying it through adenylation, acetylation, or phosphorylation
  • Clinical use
    • severe aerobic gram-negative rod infections
      • including Pseudomonas aeruginosa, Acinetobacter, Nocardia, and Actinomycetes
      • P aeruginosa resistant to gentamicin and tobramycin are often susceptible to amikacin
    • neomycin for bowel surgery
    • topical neomycin for superficial skin infections
  • Adverse effects
    • irreversible ototoxicity (cochlear and vestibular)
      • increased with loop diuretics
    • nephrotoxicity
      • increased with cephalosporins
    • neuromuscular blockade
    • teratogen

Please rate topic.

Average 4.5 of 6 Ratings

Questions (4)

(M1.MC.17.4754) A 67-year-old African American male presents to the emergency room complaining of nausea and right flank pain. He reports that these symptoms have worsened over the past two days. His past medical history is notable for congestive heart failure, hypertension, hyperlipidemia, and diabetes mellitus. He currently takes aspirin, losartan, metoprolol, atorvastatin, hydrochlorothiazide, furosemide, and metformin. He is allergic to fluoroquinolones. His temperature is 102.9°F (39.4°C), blood pressure is 100/50 mmHg, pulse is 120/min, and respirations are 28/min. On exam, he demonstrates right costovertebral angle tenderness. Urinalysis reveals 30 WBCs/hpf and positive leukocyte esterase. He is admitted and started on a broad-spectrum combination intravenous antibiotic. He recovers well and is discharged with plans to follow up in 2 weeks. At his follow-up, he reports that he has developed transient visual blurring whenever he turns his head to the right or left. He also reports that he has fallen at home multiple times. What is the mechanism of action of the drug that is most likely responsible for this patient’s current symptoms?

QID: 108930
1

Inhibition of ribosomal 30S subunit

36%

(117/326)

2

Inhibition of ribosomal 50S subunit

20%

(64/326)

3

Inhibition of dihydropteroate synthase

17%

(56/326)

4

Inhibition of transpeptidase

9%

(29/326)

5

Inhibition of DNA gyrase

12%

(40/326)

M 4 C

Select Answer to see Preferred Response

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(M1.MC.13.3) You are treating a neonate with meningitis using ampicillin and a second antibiotic, X, that is known to cause ototoxicity. What is the mechanism of antibiotic X?

QID: 100068
1

It binds the 50S ribosomal subunit and inhibits peptidyltransferase

5%

(18/351)

2

It binds the 50S ribosomal subunit and inhibits formation of the initiation complex

16%

(56/351)

3

It binds the 30s ribosomal subunit and inhibits formation of the initiation complex

60%

(209/351)

4

It binds the 30s ribosomal subunit and reversibly inhibits translocation

14%

(48/351)

5

It binds the 50s ribosomal subunit and reversibly inhibits translocation

5%

(16/351)

M 1 E

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Evidence (6)
EXPERT COMMENTS (4)
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