Ch 87: Aminoglycosides: Bactericidal Inhibitors of Protein Synthesis

Question 1

The aminoglycosides are…

Answer 1

…narrow-spectrum antibiotics used primarily against aerobic gram-negative bacilli; they are bactericidal inhibitors of protein synthesis.

(p. 1050)

Question 2

Why must aminoglycosides be administered parenterally?

Answer 2

These drugs are highly polar, and thus cannot be absorbed from the GI tract.

(p. 1050)

Question 3

Which aminoglycosides are used most commonly?

Answer 3

gentamicin, tobramycin, and amikacin

p. 1050

Question 4

What is the postantibiotic effect?

Answer 4

When bactericidal activity persists for several hours AFTER serum levels have dropped below the minimal bactericidal concentration.

(p. 1050)

Question 5

Which of the aminoglycosides is least susceptible to inactivation by bacterial enzymes?

Answer 5

amikacin

p. 1050

Question 6

Which key microorganisms are susceptible to aminoglycosides?

mnemonic

Answer 6

(think of KPEPS
Klebsiella pneumoniae
Pseudomonas aeruginosa
Escherichia coli
Proteus mirabilis
Serratia marcescens

(p. 1050)

Question 7

Aminoglycosides are highly polar polycations. As a result….

Answer 7

…they are not absorbed from the GI tract, do not cross the blood-brain barrier, and are excreted rapidly by the kidneys.

(p. 1056)

Question 8

Aminoglycosides can cause…

Answer 8

…irreversible injury to sensory cells of the inner ears, resulting in hearing loss and disturbed balance.

(p. 1056)

Question 9

The risk of ototoxicity is related primarily to…

Answer 9

…persistently elevated trough drug levels, rather than to excessive peak levels.

(p. 1056)

Question 10

Aminoglycosides are nephrotoxic, but…

Answer 10

…renal injury is usually reversible.

p. 1056

Question 11

What is the risk of nephrotoxicity from aminoglycosides related to?

Answer 11

The total cumulative dose AND elevated trough levels.

p. 1056

Question 12

Monitoring of serum levels when treating with aminoglycosides is common. Peak levels must be high enough to…
Trough levels must be low enough to…

Answer 12

…cause bacterial kill.

…minimize toxicity to the inner ears and kidneys.

(p. 1056)

Question 13

The first sign of impending vestibular damage is…

Answer 13

…headache.

p. 1053

Question 14

The first sign of impending cochlear damage is…

Answer 14

…high-pitched tinnitus (ringing in the ears).

p. 1053