Ch 86: Bacteriostatic Inhibitors of Protein Synthesis: Tetracyclines, Macrolides, and Others

Question 1

Tetracyclines are generally…

Answer 1

…bacteriostatic inhibitors of protein synthesis.

p. 1037

Question 2

What are the 4 tetracyclines available in the U. S.?

Answer 2

demeclocycline
doxycycline
minocycline
tetracycline

(p. 1037)

Question 3

Tetracyclines are first-line agents for…

Answer 3

1) rickettsial diseases
2) infections caused by Chlamydia trachomatis
3) brucellosis
4) cholera
5) pneumonia caused by Mycoplasma pneumoniae
6) Lyme disease
7) anthrax
8) gastric infection with H. pylori

(p. 1037)

Question 4

The tetracyclines form insoluble chelates with…

This is why tetracyclines should not be administred with medications or food containing any of these elements.

Answer 4

…calcium, iron, magnesium, aluminum, and zinc.

p. 1038

Question 5

Which drugs are preferred for tetracycline-responsive infections in patients with renal impairment?

Answer 5

Doxycycline and minocycline

p. 1038

Question 6

What are the key adverse effects associated with use of tetracyclines?

Answer 6

Hepatotoxicity, renal toxicity, photosensitivity, vestibular toxicity, discoloration of the teeth, and GI irritation.

(p. 1039)

Question 7

What kind of drugs are macrolides?

Answer 7

Broad-spectrum, bacteriostatic antibiotics that inhibit protein synthesis.

(p. 1040)

Question 8

What are the three examples of macrolides?

Answer 8

erythromycin (the oldest member), azithromycin, and clarithromycin

(p. 1040)

Question 9

What conditions is erythromycin the first drug of choice for?

Answer 9

Whooping cough caused by Bordetella pertussis
Acute diptheria caused by Corynebacterium diphtheriae
Some chlamydial infections (urethritis, cervicitis)
Pneumonia caused by M. pneumoniae

(p. 1041)

Question 10

Does erythromycin penetrate to the CSF?

Answer 10

No.

p. 1041

Question 11

How is erythromycin primarily eliminated?

Answer 11

by concentration in the liver and excretion into the bile

p. 1041

Question 12

What are the key adverse effects of erythromycin?

Answer 12

GI effects, QT prolongation, transient hearing loss, and hypertrophic pyloric stenosis in infants

(p. 1041)

Question 13

Which isoenzyme of the P450 system metabolizes erythromycin?

Answer 13

CYP3A4

p. 1041

Question 14

Which important drugs can erythromycin increase plasma levels of?

Answer 14

Warfarin, carbamazepine, and theophylline

p. 1042

Question 15

What is a benefit of using oral clarithromycin or azithromycin over oral erythromycin?

Answer 15

These 2 drugs do not cause the intense nausea that erythromycin does.

(p. 1042)

Question 16

Clindamycin can promote severe…

Answer 16

….C. diff. associated diarrhea.

p. 1042

Question 17

What types of microbes is clindamycin active against?

Answer 17

Most anaerobic bacteria (both gram + and gram -), and most gram + aerobes.

(p. 1043)

Question 18

What kind of drug is linezolid?

Answer 18

It’s a first-in-class oxazolidinone antibiotic.

p. 1043

Question 19

What important pathogens are linezolid used against?

Answer 19

VRE (Vancomycin-resistant enterococci) and MRSA

p. 1043

Question 20

Linezolid is active primarily against…

…but NOT active against…

Answer 20

…aerobic and facultative gram + bacteria.
…gram - bacteria

(p. 1044)

Question 21

What are the most common side effects of linezolid?

And what are the rare serious side effects?

Answer 21

diarrhea, nausea, and headache

reversible myelosuppression, reversible optic neuropathy, and irreversible peripheral neuropathy

(p. 1044)