L26: Tetracylclines/Macrolides - condensed

Question 1

Which class of drug does Erythromycin, Clarithromycin, and Azithromycin belong to?
A. Ketolides
B. Glycylcyclines
C. Tetracyclines
D. Macrolides

Answer 1

D. Macrolides

Question 2

Which part of the bacterial 70S subunit is targeted by tetracyclines and aminoglycosides?
A. 50S
B. 30S

Answer 2

B. 30S

Question 3

Which part of the bacterial 70S subunit is targeted by clindamycin and macrolides?
A. 50S
B. 30S

Answer 3

A. 50S

Question 4

True or False: Tetracylines are considered to be bacteriocidal

Answer 4

False - bacteriostatic

Question 5

True or False: Tetracylines enter bacteria via: passive diffusion and active transport, then reversibly bind 30S to block binding of next aminoacyl-tRNA to ribosome

Answer 5

True

Question 6

Two main clinical uses of Tetracycline?
A. MRSA
B. Acne/Chlamydial Infections

Answer 6

B. Acne/Chlamydial Infections

Question 7

Why are tetracyclines often not a drug of choice for gram (+) aerobic infections?

Answer 7

Resistance w/staph, strep, and pneumococci

Question 8

Which gram (-) bacteria is resistant to tetracycline? anaerobe?

Answer 8

gram (-): Psuedomonas
anaerobe: B. fragilis

Question 9

True or False: Tetracyclines can be used for periodontal disease (as in minocycline microspheres)

Answer 9

True

Question 10

Which two conditions are primarily treated with Doxy?

Answer 10

1. MRSA
2. Chlamydia

Question 11

True or False: Tetracyclines have limited use, since large number of bacterial strains are resistant

Answer 11

True

Question 12

Proteus and Pseudomonas are resistant to…
A. Tetracycline
B. Tigecycline
C. Doxycycline

Answer 12

B. Tigecycline

Question 13

True or False: Tetracyclines are time and concentration dependent killing

Answer 13

True

Question 14

True or False: Tetracyclines do not cross placental barrier

Answer 14

False - they do

Question 15

How are doxy and tigecycline excreted?

Answer 15

Non-renal mechanisms

Question 16

3 AE’s associated with tetracyclines?

Answer 16

1) Nausea, vomiting
- can dose with food, but not dairy
2) Superinfections (C.dif)
3) Discoloration and enamel dysplasia

Question 17

True or False: Macrolides are associated with skin sensitivity to sun

Answer 17

False - tetracyclines

Question 18

Nephrotoxicity (Fanconi syndrome) can result from use of degraded ______
A. tetracyclines
B. macrolides
C. glycyclines

Answer 18

A. tetracyclines

Question 19

What are two reasons why drug resistance occurs in Tetracyclines?

Answer 19

1) Impaired drug influx or increased efflux via transporters
2) Expression of proteins that interfere w binding to 30S subunit

Question 20

Why is tigecycline effective for tetracycline resistant strains?

Answer 20

Efflux drug pumps are not effective in that case

Question 21

In gram (-) bacteria, older tetracyclines may be pumped out by ____ pump

In Staphylococci, tetracycline can be pumped out by the ____ efflux pump

In gram (+) bacteria, _____ protein causes the tetracyclines to “let go” of ribosome

Answer 21

Tet(AE) pump

Tet(K) efflux pump

Tet(M) ribosomal protection protein

Question 22

True or False: Chromosomal efflux pumps in Proteus and Pseudomonas a. can pump out all tetracyclines, even tigecycline

Answer 22

True

Question 23

True or False: Like tetracyclines, macrolides are bacteriostatic. However, unlike tetracyclines, they reversibly bind to the 50S ribosomal subunit

Answer 23

True

Question 24

True or False: Macrolides inhibit transcription step and use time-independent killing

Answer 24

False - translocation step; time-dependent

Question 25

____, the prototypical macrolide, acts against S. aureus to treat diptheria, pneumonia, and chlamydial infections. A. Erythromycin B. Clarithromycin C. Azithromycin

Answer 25

A. Erythromycin

Question 26

True or False: Azithromycin is an alternative for penicillin-allergic patients for Streptococci and Staphylococci infections

Answer 26

False - Erythromycin

Question 27

Which macrolide has activity against Toxoplasma and M. leprae? A. Erythromycin B. Clarithromycin C. Azithromycin

Answer 27

B. Clarithromycin

Question 28

True or False: Clarithromycin has better activity against H. influenzae than erythromycin does

Answer 28

True

Question 29

____, a 15 membered ring and macrolide, can treat urethritis and cervicitis due to N. gonorrhoeae and Chlyamydia

Answer 29

Azithromycin

Question 30

Uses of Azithromycin?

Answer 30

1) OM 2) Pharyngitis 3) COPD exacerbations 4) Community acquired pneumonia - H. influenze, Legionella

Question 31

Which macrolide is less active than other gram (+) or (-) staph/strep, but more active for H. Influenzae?

Answer 31

Azithromycin

Question 32

Which macrolide is given as enteric coated oral capsule, since stomach acid destroys free base + food interferes with absorption?

Answer 32

Erythromycin

Question 33

True or False: Azithromycin is taken up in the CNS

Answer 33

false - is not

Question 34

Which two macrolides inhibit P450?

Answer 34

Erythromycin + Clarithromycin

Question 35

True or False: Diarrhea is an AE associated with Erythromycin

Answer 35

True

Question 36

True or False: Prolonged QT intervals, hepatitis, and C. dif superinfections are AE associated with tetracyclines

Answer 36

False - macrolides

Question 37

Drug resistance can occur in ___ because there is modified ribosome drug binding site via: chromosomal mutation or ribosome methylation (ermA, B, etc.) A. tetracyclines B. macrolids

Answer 37

B. macrolides

Question 38

Mutations in ermA, B confer resistance to MLS-Type B, which means....

Answer 38

M: Macrolides L: Lincosamides D: Streptogramins

Question 39

_____ inhibit 30S ribosomal subunit. Diminishing use due to resistance, though dox still good for chlamydia and tigecycline may help overcome resistance. ______ inhibit 50S ribosomal subunit. Three drugs differ primarily in toxicities and 1/2 life. Resistance is an issue.

Answer 39

Tetracyclines Macrolides