L26: Tetracylclines/Macrolides - condensed Flashcards
Which class of drug does Erythromycin, Clarithromycin, and Azithromycin belong to?
A. Ketolides
B. Glycylcyclines
C. Tetracyclines
D. Macrolides
D. Macrolides
Which part of the bacterial 70S subunit is targeted by tetracyclines and aminoglycosides?
A. 50S
B. 30S
B. 30S
Which part of the bacterial 70S subunit is targeted by clindamycin and macrolides?
A. 50S
B. 30S
A. 50S
True or False: Tetracylines are considered to be bacteriocidal
False - bacteriostatic
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
True
Two main clinical uses of Tetracycline?
A. MRSA
B. Acne/Chlamydial Infections
B. Acne/Chlamydial Infections
Why are tetracyclines often not a drug of choice for gram (+) aerobic infections?
Resistance w/staph, strep, and pneumococci
Which gram (-) bacteria is resistant to tetracycline? anaerobe?
gram (-): Psuedomonas
anaerobe: B. fragilis
True or False: Tetracyclines can be used for periodontal disease (as in minocycline microspheres)
True
Which two conditions are primarily treated with Doxy?
- MRSA
- Chlamydia
True or False: Tetracyclines have limited use, since large number of bacterial strains are resistant
True
Proteus and Pseudomonas are resistant to…
A. Tetracycline
B. Tigecycline
C. Doxycycline
B. Tigecycline
True or False: Tetracyclines are time and concentration dependent killing
True
True or False: Tetracyclines do not cross placental barrier
False - they do
How are doxy and tigecycline excreted?
Non-renal mechanisms
3 AE’s associated with tetracyclines?
1) Nausea, vomiting
- can dose with food, but not dairy
2) Superinfections (C.dif)
3) Discoloration and enamel dysplasia
True or False: Macrolides are associated with skin sensitivity to sun
False - tetracyclines
Nephrotoxicity (Fanconi syndrome) can result from use of degraded ______
A. tetracyclines
B. macrolides
C. glycyclines
A. tetracyclines
What are two reasons why drug resistance occurs in Tetracyclines?
1) Impaired drug influx or increased efflux via transporters
2) Expression of proteins that interfere w binding to 30S subunit
Why is tigecycline effective for tetracycline resistant strains?
Efflux drug pumps are not effective in that case
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
Tet(AE) pump
Tet(K) efflux pump
Tet(M) ribosomal protection protein
True or False: Chromosomal efflux pumps in Proteus and Pseudomonas a. can pump out all tetracyclines, even tigecycline
True
True or False: Like tetracyclines, macrolides are bacteriostatic. However, unlike tetracyclines, they reversibly bind to the 50S ribosomal subunit
True
True or False: Macrolides inhibit transcription step and use time-independent killing
False - translocation step; time-dependent
____, the prototypical macrolide, acts against S. aureus to treat diptheria, pneumonia, and chlamydial infections.
A. Erythromycin
B. Clarithromycin
C. Azithromycin
A. Erythromycin
True or False: Azithromycin is an alternative for penicillin-allergic patients for Streptococci and Staphylococci infections
False - Erythromycin
Which macrolide has activity against Toxoplasma and M. leprae?
A. Erythromycin
B. Clarithromycin
C. Azithromycin
B. Clarithromycin
True or False: Clarithromycin has better activity against H. influenzae than erythromycin does
True
____, a 15 membered ring and macrolide, can treat urethritis and cervicitis due to N. gonorrhoeae and Chlyamydia
Azithromycin
Uses of Azithromycin?
1) OM
2) Pharyngitis
3) COPD exacerbations
4) Community acquired pneumonia - H. influenze, Legionella
Which macrolide is less active than other gram (+) or (-) staph/strep, but more active for H. Influenzae?
Azithromycin
Which macrolide is given as enteric coated oral capsule, since stomach acid destroys free base + food interferes with absorption?
Erythromycin
True or False: Azithromycin is taken up in the CNS
false - is not
Which two macrolides inhibit P450?
Erythromycin + Clarithromycin
True or False: Diarrhea is an AE associated with Erythromycin
True
True or False: Prolonged QT intervals, hepatitis, and C. dif superinfections are AE associated with tetracyclines
False - macrolides
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
B. macrolides
Mutations in ermA, B confer resistance to MLS-Type B, which means….
M: Macrolides
L: Lincosamides
D: Streptogramins
_____ 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.
Tetracyclines
Macrolides
