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D&D Infectious Disease Midterm > Pharm - Macrolides + Lincosamides > Flashcards

Pharm - Macrolides + Lincosamides Flashcards

1
Q

macrolides contain a macrocyclic lactone ring. this ring usually contains how many atoms?

what is attached to the ring?

A

14-16

deoxy sugars

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2
Q

name 4 macrolides

A

erythromycin
clarithromycin
azithromycin
telithromycin

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3
Q

differentiate between the structure of erythromycin vs clarithromycin

A

clarithromycin has a CH3 at R2 rather than an H

that’s the only difference

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4
Q

recap: fedaxomycin chemical class and brief MOA

A

also a macrolide!!

c diff RNA synthesis inhibitor

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5
Q

are macrolides static or cidal

A

static

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6
Q

is spectrum of macrolides (like erythromycin) narrow or broad

A

BROAD - many gram pos and neg

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7
Q

explain MOA of macrolides***

A

reversibly binds 50s subunit - specifically 23s rRNA

seems to inhibit the translocation step — peptide chain at the A site can’t move to P (donor) site

also, they may binds and cause a conformational change that stops protein synthesis by indirectly interfering with transpeptidation and translocation

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8
Q

true or false

macrolide antibiotics bind irreversibly to the 50s 23S rRNA subunit

A

false

reversibly (everything else right)

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9
Q

3 mechanisms of macrolide resistance

A
  1. reduce permeability or increased efflux
  2. production of esterases that hydrolyze macrolides
  3. (main) - modify the ribosomal binding site of rna by chromosomal mutation OR by macrolide-inducable methylase
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10
Q

what is

“MLS Type B resistance”

A

resistance mechanism in which the ribosomal binding site is altered by chromosomal mutation

MLS = macrolides, lincosamides, streptogramins

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11
Q

important consideration with MLS antibiotics

A

once there’s MLS resistance to one of the AB’s, cant use any others in MLS (CROSS RESISTANCE!!! COMMON AND COMPLETE)

also, don’t use the MLS antibiotics together bc they act at similar place

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12
Q

_____ and _______ are the most important resistance mechanisms in gram positive organisms against macrolides

A

efflux and methylase production

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13
Q

As mentioned, esterases can be produced to hydrolyze macrolides as a resistance mechanism

which bacteria in particular does this

A

enterobacteriaceae

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14
Q

how do macrolides come and why

A

as ENTERIC COATED tablets - bc they’re susceptible to acid - want to release in small intestine.

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15
Q

how are macrolides largely excreted

A

in the BILE (feces)

only 5% in urine!

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16
Q

do macrolides cross placenta?
what about brain and CSF?

A

cross placenta but NOT brain and CSF

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17
Q

______ delays absorption of macrolides

A

food

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18
Q

MAJOR clinical uses of macrolides

A

for resp tract infections (CAP)

and for pen allergic ppl with staph or strep infections

acne (good against anaerobes!)

19
Q

2 main toxicities of macrolides

A

cardiac (arrythmia, QT prolongation)

hepatotoxicity (hepatitis)

also NVD - broad spectrum

20
Q

macrolides are administered as salts

which of these salts is the most hepatotoxic

A

estolate salt

21
Q

DDI concern with macrolides

A

they are metabolized by the CYP system in the liver. they are reversible inhibitors of CYPS (3A4, A12, 2C9)

this can increase the concentrations of some drugs - can be dangerous if they have narrow therapeutic index

22
Q

advantage of clarithromycin over erythromycin

A

clar has improved acid stability and oral absorption

23
Q

advantage of azithromycin over erythro and clar

A

NO DDI

because of its structure - doesnt really inhibit the CYPS

24
Q

which macrolide is less susceptible to resistance, BUT can also exacerbate myasthenia gravis

A

telithromycin

25
Q

indication telithromycin

A

CAP

26
Q

azithromycin is better than erythromycin for _____ and less active than eryth and clar for _______

A

azi better than ery for H. influenzae

less active than eryth and clar for staph and strep

27
Q

clindamycin is a _____-substituted derivative of ______

A

chlorine substituted derivative of lincomycin

28
Q

true or false

clindamycin is not a macrolide

A

TRUE - it is a lincosamide

29
Q

name 2 things that are resistant to clindamycin and what can be used instead

A

enterococci and gram negative aerobic

use aminoglycosides! very good against gram negative aerobic

30
Q

clindamycin has the same mechanism as…..

A

macrolides!!

31
Q

explain the spectrum of clindamycin

A

broad spectrum - both gram pos and neg

IS active against anaerobes (remember - can be used for acne)

enterobacter and gram negative aerobic are RESISTANT

32
Q

true or false

clindamycin has the same binding site and mechanism as macrolides

A

TRUE

33
Q

3 resistance mechanisms for clindamycin

A
  1. mutation of ribosomal receptor site
  2. modify receptor by constitutively expressed methylase (MLS-B)
  3. enzymatic inactivation of clindamycin
34
Q

can clindamycin be used against community acquired MRSA

A

YES

35
Q

name some clinical uses of clindamycin

A

SSTI caused by step and stap (covers gram +!)

community strains of MRSA

prevent endocarditis in pen allergies

36
Q

clindamycin can be used in combo with a ____ or ____ to penetrate the wounds of the abdomen and gut, and for femal genital tract infections

A

cephalosporin or aminoglycoside

will cover gram (-) aerobe

37
Q

clindamycin + ___________ is used for pneumocystis jiroveci pneumonia in AIDS patients

A

primaquine

38
Q

clindamycin can be used in _______ as a secondary agent

A

malaria

39
Q

clindamycin + ___________ can treat AIDS-related toxoplasmosis of the brain

A

pyrimethamine

40
Q

common AE clindamycin

A

NVD
skin rash

41
Q

serious and rare AE of clindamycin

A

neuromuscular block (in combo with neuromuscular drugs)

pseudomembranous colitis (inflammation of colon lining) that causes abdominal pain, mucus, blood in stool, impaired liver fx, etc

42
Q

true or false

clindamycin is NOT effective against gram negative anaerobes

A

FALSE - it is

not active against gram negative aerobes

43
Q
A

D&D Infectious Disease Midterm (26 decks)

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