protein synthesis inhibitors

Question 1

MOA clindamycin

Answer 1

inhibit protein synthesis by binding only to 50S

Question 2

clindamycin: bacteriostatic or bactericidal?

Answer 2

bacteriostatic

Question 3

MOR clindamycin

Answer 3

presence of erm gene, which alters the 50S binding site

no activity of mef gene against clindamycin

Question 4

main area of use for clindamycin

Answer 4

anaerobic infections
peptostreptococcus
actinomyces
bacteriodes (use metronidazole instead)
prevotella
fusobacterium
clostridium spp. (excluding C. difficile)

Question 5

best way to test for CA MRSA resistance to clindamycin?

Answer 5

SSSI infections due to MRSA, give clindamycin to see if theyre susceptible or not

Question 6

clindomycin have to be givenIV or PO?

Answer 6

no, completely and rapidly absorbed (90%)

Question 7

CSF distribution clindomycin?

Answer 7

poor distribution

Question 8

clindomycin eliminated by hemodialysis?

Answer 8

no

Question 9

elimination mechanism for clindomycin?

Answer 9

primarily by liver

Question 10

primary clinical use clindomycin

Answer 10

anaerobic infections outside of the CNS, SSSI infections due to CA MRSA

Question 11

the one major adverse effect clindomycin

Answer 11

one of the worst inducers of C. difficile colitis

Question 12

3 macrolides in clinical use

Answer 12

erythromycin, clarithromycin, azithromycin

Question 13

improvements due to purifying erythromycin into azithromycin and clarithromycin

Answer 13

better bioavailability
better tissue penetration
prolonged half lives
improved tolerability

Question 14

MOA macrolides

Answer 14

inhibit protein synthesis by binding the 50S subunit to suppress protein synthesis

Question 15

macrolides: bacteriostatic or bactericidal

Answer 15

bacteriostatic

Question 16

MOR macrolides in the US

Answer 16

mef gene encoding active efflux which confers a low level of resistance to macrolides

Question 17

MOR macrolides in Europe

Answer 17

erm gene encoding altered target sites on 50S which confers a high level of resistance to macrolides

Question 18

spectrum of activity for macrolides in G- aerobes (including macrolides rankings)

Answer 18

H. influenzae (not erythromycin)
M. catarrhalis
Neisseria
azithromycin > clarithromycin > erythromycin

Question 19

G- bacteria group that macrolides have NO activity against

Answer 19

enterobacteriacieae

Question 20

spectrum of activity for macrolides in G+ aerobes (including macrolides rankings)

Answer 20

MSSA
PSSP
Group and viridans streptococci
bacillus
corynebacteria

Question 21

activity macrolides against atypical bacteria

Answer 21

macrolides are the main mechanism of treatment for atypical bacteria
legionella pneumonia (water fountain infections)
chlamydia
mycoplasma

Question 22

Treatment of mycobacterium avid complex with these macrolides…

Answer 22

only azithromycin and clarithromycin

Question 23

absorption of erythromycin PO

Answer 23

variable absorption that is enhanced by giving with enteric coating or in ester salt formulations (destroyed by gastric acid)

Question 24

absorption of clarithromycin PO

Answer 24

well absorbed (55%) and acid tolerable
unchanged by the presence of food

Question 25

macrolides used in respiratory tract infections

Answer 25

azithromycin is best if H. influenza is suspected

Question 26

mainstay treatment that macrocodes are used for

Answer 26

CA pneumonia together with ceftriaxone

Question 27

macrolide used to treat STIs

Answer 27

single, 1 g dose of azithromycin

Question 28

macrolide used for treatment of MAC

Answer 28

clarithromycin or azithromycin

Question 29

macrolide use for prophylaxis for MAC

Answer 29

azithromycin

Question 30

most important adverse effect of using macrolides

Answer 30

prolonged QT interval, contraindicated in patients already on anti arrhythmic medications

Question 31

drug drug interactions of macrolides

Answer 31

erythromycin and clarithromycin interact with CYP450 enzymes and alter the metabolism of drugs utilizing this system

Question 32

MOA streptogramins

Answer 32

both quinpristin and daltopristine bind the 50S subunit to inhibit bacterial protein synthesis

Question 33

MOR streptogramins

Answer 33

alteration of the ribosomal binding site (erm) and enzymatic inactivation

Question 34

spectrum of activity streptogramins

Answer 34

MRSA PRSP VRE

Question 35

streptogramins: bactericidal or bacteriostatic?

Answer 35

bacteriostatic

Question 36

streptogramins: time or concentration dependent?

Answer 36

time

Question 37

absorption of streptogramins PO

Answer 37

only available IV

Question 38

distribution streptogramins to the CSF

Answer 38

does not penetrate the CSF

Question 39

clinical uses streptogramins

Answer 39

VRE (faecium) only

Question 40

major adverse effect streptogramins

Answer 40

venous irritation when administered through peripheral vein.