Inhibitors of proteins synthesis

Question 1

Aminglycosides

Answer 1

Gentamicin

Question 2

Tetracycline

Answer 2

Doxycycline

Question 3

Macrolides

Answer 3

Azithromycin

Question 4

Lincosamides

Answer 4

Clindamycin

Question 5

Oxizolindinones

Answer 5

Linezolid

Question 6

Inhibition of ribosomal function is _

Answer 6

Bacteriostatic except for aminoglycosides because they cause miscoding of the RNA which is bactericidal

Question 7

gentamicin mechanism of action

Answer 7

Attraction of negatively charged LPS in out membrane of G- bacteria
Bactericidal (also active against mycobacteria and Protozoal parasites)
peak/MIC
Irreversibly bind to 30S ribosomal subunit stops formation of initiation complex leading to misreading of mRNA and incorrect incorporation of amino acids

Question 8

Post-antibiotic effect

Answer 8

Residual activity after plasma levels fall below MIC
Gentamicin

Question 9

Resistance to gentimycin is due to

Answer 9

drug inactivation by bacterial kinase and acetyltransferase

Question 10

Gentamicin is _toxic

Answer 10

Nephro
Oto (drug accumulation in inner ear)

Question 11

Doxycycline mechanism of action

Answer 11

Binds to 30S ribosomal subunit to inhibit landing do tRNAs into A-site preventing the addition of amino acids

Question 12

Doxycycline is active against

Answer 12

G+ and G- bacteria
Atypical bacteria
Tick borne illnesses
Protozoans

Question 13

Doxycycline resistance due to

Answer 13

TetM (interfere with binding to 30S)

Question 14

Doxycycline activity is

Answer 14

AUC/MIC
Widely distributed

Question 15

Doxycycline cannot be given with

Answer 15

Dairy products, iron supplements, Mg-laxatives or antacids due to the formation of insoluble chelates leading to decreased oral absorption

Question 16

Tetracycline adverse reactions

Answer 16

GI irritation
Photosensitivity
Deposition in bones and teeth leading to discoloration and growth impairment (avoid in pregnant females and children)

Question 17

_ is the only tetracycline that may be given during pregnancy

Answer 17

Doxycycline

Question 18

Azithromycin mechanism of action

Answer 18

Bacteriostatic
Binds reversible to 50S subunit to inhibit translocation

Question 19

Azithromycin is active against

Answer 19

G+ and G- anaerobes
Atypical bacteria
Mycoplasma and protozoal parasites

Question 20

Resistance to macrolides is due to

Answer 20

High level of methylation of 50S that decreases binding affinity (erm=multi-drug resistance, MLS)

Question 21

Macrolide adverse reactions

Answer 21

Prolonged cardiac Q-T interval increases arrhythmias

Question 22

Clindamycin mechanism of action

Answer 22

Binds 50S to block peptide bond formation
Bacteriostatic

Question 23

Clindamycin adverse reactions

Answer 23

Black box warning for C diff colitis

Question 24

Linezolid mechanism of action

Answer 24

Binds to 23S rRNA of 50S subunit blocking formation of initiation complex

Question 25

Linezolid adverse effects

Answer 25

Limited by toxicity (only used against drug resistant infections) Myelosupression Lactic acidosis Black box warning for MAO inhibition, use with antidepressants, and Serotonin syndrome