protein synthesis inhibitors

Question 1

what is the target of rifampin ?

Answer 1

RNA polymerase

Question 2

which part of the protein synthewsis stage do these antibiotics work ?

Answer 2

in the translation phase

Question 3

what are the aminoglycosides ?

Answer 3

gentamicin , tobramycin, streptomycin

Question 4

what is the mechanism of aminoglycosides ?

Answer 4

block the initiation of protein synthesis
primarily bind to 30S

Question 5

what is the problem or draw back with using amino glycosides ?

Answer 5

they cannot be used against anaerobes
not effective in intracellular organisms

Question 6

most protein synthesis inhibitors are bacterio ?

Answer 6

bacteriostatic except aminoglycosides are bacteriocidal

Question 7

what drugs are given prior to bowel surgery ?

Answer 7

neomycin with erythromycin

Question 8

what drug has a synergistic effect with aminoglycosides ?

Answer 8

beta lactamase inhibitors

Question 9

what drugs are used for Cystic fibrosis patients ?

Answer 9

piperacillin and tazobactam along with tobramycin
because the targeted organism is usually pseudomonas

Question 10

what drug combo can be used for newborn meningitis ?

Answer 10

vancomycin gentamycin

Question 11

what is the most common mechanism of resistance with aminoglycosides ?

Answer 11

aminoglycosides modifying enzymes
by adding acetyl groups or by phosphorlyation

Question 12

what are the toxicities of ahminoglycosides ?

Answer 12

1- ototoxicity and balance problems whe tKEN NWIITH LOOP DIIUURETICS
2- nephrotoxicity ( ATN)
3- neuromuscular blockade ( usually with pre existing neuromuscular disease )
4- teratogenic

Question 13

what are the methods of monitoring levels of aminoglycosides ?

Answer 13

plasma levels : trough and peak levels
high trough - risk of toxicity
low peak - less effective therapy

Question 14

what are the macrolides ?

Answer 14

azithromycin
clarithromycin
erythromycin

Question 15

what is the mechanism of macrolides ?

Answer 15

bind to the 50 s ribosomal sub unit
specifically bind to the P site which is the exit tunnel
hence blocking the process of translocation

Question 16

what are the three sited associated with ribosomes ?

Answer 16

A - new tRNA brings in an amino acid
P - growing peptide chain is held at the P site
E - used tRNA exit here

Question 17

what antibiotic is commonly associayed with the blocking of the enzyme peptide transferase ?

Answer 17

chloramphenicol

Question 18

why are macrolides considered effective against intracellular pathogens ?

Answer 18

because they are concentrated inside macrophages

Question 19

good drug to cover for pneumonia ?

Answer 19

macrolides

Question 20

what are the common infections in which macrolide can be used ?

Answer 20

community acquired pneumonia
chlamydia infections

Question 21

what is the mechanism of erythromycin ?

Answer 21

binds to motilin receptors in the GI tract
stimulates smooth muscle contraction
used for motility disorders

Question 22

what is clarithromycin commonly used for ?

Answer 22

part of triple therapy of h pylori

Question 23

what antibiotic is used for IBS ?

Answer 23

erythromycin

Question 24

what are the methods of mechanism agaisnt macrolides ?

Answer 24

23 rRNa altering , the location where the macrolide bind
the bacteria will phophorylate this are to avoid macrolides binding to it

Question 25

what are the adverse effects of macrolides ?

Answer 25

1- nausea diarrhea and abdominal pain 2- prolonged QT on ekg ( potassium blocking) 3- acute cholestatic hepatitis

Question 26

what are the contraindications associated with macrolide use ?

Answer 26

patients who already have QT prolongation patients with pre existing liver disease patients with a history of macrolide allergy myasthenia gravis

Question 27

what drugs inhibit P450 enzyme, and what is the consequent effect ?

Answer 27

clarithromycin and erythromycin means that drugs that are normally metabolized by p450 stay longer in the body

Question 28

what are the main drugs that are metabolized by P450 ?

Answer 28

theophylline and warfarin

Question 29

what are the tetracyclines ?

Answer 29

tetracycline doxycycline demeclocycline

Question 30

what is the mechanism of tetracyclines ?

Answer 30

binds to 30S ribosome prevents attachement of tRNA

Question 31

what is demeclocycline used for ?

Answer 31

not used as an antibiotic used as an ADH antagonist instead used to treat SIADH causes nephrogenic DI to reverse to SIADH

Question 32

what are the clinical scenarios are associated with doxycycline ?

Answer 32

used for acne vulgaris used with intracellular pathogens zootonic community acquired MRSA

Question 33

what impairs the absorption of tetracyclines?

Answer 33

minerals and antacids: calcium magnesium \iron \dairy

Question 34

what are the mechanisms of resistance against tetracyclines ?

Answer 34

decreasing influx or increasing efflux

Question 35

what are the adverse effect of tetracyclines ?

Answer 35

GI distress photosensitivity dicoloration of the teeth ( children under the age of 8 ) inhibition of bone growth teratogenic

Question 36

what is the mechanism og chloramphenicol ?

Answer 36

inhibits peptidyl transferase at 50S ribosomoal unit

Question 37

what are the clinical uses of chloramphenicol ?

Answer 37

meningitis rickettsial disease

Question 38

what are the dangers of using chloramphenicol in pregnant patients ?

Answer 38

if used in the third trimester can cause gray baby syndrome

Question 39

what are the main side effects of chloramphenicol ?

Answer 39

anemia aplastic anemia gray baby syndrome

Question 40

what is the mechanism of clindamycin ?

Answer 40

binds to 50s ribosomal subunit binds to 23S rRNA component prevents translocation

Question 41

what is the mechanism of resistance of clindamycin?

Answer 41

same as macrolides methylation of the binding site of the macrolide which is the 23s rRNA

Question 42

what are the clinical scenarios associated with clindamycin ?

Answer 42

anaerobic infections above the diaphragm such as lung abscess , aspiration pneumonia

Question 43

what is the main adverse effect of clindamycin ?

Answer 43

pseudomembranous colitis c difficile

Question 44

which bacteria is associated with a high resistance to clindamycin ?

Answer 44

B fragilis

Question 45

what is the mechanism of linezolid ?

Answer 45

binds to the 50 S ribosome blocks the initiation of protein synthesis

Question 46

what is the main clinical use of linezold ?

Answer 46

VRE

Question 47

what is the clinical scenario associated with patients who have VRE ?

Answer 47

usually a hospitalized patient with prior antibiotic treatment

Question 48

what are the adverse effects of linezolid ?

Answer 48

because it is a weak MAO inhibitor it can cause seretonin syndrome especially when co administered with an SSRI

Question 49

what drugs are used for vancomycin resistant bacteria ?

Answer 49

synercid

Question 50

what are the common organusms associated with pneumonia in cystic fibrosis patients ?

Answer 50

Pseudomonas aeruginosa, Staphylococcus aureus, and Burkholderia cepacia.