Protien Synthesis Inhibitors

Question 1

Which are the antibiotics that bind to 30S ribosome

Answer 1

Aminoglycosides, tetracycline

Question 2

What are the antibiotics that bind to 50s ribosome

Answer 2

CELLS
Chloramphenicol
Erythromycin
Lincosamide
Linezolid
Streptogramins

Question 3

What is the mode of action for aminoglycosides

Answer 3

Bactericidal

Question 4

Explain the pharmacokinetics of aminoglycosides

Answer 4

Not well absorbed orally so must be given IV or IM
Limited distribution due to polarity

Question 5

What is the mechanism of action for aminoglycosides

Answer 5

Inhibit protein synthesis by binding to the 30S ribosome, leading to mRNA misreading causing production of abnormal proteins and causing bacterial cell death

Question 6

Explain why bacterias are resistant to aminoglycosides

Answer 6

Production of inactivating enzymes called group transferases
Or due to decreased penetration of aminoglycosides

Question 7

What are the adverse effects of aminoglycosides

Answer 7

Ototixicity- damage to cochlea and vestibular apparatus results in impaired hearing and balance
Nephrotoxicity- tubular damage resulting in LOW GFR and loss of urinary concentrating capacity
Neuromuscular juntion blockade

Question 8

Gentamicin is an aminoglycoside. What is its clinical use

Answer 8

Enterococci

Question 9

What is gentamicin and tobramycin used for?

Answer 9

Conjunctivitis caused by gram negative bacteria

Question 10

What is streptomycin( aminoglycoside) used against

Answer 10

Tuberculosis

Question 11

What is neomycin used against

Answer 11

Given orally to suppress the gut flora in hepatic encephalopathy

Question 12

What is spectinomycin (aminoglycoside) used for?

Answer 12

backup for TB and gonorrhea

Question 13

What is the mode of action for tetracycline

Answer 13

Bacteriostatic

Question 14

What is the spectrum of tetracycline

Answer 14

Broad

Question 15

What are the short acting tetracycline drugs

Answer 15

Tetracycline, Oxytetracyline

Question 16

What are the intermediate acting tetracyclines

Answer 16

Demeclocycline, methocycline

Question 17

What are the long acting tetracycline drugs

Answer 17

Doxycycline, minocycline

Question 18

What is the mechanism of action for tetracyclines

Answer 18

Binds to 30S ribosomal subunit and prevents binding of tRNA to mRNA, which prevents the addition of amino acids to the growing peptide

Question 19

What is the mechanism of resistance for tetracyclines

Answer 19

Efflux pumps develop that cause decreased uptake

Question 20

What are the clinical uses of tetracycline

Answer 20

Primary uses include:
In infections caused by mycoplasma pneumoniae, chlamydiae, rickettsia spirochetes, legionella
Secondary uses: alternative drug used in syphillis
Treatment of leptospirosis
Treatment of propionibacterium acne

Question 21

What is doxycycline used for

Answer 21

Used to treat periodontal disease
Also for prostatitis

Question 22

What are the adverse effects of tetracycline

Answer 22

Pseudomembranous colitis , superinfection caused by C. Difficile

Tetracyclines decrease absorption of iron, magnesium, aluminium and zinc
Irritation of GI tract

Hepatic toxicity due to high doses (lead to necrosis especially in pregnant women)

Renal toxicity by using outdated tetracyclines

Photosensitivity
(especially caused by demeclocycline and doxycycline)

Vestibular toxicity

Question 23

What is the mode of action of macrolides

Answer 23

Bacteriostatic

Question 24

Give some examples for macrolides

Answer 24

Erythromycin, clarithromycin, azithromycin

Question 25

What is the mechanism of action of macrolides

Answer 25

Binds to 50S subunit Inhibits polypeptide chain elongation and protein synthesis inhibitors which then inhibits bacterial growth and multiplication

Question 26

What are the clinical uses of macrolides

Answer 26

Treatment of -Legionnaires disease -Diphtheria -Whooping cough -Chlamydial infections -Syphilis Drug of choice for community acquired pneumonia caused by mycoplasma legionella and chlamydia

Question 27

What is the adverse effect of macrolides

Answer 27

GI disturbances Hepatic elimination ( contraindicated in patients with liver disorders)

Question 28

What is clindamycin used for?

Answer 28

Used for bacteroides fragilis Prescribed for prophylaxis of endocarditis

Question 29

What are the adverse effects of lincosamides

Answer 29

Bleeding tendencies such as agranulocytosis and hypersensitivity

Question 30

What is the mode of action for chloramphenicol

Answer 30

Broad spectrum antibiotics

Question 31

What is the spectrum of chloramphenicol

Answer 31

Broad spectrum

Question 32

What is the mechanism of action

Answer 32

Binds to bacterial 50S subunit and blocks transpeptidation and prevents protein synthesis

Question 33

What is the therapeutic use for chloramphenicol

Answer 33

Alternative for cephalosporin in meningitis, brain abcess Alternative for tetracycline in rocky mountain spotted fever Enteric fever

Question 34

What are the adverse effects of chloramphenicol

Answer 34

Fatal aplastic anemia Grey baby syndrome

Question 35

What is the therapeutic use of spectinomycin

Answer 35

Anogenital gonorrhoea

Question 36

What is the adverse effects of spectinomycin

Answer 36

Urticaria, dizziness, nausea, chills, fever, insomnia

Question 37

What is the therapeutic use for streptogramins?

Answer 37

Methicilin resistant S. aureus and VRSA

Question 38

What are the adverse effects of streptogramin

Answer 38

Hepatotoxic, so bilrubin test should be performed twice

Question 39

What is the mode of action for linezolid

Answer 39

Bacteriostatic

Question 40

What is the mechanism of action for linezolid

Answer 40

Binds to 50S and prevents protein synthesis, inhibits formation of the initiation in translation

Question 41

Therapeutic use of linezolid

Answer 41

Vancomycin resistant E. faecium

Question 42

Adverse effects of linezolid

Answer 42

Headache and GI Distress