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PA2131 Pharmacology > Bacterial Protein Synthesis inhibitors > Flashcards

Bacterial Protein Synthesis inhibitors Flashcards

1
Q

Name 2 key targets of antimicrobials that work by inhibiting bacterial protein synthesis?

A

50S, 30S bacteria ribosomal subunits

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2
Q

Name at least 2 classes of antibiotics which are 30S protein synthesis inhibitors

A

tetracyclines, glycylcycline, aminoglycosides

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3
Q

Name 3 examples of tetracyclines

A

tetracycline, doxycycline, minocycline

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4
Q

Tetracycline prevents binding of ___________ to the A site of mRNA-ribosome complex

A

tRNA

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5
Q

Tetracyclines should not be administered with dairy products or substances that contain divalent and trivalent cations as this would lead to the formation of ___________, which would ___________ the absorption of the drugs.

A

non-absorbable chelates,

reduce

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6
Q

Comment on tetracycline’s antimicrobial coverage

A

It has broad spectrum activity against many Gram-negative and Gram-positive bacteria. It also has coverage against atypical bacteria. It does not have adequate coverage against Pseudomonas aeruginosa and Proteus

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7
Q

How is tigecycine administered?

A

Intravenously (It has poor oral bioavailability unlike the tetracyclines.)

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8
Q

Glycylcyclines (tigecycline) were designed to overcome which two mechanisms of tetracycline resistance?

A

Expression of efflux pumps, and ribosomal protection

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9
Q

Tigecycline is useful in targeting some of the resistant microbes including

A
  1. Methicillin resistant staphylococci (MRSA),
  2. Multidrug-resistant streptococci,
  3. Vancomycin-resistant enterococci (VRE),
  4. useful against carbapenem resistant strains of Extended-spectrum β-lactamase–producing gram-negative bacteria
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10
Q

Name at least 4 adverse effects associated with the use of tetracyclines

A
  1. Gastrointestinal distress (To reduce ulceration, drink plenty of fluids and do not take it before sleep)
  2. Phototoxicity (Like fluoroquinolones)
  3. Superinfection like thrush
  4. Deposition in bone/primary dentition and may cause discoloration of teeth
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11
Q

The use of tetracyline and tigecycline is contraindicated in which populations of patients?

A
  1. Pregnant women,
  2. Breastfeeding women
  3. Children less than 8 years of age
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12
Q

Aminoglycosides are transported across the inner membrane of Gram-negative bacteria by ___________ , which is an energy dependent process.

A

active transport

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13
Q

Aminoglycosides are particularly effective against _______ Gram-negative bacteria

A

aerobic

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14
Q

Name 5 examples aminoglycosides

A

gentamicin, streptomycin, tobramycin, amikacin, neomycin

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15
Q

Aminoglycosides demonstrate synergism when combined with which class of antibiotics? Name one class.

A

Beta lactams (e.g. gentamicin and ceftriaxone for the management of staphylococcus endocarditis)

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16
Q

How are aminoglycosides commonly administered?

A

Parenterally (They have poor oral bioavailability)

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17
Q

Name an aminoglycoside that is used in the management of tuberculosis

A

Streptomycin (administered IM)

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18
Q

How are aminoglycosides cleared?

A

Renally

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19
Q

Name at least 2 adverse effects associated with aminoglycosides

A
  1. Ototoxicity
  2. Nephrotoxicity (Do not combine with other nephrotoxicity)
  3. Neuromuscular paralysis (Especially when used with neuromuscular blockers)
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20
Q

Name an aminoglycoside that is administered orally

A

Neomycin (bowel prep)

21
Q

Name 2 groups of patients in whom aminoglycosides would be contraindicated

A
  1. Pregnant women,
  2. Patients suffering from myasthenia gravis because of the risk of prolonged neuromuscular blockade
  3. Patients with severe renal Impairment
22
Q

What are the 6 “NOs” in relation to aminoglycosides?

A
  1. No to protein synthesis
  2. Particularly active against aerobic Gram-Negative Organisms
  3. No to use during pregnancy
  4. No to oral administration
  5. No to CSF penetration
  6. Nephro- and Oto- toxicities
23
Q

Name 3 types of 50S protein synthesis inhibitors

A

Macrolides, clindamycin, linezolid

24
Q

Name 3 macrolides

A

Erythromycin, clarithromycin, azithromycin

25
Q

25 Are macrolides bacteriostatic or bactericidal antibiotics?

A

Bacteriostatic

26
Q

How can macrolides be administered?

A

Oral and IV

27
Q

Name some of the microbial infections that the macrolides are useful against

A

Respiratory infections caused by S.pneumoniae, H. influenzae and Moraxella catarrhalis and those caused by atypical bacteria such as Legionella pneumophilia, Mycoplasma and Chlamydia
STDs caused by Chlamydia trachomatis and Neisseria gonorrhoea
H.pylori infections

28
Q

Name 2 adverse effects associated with macrolides

A
  1. Gastric Distress
  2. Hepatotoxicity
  3. Ototoxicity
  4. May prolong QT interval
29
Q

How are macrolides cleared?

A

Erythromycin and clarithromycin undergoes hepatic clearance

Azithromycin – is mainly eliminated unchanged in faeces

30
Q

Which of the macrolides cause the most GI distress?

A

Erythromycin

31
Q

Name 2 mechanisms via which bacteria may acquire macrolide resistance

A

ERM gene expression, efflux pumps

32
Q

Which drug(s) can exhibit cross resistance with macrolides?

A

Clindamycin (if the microbes acquire resistance by expressing erm methylases)

33
Q

Clindamycin is primarily used to treat _________ infections

A

anaerobic

34
Q

Linezolid works by ___________

A

It binds the bacterial 23S ribosomal RNA of the 50S subunit and inhibits the formation of the initiation complex needed for protein synthesis.

35
Q

How is clindamycin administered?

A

Oral / IV

36
Q

Can clindamycin be used to treat MRSA?

A

Yes

37
Q

Name an adverse effect associated with the use of clindamycin

A

Clostridium difficile associated diarrhoea

38
Q

What is linezolid’s mechanism of action?

A

It binds the bacterial 23S ribosomal RNA of the 50S subunit and inhibits the formation of the initiation complex needed for protein synthesis.

39
Q

Linezolid is effective against Gram _________ bacteria?

A

positive

40
Q

Linezolid binds to bacterial _________ ribosomal RNA of 50S subunit

A

23S

41
Q

Name 3 antibiotics that only covers Gram positives?

A

Vancomycin, penicillinase resistant penicillin, linezolid

42
Q

How is linezolid administered?

A

Oral / IV

43
Q

What does linezolid cover?

A

Many of the resistant Gram-positive strains such as MRSA, VRE, VRSA

44
Q

Name at least 2 key adverse effects associated with prolonged use of linezolid

A
  1. Irreversible peripheral neuropathies
  2. Optic neuritis
  3. Bone marrow suppression
45
Q

Linezolid can cause _________ if administered concomitantly with SSRI or MAO inhibitors?

A

serotonin syndrome

46
Q

Can linezolid be used for the treatment of catheter-related bloodstream infections?

A

No, it is not approved. (Based on FDA recommendation)

47
Q

Name 2 antibiotics that can be administered orally for MRSA

A

Linezolid and clindamycin

48
Q

Which of the protein synthesis inhibitors are safe for use in pregnant women?

A

Macrolides, clindamycin

PA2131 Pharmacology (14 decks)

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