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MEDI 203 - Body Defence > Antibacterials - Part II > Flashcards

Antibacterials - Part II Flashcards

1
Q

What are the classifications of antimicrobials?

A

Inhibitors of cell synthesis
Inhibitors of protein synthesis
Inhibitors of folic acid synthesis
Inhibitors of DNA synthesis and structure

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2
Q

What are the examples of inhibitors of protein synthesis?

A

Aminoglycosides, Chloramphenicol, Tetracyclines, Macrolides, and Lincosamides

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3
Q

What are aminoglycosides?

A

Two amino sugars joined by a glycoside linkage to a central hexose nucleus

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4
Q

Where are aminoglycosides derived from?

A

Streptomycins (have a -mycin ending)
Micromonospora (have a -micin ending)

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5
Q

What is the spectrum for aminoglycosides?

A

Broad gram negative

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6
Q

What is the pharmacokinetics of aminoglycosides?

A

Mostly given intravenously
Mostly excreted unchanged in the urine

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7
Q

What is the exception of aminoglycosides regarding pharmacokinetics?

A

Neomycin - because of nephrotoxicity
It is used topically

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8
Q

Why should plasma drug levels be monitored while on aminoglycosides?

A

They have a low therapeutic index so monitoring is important in order to prevent a toxic effect

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9
Q

What characteristics do aminoglycosides exert?

A

Concentration-dependent bactericidal activity and post-antibiotic effect.

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10
Q

What is the mechanism of aminoglycosides?

A

Inhibit bacterial protein synthesis

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11
Q

How do aminoglycosides inhibit bacterial protein synthesis?

A

Diffuse through porin channels in the outer membrane; use the oxygen-dependent system to move across the cytoplasmic membrane

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12
Q

Where do aminoglycosides bind in the ribosome?

A

They bind to the 30s subunit

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13
Q

What effect does the binding of aminoglycosides to the 30s subunits have?

A

Distorts the structure and causes misreading of the mRNA

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14
Q

What is the therapeutic use of aminoglycosides?

A

Effective for the majority of aerobic gram (-) bacilli
Often combined with a β-lactam for synergistic effect
Treatment of serious infections due to aerobic gram (-) bacilli, serious toxicity limits their clinical utility.

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15
Q

What multidrug-resistant pathogens are sensitive aminoglycosides?

A

Pseudomonas aeruginosa,
Klebsiella pneumoniae,
Enterobacter sp.

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16
Q

What is the resistance of aminoglycosides?

A

Efflux pumps, decreased uptake, and/or modification and inactivation by plasmid-associated synthesis of enzymes

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17
Q

What are the adverse effects of aminoglycosides?

A

Ototoxicity
Nephrotoxicity
Neuromuscular paralysis & allergic reaction

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18
Q

What kind of allergic reactions can happen with aminoglycosides?

A

Contact dermatitis

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19
Q

What is ototoxicity?

A

Toxic to neuroepithelium of inner ear & destroy hair cells

20
Q

Why are anaerobic bacteria not susceptible to aminoglycosides?

A

Due to a lack of an oxygen-dependent active transport mechanism for amino glycoside uptake.

21
Q

What are examples of tetracyclines?

A

Tetracycline
Doxycycline
Minocycline

22
Q

What are tetracyclines?

A

Bacteriostatic

23
Q

What is the mechanism of tetracyclines?

A

Bind reversibly to 30s ribosomal subunit
Prevent binding of tRNA to m-RNA ribosome complex
Inhibit bacterial protein synthesis

24
Q

What is the coverage of tetracyclines?

A

Broad-spectrum, effective against gram (+) and gram (-) bacteria

25
Q

What are tetracyclines usually used for?

A

Acne and chlamydia infections

26
Q

What is the resistance of tetracyclines?

A

Mainly efflux pumps
Enzymatic inactivation and by proteins that prevent binding to ribosomes

27
Q

What is the pharmacokinetics of tetracyclines?

A

They are usually given orally
Also available as IV
Widely distributed into body fluids, including CSF, can cross placenta
Eliminated via kidney

28
Q

Why are tetracyclines not given to pregnant women?

A

Can travel through the placenta so unsafe for embryo, also cause tatragenicity

29
Q

What are the adverse effects of tetracyclines?

A

Diarrhea, nausea, abdominal pain, anorexia
Deposition of the drug in the bones and teeth
Vestibular dysfunction
Pseudomotor cerebi
Teratogenicity

30
Q

What is pseudomotor cerebi?

A

Benign, intracranial hypertension characterized by headache and blurred vision.

31
Q

What are the contraindications of tetracyclines?

A

Pregnancy
Age below 8

32
Q

What is an example of glycylcyckines?

A

Tigecycline

33
Q

What are glycylcyclines structurally similar to?

A

Tetracyclines

34
Q

What is the spectrum of the glycylcyclines?

A

Broad spectrum for both gram (+) and gram (-)
Extended-spectrum β-lactamase; producing gram (-) bacteria and anaerobes

35
Q

What re some examples of pathogens that are sensitive to glycylclines?

A

MRSA, VRE

36
Q

Which pathogen do not get affected by glycylcyclines?

A

Pseudomonas spp.
Proteus spp.

37
Q

What is the mechanism of glycylcyclines?

A

Inhibits protein synthesis by interfering with bacterial 30s ribosomal units.

38
Q

What is the pharmacokinetics of glycylcyclines?

A

Given by slow IV infusion, penetrates tissue.
Biliary/fecal elimation

39
Q

What is the resistance of the glycylclines?

A

Developed to tackle the resistance of tetracyclines but over-expression of efflux pumps can cause resistance

40
Q

What are common side effects of glycylclines?

A

Diarrhea, nausea, vomiting

41
Q

Complicated skin and soft tissue infections are indications of which antibacterial?

A

Glycylclines

42
Q

What are examples of macrolides?

A

Erythromycin, Azithromycin and Clarithromycin

43
Q

What is bacteriostatic?

A

May be bactericidal in high concentrations

44
Q

Where do erythromycin and clindamycin attach?

A

They bind to the 50s subunits, they inhibit translocation.

45
Q
A
46
Q
A

MEDI 203 - Body Defence (6 decks)

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