FA - Micro - Antimicrobials (2016) Flashcards

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1
Q

Carbapenems - Mechanism of imipenem:

A
  1. Broad-spectrum, β-lactamase-resistant carbapenem.
  2. ALWAYS administered with cilastatin (inhibitor of renal dihydropeptidase I) to DECREASE inactivation of drug in renal tubules.
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2
Q

Newer carbapenems include:

A
  1. Ertapenem –> LIMITED PSEUDOMONAS coverage.

2. Doripenem.

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3
Q

Carbapenems - Clinical use:

A
  1. Gram (+) cocci.
  2. Gram (-) rods.
  3. Anaerobes.
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4
Q

Carbapenems - Clinical use limited to …?

A

Life-threatening infections or after other drugs have failed.
–> Significant side effects.

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5
Q

Meropenem has …?

A

Decr. risk for SEIZURES and is STABLE to dehydropeptidase I.

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6
Q

Carbapenems - Adverse effects:

A
  1. GI distress.
  2. Skin rash.
  3. CNS toxicity (seizures).
    At high plasma levels.
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7
Q

Vancomycin - Mechanism:

A

Inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors.

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8
Q

Vancomycin - Bacteriostatic/cidal?

A

Bactericidal against MOST bacteria.

  • -> Bacteriostatic against C.difficile.
  • -> Not susceptible to beta-lactamases.
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9
Q

Vancomycin - Clinical use:

A

Gram (+) bugs ONLY –> Serious multidrug-resistant organisms, including:

  1. MRSA.
  2. S.epidermidis.
  3. Sensitive Enterococcus species.
  4. C.difficile (ORAL dose).
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10
Q

Vancomycin - Adverse effects:

A
  1. Well tolerated in general - But NOT trouble free.
  2. Nephrotoxicity.
  3. Ototoxicity.
  4. Thrombophlebitis.
  5. Diffuse flushing - Red man syndrome (pretreat with antihistamines + slow infusion rate).
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11
Q

Vancomycin - Mechanism of resistance:

A

Occurs in bacteria via amino acid modification of D-ala D-ala to D-ala D-lac.

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12
Q

Oxazolidinones:

A

Linezolid.

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13
Q

Linezolid - Mechanism:

A
  1. Inhibits protein synthesis by binding to 50S.

2. Prevents formation of the initiation complex.

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14
Q

Linezolid - Clinical use:

A

Gram (+) species including MRSA + VRE.

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15
Q

Linezolid - Adverse effects:

A
  1. Bone marrow suppression (esp. thrombocytopenia).
  2. Peripheral neuropathy.
  3. Serotonin syndrome.
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16
Q

Linezolid - Mechanism of resistance:

A

Point mutation of ribosomal RNA.

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17
Q

Dapsone - Mechanism:

A

Similar to sulfonamides, but structurally distinct agent.

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18
Q

Dapsone - Clinical use:

A
  1. Leprosy (lepromatous and tuberculoid).

2. PCP proph.

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19
Q

Dapsone - Side effects:

A

Hemolysis if G6PD deficient.

20
Q

Daptomycin - Mechanism:

A

LIPOPEPTIDE that disrupts cell membrane of gram (+) cocci.

21
Q

Daptomycin - Clinical use:

A
  1. S.aureus skin infections (esp. MRSA).
  2. Bacteremia.
  3. Endocarditis.
  4. VRE.
22
Q

Daptomycin - Side effects:

A
  1. Myopathy.

2. Rhabdomyolysis.

23
Q

Daptomycin - NOT used for …?

A

PNEUMONIA!!!

AVIDLY BINDS AND INACTIVATES SURFACTANT!!!

24
Q

Rifamycins - Mechanism of resistance:

A

Mutations reduce drug binding to RNA polymerase.

–> Monotherapy rapidly leads to resistance.

25
Q

Streptomycin - Mechanism:

A

Interferes with 30S.

26
Q

Streptomycin - Clinical use:

A

Mycobacterium tuberculosis (2nd line).

27
Q

Streptomycin - Adverse effects:

A
  1. Tinnitus.
  2. Vertigo.
  3. Ataxia.
  4. Nephrotoxicity.
28
Q

Treatment of highly-resistant bacteria - Multidrug-resistant P.aeruginosa, multidrug-resistant Acinetobacter baumannii:

A
  1. Polymyxin B.

2. Polymyxin E (colistin).

29
Q

Azoles inhibit which CYP450 enzyme involved in ergosterol synthesis?

A

14-alpha-demethylase.

30
Q

Anti-mite/louse therapy:

A
  1. Permethrin (blocks Na channels –> Neurotoxicity).
  2. Malathion (AChE inhibitor).
  3. Lindane (Blocks GABA –> Neurotoxicity).
    - -> Used to treat scabies (Sarcoptes scabiei) + Lice (Pediculus and Pthirus).
31
Q

Hep C therapy:

A
  1. Ribavirin.
  2. Sofosbuvir.
  3. Simeprevir.
32
Q

Sofosbuvir - Mechanism:

A

Inhibits HCV RNA-dependent RNA polymerase –> Acts as a chain terminator.

33
Q

Sofosbuvir - Clinical use:

A
  1. Chronic HCV in combination with ribavirin, +/- Peg-IFN.

2. DO NOT use as MONOTHERAPY.

34
Q

Sofosbuvir - Adverse effects:

A
  1. Fatigue.
  2. Headache.
  3. Nausea.
35
Q

Simeprevir - Clinical use:

A
  1. Chronic HCV in combination with LEDIPASVIR.

2. DO NOT USE AS MONOTHERAPY.

36
Q

Simeprevir - Adverse effects:

A
  1. Photosensitivity.

2. Rash.

37
Q

Ledipasvir:

A

NS5A INHIBITOR.

38
Q

5 infection control techniques:

A
  1. Autoclave.
  2. Alcohols.
  3. Chlorhexidine.
  4. Hydrogen peroxide.
  5. Iodine and iodophors.
39
Q

Infection control techniques - Goals include:

A
  1. Disinfection.

2. Sterilization.

40
Q

Disinfection:

A

Reduction of pathogenic organism counts to safe levels.

41
Q

Sterilization:

A

Inactivation of self-propagating biological entities.

42
Q

Autoclave:

A

Pressurized steam at >120C - May be sporicidal.

43
Q

Alcohols:

A

Denature proteins and disrupt cell membranes. Not sporicidal.

44
Q

Chlorhexidine:

A

Denatures proteins and disrupts cell membranes. NOT sporicidal.

45
Q

Hydrogen peroxide:

A

Free radical oxidation - Sporicidal.

46
Q

Iodine and iodophors:

A

Halogenation of DNA, RNA, and proteins - May be sporicidal.

47
Q

Cephalosporins (I-V) - Mechanism of resistance:

A

Structural change in penicillin-binding proteins (transpeptidases).