FA - Micro - Antimicrobials (2016)

Question 1

Carbapenems - Mechanism of imipenem:

Answer 1

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.

Question 2

Newer carbapenems include:

Answer 2

1. Ertapenem –> LIMITED PSEUDOMONAS coverage.

2. Doripenem.

Question 3

Carbapenems - Clinical use:

Answer 3

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

Question 4

Carbapenems - Clinical use limited to …?

Answer 4

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

Question 5

Meropenem has …?

Answer 5

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

Question 6

Carbapenems - Adverse effects:

Answer 6

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

Question 7

Vancomycin - Mechanism:

Answer 7

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

Question 8

Vancomycin - Bacteriostatic/cidal?

Answer 8

Bactericidal against MOST bacteria.

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

Question 9

Vancomycin - Clinical use:

Answer 9

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

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

Question 10

Vancomycin - Adverse effects:

Answer 10

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).

Question 11

Vancomycin - Mechanism of resistance:

Answer 11

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

Question 12

Oxazolidinones:

Answer 12

Linezolid.

Question 13

Linezolid - Mechanism:

Answer 13

1. Inhibits protein synthesis by binding to 50S.

2. Prevents formation of the initiation complex.

Question 14

Linezolid - Clinical use:

Answer 14

Gram (+) species including MRSA + VRE.

Question 15

Linezolid - Adverse effects:

Answer 15

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

Question 16

Linezolid - Mechanism of resistance:

Answer 16

Point mutation of ribosomal RNA.

Question 17

Dapsone - Mechanism:

Answer 17

Similar to sulfonamides, but structurally distinct agent.

Question 18

Dapsone - Clinical use:

Answer 18

1. Leprosy (lepromatous and tuberculoid).

2. PCP proph.

Question 19

Dapsone - Side effects:

Answer 19

Hemolysis if G6PD deficient.

Question 20

Daptomycin - Mechanism:

Answer 20

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

Question 21

Daptomycin - Clinical use:

Answer 21

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

Question 22

Daptomycin - Side effects:

Answer 22

1. Myopathy.

2. Rhabdomyolysis.

Question 23

Daptomycin - NOT used for …?

Answer 23

PNEUMONIA!!!

AVIDLY BINDS AND INACTIVATES SURFACTANT!!!

Question 24

Rifamycins - Mechanism of resistance:

Answer 24

Mutations reduce drug binding to RNA polymerase.

–> Monotherapy rapidly leads to resistance.

Question 25

Streptomycin - Mechanism:

Answer 25

Interferes with 30S.

Question 26

Streptomycin - Clinical use:

Answer 26

Mycobacterium tuberculosis (2nd line).

Question 27

Streptomycin - Adverse effects:

Answer 27

1. Tinnitus. 2. Vertigo. 3. Ataxia. 4. Nephrotoxicity.

Question 28

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

Answer 28

1. Polymyxin B. | 2. Polymyxin E (colistin).

Question 29

Azoles inhibit which CYP450 enzyme involved in ergosterol synthesis?

Answer 29

14-alpha-demethylase.

Question 30

Anti-mite/louse therapy:

Answer 30

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).

Question 31

Hep C therapy:

Answer 31

1. Ribavirin. 2. Sofosbuvir. 3. Simeprevir.

Question 32

Sofosbuvir - Mechanism:

Answer 32

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

Question 33

Sofosbuvir - Clinical use:

Answer 33

1. Chronic HCV in combination with ribavirin, +/- Peg-IFN. | 2. DO NOT use as MONOTHERAPY.

Question 34

Sofosbuvir - Adverse effects:

Answer 34

1. Fatigue. 2. Headache. 3. Nausea.

Question 35

Simeprevir - Clinical use:

Answer 35

1. Chronic HCV in combination with LEDIPASVIR. | 2. DO NOT USE AS MONOTHERAPY.

Question 36

Simeprevir - Adverse effects:

Answer 36

1. Photosensitivity. | 2. Rash.

Question 37

Ledipasvir:

Answer 37

NS5A INHIBITOR.

Question 38

5 infection control techniques:

Answer 38

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

Question 39

Infection control techniques - Goals include:

Answer 39

1. Disinfection. | 2. Sterilization.

Question 40

Disinfection:

Answer 40

Reduction of pathogenic organism counts to safe levels.

Question 41

Sterilization:

Answer 41

Inactivation of self-propagating biological entities.

Question 42

Autoclave:

Answer 42

Pressurized steam at >120C - May be sporicidal.

Question 43

Alcohols:

Answer 43

Denature proteins and disrupt cell membranes. Not sporicidal.

Question 44

Chlorhexidine:

Answer 44

Denatures proteins and disrupts cell membranes. NOT sporicidal.

Question 45

Hydrogen peroxide:

Answer 45

Free radical oxidation - Sporicidal.

Question 46

Iodine and iodophors:

Answer 46

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

Question 47

Cephalosporins (I-V) - Mechanism of resistance:

Answer 47

Structural change in penicillin-binding proteins (transpeptidases).