Antibiotics 3 and 4 Flashcards

1
Q

polymyxin B

A

selective against G- enteric rods

binds LPS and then cytoplasmic phospholipids in membrane, causing membrane leakage

used as a topical agent

good against PA

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2
Q

daptomycin

A

lipopeptide that inserts into membrane of bacteria

cubicin

IV

only works on G+

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3
Q

aminoglycosides

A

bacteriocidal, ex. streptomycin, gentamycin

proposed mechanisms

binds to 30S distorting acceptor site and causing misreading that leads to bad proteins

at higher concentrations, it inhibits formation of the initiation complex

some bacteria are resistant. is inhibited under anaerobic or acidic conditions

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4
Q

streptomycin

A

only used for TB and select other

once used for G-

requires aerobic conditions

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5
Q

gentamycin

A

bacteriacidal

disrupts 30S ribosme, but also other things, so resistance cannot form in one step

requires aerobic conditions

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6
Q

under what conditions are aminoglycosides inhibited

A

anerobic, acidic conditions

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7
Q

tetracyclins

A

ex. tetracyline, doxycycline, minocycline

bacterioSTATIC

taken orally. broad spectrum. cant be taken pregnant or under 8.

inhibit 30 S ribosome

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8
Q

what are the important tetracyclins?

A

tetracycline, doxycycline, minocycline

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9
Q

inhibitors of 50S ribosome

A
erythromycin (macrolide)
choramphenicol
clindomycin
azithromycin
sreptogramins
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10
Q

erythromycin

A

bacterioSTATIC. blocks chain elongation. binds 50S

similar spectrum to penicillin G

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11
Q

azithromycin

A

related to erythromycin, but higher activity and broader spectrum. sustained tissue concentrations

bacterioSTATIC. binds 50S

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12
Q

chloramphenicol

A

bacterioSTATIC. blocks chain elongation. binds 50S

can cause lethal aplastic anemia.

useful against bowel anaerobes

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13
Q

clindamycin

A

STATIC. derivative of lincomycin. binds 50 S subunit

activity against G+ and anaerobes

binds 50S subunit. inhibits peptidyl transfer

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14
Q

sreptogramins

A

STATIC. binds 50 S.

potential for treating resistant bacteria- MRSA VREF, etc.

2 types: dalfopristin and quinupristin

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15
Q

what are the 2 types of sretpogramins

A

dalfopristin and quinupristen

combined form synergin

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16
Q

oxazolidinones

A

STATIC. active G+

linezolid (zyvox)
IV and oral
potential for treating resitant MRSA, VREF, VRSA
inhibits tRNA translocation

17
Q

mupirocin

A

STATIC at low concentrations, CIDAL at high concentrations

inhibits tRNA

useful for treatment of MRSA

18
Q

quinolones

A

ciprofloxacin, moxiflaxacin

inhibits DNA gyrase necessary for DNA synthesis

CIDAL

rapidly emerging resistance- no longer MRSA drug

no pregos

19
Q

examples of quinolones

A

ciprofloxacin, moxiflaxacin

20
Q

nitroimidazoles

A

ex. metronidazole

binds DNA and fragments it

anaerobic, CIDAL

requires anerobic conditions

21
Q

rifampin

A

broad spectrum, CIDAL

binds RNA polymerase, inhibiting binding to DNA

useful w/ isoniazid agaisnt TB

efficiently secreted in saliva

22
Q

ethambutol

A

anti TB, unknown MOA, STATIC

23
Q

pyrazinamide

A

anti TB, unknown MOA, CIDAL

require mycobacteria amidase

24
Q

what are the indications for using multiple drugs?

A
synergy can be expected
pathogens require 
likelihood of resistance is reduced
dosage of a toxic drug can be reduced
poly-infection
25
what are the disadvantages of
side effects antagonism cost resistance
26
general mechanisms of resistance
enzymatic inactivation cannot enter cell or is pumped out cell contains altered enzyme that resists drug binding target replaced
27
enzymatic inactivation examples
b-lactamases chlorampheticol acteyltransferase erythromycin esterase
28
altered membrane permeability resistance examples
outer membrane porins decreased inner membranes transporters altered
29
antibiotic flux from the cell resistance examples
tetracycline resistance
30
alteration of ribosomal target resistance examples
erythromycin. methylation of 23S rRNA streptomycin- alter S12 of 30S
31
alteration of cell wall precursor examples
vancomycin resistance enzyme forms D-ala-D-lactate instead of D-ala-D-ala
32
alteration of target enzymes examples
PBP- methicillin DHF synthetase- sulfonamide
33
bypass pathways
trimethroprim resistance- other ways to form dna precursors