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Micro Antibiotics > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

penicillins

A

Beta-lactam - inhibits transpeptidation (cell wall)

Natural: Pen G, Pen V (best for G+)
Beta-lactamase resistant: nafcillin, oxacillin, cloxacillin
G+ and G-: ampi-, pipera-, mezlo-, ticarcillin
Acid resistant/oral: amoxicillin, pen V, oxacillin
Pen + beta-lactamase inhib: Augmentin (amox/clav), ampicillin + sulbactam, piperacillin + tazobactam

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2
Q

penicillin resistance?

A

beta-lactamases
lack of PBPs
autolysin mutations “tolerance”

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3
Q

cephalosporins

A

Beta-lactams (cell wall), but less sensitive to beta-lactamases

1G: prophylaxis only - cephalexin, cephalothin, cefazolin
2G: G+ and G-: cefaclor, cefuroxime, cefoxitin
3G: G+ and G-, w/ pseudomonas:

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4
Q

monobactams

A

monocyclic beta-lactam ring (cell wall), resistant to beta-lactamases for G- only

aztreonam

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5
Q

carbapenems

A 
beta lactam (cell wall) - G+ and G-, but may be toxic 
allergy, toxicity - seizures

imipenem, ertapenem, meropenem (less toxicity)

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6
Q

bacitracin

A

blocks dephosphorylation of bactroprenol (cell wall)
topical, G+
poorly absorbed, renal toxicity

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7
Q

glycopeptides

A

bind aa side chain - block transglycosylation and transpeptidation (cell wall) for G+

Vancomycin, telavancin

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8
Q

glycopeptide resistance

A

use -Ala-Lac instead of -Ala-Ala for pentapeptide - via chromosomal vanB and plasmid vanA genes

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9
Q

how can you overcome vancomycin resistance?

A

replace disaccharide with -H

replace =O in amide binding site with =N

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10
Q

cycloserine

A

D-ala analog - inhibits Ala racemase (cell wall), but neurotoxic

sometimes for UTI, 2nd line TB drug

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11
Q

Mycobacterium drugs

A
  1. isoniazid (INH), ethionamide - inhibit pyridoxine step in mycolic acid synthesis
  2. ethambutol (EMT) - inhibit arabinogalactan synthesis
  3. pyrazinamide (PZA) - inhibits trans-translation
  4. rifampicin (RMP)
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12
Q

polymyxins/ colistin

A

dissolve phosphatidlethanolamine, part of G- (cell membrane)
toxic - topical only, often w/ bacitracin and neomycin

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13
Q

daptomycin/ cubicin

A

cyclic lipopeptide - dissolves in membrane, disrupts membrane potential (cell membrane)

G+, MRSA - must be IV, synergy with beta-lactams

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14
Q

sulfonamides (sulfone) and trimethoprim, aka bactram/SxT

A

inhibit steps in path: PABA -> DHF -> THF -> pyrimidines (antimetabolite)

uses: Nocardia, Salmonella, shigella, UTIs

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15
Q

SxT resistance

A

overproduction of PABA, altered enzymes

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16
Q

(fluoro)quinolones

A

inhibit DNA gyrase (nucleic acid inhibitor) but can get prolonged QT segment (EKG)

Use: not very soluble, use fluoro instead (ciprofloxacin and derivatives) for UTI, G-, G+, Pseudomonas

ciprofloxacin, moxifloxacin

17
Q

(fluoro)quinolone resistance

A

altered DNA gyrase, drug exclusion

18
Q

fidaxomycin/ dificid

A

targets “switch region”/ loading clamp of RNA pol - prevents interaction of RNA pol and DNA (nucleic acid inhibitor)

19
Q

rifamycin

A

blocks RNA pol elongation subunit (nucleic acid inhibitor) - but makes sweat/urine orange!

rifampin, rifabutin, rifaximin

use: Mycobacterium + INH, crosses BBB, blocks assembly of poxviruses

20
Q

rifamycin resistance

A

altered RNA pol beta subunit

21
Q

metronidazole

A

partially reduced complex with ferredoxin interacts with DNA and breaks DNA strands - free radical (nucleic acid inhibitor)

use: antiprotozoal, anaerobes (first time for C. diff)

22
Q

aminoglycosides

A

bind 30S subunit, block initiation by preventing attachment of tRNA-fMet (protein synthesis inhibitor)

streptomycin, neomycin, gentamicin, tobramycin, amikacin

use: G- enterics, synergy with cephs/pens (facilitate entry)

23
Q

aminoglycoside resistance

A

altered P12 ribosomal protein
aminoglycosidases
altered permeability

24
Q

tetracycline

A

inhibits binding of aa-tRNA to A-site of 30S subunit (protein synthesis inhibitor) but side effects: toxicity, dizzy, tinnitus, fluorescent teeth, NOT FOR PREGGERS

doxycycline, tigecycline

use: rickettsia, chlamydia, mycoplasmas

25
Q

chloramphenicol

A

inhibits peptidyl transferase rxn - 50S (protein synthesis inhibitor)

no longer a drug of choice, toxicity and resistance - chloramphenicol acetyl transferase (CAT)

26
Q

macrolides

A

bind rRNA, inhibit translocation - 50S (protein synthesis inhibitor) - prolonged QT interval (EKG), increased CV risk

erythromycin, clarithromycin, azithromycin (Z-pack)

use: G+, some G-

27
Q

macrolide resistance

A

methylation of rRNA

28
Q

lincosamides

A

bind rRNA, inhibit translocation - 50S (protein synthesis inhibitor) - same as macrolides

clindamycin

use: anaerobes, anti-malarial, doesn’t cross BBB

29
Q

nitrofurantoin

A

inhibits 30S (protein synthesis inhibitor)

use: UTIs

30
Q

mupirosin

A

inhibits Ile-tRNA (protein synthesis inhibitor)

use: topical, G+

31
Q

streptogramins/ synercid

A 
inhibits 50S (protein synthesis inhibitor)
quinupristin + dalfopristin

use: VRE, VRSA

32
Q

oxazolidinones - linezolid

A

inhibits 50S (protein synthesis inhibitor)

use: VRE, MRSA

33
Q

methenamine

A

releases formaldehyde in acidified urine

use: UTIs

34
Q

how do you target persistor cells?

A

C10, BF8 - wake up persistor cells, then use other abx to target the newly growing cells

35
Q

which drugs should not be used for pregnant women?

A
  • amikacin
  • kanamycin
  • streptomycin
  • tobramycin
  • sulfa drugs
  • all tetracyclines
  • erythromycin
  • macrobid and nitrofurantoin
36
Q

which drugs are cell wall inhibitors?

A
  • beta-lactams (penicillins, cephalosporins, monobactams, carbapenems)
  • bacitracin
  • glycopeptides (vancomycin, telavancin)
  • cycloserine
37
Q

which drugs are cell membrane disruptors?

A
  • polymyxins (colistin)
  • daptomycin (cubicin)
  • sulfonamides (sulfones) + trimethoprim (aka bactram, SxT)
38
Q

which drugs are nucleic acid inhibitors?

A
  • (fluoro)quinolones (ciprofloxacin, moxifloxacin)
  • fidaxomycin (dificid)
  • rifamycin (rifampin, rifabutin, rifaximin)
  • metronidazole
39
Q

which drugs are protein synthesis inhibitors?

A
  • aminoglycosides (streptomycin, neomycin, gentamycin, tobramycin, amikacin)
  • tetracycline (doxycycline, tigecycline)
  • chloramphenicol
  • macrolides (erythromycin, clarithromycin, azithromycin)
  • lincosamides (clindamycin)
  • nitrofurantoin
  • mupirosin
  • streptogramins/ synercid
  • oxazolidinones (linezolid)
  • methenamine

Micro Antibiotics (2 decks)

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