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Antimicrobials > Antimictobials > Flashcards

Antimictobials Flashcards

1
Q

Colistin

A

Polymyxin E

  • Targets cell membrane
  • Active against gram - and non growing
  • low resistance
  • high toxicity
  • limited to topicals
  • resistance due to an enzyme that modifies lipid A
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2
Q

Daptomycin (cubicin)

A
  • Targets cytoplasmic membrane resulting in depolarization
  • bactericidal
  • active only against gram + (MRSA, VRSA, and VRE)
  • resistance due to accumulation of mutations in different genes rather than a single mutation
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3
Q

Beta lactams

A
  • largest class of cell wall inhibitors
  • only active against growing cells
  • penicillins
  • cephalosporins
  • carbapenems
  • monobactams
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4
Q

Anti pseudomonals

A
  • Ticarcillin and clavulanate/beta lactam and beta lactamase inhibitor
  • Piperacillin and tazobactam
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5
Q

Ampicillin

A
  • Aminopenicillin

- increased activity against gram -

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6
Q

Amoxicillin

A

Aminopenicillin

  • increased activity against gram -
  • greater oral bioavailability
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7
Q

Methicillin

A
  • semi synthetic
  • decreased susceptibility to beta lactamase
  • acid sensitive/can’t be given orally
  • never used
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8
Q

Nafcillin

A
  • semi synthetic
  • beta lactamase resistance
  • give Naf for Staph
  • acid stable; absorbed from GI
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9
Q

Oxacillin

A
  • semi synthetic
  • beta lactamase resistance
  • acid stable
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10
Q

MRSA resistance

A
  • acquisition of unique gene (mecA) encoding a unique PBP (PBP2A
  • confers resistance to all bets lactam antibiotics
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11
Q

1st generation cephalosporins

A
  • narrow spectrum
  • mostly gram positive with a few gram negatives
  • cephalexin, cefazolin, cephalothin, cefadroxil
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12
Q

2nd generation cephalosporins

A
  • expanded spectrum
  • better gram negative and some anaerobes
  • cefoxitin, cefotetan, cefaclor, cefonicid
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13
Q

3rd generation cephalosporins

A
  • broad spectrum
  • even better gram negative
  • cefoperazone, ceftazidime, ceftriaxone, cefotaxime
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14
Q

4th generation cephalosporins

A
  • extended spectrum
  • broad spectrum but not active against enterococci or anaerobes
  • relatively resistant to beta lactamase
  • cefepime
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15
Q

5th generation cephalosporins

A
  • active against MRSA, streptococcus, and several gram negatives including klebsiella
  • ceftaroline
  • prodrug that gets metabolized to active form
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16
Q

Carbapenems

A
  • imipenem
  • meropenem
  • widely used and broadest spectrum of beta lactams
  • not active against MRSA and VRE
  • resistance due to production of carbapenamase, efflux pumps, and porin change/loss
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17
Q

Monobactams

A
  • very narrow spectrum; active only against gram negative aerobes
  • aztreonam
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18
Q

Carbapenem resistance

A
  • production of carbapenamase

- resistance in gram negative: klebsiella, acinetobactor, and pseudomonas

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19
Q

Glycopeptides

A
  • bind rapidly and irreversibly to the D-alanyl-D-alanine terminus
  • inhibits transport across cell membrane and cross linking or parallel peptidoglycan chains
  • vancomycin, bacitracin, teicoplanin
  • gram negative resistance because too large to pass through outer membrane
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20
Q

Vancomycin resistance

A
  • substitution of terminal D-alanine with D-lactate and won’t bind vancomycin
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21
Q

New drugs to treat VRSA

A
  • daptomycin
  • linezolid (zyvox)
  • synercid
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22
Q

Lipoglycopeptides

A
  • newer derivatives of glycopeptides that have a tail that anchors them in the cell membrane
  • telavancin, dalbavancin, and oritavancin
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23
Q

Bacitracin

A
  • cell wall inhibitor (inhibits translocation of peptidoglycan precursors)
  • relatively toxic (restricted to topicals)
  • most active against gram positive
  • often combined with polymyxin and an aminoglycoside (neomycin)
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24
Q

Fosfomycin

A
  • cell wall inhibitor (inhibits formation of cytoplasmic subunits)
  • used for single dose treatment of UTIs
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25
Q

Cycloserine

A
  • cell wall inhibitor (inhibits translocation and cross linking)
  • anti TB, but NOT first choice
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26
Q

Rifampin

A
  • inhibits DNA dependent RNA polymerase
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27
Q

Antimicrobials that target 30s subunit

A

Tetracyclines and amnioglycosides

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28
Q

Tetracycline

A
  • reversibly bind 30s ribosomal subunit, which inhibits binding and aminoacly tRNA to the A site
  • bacteriostatic
  • broad spectrum that includes both gram negative and positive
  • effective against mycoplasma pneumoniae (which is important because don’t have cell wall), rickettsia, chlamydia (both of which are obligate intracellular pathogens), and borrelia (Lyme disease)
29
Q

Minocyclin

A
  • Tetracyline
  • reversibly bind 30s ribosomal subunit, which inhibits binding and aminoacly tRNA to the A site
  • bacteriostatic
  • broad spectrum that includes both gram negative and positive
  • effective against mycoplasma pneumoniae (which is important because don’t have cell wall), rickettsia, and chlamydia (both of which are obligate intracellular pathogens)
30
Q

Doxycline

A
  • Tetracycline
  • reversibly bind 30s ribosomal subunit, which inhibits binding and aminoacly tRNA to the A site
  • bacteriostatic
  • broad spectrum that includes both gram negative and positive
  • effective against mycoplasma pneumoniae (which is important because don’t have cell wall), rickettsia, and chlamydia (both of which are obligate intracellular pathogens)
31
Q

Tetracycline resistance

A
  • acquisition of exogenous DNA that encodes proteins involved in the active efflux of the antibiotic
  • these proteins are designated Tet
  • derivatives of tetracycline such as minocyline do not bind Tet and therefore not pumped out as efficiently
32
Q

Tigecycline

A
  • semisynthetic glycylcycline that binds 30s subunit and inhibits protein synthesis
  • less susceptible to removal by efflux pumps
33
Q

Aminoglycosides

A
  • binds irreversibly to 30s ribosomal subunit and prevent formation of the 70s initiation complex
  • bactericidal
  • relatively broad spectrum and used to treat gram negative and gram positive
  • often combined with cell wall inhibitors to increase uptake
  • streptomycin, gentamicin, kanamycin, tobramycin, neomycin, and amikacin
34
Q

Spectinomycin

A
  • closely related aminoglycoside
  • binds reversibly within 30s ribosome
  • bacteriostatic
35
Q

Aminoglycoside resistance

A
  • intrinsic resistance due to variations in membrane porins

- acquired resistance due to modifying enzymes that alter the antibiotic so it can’t bind ribosomal target

36
Q

Chloramphenicol

A
  • targets 50s subunit
  • inhibits peptidyl transferase and thereby prevents formation of the peptide bond
  • bacteriostatic with broad spectrum
  • relatively toxic and used primarily for topical purposes, particularly eye drops
  • resistance due to production of enzyme that modifies the antibiotic: chloramphenicol acetyltransferase
37
Q

Targets 50s and inhibits translocation

A

Macrolides, lincosamides, and streptogamins

38
Q

Erythromycin

A
  • macrolide
  • bind 50s and inhibit translocation of growing peptide
  • only effect proteins being actively synthesized and therefor bacteriostatic
39
Q

Azithromycin

A
  • macrolide
  • bind 50s and inhibit translocation of growing peptide
  • only effect proteins being actively synthesized and therefore bacteriostatic
40
Q

Clarithromycin

A
  • macrolide
  • bind 50s and inhibit translocation of growing peptide
  • only effect proteins being actively synthesized and therefore bacteriostatic
41
Q

Macrolides

A
  • erythromycin, azithromycin, and clarithromycin
  • broad spectrum with good activity against gram positive infections
  • good for patients allergic to penicillin
42
Q

Clindamycin

A
  • lincosamide
  • active against staphylococci and anaerobic gram negative bacilli
  • generally inactive against aerobic gram negatives
  • activity against anaerobes accounts for its association with pseudomembraneous colitis
43
Q

MLS resistance (macrolides, lincosamides, and streptogamins)

A
  • methylation of the bacterial 23s rRNA of the 50s (modification of the target)
  • intrinsic resistance in gram negative due to MLS low membrane permeability b/c highly hydrophobic compounds
44
Q

Synercid

A
  • streptogramin
  • bactericidal
  • bind 50s subunit and inhibits translocation
45
Q

Oxazolidinones

A
  • protein synthesis inhibitor which bind 50s subunit and block formation of the 70s initiation complex. This prevents formation of the first peptide bond
  • Linezolid (zyvox)
  • bacteriostatic
46
Q

Zyvox resistance

A
  • single point mutation in the gene encoding 23s RNA
47
Q

Tedizolid

A
  • 2nd generation oxazolidinone
  • active against linezolid resistant gram positive cocci
  • active against most MRSA
48
Q

Nalidixic acid

A
  • quinolone
  • targets nucleic acid synthesis by interfering with DNA supercoiling
  • binds DNA topoisomerase, most notably DNA gyrase
49
Q

Norfloxacin

A
  • fluoroquinolone

- binds DNA gyrase

50
Q

Ciprofloxacin

A
  • fluoroquinolone

- binds DNA gyrase

51
Q

Levofloxacin

A
  • fluoroquinolone

- binds DNA gyrase

52
Q

Quinolones

A
  • broad spectrum, but most active against aerobic, gram negatives
  • not very active against anaerobics
  • concentrated as much as 20 fold inside phagocytic cells
  • resistance due to mutations of DNA gyrase genes leading to reduced binding of antibiotic
53
Q

Rifampicin

A
  • inhibits transcription by binding beta subunit of DNA dependent RNA polymerase
  • good for gram positive and mycobacteria
  • gram negative intrinsically resistant due to outer membrane
  • cornerstone drug for TB
  • resistance due to point mutation in gene coding beta subunit of polymerase which inhibits binding. For this reason, always use with one or more antibiotics
54
Q

Metronidazole

A
  • targets DNA via free radicals which causes double stranded breaks
  • not commonly used because no activity against aerobic or facultatively anaerobic bacteria
  • important for treatment of anaerobic infections including pseudomembranous colitis (clostridium difficile)
55
Q

Sulfonamides

A
  • Antimetabolite which inhibits synthesis of tetrahydrofolate
  • competitive inhibitor of DHPS
  • bacteriostatic
  • bactericidal when used in combination with trimethoprim
  • resistance due to decreased permeability and some gram positives (enterococcus) utilize exogenous thymine to bypass the need for THF
  • acquired high level resistance for a specific chromosomalgene that encodes DHFR or DHPS enzymes with altered active sites that are not bound by antibiotic. May arise from chromosomal mutations, but more often found on plasmids and/or transposons
56
Q

Trimethoprim

A
  • Antimetabolite which inhibits synthesis of tetrahydrofolate
  • competitive inhibitor of DHFR
  • bacteriostatic
  • bactericidal when used in combination with sulfonamide
  • resistance due to decreased permeability and some gram positives (enterococcus) utilize exogenous thymine to bypass the need for THF
  • acquired high level resistance for a specific chromosomalgene that encodes DHFR or DHPS enzymes with altered active sites that are not bound by antibiotic. May arise from chromosomal mutations, but more often found on plasmids and/or transposons
57
Q

Unasyn

A
  • ampicillin + sulbactam
58
Q

Augmentin

A
  • amoxicillin + clavulanate
59
Q

Timentin

A
  • ticarcillin + clavulanate
60
Q

Zosyn

A
  • piperacillin + tazobactam
61
Q

Cilastatin

A

Peptidase inhibitor

62
Q

Fidaxomicin (dificid)

A
  • macrolide

- expensive, but also used for C. difficile

63
Q

Isoniazid

A
  • cell wall inhibitor

- anti mycobacterial

64
Q

buy AT 30, CELLS at 50

A

30s subunit

  • Aminoglycosides
  • Tetracycline

50s subunit

  • Chloramphenicol or Clindamycin
  • Erythromycin
  • Lincomycin or cLindamycin
  • Linezolid
  • Streptogramins (Synercid)
65
Q

Isoniazid

A

Anti mycobacterial

66
Q

Ethambutol

A

Anti mycobacterial

67
Q

Cycloserine

A

Anti mycobacterial

68
Q

Ethionamide

A

Anti mycobacterial

Antimicrobials (1 decks)

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