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Micro > Lecture 5 > Flashcards

Lecture 5 Flashcards

1
Q

What are three forms of Abx synergism?

A
  1. Block sequential steps
  2. Facilitate drug entry (this is done by cell wall or membrane inhibitors)
  3. Inhibit a drug detox enzyme
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2
Q

What is an example of syergism?

A

Loperamide and Tet allow entry of each other

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3
Q

Example of Abx antagonism?

A

Chloramphenicol and PCN If chloramphenicol acts first, it is bacteriostatic and PCN can’t kill

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4
Q

What is SxT

A

Sulmethoxazole/Trimethoprim (Septra and Bactrim)

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5
Q

What structural congregation of bacteria are very difficult to kill?

A

Biofilms

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6
Q

When should you use multiple Abx?

A

System infection To delay resistance in long-term use For synergism

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7
Q

What is Synercid?

A

Quinupristin and dalfopristin Together are bacteriocidal

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8
Q

What is the best treatment for biofilms?

A

Prevention

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9
Q

How are new coatings on implantable devices working to inhibit biofilms?

A

Kill with cationic detergent and then hydrolyze

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10
Q

Beta lactam mode of action

A

Cell wall inhibitors by:
Inhibiting transpeptidation
Activate autolysins

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11
Q

Causes of beta lactam resistance?

A

Beta lactamases
Lack of PBPs (PCN binding proteins)
Autolysin mutations

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12
Q

Common beta-lactamase inhibitors?

A

Clavulinic acid
Sulbactam
Tazobactam

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13
Q

What are the natural forms of PCN?

A

Pen G

Pen V

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14
Q

Use for natural PCNs?

A

GramPos

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15
Q

What forms of PCN are beta-lactamase resistant? What is their weakness?

A

Nafcillin
Oxacillin
Cloxacillin
They have lower activity

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16
Q

What is spectrum of expanded spectrum PCNs?

A

GramPos

GramNeg

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17
Q

What are the expanded spectrum PCNs?

A

Ampicillin
Piperacillin
Mezlocillin
Ticarcillin (vs. pseudomonas)

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18
Q

What are the acid resistant PCNs?

A

Amoxycillin
Pen V
Oxacillin

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19
Q

What is ampicillin often paired with?

A

Sulbactam

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20
Q

What is zosyn, tazomed?

A

Piperacillin + tazobactam

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21
Q

What is a benefit of cephalosporins?

A

Less sensitive to beta-lactamases

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22
Q

What are the classes of beta-lactams?

A

PCNs
Cephalosporins
Carbapenems
Monobactams

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23
Q

1st gen cephalosporin spectrum?

A

GramPos

For prophylatic use only

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24
Q

1st gen cephalosporins?

A

Cephalexin
Cephalothin
Cefazolin

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25
Q

2nd gen cephalosporin spectrum

A

GramPos and GramNeg
Will cover bacteroides
Does not cover pseudomonas

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26
Q

2nd gen cephalosporins

A

Cefaclor
Cefuroxime
Cefoxitin

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27
Q

3rd gen cephalosporin spectrum

A

GramPos, GramNeg, and pseudomonas

Used for GramNeg only to protect against overuse

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28
Q

3rd gen cephalosporins

A

Ceftazidime
Cephotaxime
Cephtriaxone

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29
Q

4th gen cephalosporin spectrum

A

Slight expanded from 3rd gen

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30
Q

Monobactam spectrum

A

GramNeg only!

No GramPos or anaerobes

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31
Q

4th gen cephalosporin

A

Cefepime

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32
Q

5th gen cephalosporins spectrum

A

Activity against MRSA and drug resistant S. pneumoniae

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33
Q

5th gen cephalosporins

A

Ceftaroline

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34
Q

Benefit of monobactams

A

Resistant to beta-lactamases

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35
Q

Monobactam example

A

Aztreonam

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36
Q

Carbapenem spectrum

A

Broad

GramPos and GramNeg

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37
Q

Risk of carbapenems

A

May be toxic –> seizures

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38
Q

Carbapenem examples

A

Imipenem, ertapenem, meropenem

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39
Q

Meropenem benefit

A

Might be less toxic than other carbopenems

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40
Q

What is a side effect of cephalosporins

A

Might cause thrombophlebitis

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41
Q

Who might experience a PCN rash?

A

Someone infected with mono virus

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42
Q

Bacitracin mode of action

A

Blocks de~P of bactoprenol

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43
Q

Bacitracin spectrum

A

Topical only because renal toxicitiy, poorly absorbed

GramPos (commonly used with others)

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44
Q

Glycopeptide Abx examples?

A

Vancomycin

Telavancin

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45
Q

Glycopeptide Abx mode of action?

A

Bind to amino acid side chain

Block transglycosylation and transpeptidation

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46
Q

What causes glycopeptide Abx resistance?

A

Organism uses ala-pyruvate instead of ala-ala on pentapeptide side chain

47
Q

What two genetic alterations leads to glycopeptide Abx resistance?

A

VanA gene confers full glycopeptide resistance

VanB gene confers moderate glycopeptide resistance

48
Q

Glycopeptide Abx uses?

A

Staphylococci
Enterococci
NOT GramNeg

49
Q

Cycloserine action?

A

Inhibits alanine racemase

50
Q

Cycloserine side effect?

A

Neurotoxic

51
Q

Uses for cycloserine?

A

UTIs

2nd line drug for TB

52
Q

What drug classes are cell wall inhibitors?

A

Beta-lactams
Bacitracin
Glycopeptides
Cycloserines

53
Q

What special drugs are used for mycobacterium?

A 
Isoniazide
Ethionamide 
Ethambutol
Pyrazinamide
Rifampicin
54
Q

Isoniazide and ethionamide for mycobacterium action

A

Inhibit mycolic acid synthesis (pyroxidine step)

55
Q

Ethambutol mechanism in mycobacterium

A

Inhibits arabinogalactan synthesis (rapid resistance)

56
Q

Pyrazinamide mechanism in mycobacterium

A

Inhibits trans-translation

57
Q

What are the 5 most broad classes of antibiotics?

A 
Cell wall inhibitors
Cell membrane disrupter
Antimetabolites
Nucleic acid inhibitor 
Protein synthesis inhibitors
58
Q

What are the two classes of cell membrane disrupters?

A

Polymixin

Daptomycin

59
Q

What pathway do sulfonamides and trimethoprim interrupt?

A

Pyrimidine synthesis by blocking PABA –> pyrimidine synthesis

60
Q

Polymyxin mode of action?

A

Dissolve phosphatidylethanolamine

Specialized PL in GramNeg membranes

61
Q

Polymyxin side effects

A

Toxic so often used with other antibiotics or as a last resort

62
Q

Daptomycin mode of action

A

It’s a cyclic lipopeptide that dissolves in a membrane and disrupts the membrane potential

63
Q

Daptomycin uses?

A

GramPos Cocci including MRSA

Must be given IV beta-lactams

64
Q

What are the main antimetabolite Abx

A

Sulfonamides

Trimethoprim

65
Q

What would cause resistance to sulfonamides or trimethoprim?

A

Overproduction of PABA

66
Q

What are uses for trimethoprim and sulfonamides?

A

Nocardia

Synergistic for UTI, Salmonella, Shigella

67
Q

What are the main nucleic acid inhibitors?

A

Fluoroquinolones
Fidaxomycin
Rifamycin
Metronidazole

68
Q

What are the fluorquinolones?

A

Ciprofloxacin

Moxifloxacin

69
Q

Fluoroquinolone MOA

A

Inhibit DNA gyrase

70
Q

Fluoroquinolone resistance?

A

Altered DNA gyrase, drug exclusion

71
Q

Fluoroquinolone use?

A

UTI’s

GramNeg and GramPos infections including mycobacteria and pseudomonas

72
Q

Fidaxomycin aka?

73
Q

Fidaxomycin MOA

A

Targets “switch region” of RNAP

Inhibits RNAP-DNA interaction

74
Q

Fidaxomycin uses

A

Vanco alternate for c-diff

75
Q

Rifamycin aka

A

Rifampin
Rifabutin
Rifaximin

76
Q

Rifamycin MOA

A

Blocks RNAP elongation subunit

77
Q

Rifamycin resistance

A

Altered RNAP polymerase beta subunit

78
Q

Rifamycin uses

A

with Isoniazid to delay resistance in mycobacteria
Crosses CNS so useful for meningitis
Blocks assembly of poxvirus

79
Q

Rifamycin side effects?

A

Turns skin and urine orange (harmless)

80
Q

Metronidazole MOA

A

Is partially reduced

Interacts with DNA to break strand

81
Q

Where can metronidazole be used?

A

Only anaerobic conditions

If aerobic, it will become oxidized and ineffective

82
Q

Metronidazole uses?

A 
Antiprotozoal (Giardia)
Anaerobic bacteria (Bacteroides, clostridium)
83
Q

Main protein synthesis inhibitors

A 
Aminoglycosides
Tetracycline
Chloramphenicol
Macrolides
Lincosamides
Others
84
Q

Aminoglycoside AKA

A 
Streptomycin
Neomycin
Gentamycin
Tobramycin
Amikacin
85
Q

Aminoglycosides MOA

A

Binds to 30S ribosome

Blocks first Met being added

86
Q

Aminoglycoside resistance

A

Altere P12 ribosomal protein
Aminoglycosidase
Altered permeability (Streptococci)

87
Q

Aminoglycoside uses

A

GramNeg enterics

Use with cephalosporins or PCNs (facilitate entry)

88
Q

Tetracycline AKA

A

Doxycycline

Tigecycline

89
Q

Tetracycline MOA

A

Inhibits binding of aa-tRNA to the A-site of 30S

90
Q

Tetracycline resistance

A

Efflux pumps

91
Q

Tetracycline uses

A

Rickettsia
Chlamydia
Mycoplasms

92
Q

Tetracycline side effects

A 
Toxicity
Dizziness
Tinnitus 
Fluorescent teeth
Possible bone damage in newborns
Replacement of native flora
93
Q

Chloramphenicol MOA

A

Inhibits peptidyl transferase reaction 50S

94
Q

Chloramphenicol resistance

A

Chloramphenicol acetyl transferase

No longer the drug of choice

95
Q

Macrolides AKA

A

Erthromycin
Clarithromycin
Azithromycin

96
Q

Macrolide MOA

A

Binds to rRNA and inhibits translocation

97
Q

Macrolide resistance

A

Methylation of rRNA

98
Q

Macrolide uses

A

GramPos

Some GramNeg

99
Q

Lincosamides AKA

A

Clindamycin

100
Q

Lincosamides MOA

A

Same as macrolides

Binds to rRNA and inhibits translocation

101
Q

Lincosamide uses

A

Anaerobes (bacteroides)
Anti-malarial
Associated with c-diff development

102
Q

Nitrofurantoin MOA

A

Inhibits 30S

103
Q

Nitrofurantoin uses

A

UTI because it concentrates in urine

104
Q

Mupirosin MOA

A

Inhibits ile-tRNA synthase

105
Q

Mupirosin uses

A

Topically for GramPos

106
Q

Streptogramins “Synercid” combination

A

Quinupristin + dalfopristin

107
Q

Streptogramin MOA

A

Inhibits 50s

108
Q

Streptogramin uses

A

VRE and VRSA

109
Q

Oxazolidinones AKA

110
Q

Oxazolidinone MOA

A

Inhibits 50s

111
Q

Oxazolidinone uses

A

VRE and MRSA

112
Q

Methenamine MOA

A

Releases formaldehyde to acidify urine

113
Q

Methenamine uses

114
Q

What two drugs are being tested to wake up persister cells

Micro (13 decks)

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