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Micro Exam #2 > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

Three desired properties of antibiotics

A

Broad Range (until + diagnosis)
Able to get to body tissues
Selectively Toxic

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2
Q

Give an three examples of a synergistic antibiotic interaction.

A

SxT will block sequential steps
Cell Wall/Membrane Inhibitors may allow drug entry
One drug may inhibit detox enzymes

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3
Q

Give three reasons for use of multiple antibiotic drugs

A

Systemic/multiple infections
Delaying resistance to long-term use
Synergisms

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4
Q

Three categories of patients that should be prescribed prophylactic antibiotics.

A

Known contact with a known agent
Before surgery with high likelihood of complications
Special Cases – ex. predisposed to endocarditis, UTI, immunocompromised

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5
Q

How do new biofilm preventing coatings work?

A

Implanted devices are coated with a cationic detergent that interacts with the quaternary amine

Over the next several days, hydrolysis occurs and releases dead cells

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6
Q

What is fidaxomicin active against?

A

Inhibits RNA polymerase

G+

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7
Q

What is Bedaquiline active against?

A

c Subunit of ATP synthase rotor

Mycobacteria

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8
Q

Why is amoxicillin rarely prescribed alone?

A

Heightened resistance to the drug

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9
Q

Three primary types of cell wall inhibitors?

A

beta-lactams
Bacitracin
Glycopeptides (Vancomycin, Telavancin)

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10
Q

How do beta-lactams work?

A

Inhibit transpeptidation and activate autolysins in the cell wall

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11
Q

How do bacteria resist beta lactams?

A

beta-lactamases, lack of PBPs, autolysin mutations

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12
Q

What drugs are often given with beta lactams?

A

Beta lactamase inhibitors (Clavulinic acid, aulbactam, tazobactam)

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13
Q

Which penicilins are natural? Why use them?

A

Pen G, Pen V

Best vs. Gram + bacteria

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14
Q

Which penicillins are expanded spectrum? (i.e. also good against Gram -)

A

Ampicillin
Piperacillin
Mezlocillin

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15
Q

Which Penicillins are beta-lactamase resistant? (3)

A

Nafcillin
Oxacillin
Cloxacillin

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16
Q

Which penicillins are acid resistant?

A

Amoxycillin
Pen V
Oxacillin

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17
Q

Three most common penicillin +lactamase inhibitor combos

A

Augmentin = amoxicillin + Clavulanic acid
Ampicillin + Sulbactam
Zosyn/Tazomed = Piperacilin + Tazobactam

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18
Q

Which beta lactam structure provides some natural resistance to beta-lactamase?

A

Monobactams

beta-lactam with one ring

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19
Q

Three types of beta lactams?

A

Penicillins
Cephalosporins
Monobactams

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20
Q

Perks of 3rd and 4th generation cephalosporins?

A

Work on Gram +/-

Can Cross BBB

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21
Q

Examples of 3rd and 4th gen cephalosporins?

A

Ceftazidime, Cephotaxime, Caphtriaxone

Cefepime

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22
Q

Two downsides to monobactams

A

Effective vs G- only

Expensive

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23
Q

name a monobactam

A

Aztreonam

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24
Q

Pro and con of carbapenems?

A 
Broad spectrum
Possibly toxic (leads to seizures)
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25
Q

Common problem with beta lactams?

A

Allergy (Pen>Ceph>Mono)

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26
Q

How does bacitracin work?

A

Blocks the de-phosphorylation of bactoprenol

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27
Q

When would you use bacitracin?

A

Topical

Almost only vs. G+

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28
Q

Side effects of bacitracin

A

Poor absorption

Renal Toxicity

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29
Q

Why is bacitracin so hard to absorb?

A

Its freakin huge

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30
Q

How do antibiotic glycopeptides (vancomycin, telavancin) work?

A

Bind to the end of amino acid side chain, blocking transglycosylation and transpeptidation.

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31
Q

What mutation provides bacteria resistance to anti-biotic glycopeptides?

A

Using Ala-Lactate rather than Ala-Ala

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32
Q

What bacterial subtype are Glycopeptides ineffective against?

A

G-

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33
Q

Why is oral vancomycin only effective in the GI tract?

A

Its fuckin huge. Its not getting through to the system.

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34
Q

What is cycloserine?

A

a D-ala analog that inhibits alanine racemase

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35
Q

Why should you exhibit caution with cycloserine?

A

Neurotoxic

36
Q

What four types of drugs are used for Mycobacterium? (4)

A

Isoniazid/Ethionamine (INH)
Ethambutol (EMB)
Pyrazinamide (PZA)
RMP (Rifampicin)

37
Q

How do isoniazid, ethionamines work?

A

Inhibit pyroxidine step in mycolic acid synthesis

38
Q

How does ethambutol work?

A

Inhibition of arabinogalactan synthesis

39
Q

How does pyrazinamide work?

A

Activated by mycobac enzyme, inhibits trans-translation

40
Q

Concerns with using INH?

A

Also blocks your own Vitamin B6 synthesis

41
Q

Two primary kinds of cell membrane disruptors?

A

Polymyxins (Colistin)

Daptomycins (Cubicin)

42
Q

How do polymyxins work?

A

Dissolve phosphatidylethanolamine (a specialized PL in G- membranes)

43
Q

When would you use Polymyxins?

A

As a last resort for resistant bugs

Topically

44
Q

How does daptomycin work?

A

Dissolves in the membrane and disrupts potential

45
Q

When would you use daptomycins?

A

G+ Cocci (MRSA)

46
Q

How would you give daptomycins?

A

IV probably with beta-lactams

47
Q

Two examples of anti-metabolites?

A

Sulfonamides (Sulfone) and Trimethoprim

48
Q

How do anti-metabolites work?

A

They inhibit individual steps in the pyramidine synthesis pathway

49
Q

How might bacteria become resistant to antimetabolites?

A

Overproduction of PABA

50
Q

Four common nucleic acid inhibitors?

A

Fluoroquinolones (Ciprofloxacin, moxifloxacin)
Fidaxomycin (Dificid)
Rifamycin (Rifampin, Rifabutin, Rifaximin)
Metronidazole

51
Q

How how fluoroquinolones work?

A

Inhibition of DNA gyrase

52
Q

Important side effects of fluoroquinolones?

A

Associated with prolonged QT interval

53
Q

How does fidaxomycin (Dificid) work?

A

Targets the switch region of RNAP

Prevents interaction of RNAP with DNA

54
Q

When would you use fidaxomycin?

A

Its an alternative to vancomycin commonly used in cases of vancomycin resistance.

55
Q

How does rifamycin (rifampin, rifabutin, rifaximin) work?

A

Blocks RNA polymerase elongation subunit

56
Q

When would you use rifamycin?

A

With Isoniazid to delay mycob. resistance
Meningitis
Poxviruses

57
Q

Significant side effect of rifamycin?

A

Can make you sweat and turns urine orange

58
Q

How does metronidazole work?

A

Reduced complex with ferredoxin interacts with DNA and breaks DNA strands (Free Radical)

59
Q

Two targets metronidazole tends to be used against?

A

Protazoa

Anerobic Bacteria

60
Q

List five common protein synthesis inhibitors.

A 
Aminoglycosides
Tetracycline
Chloramphenicol
Macrolides
Lincosamides
61
Q

How do aminoglycosides work?

A

Bind to 30S Ribosome, block initiation by preventing attachment of tRNA(methinonine)

62
Q

Examples of aminoglycosides?

A

Streptomycin, Neomycin, Gentamycin, Tobramysin, amikacin

63
Q

What would you use aminoglycosides for?

A

G- enterics

Synergy with cephalosporin/penicillin

64
Q

How does tettacycline work?

A

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

65
Q

Examples of tetracyclines?

A

Doxycycline, tigecycline

66
Q

How do bacteria become resistant to tetracycline?

A

Efflux Pumps

67
Q

What do you use tetracyclines for?

A

Rickettsia, Chlamydia, Mycoplasmas

68
Q

Side effects of tetracyclines?

A

Toxicity, Dissiness, Tinnitus, Fluorescent teeth

69
Q

Who should you never give tetracycline to?

A

Pregnant people

70
Q

How does chloramphenicol work?

A

Inhibits peptidyl transferase rxn

71
Q

Why is chloramphenicol use no longer recommended?

A

Resistance and Toxicity

72
Q

Examples of macrolides?

A

Erythromycin, Clarithromycin, Azithromycin

73
Q

How do macrolides work?

A

Bind to rRNA and inhibit translocation (50s)

74
Q

How might bacteria resist macrolides?

A

Methylation of rRNA

75
Q

When would you use macrolides?

A

G+ and some G-

76
Q

Side effects of macrolides?

A

Assoc. with prolonged QT

Increased risk of CV death

77
Q

Example of a lincosamide?

A

Clindamycin

78
Q

How do lincosamides work?

A

bind to rRNA and inhibit tanslocation (50S)

79
Q

When would you use lincosamides?

A

Anerobes, Anti-Malarial

80
Q

Problems with lincosamides?

A

Can’t get to CNS
One use can cause major disruption of native flora
Long term use allows C diff colonization

81
Q

When would you use nitrofurantoin?

A

UTI

82
Q

When would you use Streptogramins?

A

VRE and VRSA

83
Q

What do Mupirosins do? When would you use them?

A

Inhibit ile-tRNA synthase

G+

84
Q

When would you use Oxazolidinones?

A

Treat VRE and MRSA

85
Q

What do methenamines do? What do you treat with them?

A

Releases formaldehyde in acidified urine

UTI

86
Q

What two drugs are used to wake up persister cells?

A

C10

BF8

Micro Exam #2 (15 decks)

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