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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
Common problem with beta lactams?
Allergy (Pen>Ceph>Mono)
26
How does bacitracin work?
Blocks the de-phosphorylation of bactoprenol
27
When would you use bacitracin?
Topical | Almost only vs. G+
28
Side effects of bacitracin
Poor absorption | Renal Toxicity
29
Why is bacitracin so hard to absorb?
Its freakin huge
30
How do antibiotic glycopeptides (vancomycin, telavancin) work?
Bind to the end of amino acid side chain, blocking transglycosylation and transpeptidation.
31
What mutation provides bacteria resistance to anti-biotic glycopeptides?
Using Ala-Lactate rather than Ala-Ala
32
What bacterial subtype are Glycopeptides ineffective against?
G-
33
Why is oral vancomycin only effective in the GI tract?
Its fuckin huge. Its not getting through to the system.
34
What is cycloserine?
a D-ala analog that inhibits alanine racemase
35
Why should you exhibit caution with cycloserine?
Neurotoxic
36
What four types of drugs are used for Mycobacterium? (4)
Isoniazid/Ethionamine (INH) Ethambutol (EMB) Pyrazinamide (PZA) RMP (Rifampicin)
37
How do isoniazid, ethionamines work?
Inhibit pyroxidine step in mycolic acid synthesis
38
How does ethambutol work?
Inhibition of arabinogalactan synthesis
39
How does pyrazinamide work?
Activated by mycobac enzyme, inhibits trans-translation
40
Concerns with using INH?
Also blocks your own Vitamin B6 synthesis
41
Two primary kinds of cell membrane disruptors?
Polymyxins (Colistin) | Daptomycins (Cubicin)
42
How do polymyxins work?
Dissolve phosphatidylethanolamine (a specialized PL in G- membranes)
43
When would you use Polymyxins?
As a last resort for resistant bugs | Topically
44
How does daptomycin work?
Dissolves in the membrane and disrupts potential
45
When would you use daptomycins?
G+ Cocci (MRSA)
46
How would you give daptomycins?
IV probably with beta-lactams
47
Two examples of anti-metabolites?
Sulfonamides (Sulfone) and Trimethoprim
48
How do anti-metabolites work?
They inhibit individual steps in the pyramidine synthesis pathway
49
How might bacteria become resistant to antimetabolites?
Overproduction of PABA
50
Four common nucleic acid inhibitors?
Fluoroquinolones (Ciprofloxacin, moxifloxacin) Fidaxomycin (Dificid) Rifamycin (Rifampin, Rifabutin, Rifaximin) Metronidazole
51
How how fluoroquinolones work?
Inhibition of DNA gyrase
52
Important side effects of fluoroquinolones?
Associated with prolonged QT interval
53
How does fidaxomycin (Dificid) work?
Targets the switch region of RNAP | Prevents interaction of RNAP with DNA
54
When would you use fidaxomycin?
Its an alternative to vancomycin commonly used in cases of vancomycin resistance.
55
How does rifamycin (rifampin, rifabutin, rifaximin) work?
Blocks RNA polymerase elongation subunit
56
When would you use rifamycin?
With Isoniazid to delay mycob. resistance Meningitis Poxviruses
57
Significant side effect of rifamycin?
Can make you sweat and turns urine orange
58
How does metronidazole work?
Reduced complex with ferredoxin interacts with DNA and breaks DNA strands (Free Radical)
59
Two targets metronidazole tends to be used against?
Protazoa | Anerobic Bacteria
60
List five common protein synthesis inhibitors.
``` Aminoglycosides Tetracycline Chloramphenicol Macrolides Lincosamides ```
61
How do aminoglycosides work?
Bind to 30S Ribosome, block initiation by preventing attachment of tRNA(methinonine)
62
Examples of aminoglycosides?
Streptomycin, Neomycin, Gentamycin, Tobramysin, amikacin
63
What would you use aminoglycosides for?
G- enterics | Synergy with cephalosporin/penicillin
64
How does tettacycline work?
Inhibits binding of aa-tRNA to the A-site of 30S ribosome
65
Examples of tetracyclines?
Doxycycline, tigecycline
66
How do bacteria become resistant to tetracycline?
Efflux Pumps
67
What do you use tetracyclines for?
Rickettsia, Chlamydia, Mycoplasmas
68
Side effects of tetracyclines?
Toxicity, Dissiness, Tinnitus, Fluorescent teeth
69
Who should you never give tetracycline to?
Pregnant people
70
How does chloramphenicol work?
Inhibits peptidyl transferase rxn
71
Why is chloramphenicol use no longer recommended?
Resistance and Toxicity
72
Examples of macrolides?
Erythromycin, Clarithromycin, Azithromycin
73
How do macrolides work?
Bind to rRNA and inhibit translocation (50s)
74
How might bacteria resist macrolides?
Methylation of rRNA
75
When would you use macrolides?
G+ and some G-
76
Side effects of macrolides?
Assoc. with prolonged QT | Increased risk of CV death
77
Example of a lincosamide?
Clindamycin
78
How do lincosamides work?
bind to rRNA and inhibit tanslocation (50S)
79
When would you use lincosamides?
Anerobes, Anti-Malarial
80
Problems with lincosamides?
Can't get to CNS One use can cause major disruption of native flora Long term use allows C diff colonization
81
When would you use nitrofurantoin?
UTI
82
When would you use Streptogramins?
VRE and VRSA
83
What do Mupirosins do? When would you use them?
Inhibit ile-tRNA synthase | G+
84
When would you use Oxazolidinones?
Treat VRE and MRSA
85
What do methenamines do? What do you treat with them?
Releases formaldehyde in acidified urine | UTI
86
What two drugs are used to wake up persister cells?
C10 | BF8

Micro Exam #2 (15 decks)

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