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microbiology > C-7 > Flashcards

C-7 Flashcards

1
Q

where do antibiotics come from

A

discovered in a contaminant - penicillium

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2
Q

natural antibiotics

A

Antimicrobial agents that are produced naturally by an organism (ex. Penicillin)

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3
Q

semi-synthetic antibiotics

A

Chemically altered antibiotics that are more effective, more stable, or easier to administer than their natural counterpart. (Ex. Can pass through the stomach without degradation)

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4
Q

synthetic antibiotics

A

Antimicrobials completely synthesized in a lab (Ex. Sulfonamides)

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5
Q

mechanism of action used by antimicrobial agents (what do they target inside the microbial cell)

A
  • cell walls
  • ribosomes
  • cytoplasmic membranes
  • metabolic pathways
  • nucleic acid synthesis
  • blocks attachment
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6
Q

selective toxicity and why it’s important

A

targeting structures unique to that microbe; antibiotic must be more toxic to the pathogen than the host

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7
Q

penicillin and cephalosporin

A
  • Beta-lactam
  • Cell wall biosynthesis inhibitor
  • Gm+ mostly (hard to cross OM of Gm– bacteria) (bactericidal)
  • some allergic reactions
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8
Q

Lipoglycopeptides

A
  • Cell wall biosynthesis inhibitor
  • Gm+ mostly (hard to cross OM of Gm– bacteria) (bactericidal)
  • “red man syndrome” (RMS) –
    flushing, hypotension, itching with
    IV use, phlebitis
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9
Q

Macrolides

A
  • Inhibit protein synthesis – bind large ribosomal subunit
  • Broad spectrum - Gm+ and a few Gm- and fungi (bacteriostatic)
  • Nausea, GI pain, vomiting
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10
Q

Aminoglycosides

A
  • Inhibit protein synthesis – bind small ribosomal subunit
  • Broad spectrum (usually Gm -) –
    not effective against anaerobic
    bacteria (bactericidal)
  • Toxic to kidneys (nephrotoxicity),
    can cause deafness - inner ear and auditory nerves (ototoxicity)
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11
Q

Tetracyclines

A
  • Inhibit protein synthesis – prevent tRNAs from binding small ribosomal subunit
  • Broad spectrum: Gm+ and Gm-
    and Mycoplasma (bacteriostatic)
  • Binds calcium – can stain fetus
    teeth, nausea, diarrhea
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12
Q

Polymyxins

A
  • Binds to and destroys LPS in outer membrane
  • Gm- bacteria, (bactericidal)
  • toxic to kidneys
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13
Q

Rifamycin

A
  • Inhibits transcription (RNA polymerase)
  • Broad spectrum - mycobacteria
    and Gm+, (bacteriostatic)
  • no major side effects
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14
Q

Sulfonamides

A
  • Inhibits folate biosynthesis, which inhibits DNA and RNA synthesis
  • Broad spectrum Gm+ and Gm-
    (bacteriostatic)
  • some allergic reactions and GI issues
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15
Q

Quinolones

A
  • Inhibit DNA replication (gyrase)
  • Broad spectrum Gm+ and Gm-
    (bactericidal)
  • Tendonitis, tendon rupture
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16
Q

Echinocandins (mechanism of action)

A
  • Fungal cell wall inhibitor
  • affects fungi
17
Q

Polyenes

A
  • Fungal membrane inhibitor – bind ergosterols and form holes
  • affects fungi and some protozoa
18
Q

Azoles

A
  • Fungal membrane inhibitor – prevent ergosterol synthesis
  • affects fungi
19
Q

Chloroquine/Quinine

A
  • Inhibit metabolism (including nucleic acid synthesis) in
    protozoa that cause malaria
  • affects protozoa
20
Q

Nitroimidazoles

A
  • Inhibits nucleic acid synthesis in protozoa
  • affects protozoa
21
Q

Nucleoside/Nucleotide analogs

A
  • Inhibits viral nucleic acid synthesis
  • affects viruses
22
Q

Reverse Transcriptase inhibitors

A
  • Inhibits replication of retroviruses
  • affects viruses
23
Q

Narrow-spectrum drugs

A
  • Act on only a few kinds of pathogens
  • use when the causative agent is known - decreases chances of killing normal bacteria
24
Q

Why can’t you use antibiotics to treat viral infections?

A

viruses lack what antibiotics target

25
Q

Differentiate between –cidal and –static antimicrobials. When might a -static antimicrobial be preferred over a -cidal one?

A

cidal: kills bacteria
static: inhibits growth

when we aren’t trying to kill off every bacteria - in Gm+ and Gm- situations when you aren’t wanting to get rid of one vs the other

26
Q

Kirby-Bauer (disk diffusion test)

A
  • given bacterial strain is spread on Petri dish
  • Disks infused with various antibiotics are placed on the plate and incubated with the bacteria
  • antibiotics then diffuse into media
27
Q

MIC (minimum inhibitory concentration test)

A
  • use broth dilution test
  • bacteria is added to serial dilutions of given antimicrobial agent
  • turbidity is measured to determine growth
28
Q

MBC (minimum bactericidal concentration test)

A
  • extension of MIC
  • samples from clear wells are grown on plates without antimicrobial agent
  • differentiates between bacteriocidal and static
29
Q

topical route

A
  • for external infections
  • apply drug directly
30
Q

intramuscular route

A
  • allows drug to slowly diffuse into blood vessels
  • doesn’t achieve doses as high as IV
  • consider how drug affects liver and kidneys
31
Q

intravenous route

A
  • fastest delivery to blood
  • continuous and steady concentrations
32
Q

oral route

A
  • easy to self-administer
  • doesn’t achieve high blood concentrations
  • easy for patients to miss doses
  • have to consider how drug is metabolized
33
Q

therapeutic range/window

A

the range of doses that can still achieve a therapeutic benefit without causing adverse side effects or toxicity

34
Q

therapeutic dose

A

(index) compare the largest dose of grid that is not toxic to the drugs smallest effective dose (higher index= safer drug)

35
Q

toxic dose

A

dose that causes adverse side effects

36
Q

Outline the possible toxic effects and side effects of the specific antimicrobial agents we
discussed and the organs affected

A

polymyxin and ahminoglycosides: kidneys

tetracycline: fetal bones and teeth

fluroquinolones: tendon rupture and nerve damage

37
Q

Explain how microorganisms acquire resistance to chemotherapeutic agents like antibiotics and how humans contribute to this; what can humans do to slow antibiotic resistance?

A
  1. cells can mature their won chromosomal genes due to selective pressure
  2. cells can acquire resistance genes form other bacteria using horizontal gene transfer

we can maintain proper concentration of drug and take when needed; we combat by taking drugs when necessary

38
Q

Broad-spectrum drugs

A
  • Act on many different kinds of pathogens
  • use if you suspect an infection with multiple pathogens at work

microbiology (15 decks)

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