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ABS > Micro 2- antimicrobial drugs > Flashcards

Micro 2- antimicrobial drugs Flashcards

1
Q

chemotherapy

A

the use of chemicals to treat a disease

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2
Q

antibiotic

A

a substance produced by a microbe that, in small amounts, inhibits another microbe
(example: streptomyces)

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3
Q

antimicrobial drug

A

synthetic substances that interfere with the growth of microbes

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4
Q

selective toxicity

A

selectively finding and destroying pathogens without damaging the host

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5
Q

narrow spectrum of microbial activity

A

drugs that affect a narrow range of microbial types

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6
Q

broad-spectrum antibiotics

A

affect a broad range of gram positive and gram negative bacteria

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7
Q

bactericidal

A

kills microbes directly

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8
Q

bacteriostatic

A

prevent microbes from growing

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9
Q

what is a superinfection and how is it caused

A

overgrowth of normal microbiota that is not sensitive to antibiotics (candida albicans)
-growth of target pathogen that has developed resistance to antibiotics

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10
Q

superinfection is a disadvantage of

A

broad spectrum drugs

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11
Q

5 ways antimicrobial drugs target essential functions of the microbe

A
  1. inhibition of cell wall synthesis
  2. inhibition of protein synthesis
  3. inhibition of nucleic acid replication and transcription
  4. injury to plasma membrane
  5. inhibition of essential metabolite synthesis
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12
Q

example of cell wall synthesis inhibitor and how it works

A

penicillin, contains beta-lactam ring and prevents the cross-linking of peptidoglycan, interfering with cell wall construction (primarily gram-positives)

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13
Q

natural penicillins are

A
  • extracted from penicillium cultures, G (injected) and V (oral)
  • narrow spectrum of activity
  • susceptible to penicillinases (Beta-lactamases)
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14
Q

semisynthetic penicillins

A

contain chemically added side chains, making them resistant to penicillinases

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15
Q

list of inhibitors of protein synthesis

A
  1. aminoglycosides (including streptomycin)
  2. chloramphenicol
  3. tetracyclines
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16
Q

aminoglycosides

A
  • amino sugars linked by glycoside bonds
  • change the shape of the 30S subunit of the 70S ribosome
  • can cause auditory damage
  • streptomycin, neomycin, gentamicin
17
Q

chloramphenicol

A
  • inhibits peptide bond formation
  • binds to 50S subunit of the 70S ribosome
  • synthesized chemically, broad spectrum
  • can suppress bone marrow and affect blood cell formation
18
Q

tetracyclines

A
  • produced by streptomyces spp.
  • interfere with the tRNA attachment to the ribosome
  • broad spectrum, penetrate tissues, making them valuble against rickettsias and chlamydias
  • can suppress normal intestinal microbiota
19
Q

what substances injury the plasma membrane

A
  1. lipopeptide

- includes daptomycin and polymixin B

20
Q

daptomycin

type of lipopeptide

A
  • produced by streptomycetes, used for skin infections

- attacks the bacterial cell membrane

21
Q 
polymixin B
(type of lipopeptide)
A
  • topical, bacteriocidal, effective against gram negatives

- combined with bacitracin and neomycin in nonprescription ointments

22
Q

how do “inhibiting synthesis of essential metabolites” work

A
  • antimetabolites compete with normal substrate for enzyme
  • sulfonamides compete with para-aminobenzoic acid (PABA), stopping the synthesis of folic acid
  • folic acid needed for nucleic acid and protein synthesis
23
Q

types of inhibitors of nucleic acid synthesis

A

-rifamycin
-quinolone and fluoroquinolones
(nalidixic acid, norfloxacin and ciprofloxacin)

24
Q

rifamycin

A

inhibits mRNA synthesis

-penetrates tissues, antitubercular activity

25
Q

quinolone-

nalidixic acid

A

synthetic, inhibits DNA gyrase

26
Q

quinolone-

norfloxacin and ciprofloxacin

A

broad spectrum, relatively nontoxic

27
Q

list 2 types of diffusion methods

A
  1. disk-diffusion method (Kirby-Bauer)

2. E test

28
Q

disk diffusion method (Kirby Bauer)

A
  • tests the effectiveness of chemotherapeutic agents
  • paper disks with chemotherapeutic agent are placed on agar containing the test organism
  • zone of inhibition around the disk determines the sensitivity of the organism to the antibiotic
29
Q

E test

A

determines the minimal inhibitory concentration (MIC)

-lowest antibiotic concentration preventing bacterial growth

30
Q

broth dilution tests

A
  • determine the MIC and minimal bacterial concentration (MBC) of an antimicrobial drug
  • test organism is placed into the wells of a tray containing dilutions of a drug, growth is determined
31
Q

what are antibiograms

A

reports that record the susceptibility of organisms encountered clinically

32
Q

what are persister cells

A

microbes with genetic characteristics allowing for their survival when exposed to an antibiotic

33
Q

superbugs

A

bacteria that are resistant to large numbers of antibiotics

34
Q

how are resistance genes spread

A

often spread horizontally among bacteria on plasmids or transposons via conjugation or transduction

35
Q

list of mechanisms of resistance

A
  • enzymatic destruction or inactivation of the drug
  • prevention of penetration to the target site within the microbe
  • alteration of the drug’s target site
  • rapid efflux (ejection) of the antibiotic
  • variations of mechanisms of resistance

ABS (31 decks)

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