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NYCC Microbiology > Agars & Antibiotics (Lab Only) > Flashcards

Agars & Antibiotics (Lab Only) Flashcards

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Biology 101 flashcards
1
Q

what is microbiological media?

A

(AKA bacterial culture media)
growth medium used to grow bacteria

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2
Q

when is bacterial culture media used?

A

when a specific bacterium must be grown in order to confirm the presence of an infection or study a specific bacterium further

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3
Q

chemical media

A
  • uses chemicals in precise amounts to provide needed nutrients to an organism
  • AKA chemically defined & can be duplicated exactly
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4
Q

organic media

A
  • contains organic material (blood, egg yolk) that a certain bacterium may need to grow
  • AKA complex, and cannot be duplicated exactly due to hormones & other factors based on the source & host of additive
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5
Q

selective media allows for…

A

growth of certain organisms while excluding others

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6
Q

differential media allows for…

A

determination of certain types or strains of bacteria based on a reaction

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7
Q

name 5 types of selective media

A
  • eosin methylene blue
  • YM (yeast extract, malt extract agar)
  • MacConkey agar
  • mannitol salt agar
  • sabouraud’s agar
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8
Q

name 4 types of differential media

A
  • blood agar
  • eosin methylene blue
  • MacConkey agar
  • mannitol salt agar
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9
Q

define selective toxicity

A

selectively finding and destroying pathogens without damaging the host

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10
Q

define antibiotic

A

a substance produced by a microbe that, in small amounts, inhibits another microbe

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11
Q

define antimicrobial drugs

A

synthetic substances that interfere with growth of microbes

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12
Q

define narrow spectrum of microbial activity

A

drugs that affect a narrow range of microbial types (given first to avoid resistance)

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13
Q

define broad-spectrum antibiotics

A

affect a broad range of gram+ or gram- bacteria (what we worry about for antibiotic resistance)

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14
Q

name 2 actions of antimicrobial drugs

A

bactericidal
bacteriostatic

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15
Q

define bactericidal

A

kill microbes directly (eg. cooking)

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16
Q

define bacteriostatic

A

prevent microbes from growing (eg. freezing)

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17
Q

Name 5 actions of antibiotics upon bacteria

A
  • inhibit cell wall synthesis
  • inhibit protein synthesis
  • injure plasma membrane
  • inhibit nucleic acid synthesis
  • inhibit synthesis of essential metabolites
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18
Q

why are the best antibiotics for humans ones that act by inhibiting cell wall synthesis?

A

humans have no cell walls

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19
Q

what effect do antibiotics that inhibit protein synthesis have on males and females?

A

Males: sterilization (should avoid giving to young men)
Females: stops activity of birth control pills

20
Q

How do antimycotics act to kill fungi? Which human cell is impacted the most by this?

A
  • injures the plasma membrane (very permeable)
  • RBCs
21
Q

why do we avoid giving Cipro (quinolone) to people of childbearing age?

A

inhibits nucleic acid synthesis, which impacts human cell division

22
Q

antibiotics that inhibit synthesis of essential metabolites are often used to treat ____

A

UTI’s
(eg. sulfanilimide)

23
Q

the “-cillin” antibiotics inhibit cell wall synthesis because they contain a ____

A

B-lactam ring

24
Q

Over the counter drugs/ointments such as Neosporin should not be used long term because…

A

they cause injury to the plasma membrane

25
Q

the quinolones, particularly Cipro, are very potent, and can cause what negative effects to humans?

A
  • phototoxicity (eyes)
  • neurotoxicity (nerve endings)
  • cardiotoxicity
  • glucose metabolism dysfunction (^diabetes risk)
  • increased risk (400x) for tendon rupture (achilles)
26
Q

the disk-diffusion method (Kirby-Bauer test) tests the effectiveness of ____

A

chemotherapeutic agents

27
Q

in the disk-diffusion method, a zone of inhibition (clearing) around the disk determines…

A

sensitivity of the organism to the antibiotic and/or antiseptics/disinfectants
(no clearing = resistant)

28
Q

name 4 mechanisms of resistance (i.e., how bacteria get rid of an antibiotic)

A
  • enzymatic destruction/inactivation of the drug
  • prevention of penetration to target site within the microbe (seal off)
  • alteration of drug’s target site
  • rapid efflux (ejection) of antibiotic
29
Q

name 5 examples of misuse of antibiotics

A
  • using outdated/weakened antibiotics
  • using antibiotics for common cold and other inappropriate conditions
  • using antibiotics in animal feed
  • failing to complete prescribed regimen
  • using someone else’s leftover prescription
30
Q

name 3 sources for mannitol salt agar?

A

skin
nose
fomites (surfaces)

31
Q

what effect does staphylococcus epidermidis have on any media? why?

A
  • no effect on any media (may turn slightly purple)
  • has NO TOXINS!
32
Q

A boil was sampled from the leg of a 27-year-old student. It was plated onto mannitol salt agar and turned the media yellow. What is the most likely organism seen here?

A

staphylococcus aureus
(source: skin)

33
Q

A toddler comes into your practice with a weepy eye. You gather a sample and send it to a testing lab where it is grown out. It grew on mannitol salt and did not cause any change to the media.

A

staphylococcus epidermidis

34
Q

The terms “complete or incomplete” hemolysis on blood agar are used to indicate a sample of what organism?

A

staphylococcus aureus

35
Q

The terms “beta or alpha” hemolysis on blood agar are used to indicate a sample of what organism?

A

Streptococcus

36
Q

A sample taken from a throat swab is plated on blood agar. You see complete clearing. What type of hemolytic activity is most likely seen here? Why?

A

throat (source) = most likely streptococcus pyogenes, which has beta hemolytic activity

37
Q

A sample taken from a boil is plated on blood agar. You see complete clearing. What hemolytic activity is seen here? Why?

A

skin (source) = most likely staphylococcus aureus which has complete hemolytic activity

38
Q

What is the difference between complete and incomplete hemolysis?

A

complete = can see through it
incomplete = cannot see through it

39
Q

A sample is taken from skin/nose/surface and plated on blood agar. When grown out, you cannot see through the media. What is the most likely organism and what hemolytic activity is seen?

A

staphylococcus aureus will cause incomplete hemolysis
(staph epi doesn’t change media, just grows)

40
Q

A sample is taken from a throat swab and plated on blood agar. When grown out, you see incomplete clearing and a greenish change to the media. What is/are the most likely organism(s) and what hemolytic activity is seen?

A
  • any other streptococcus (eg. strep viridans, strep pneumonaie)
  • alpha hemolysis
41
Q

How does E. Coli appear when grown on Eosin methylene blue agar? What diagnosis is this method commonly used for?

A
  • GREEN SHEEEEEEEN!!!!!!
  • UTI’s
42
Q

What will grow on MacConkey agar?

A

feces (enterics)

43
Q

What will grow on Sab Dextrose agar? Why?

A

selective for fungi due to presence of sugar and acid
(will rarely grow bacteria)

44
Q

How do yeast and molds differ in appearance when grown on Sab Dextrose agar?

A

yeast = slimy colonies
molds = fuzzy/hairy

45
Q

Chromagar MRSA II is selective/differential for ____, which will grow as ____ colonies

A
  • methicillin-resistant staphylococcus aureus (MRSA)
  • reddish-pigmented

NYCC Microbiology (17 decks)

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