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Flashcards in Exam 2 Deck (82):
1

types of spiral bacteria

vibrio, spirullus, spirochete

2

steps in gram stain

crystal violet 30 seconds
Gram's iodine 1 minute
95% ethanol - 25-30 seconds
safranin 60-80 seconds

3

purpose of 95% ethanol in gram staining

gram negative cells are decolorized

4

purpose of iodine in gram staining

to enhance color or mordant

5

most crucial step in gram staining

decolorizer - 95% ethanol

6

what part of the cell differentiates in gram negative and positive cells

peptidoglycan layer

7

in serial diluton plates how many colonies should you have

30-300

8

serial dilution

to calculate the colony forming units/ml of orginial culture of bacteria

9

mannitol salt

both selective and differential

10

Hektoen Enteric

both selective and differential medium designed to isolate and differentiate members of the species Salmonella and Shigella from other Enterobacteriacea

11

MacConley

both selective and differential

12

mannitol salt determines what to characteristics

salt tolerance and mannitol fermentation

13

what bacteria grows well in mannitol salt agar

staphylococci

14

if bacteria grown in mannitol salt agar they are

salt tolerant

15

mannitol salt contains indicator

phenol red

16

if organism can ferment mannitol is will produce

acid as by-product and will turn yellow

17

Complex media, used for general growth purposes

nutrient agar

18

favors the growth of one type of organism while inhibiting the groth of another

selective media

19

distinguishes between different groups of bacteria;
grow both but can tell the difference between the two

differential media

20

mannitol salt is selective for what type of bacteria

Gram positive

21

mannitol fermenters turn MSA what color as they produce acid

yellow

22

mannitol nonfermenters remain what color as they do not produce acid

red

23

Hektoen Enteric Agar inhibit

Gram positive cocci

24

Hektoen carbon source

Lactose, Sucrose, Salicin

25

Hektoen non fermenters are what color

blue-green colonies

26

Hektoen fermenter pink/orange

not shigella or salmonella

27

Hektoen are selective for

gram negative

28

MacConkey selective for

gram negative

29

macConkey carbon source

lactose

30

macConkey lactose fermenters produce

acid and colonies are pinkish/red

31

macConkey lactose nonfermenters have

colorless colonies

32

when considering antibiotics

zone of inhibition is specific to antibiotic

33

blood agar is what type of medium

differential

34

alpha hemolysis

partial - green

35

beta hemolysis

complete - clear

36

gamma hemolysis

no hemolysis

37

oxidation fermentation purpose

to differentiate bacteria based on their ability to oxidize or ferment specific sugars

38

oxidation fermentation sealed green or blue in color
and unsealed any amount of yellow

oxidation

39

oxidation feremntation sealed and unsealed yellow throughout

oxidation and fermentation or fermentation only

40

oxidation fermentation sealed and unsealed slightly yellow at the top

oxidation and slow feremntation or slow feremntation only

41

oxidation fermentation sealed and unsealed green or blue

no sugar metabolism, organism is nonsaccharolytic

42

phenol red broth purpose

to differentiate between members of Enterobacteriaceae

43

phenol red - yellow broth, bubble in tube

fermentation with acid and gas products

44

phenol red - yellow broth, no bubble in tube

fermentation with acid end products; no gas produced

45

phenol red - red broth, no bubble in tube

no fermentation

46

phenol red - pink broth, no bubble in tube

degradation of peptone, alkaline end products

47

in nitrate reduction test red color upon addition of nitrate reagent A and B indicates

positive result for nitrate reduction to nitrite

48

methyl red test purpose

MR is designed to detect organisms capable of performing mixed acid fermentation, which overcomes the phosphate buffer in the medium and lowers the pH

49

Voges-Proskauser Test purpose

designed for organisms that are able to ferment glucose, but quickly convert their acid products to acetoin and 2,3 butanediol

50

citrate test purpose

to determine the ability of an organism to use citrate as sole cource of carbon

51

citrate test smallest amount of blue

citrate is utilized

52

citrate test growth with no color change

citrate is utilized

53

citrate test no growth and no color change

citrate is not utilized

54

phenylalanine deaminase test result is green color

phenylalanine deaminase is present

55

phenylalanine deaminase test result is no color change

phenylalanine deaminase is absent

56

bile esculin test purpose

identification of enterococci and members of group D streptococci, which are all positive

57

darken medium on bile esculin test

presumptive ID as group D streptococcus or enterococcus

58

urease test all pink

rapid urea hydrolysis, strong urease production

59

urease test partially pink at 24 hours and at 6 days

slow urea hydrolysis, weak urease production

60

urease test orange or yellow at 24 hours and pink at 6 days

slow urea hydrolysis, weak urease production

61

urease test orange or yellow at 24 hours and 6 days

no urea hydrolysis, urease is absent

62

SIM medium is a combination differential medium that test 3 parameters

Sulfur reduction
Indole production
Motility

63

as a whole SIM test is used for

differentiating Salmonella and Shigella

64

Triple sugar Iron agar

combination differential medium that contains lactose, sucrose, glucose, ferrous sulfate, and pH indicator phenol red

65

Bacitracin is produced by the microorganism

Bacillus licheniformis

66

Bacitracin works by

inhibiting cell wall synthesis

67

what is considered bacterial susceptibility for bacitracin

clearing of 10mm or more

68

Novobiocin is produced by the microorganism

Streptomyces niveus

69

Novobiocin works by

interfering with ATPase and production of ATP

70

what is considered bacterial susceptibility for novobiocin

clearing of 16mm or greater

71

optochin is an antibiotic that interferes with

ATPase and production of ATP

72

what is bacterial susceptibility for optochin

clearing of 14mm or more

73

If the SIM tube has any black is in the tube it interpretation is

sulfur reduction

74

Check SIM tube for motility by

checking for growth radiating outward from the stab line

75

in SIM tube after you have check for sulfur reduction and motility

add about 5 drops of Kovac's reagents to each tube

76

Indole production in SIM test

Red in the alcohol layer of Kavac's reagent
-tryptophan broken down into indole and pyruvate

77

Triple Sugar Iron Agar used to

differentiate enterics based on their ability to reduce sulfur and ferment carbohydrate

78

Triple sugar iron agar glucose only fermenters

red slant/yellow butt

79

triple sugar iron agar lactose and/or sucrose fermenters

yellow slant/yellow butt

80

triple sugar iron agar no fermentation

red slant/red butt

81

triple sugar iron agar gas production

fissures or cracks in medium
lifting of agar

82

triple sugar iron gas hydrogen sulfide production

reduction of sodium thiosulfate to form black precipitate
also indicator of fermentation