Micro Lab Exam 3 Review

Front 1

MSA stands for_____?

Back 1

Mannitol Salt Agar

Front 2

What is the selective agent in MSA?

Back 2

7.5% sodium chloride

Front 3

What is the differential test in MSA?

Back 3

Mannitol (differentiates b/w pathogenic and non-pathogenic Staphylococcus sp.)

Front 4

What is the test indicator in MSA?

Back 4

Phenol Red

Front 5

What does the test indicator in MSA indicate?

Back 5

pH level/acidity

Front 6

MSA was designed for the selection and differentiation of which MOs?

Back 6

Staphylococcus sp.

Front 7

A positive mannitol fermentation is indicated by the formation of a _______ color?

Back 7

Yellow

Front 8

What causes the test indicator in MSA to change color when mannitol was fermented?

Back 8

The presence of acid

Front 9

Which known MO used in lab gives a positive test on MSA?

Back 9

Staphylococcus aureus

Front 10

Which known MO used in lab gives a negative test on MSA?

Back 10

Staphylococcus epidermidis

Front 11

Poor growth on MSA indicates which type of MO?

Back 11

MO inhibited by NaCl/not Staphylococcus sp.

Front 12

At what pH is phenol red yellow? At what pH is it pink?

Back 12

Yellow 6.8-8.2

Pink >8.2

Front 13

EMB stands for ______?

Back 13

Eosin Methylene Blue

Front 14

What are the sugars found in EMB agar?

Back 14

Lactose and sucrose

Front 15

What are the dyes found in EMB agar?

Back 15

Eosin Y and Methylene Blue

Front 16

What type of medium is EMB agar?

Back 16

Complex, selective, and differential

Front 17

EMB agar is used for the isolation of ______?

Back 17

enteric bacteria

Front 18

What is the purpose of sugars in EMB agar?

Back 18

supports the growth of enteric bacteria

Front 19

Which group of MOs do the dyes inhibit in EMB agar?

Back 19

Gram +

Front 20

Besides inhibiting a certain group of MOs, what is another function of the dyes in EMB agar?

Back 20

reacts with lactose fermenters whose acidic conditions turn the EMB agar dark purple with green metallic sheen

Front 21

A pink colored colony indicates that the MO is a ____?

Back 21

possible coliform

Front 22

A dark purple colony with green metallic sheen indicates that the MO is a ______?

Back 22

probable coliform

Front 23

If a MO is unable to grow on EMB agar, it is most likely a _____?

Back 23

Gram +

Front 24

Colorless colonies on EMB agar means that the MO is a _______?

Back 24

Gram -

Front 25

Good growth on EMB agar means that the MO is a _______?

Back 25

Gram -

Front 26

HE agar stands for ______?

Back 26

Hektoen Enteric

Front 27

Is HE agar a defined medium?

Back 27

No, it is complex (chemically undefined)

Front 28

What type of medium is HE agar?

Back 28

complex, selective, and differential

Front 29

What was HE agar designed to do?

Back 29

to select for and differentiates Salmonella and Shigella sp.

Front 30

What is the purpose of bile salts in HE agar?

Back 30

inhibit Gram + cocci

Front 31

What is the purpose of ferric ammonium citrate in HE agar?

Back 31

Indicate that an MO can reduce sulfur to hydrogen sulfide (H2S)

Front 32

What is the sulfur source in HE agar?

Back 32

Sodium thiosulfate

Front 33

Why is it necessary to have a sulfur source in HE agar?

Back 33

to determine if MO can reduce sulfur to hydrogen sulfide (H2S)

Front 34

What three sugars are in HE agar?

Back 34

lactose, sucrose, and salicin

Front 35

What is the purpose of having three sugars in HE agar?

Back 35

to see if MO can ferment sugar to acid (fermentation)

Front 36

What are the dyes in HE agar?

Back 36

Bromthymol blue and acid fuchsin

Front 37

What is the purpose of the dyes in HE agar?

Back 37

test indicators

Front 38

Poor or no growth on HE agar indicates that the MO is a ______?

Back 38

Gram +

Front 39

Good growth on HE agar indicates that the MO is a _____?

Back 39

Gram -

Front 40

Pink or orange growth on HE agar indicates that the MO is capable of fermenting ______?

Back 40

lactose

Front 41

Pink or orange growth on HE agar indicates that the MO is a ___________?

Back 41

negative test for Shigella or Salmonella but ferments lactose to acid

Front 42

Blue-green growth with black precipitate indicates that the MO is a possible _______?

Back 42

Salmonella

Front 43

Blue-green growth without a black precipitate indicates that the MO is a possible _______?

Back 43

Shigella or Salmonella

Front 44

Blue-green growth indicates the MO does not ferment ________?

Back 44

lactose

Front 45

Black precipitate indicates that themicroorganism is capable of producing _______?

Back 45

hydrogen sulfide (H2S)

Front 46

MAC stands for _______?

Back 46

MacConkey Agar

Front 47

What type of medium is MAC agar?

Back 47

selective and differential

Front 48

MAC agar is used to isolate and differentiate ______ based on their ability to _______?

Back 48

Coliforms; ferment lactose

Front 49

What is the test indicator in MAC agar?

Back 49

neutral red

Front 50

The test indicator in MAC agar is colorless above ___ and red below _____?

Back 50

6.8pH

Front 51

What is the purpose of bile salts and crystalviolet in MAC agar?

Back 51

inhibit growth of Gram +

Front 52

Poor or no growth on MAC agar indicates that themicroorganism is a ______?

Back 52

Gram +

Front 53

Good growth on MAC agar indicates themicroorganism is a ______?

Back 53

Gram -

Front 54

Red or pink growth on MAC agar indicates thatthe microorganism is a ______?

Back 54

probable coliform

Front 55

Red or pink growth on MAC agar indicates thatthe microorganism is capable of fermenting _______?

Back 55

lactose

Front 56

Colorless growth on MAC agar indicates that themicroorganism is unable to ferment?

Back 56

lactose

Front 57

Colorless growth on MAC agar indicates that themicroorganism is a _______?

Back 57

noncoliform

Front 58

Bactracin inhibits microorganisms by _____?

Back 58

inhibiting cell wall synthesis

Front 59

What type of antibiotic is Bactracin?

Back 59

peptide antibiotic

Front 60

Bacitracin is produced by _______?

Back 60

Bacillus licheniformis

Front 61

For Bactracin to inhibit the growth of amicroorganism, the microorganism must be _____?

Back 61

In the process of growing

Front 62

What medium is used for the Bactracin test?

Back 62

Blood agar

Front 63

The Bactracin test is used differentiate whichmicroorganisms?

Back 63

Staphylococcus sp. from Micrococcus sp.

Front 64

Susceptibility to Bacitracin is indicated by ____?

Back 64

a zone of clearing 10 mm or greater

Front 65

What type of test is the Bacitracin test?

Back 65

differential

Front 66

Zone of clearing less than 10 mm, for theBactracin test, indicates that the microorganism is ____?

Back 66

resistant to bacitracin

Front 67

Zone of clearing greater than 10 mm, for theBactracin test, indicates that the microorganism is _______?

Back 67

sensitive to bacitracin

Front 68

What is the function of a hemolysin?

Back 68

Cause the lysis or partial lysis of RBCs

Front 69

A hemolysin is a _______?

Back 69

chemical (toxin) produced by certain bacteria that cause the lysis or partial lysis of RBCs

Front 70

Blood agar is what type of medium?

Back 70

differential

Front 71

What is hemolysis?

Back 71

the type of lysis or partial lysis of RBCs

Front 72

What is beta-hemolysis?

Back 72

complete breakdown of RBCs resulting in clearing around microbial growth on blood agar

Front 73

What is alpha-hemolysis?

Back 73

partial hemolysis of RBCs resulting in an indistinct zone around the microbial growth which appears greenish to brownish

Front 74

What is gamma-hemolysis?

Back 74

no breakdown of RBCs resulting in no zone around microbial growth

Front 75

Blood agar is used for _______?

Back 75

Blood agar test & Bacitracin Susceptibility test

Front 76

What are streptolysins?

Back 76

Hemolysins that are produced by Streptococcus sp.

Front 77

What forms do streptolysins come as?

Back 77

Type O and Type S

Front 78

What is the difference between the two forms of streptolysin?

Back 78

Type O is oxygen labile and expresses maximal activity under anaerobic conditions

Type S is oxygen stabile but expresses itself optimally under anaerobic conditions as well

Front 79

Clearing around the growth on Blood agar indicates that the MO produces ______?

Back 79

beta-hemolysis

Front 80

Greening or a fuzzy area around the growth onBlood agar indicates that the microorganism _____ which causes _______?

Back 80

hemolyzes RBCs partially; alpha-hemolysis

Front 81

No change in the medium around the growth onBlood agar indicates that the microorganism _____.

Back 81

does not hemolyze RBCs

Front 82

What type of pathogen is Staphylococcus aureus?

Back 82

virulent pathogen

Front 83

What forms does coagulase appear as?

Back 83

Clotted or liquid

Front 84

What is the function of coagulase?

Back 84

converts fibrinogen into fibrin to form a protective barrier around the MO, shielding it from phagocytosis and other immune responses

Front 85

Why would a MO want to produce coagulase?

Back 85

to shield it from phagocytosis and other immune responses

Front 86

What benefit would producing coagulase provide a MO?

Back 86

resistance to normal immune responses and antimicrobial agents

Front 87

Describe how coagulase is able to clot serum?

Back 87

by converting fibrinogen into fibrin

Front 88

A positive coagulase test appears as a _____?

Back 88

clotted serum

Front 89

A negative coagulase test appears as a _____?

Back 89

liquid serum

Front 90

Clumped serum indicates that the MO produces ____?

Back 90

coagulase

Front 91

Un-clumped serum indicates that the MO ______?

Back 91

does not produce coagulase

Front 92

Medium is solid says that the serum is _____?

Back 92

coagulated

Front 93

Medium is liquid says that the serum is _____?

Back 93

not coagulated

Front 94

Why does the coagulase test have to be read in 24 hours?

Front 95

In motility test medium a positive for motility is indicate by _______?

Back 95

a red stab line with movement away from stab line

Front 96

Know how to calculate the CFUs/mL

Back 96

(# of plaques/dilution counted) X dilution factor

Front 97

What does CFUs/mL stand for?

Back 97

colony forming units/mL

Front 98

Know how to conduct serial dilution

Front 99

What is the range of colonies on a viable plate count plate that is countable?

Back 99

30 to 300

Front 100

What does TNTC stand for?

Back 100

too numerous to count

Front 101

What is the formula for determining a dilution?

Back 101

(# of plaques/dilution counted) X dilution factor

Front 102

What is the difference between the spread plate procedure and the pour plate procedure of the viable plate count technique?

Front 103

What type of viruses attack bacterial cells?

Back 103

Bacteriophages

Front 104

What is the substrate for the coagulase test?

Back 104

Fibrinogen

Front 105

What is the enzyme for the coagulase test?

Back 105

Coagulase

Front 106

What is the end product for coagulase test?

Back 106

Fibrin

Front 107

Why was the E. Coli B used in the Plaque Assay?

Back 107

T4 is host specific

Front 108

Clearings in the lawn of E. Coli B cells are called?

Back 108

Plaques

Front 109

Why was the dilution of the virus done before mixing of the virus and host cell together?

Back 109

so the viral particles could attach to the bacterial cells

Front 110

What does PFUs/mL stand for?

Back 110

Plaque forming units

Front 111

What is the range of plaques that are countable in the Plaque Assay?

Back 111

30 to 300

Front 112

What viral replication cycle was observed in the plaque assay?

Back 112

lytic and lysogenic cycle

Front 113

What specific type of virus was used in the Plaque Assay?

Back 113

T4 virus

Front 114

What general type of virus was used in the Plaque Assay?

Back 114

T even coliphage/complex virus

Front 115

Why was the host cell and virus mixed together in the soft agar?

Back 115

necessary for virus to be able to replicate

Front 116

What was the purpose of soft agar in the Plaque Assay?

Back 116

used to mix the bacteria and page dilutions which is then spread over hard agar

Front 117

Why was TSA used in the Plaque Assay?

Back 117

Plaque forms most easily and evident on TSA plates

Front 118

What is meant by a lawn of bacteria?

Back 118

solid growth of bacteria covering an entire surface of a growth agar in a petri dish

Front 119

Define an antibiotic

Back 119

Natural antimicrobial agents produced by MOs

Front 120

Give 2 examples of antibiotics used in the antimicrobial susceptibility test

Back 120

Penicillin and Ciproflaxin

Front 121

What medium was used in the antimicrobial susceptibility test?

Back 121

Mueller-Hinton Agar

Front 122

What do R, I, and S stand for in the antimicrobial susceptibility test?

Back 122

R=resistant, I=intermediate, S=susceptible

Front 123

What was the specific name of the antimicrobial susceptibility test that was conducted in lab?

Back 123

Kirby Bauer Method

Front 124

Why was E. Coli and Staphylococcus aureus used in the antimicrobial susceptibility test?

Back 124

They inhibit different modes of action on bacterial cells

Front 125

What determines whether a MO is R, I, or S in the antimicrobial susceptibility test?

Back 125

the diameter of the zone of inhibition

Front 126

What is the zone of clearing in the microbial growth around a disc of antibiotic called?

Back 126

zone of inhibition

Front 127

Define a fecal coliform?

Front 128

Define a total coliform?

Front 129

What medium was used to enumerate fecal coliforms? What color are fecal coliforms on this medium?

Front 130

What medium was used to enumerate total coliforms? What color are total coliforms on this medium?

Front 131

Whatwas the purpose of adding the sterile saline to the filtration unit beforeadding the water sample?

Front 132

Whatwas the purpose of rinsing the filtration unit three times with sterile salineafter filtering the water sample?

Front 133

Knowhow to calculate fecal and total coliforms per 100 mL of water sample.

Front 134

Whycan there not be air bubbles under the membrane filter when it is placed on themedia?

Front 135

What does XLD stand for?

Back 135

Xyloselysine Desoxycholate Agar

Front 136

What type of medium is XLD agar?

Back 136

selective and differential

Front 137

What is the function of desoxycholate in XLD agar?

Back 137

inhibit Gram +

Front 138

What is the sugar in XLD agar?

Back 138

xylose

Front 139

What is the amino acid in XLD agar?

Back 139

lysine

Front 140

What is the function ferric ammonium citrate inXLD agar?

Back 140

Hydrogen sulfide (H2S) production indicator

Front 141

What is the test indicator in XLD agar?

Back 141

phenol red

Front 142

What microorganisms is XLD agar able todifferentiate?

Back 142

Shigella, Providencia, E. Coli, and Salmonella

Front 143

Xylose fermentation is indicated on XLD agar bythe formation of _____?

Back 143

yellow growth

Front 144

Poor growth of a microorganism on XLD agarindicates that it is a _____?

Back 144

Gram +

Front 145

Good growth of a microorganism on XLD agarindicates that it is _____?

Back 145

Gram -

Front 146

Yellow growth on XLD agar indicates that themicroorganism is able to ______

Back 146

produce acid from xylose fermentation

Front 147

Red growth on XLD agar indicates that themicroorganism is able to _______

Back 147

decarboxylate lysine

Front 148

Black coloration on XLD agar indicates that themicroorganism is able to ______

Back 148

reduce sulfur to hydrogen sulfide (H2S)

Front 149

What three processes can be determined about amicroorganism on XLD agar?

Back 149

decarboxylation, reduction, fermentation

Front 150

Phenol red is _____ at acidic pHs?

Back 150

yellow

Front 151

Phenol red is _______ at alkaline pHs?

Back 151

red/pink