Lab Final: tests to study

Question 1

Selective

Answer 1

inhibits the growth of certain organisms and thus selects for growth of another

Question 2

Differential

Answer 2

distinguishes one microbe from another, usually by color

Question 3

What plate is differential only?

Answer 3

BAP BLOOD AGAR PLATES

Question 4

What plate is selective only?

Answer 4

PEA PHENY ETHYL ALCOHOL

Question 5

What plate is both selective and differential?

Answer 5

MSA MANNITOL SALTS AGAR
D. MAC MacCONKEY AGAR
E. EMB EOSINE METHYLENE BLUE

Question 6

What does BAP look for?

Answer 6

Hemolysis

Question 7

Types of Hemolysis on a BAP?

Answer 7

Beta hemolysis = clear zone surrounding perimeter (see through)
Alpha hemolysis = olive green or brown colored zone
Gamma = no zone or no-hemolysis (non-hemolytic).

Question 8

What makes PEA selective only?

Answer 8

Only Gram Positive bacteria grow on it
Examples:
Gram negative bacteria is prohibited by ETHYL ALCOHOL
STAPHYLOCCOCCI AND BACILLUS

Question 9

What makes MSA selective and differential?

Answer 9

Selective: Salt (NaCl), Staphylococcus species (halophiles) will grow on this agar
Colonies= halophile (Staph species)
Differential: Mannitol sugars, Staph aureus ferments mannitol and turns the agar yellow
Yellow= mannitol fermenter

Question 10

What makes MAC selective and differential?

Answer 10

Selective: only for Gram negatives organisms, gram positive inhibited by bile salts, crystal violet dye, and neutral red dye
Colonies = gram negative organisms
Differential: Lactose bonded to a pink dye
Pink colonies = lactose fermenters

Question 11

What makes EMB differential and selective?

Answer 11

Selective: only for Gram negatives, gram positives are inhibited by Eosin Methyl Blue dye
Colonies = gram negative organisms
Differential: Lactose bonded to a pink dye
Purple color = lactose fermenter

Question 12

What organism makes a green shine on and EMB plate?

Answer 12

E. coli, Citrobacter freundii, and Klebsiella oxytoca

Question 13

What is in a TSIA tube?

Answer 13

Slant = Sucrose and Lactose
Butt = glucose

Question 14

What makes H2S present in TSIA?

Answer 14

Iron

Question 15

What does an SIM tube test?

Answer 15

Sulfide, Indole, motility

Question 16

What is the proper transport medium?

Answer 16

Stuart’s Transport Medium

Question 17

How much urine does a calibrated loop hold?

Answer 17

.001 mL or 1 microliter

Question 18

Urine specimen classification

Answer 18

0-9 = insignificant
10-99 = infection
>100= acute infection

Question 19

What do you multiply the colonies of a urine sample by?

Answer 19

1,000

Question 20

What reagent is used for a catalase test?

Answer 20

Hydrogen peroxide

Question 21

What is catalase test used for?

Answer 21

Identifies the Gram (+) cocci genus Staphylococcus (any species) from the Gram (+) cocci genus Streptococcus (any species).

Question 22

Catalase test results

Answer 22

Bubbling is a (+) reaction =All Staphylococcus species
No bubbling is a (-) reactive = All Streptococcus species

Question 23

What is used in a coagulase test?

Answer 23

Rabbit plasma

Question 24

What is a coagulase test used for?

Answer 24

identifies Staphylococcus aureus from Staphylococcus epidermidis

Question 25

Coagulase test results

Answer 25

The presence of clotting is a positive reaction.(+) = S. aureus The absence of clotting is a negative reaction. (-) = S. epidermidis

Question 26

What is the bacitracin test used for?

Answer 26

Gram-positive cocci is Catalase (-), it is a species of Streptococcus specifically identifies Streptococcus pyogenes = Strep group A

Question 27

Bacitracin results

Answer 27

Zone of inhibition around bacitracin disk is positive for S. pyogenes No Zone of inhibition means

Question 28

What is the CAMP test used for?

Answer 28

when the Bacitracin Test is (-) and the Streptococcus species is not S. pyogenes test confirms Streptococcus agalactiae = Strep group B

Question 29

CAMP test result

Answer 29

Arrowhead clearing is (+) for the CAMP test. The pathogen is S. agalactiae A negative CAMP test means that the Streptococcus is yet another Streptococcus species and not S. agalactiae

Question 30

What is the Oxidase test used for?

Answer 30

differentiate Gram-Negative rods of the Family Enterobacteriaceae from those organisms that are Non-Enterobacteriaceae

Question 31

Oxidase test results

Answer 31

Purple color = positive test = Pseudomonas and Acinetobacter No color = negative test = Family Enterobacteriaceae

Question 32

METHYL RED (MR) TEST results:

Answer 32

A red color is a positive (+) test result = acid was produced. A yellow color indicates a negative (-) reaction

Question 33

What reagent is needed in a MR test?

Answer 33

Methyl Red Reagent

Question 34

VOGES PROSKAUER (VP) TEST

Answer 34

The cherry red color is Positive (+) = presence of acetoin, the product of the reaction from glucose fermentation . A yellow color indicates a negative (-) reaction

Question 35

NUTRIENT GELATIN TEST: result

Answer 35

Gelatin is a liquid = Positive (+) for gelatinase Gelatin is a solid = Gelatinase is absent (-)

Question 36

VOGES PROSKAUER (VP) TEST: reagents

Answer 36

Alpha-Naphthol Reagent, followed by KOH (Potassium Hydroxide) Reagent