Wsu Exam 4 Microbiology Lab Review

Front 1

What organisms are identified and why?

Back 1

Left = s. pyogenes
Right = GBS

Bacitracin sensitivity:
This is used to test for s. pyogenes versus group B strep. Both are beta hemolytic.

S. pyogenes is bacitracin sensitive meaning that it will not grow around the b (A) disk.

GBS will grow right up to the disk.

Front 2

Bug and disease?

MAC colorless
Lactose (-)

HEK = blue green w/o black dots
Lactose (-)

G(-) rod

Back 2

Shigella sonnei

Bloody Diarrhea
(bacillary dysentery)

Front 3

What test is used to differentiate between Strep and staph species?

Back 3

Catalase Test

Postitive = bubbles upon addition of H2O2 to bacteria.
Staph spp. Is positive.

Negative = Strep

Front 4

Bug and disease?
-BAP = NO growth
- CAP = Growth
- Thayer Martin

Gram (-) Diplococci
Oxidase (+)

CTA=glc (+), maltose (-)

Back 4

Neisseria gonorrhoeae
Urethritis/Cervicitis

Front 5

Describe chocolate agar plate?

Back 5

This is enriched of blood agar essential for some organisms
like Neisseria and haemophilus.

Haemophilus needs X and V factor to grow.

Because this media is not selective, Neisseria must also
be put through the cytochrome oxidase and CTA sugar test.

Haemophilus should be test on another media with the
addition of X and V factor.

Front 6

Bug and disease?

Gram (-) Rod

- MAC= Colorless (lactose (-))
- HEK = Blue W/ black dots
(lactose (-))
- SMAC = Pink (sorbitol (+))
Facultative

Back 6

Salmonella enteridis

Bloody diarrhea

Front 7

Bug?

SMAC=Colorless (sorbitol -)
MAC=Pink (lactose+)

Gram – rod
Oxidase –
Lactose Fermenter

Back 7

E. coli O157
(EHEC)

Front 8

You want to identify your unknown for Pseudomonas aeruginosa.

Name and describe test.

Back 8

OF Dextrose:
This aids in the identification of organisms oxidizing dextrose
in either an aerobic or fermentative way.
This is used to identify pseudomonas aerugionosa.

Tue from green -> yellow with growth.

One tube is open and one has mineral oil over it.

Pseudomonas will only grow on the one without the
mineral oil.

Front 9

Bug and Disease?

Bile Esculin = Growth (black colonies)
NaCl = Growth (cloudy)

Gram (+) Cocci
Catalase (-)

Back 9

Enterococcus faecalis (Group D)

UTI

Front 10

Definitive lab test for Strep. agalactiae (Group B)?

Back 10

CAMP Test = “Arrowhead”

Front 11

Bug?
Gram (-) coccobacillus
- BAP = NO Growth
- CAP = Growth

Back 11

Haemophilus influenzae

Front 12

Compare and contrast N. gonorrhoeae and N. meningitides?

Back 12

CAP = Growth - N. meningococcus=glc(+),maltose(+)

Thayer Martin - N. gonococcus=glc (+),maltose (-) Gram (-) Diplococci

Front 13

Bug?

Gram (+) Cocci clusters
Catalase (+)
Coagulase (+)

Novobiocin Sensitive
NaCl Growth

Back 13

Staph. aureus

Front 14

Bug?

- MAC = Pink (lactose (+))
- SMAC = Pink (sorbitol (+))

Back 14

Other E. Coli NOT EHEC

Front 15

Bug?

Gram (+) Cocci
Catalase (-)
-Hemolytic
Bacitracin Sensitive (A)
CAMP Test
-NO Arrowhead

Back 15

Strep. pyogenes (Group A)

Front 16

Which plate is selective for Gram + bugs?

Back 16

CNA

Front 17

Bug and disease?

- MAC = Pink (lactose (+))
- SMAC = Pink (sorbitol (+))

Back 17

E. Coli
UTI

Front 18

Which plate is selective and differential for isolating certain
pathogenic members of enterobacteraceae while inhibiting
the more numerous members?

Which bugs will grow on this plate?

Back 18

Hektoen enteric agar
Salmonella, shigella, e coli and Proteus

Front 19

Bug?

MAC = Growth
OF Dextrose = Aerobe

Gram (-) Rod
Oxidase (+)
Obligate Aerobe

Back 19

Pseudomonas aeruginosa

Front 20

Bug and Disease?

Gram (+) Cocci clusters
Catalase (+)
Coagulase (-)
Facultative
Novobiocin Resistant **key

Back 20

Staph. saprophyticus

Front 21

Bug and name of plate?

Back 21

Salmon to orange colonies: lactose fermenters -> e. coli
Hektoen enteric agar

Front 22

Describe test and relevant bugs. If a tube of glucose was added, how would the results change?

Back 22

CTA sugar Test
This is used to determine Neiserria spp.

It is sucrose, glucose and maltose and a positive YELLOW
reaction indicates fermentation. Negative is red.


N. gonococcus = glc (+), maltose (-)
N. meningococcus = glc (+), maltose (+)

Front 23

What organisms are identified and why?

Back 23

Right=Staph epidermidis
Left=Staph saprophyticus


Novobicin Resistance:
This test is used to speciate Staph. S. saprophyticus
is the only resistant staph. Meaning that S. epidermidis is susceptible.

Front 24

The growth around XV is indicative of which bug?

Back 24

X, V, and XV factor on TSA for haemophilus

Front 25

What organism is identified on this MAC and why?

Back 25

E. coli is a lactose fermenter

MacConkey Agar:
Used for the isolation of lactose fermenting gram – rods.
The bile salts inhibit all gram + except enterococcus.

Pink or read indicating lactose fermentation

colorless indicate non lactose fermenters.

Front 26

Possible bugs?

Back 26

Cytochrome Oxidase test:

Neisseria, vibrio. and pseudomonas are oxidase positive.

Front 27

ID this organism on MAC plate.

Back 27

Shigella and Salmonella do not ferment lactose

Front 28

What bugs are identified and why?

Back 28

Bile Esculin Agar:
This contains bile as an inhibitor and esculin as a substrate.

This presumptively identifies Group D strep and Listeria.
Group D strep shows a positive reaction meaning black colonies surrounded by brownish black halos.

Listeria shows minute black colonies.

Front 29

Left tube is positive for which 2 possible bugs?
Right?

Back 29

Salt tolerance for enterococcus

S. aureus will also grow so it is important to do a catalase test.

Right tube is (-) = Streptococcus

Front 30

What bugs and describe plate?

Back 30

TCBS
Selective medium for vibrio cholera.
Other enterics will grow, but they can be easily dif.
Btwn vibrio by color.
Vibrio cholera – yellow
Vibrio parahemolyticus – green
e. coli – transluscent
proteus – yellow
pseudomonas – blue

Front 31

Bug?

Back 31

SIM tube:
Listeria exhibits mushroom shaped growth at room temp.

Front 32

Interpret

Back 32

Virus agglutination

A – agglutination,
B -weak agglutination,
C- no agglutination

Front 33

Interpret this test.

Back 33

This is an API from a stool culture of E. coli.

First half-yellow or clear = (-)
Second half-yellow = (+)
Add up results and look up in book for organism

Front 34

Bug?

Back 34

N. gonorrhoeae ferments only glucose.

Gonorhoeae=Glucose
Meningitidis=Maltose AND Glucose

Front 35

Which plate uses sorbital instead of lactose as the sugar. If the strain is the 0157:H7 bad strain it will not grow. Everything else should grow the same. Meaning gram neg enterics such as shigella, salmonella, and e coli non- 0157:H7?

Back 35

sMac
Salmonella is a sorbitol fermenter. (pictured above)

Front 36

Describe test and bug?

Back 36

Coagulase test:
Used to test between staph species.

S. aureus is the only coagulase positive

Front 37

Bug and plate?

Back 37

non lactose fermenters -> shigella

Hektoen enteric agar

Front 38

Describe this test including the 3 bugs involved.

Back 38

A=GBS (Strep agalactiae)
B=GAS (Strep pyogenes)
Center=Staph aureus

CAMP Test:
This provides identification for GBS.

GBS produces a Camp factor that enhances the beta hemolysis of S. aureus.

Because of this a large
“arrow head” of hemolysis will show a positive reaction

Front 39

Describe this plate and which bugs are associated.

Back 39

Blood Agar - Basically everything grows on blood agar except Haemophilus spp. Neisseria spp. are require the blood products to be lysed, not whole.

When you look at a BAP you want to see if the
growth shows one of 3 things:
- Beta -hemolysis: a clear/yellowish zone of
complete lysis beneath colonies. This indicates
that whatever was growing here has a lysine such as SLO that will cause the blood cells to be lysed. S. pyogenes and GBS

- Alpha hemolytic: a greenish less distinct zone
of partial hemolysis. S. pneumoniae, viridans strep,
and group D enterococcus

- Gamma hemolytic: a lack of hemolysis.

Front 40

Which plate here is selective for gram + organisms. It specifically inhibits the growth of most facultative and aerobic gram -. It also will show the hemolytic pattern of Strep spp.?

Back 40

CNA agar
CNA plate (only G+ grows) S. aureus on the left and e. coli, on the right not growing

Front 41

Bugs and name of plate?

Back 41

Black centers: H2S production -> proteus (green) and salmonella (blue)
Hektoen enteric agar

Front 42

Bacitracin Sensitivity (A disk)

disease / possible organism?

Back 42

(+)/sensitive – Group A Strep
(-)/resistant – Group B Strep

Front 43

disease / possible organism?

BE (bile esculin agar)
(+) = black colonies

Back 43

(+) – Enterococcus spp
(+) – Streptococcus spp

Front 44

disease / possible organism?

BAP (blood agar)
->CO2

Back 44

HEMOLYSIS:
α – S pneumo
β – S pyogenes (Gp A), S agalactiae (Gp B)
γ – (non-hemolytic) Enterococcus spp.

Front 45

disease / possible organism?

CAMP Test
BAP w/ S aureus

Back 45

(+) – Group B Strep -> “arrowhead” hemolysis

Front 46

disease / possible organism?

Catalase Test
3% H2O2 -> bubbles

Back 46

(+) Staph
(-) Strep

Front 47

disease / possible organism?

CAP (chocolate agar)/Thayer Martin
-> CO2

Back 47

(+)/growth – Neisseria spp, Haemophilus spp.

Front 48

disease / possible organism?

Coagulase Test
rabbit plasma (citrated if fast coag test)

Back 48

(+) S aureus
(-) all other Staph

Front 49

disease / possible organism?

CNA
-> CO2

Back 49

Gram (+) organisms ONLY

(If incubated anaerobically, Bacteroides will grow)

Front 50

disease / possible organism?

CTA Test (carbohydrate degradation)
-> incubate O2
(+) = yellow

Back 50

Neisseria differentiation
N gonorrhoeae – gluc (+)
N meningitidis – gluc (+) AND malt (+)

Front 51

disease / possible organism?

Latex Aggluttination
(+) = grainy ppt
(-) = milky

Back 51

Check serum antibodies against viruses
- CMV
- VZV
- Rubella

Front 52

disease / possible organism?

Gram Stain
(+) = blue
(-) = red

Back 52

(colony + water droplet, dry, heat fix)

1. Crystal Violet Soln
2. Iodine Soln
3. Acetone-Alcohol decolorization
4. Safranin Soln

G(+) = blue
G(-) = red

Front 53

disease / possible organism?

HEK (Hektoen agar)
Colonies:
- orange = lactose ferm
- blue-green = lactose nonferm
- black centers = H2S

Back 53

Enterobacteriaceae differentiation

E coli = lactose (+), H2S (-) <orange, no black ctr>

Shigella = lactose (-),H2S (-) <green, no black ctr>

Salmonella = lactose (-), H2S (+) <blue, black ctr>

Front 54

disease / possible organism?

MAC (Lactose)
Pink = lactose ferm, gram (-) rods

Clear = lactose nonferm, gram (-) rods

Back 54

E coli = lactose (+)
Shigella = lactose (-)
Salmonella = lactose (-)

Front 55

disease / possible organism?

SMAC (Sorbitol)
Pink = sorbitol ferm
Clear = sorbitol nonferm

Back 55

E coli O157:H7 = sorbitol (-)

Other E coli = sorbitol (+)

Front 56

disease / possible organism?

Novobiocin resistance (NB disk)

Back 56

(+)/sensitive – S aureus, S epidermidis

(-)/resistant – S aprophyticus

Front 57

disease / possible organism?

O/F Dextrose
ID Pseudomonas

Back 57

Sugar -> Acid
Oxidative fermentation only in open air tube = aerobic

Front 58

disease / possible organism?

Optochin Test (P disk)

Back 58

(+)/sensitve – S pneumo

Front 59

disease / possible organism?

Oxidase Test
(+) = blue

Back 59

Neiserria spp = (+)
Pseudomonas = (+)
Vibrio spp = (+)

E coli = (-)

Front 60

disease / possible organism?

Salt Tolerance – 6.5% NaCl broth
(+) = turbidity

Back 60

(+)/turbid – Enterococcus

(-)/clear - Streptococcus

Front 61

disease / possible organism?

SIM Tube Motility assay – grown at rm temp

Back 61

Listeria monocytogenes
SIM: umbrella, semi-solid agar
Nutrient broth: liquid

Front 62

disease / possible organism?

API – stool cx

Back 62

First half – yellow or clear = (-)

Second half – yellow = (+)

Add up results -> look up in book for organism

Front 63

disease / possible organism?

TCBS

Back 63

Vibrio = yellow

E coli = clear

Front 64

disease / possible organism?

T soy plate: Factors X & V

Back 64

H influenzae -> satellite colony around X+V

Front 65

Which plate is selective for Gram (-) bugs?

Back 65

HEK

Front 66

How can Strep. pneumoniae be determined by lab ID?

Back 66

Gram (+) Cocci
Catalase (-)
Optochin Sensitive (P)
Alpha Hemolytic