Lab Midterm

Question 1

MSA selective ingredient

Answer 1

7.5% NaCl

Question 2

MSA differential ingredient

Answer 2

mannitol

Question 3

are GP or GN more sensitive to salt?

Answer 3

Gram negative

Question 4

enzyme needed to ferment mannitol?

Answer 4

MOH

Question 5

color of a mannitol fermenter?

Answer 5

yellow

Question 6

key Man+ organism

Answer 6

S. aureus

Question 7

is coagulase performed with serum or plasma?
why?

Answer 7

plasma
it contains clotting factors

Question 8

molecule that forms a clot

Answer 8

fibrin

Question 9

CNS besides S. epidermidis

Answer 9

S. haemolyticus

Question 10

coagulase detects (bound/free) enzyme

Answer 10

bound

Question 11

bile esculin selective ingredient

Answer 11

bile

Question 12

bile esculin differential ingredient

Answer 12

esculin

Question 13

sugar in esculin

Answer 13

glucose

Question 14

what reacts with esculin to give brown-black color?

Answer 14

iron

Question 15

special bile esculin condition for Bacteroides

Answer 15

anaerobic environment

Question 16

organism that would grow on bile esculin

Answer 16

E. faecalis

Question 17

type II cytotoxins cause —- hemolysis

Answer 17

beta

Question 18

y-hemolysis organism

Answer 18

E. faecalis

Question 19

green colored hemolysis

Answer 19

alpha

Question 20

a-hemolysis organism

Answer 20

S. pneumoniae

Question 21

a-hemolysis results from…

Answer 21

oxidation of hemoglobin by peroxide to methemoglobin

Question 22

hemolysin expressing maximal activity under anaerobic conditions

Answer 22

streptolysin O (SLO)

Question 23

optochin inhibits…

Answer 23

ATPase

Question 24

zone required to indicate susceptibility to 5 μg optochin

Answer 24

≥ 14mm

Question 25

organism indicated by optochin sensitivity

Answer 25

S. pneumoniae

Question 26

bacitracin mode of action

Answer 26

inhibits cell wall synth

Question 27

S. pyogenes -- bacitracin

Answer 27

sensitive

Question 28

Staphylococcus -- bacitracin

Answer 28

resistant

Question 29

Bacillus licheniformis -- bacitracin

Answer 29

resistant

Question 30

Micrococcus -- bacitracin

Answer 30

sensitive

Question 31

SXT mode of action

Answer 31

inhibits folic acid metabolism

Question 32

Group A strep example

Answer 32

S. pyogenes

Question 33

Group B strep example

Answer 33

S. agalactiae

Question 34

which strep group grows in the presence of bacitracin?

Answer 34

Group B grows Group A does not grow

Question 35

what is on the Staphaurex beads?

Answer 35

antibody against S. aureus

Question 36

DNase positive result

Answer 36

colorless halo around DNase positive colonies

Question 37

Example of DNase pos organism

Answer 37

S. marscesens

Question 38

CAMP positive

Answer 38

arrowhead zone

Question 39

is CAMP factor higher closer or further from the arrowhead?

Answer 39

further

Question 40

organism streaked on CAMP plate (not being tested)

Answer 40

S. aureus

Question 41

example of pos CAMP organism

Answer 41

Streptococcus agalactiae

Question 42

novobiocin mode of action

Answer 42

interferes with DNA replication by inhibiting DNA gyrase

Question 43

resistant to novobiocin

Answer 43

Staphylococcus saprophyticus

Question 44

steps of growth-dependent microbiology

Answer 44

enrichment (selective or differential media) isolation (pure culture) identification

Question 45

reducing agent used for

Answer 45

anaerobes

Question 46

swaps placed in transport tube with...

Answer 46

sterile saline

Question 47

specificity few false -----

Answer 47

ability of test to recognize a pathogen few false positives

Question 48

sensitivity few false ------

Answer 48

smallest quantity of pathogen that can be detected few false negatives

Question 49

rare organism, few false positives

Answer 49

GNC ex. N. gonorrhoeae

Question 50

(males/females) give more cells

Answer 50

males

Question 51

N. gonorrhoeae swabs are plated on ----- agar

Answer 51

Thayer-Martin

Question 52

------ used for further confirmation of N. gonorrhoeae

Answer 52

oxidase

Question 53

selective media

Answer 53

contain poisons or inhibitors which prevent growth of specific competitors

Question 54

differential media

Answer 54

indicators that change color often a pH indicator for acid production

Question 55

sensitivity for finding a cell from a spinal tap smear

Answer 55

10^5

Question 56

------ often required for spinal taps

Answer 56

culturing

Question 57

------ mL blood needed to inoculate "blood bottles"

Answer 57

10-20 mL

Question 58

2 blood bottles

Answer 58

aerobic anaerobic

Question 59

can take 5 days to grow in blood bottles

Answer 59

anaerobes

Question 60

can take 2 weeks to grow in blood bottles

Answer 60

TB

Question 61

preferred media for IDing UTI organisms

Answer 61

MacConkey EMB

Question 62

----- and ----- are very sensitive to acid buildup, so fecal samples must be handled rapidly

Answer 62

Salmonella Shigella

Question 63

------ parasites can be directly observed in fecal samples

Answer 63

Giardia

Question 64

first step for bites/wounds

Answer 64

selective & differential media

Question 65

if swap doesn't work on bite/wound

Answer 65

syringe aspiration or surgical biopsy

Question 66

chromagar

Answer 66

colorimetric substrate broken down to give distinct color

Question 67

cause urethritis (4)

Answer 67

Chlamydia Ureaplasma Trichomonas N. gonorrhoeae

Question 68

in (males/females) organisms can be found in exudates by microscopy

Answer 68

males

Question 69

media choices for N. gonorroeae

Answer 69

chocolate agar modified TM agar with 4 antibiotics NYC medium lacking blood, plasma and soluble hemoglobin instead

Question 70

culturing N. gonorrhoeae requires what environment?

Answer 70

3-7% CO2 incubator

Question 71

N. gonorrhoeae oxidase? gram? arrangement/shape?

Answer 71

oxidase pos G N diplococci