Media/ Tests

Question 1

Trypticase soy agar

Answer 1

supportive media (non-fastidious)

Question 2

BAP

Answer 2

enrichment (fastidious)/ selective/ differential
contains: 5% sheep blood agar trypticase soy base
ID aerobic GPC
Hemolysis: strep only report Enterococcus/group D gamma, GAS/GBS/group C,F,G beta, viridian/pneumonia alpha

Question 3

BCYE

Answer 3

buffered charcoal yeast extract
enrichment media
contains: L-cysteine (enrichment)
Legionella pneumophila

Question 4

CVA CAMPY

Answer 4

Campylobacter-blood agar
enrichment/ selective
contains: AB (selective), Brucella agar (enrichment) (sheep blood, yeast extract, casein)
Campylobacter; inhibits GI flora
increase temp 42*C; micro-aerophilic environment

Question 5

Chocolate Agar

Answer 5

enrichment
contains: hemin (x factor) and NAD (V factor), vit B12, Fe & Mg, Cysteine
Neisseria and Haemophilus

Question 6

PEA

Answer 6

phenyl-ethyl alcohol agar
selective
contains: sheep BA, phenylethyl alcohol
isolates GPC from mixtures; inhibits GNR

Question 7

MAC

Answer 7

MacConkey agar
selective/differential
contains: lactose (differential), bile salts (selective), crystal violet, neutral red indicator
isolates GNR
ferments lactose- pink 
non fermenter- colorless

Question 8

S-MAC

Answer 8

Sorbitol MacConkey
differential
contains: lactose, bile salts, crystal violet, neutral red indicator
ID E. coli O157:H7 sorbitol negative (clear)

Question 9

SXT

Answer 9

sulfamethoxazole/trimethoprim
selective/differential
contains: SXT (antimicrobial against normal throat flora alpha Strep)
isolate GAS

Question 10

HIM

Answer 10

Hemophilus isolation media
enrichment/differential
contains: X (Hemin) and V (NAD) factors, horse blood,
ID Haemophilus

Question 11

CNA

Answer 11

columbia colistin-naldixic acid
selective
contains: colistin, naldixic acid
selects for GP

Question 12

Hektoen agar

Answer 12

differential/selective
contains: bile salts (inhibit GP), lactose, sucrose, salicin (if use turn yellow), Na thiosulfate (H2S prod.= black color)
ID Salmonella spp & Shigella spp.= colorless
Salmonella black

Question 13

XLD

Answer 13

xylose-lysine-desoxycholate agar
selective/differential
contains: bile salts (inhibit GP), latose, sucrose, xylose (yellow), Na thiosulfate (black)
ID Salmonella spp, & Shigella spp. = colorless
Salmonella black

Question 14

Thayer Martin agar

Answer 14

enrichment/selective
contains: vancomycin (inhibit GPC), colistin (inhibit GNR), trimethoprim (stop Proteus swimming), nystatin (inhibits fungus)
Isolate Neisseria gonorrhoeae

Question 15

Martin Lewis agar

Answer 15

enrichment/selective
contains: anisomycin (antifungal), vancomycin (more than Thayer Martin agar)
Neisseria isolates

Question 16

V-agar

Answer 16

vaginalis agar
enrichment
contains: human blood, peptones, yeast extract
isolates Gardnerella vaginalis

Question 17

MSA

Answer 17

mannitol salt agar
contains: peptones, beef extracts, 7.5% NaCl, mannitol, phenol red
ID Staphylococcus aureus (ferments mannitol= yellow)

Question 18

Thioglycolate Broth

Answer 18

holding media (wounds & fluid cultures)
supports aerobic (top)/anaerobic(bottom) growth
contains: casein, soybean peptones, NaCl, Na thioglycollate

Question 19

GN and Selenite Broth

Answer 19

support growth of Salmonella spp. & Shigella spp.
stool cultures subbed in this
good for small #s

Question 20

Coagulase tube test

Answer 20

Staph rxts w/ coagulase-reacting factor (thrombin like thermostable molecule) to form complex that converts fibrinogen to fibrin

Question 21

Rapid agglutination S. aureus

Answer 21

Use latex that detects clumping factor (w/ fibrinogen) and protein A (w/ IgG)

Question 22

Coagulase slide test

Answer 22

Clumping factor causes agglutination in human/rabbit/pig plasma by converting fibrinogen to fibrin

Question 23

sodium hippurate test

Answer 23

tests if bacteria can hydrolyze sodium hippurate to hippuric acid, glycine, and benzoic acid.
glycine deaminated by ninhydrin (oxidizer)
end prod. of oxidation forms purple dye

Question 24

CAMP test

Answer 24

ID Streptococcus agalactiae & Listeria monocytogenes
prod. proteins that interact with beta hemolysin in S. aureus to produce enhanced hemolysis
streak S. aureus in middle, test streak perpendicular to Staph but not touching
S. agalactia- arrow shaped zone of hemolysis
L. monocytogenes- rectangular shaped zone of hemolysis

Question 25

catalase test

Answer 25

catalase decomposes hydrogen peroxide into oxygen and water
except for Strep most aerobic and facultative anaerobic bact. posses catalase
transfer colonies to slide, add 1-3 drops 3% h2o2, look for bubbles w/in 5 sec.
+: vigorous bubbling (S. aureus)
-: no bubbles (S. pyogenes)
weak +: a few bubbles (Enterococcus)

Question 26

DNase test

Answer 26

DNase test agar: toluidine blue
differential
detect deoxyribonuclease activity: DNase depolylmerizes DNA= in presence of nucleotides from depolymerization pink to red zones around bact. growth
differentiates Serratia from Enterobacter, S. aureus from CNS, and Moraxella catarrhalis from Neisseria spp.
+: pink-red zone around growth (Serriatia marcescens, S. aureus)
- : media blue/ unchanged (CNS)

Question 27

Microdase test

Answer 27

differentiates Staph from Micrococcus
DMSO in microdase disk provides solubility and stability against auto-oxidation; enhances permeability of TMDP into bact. cell
in oxygen, oxidase + TMPD + cytochrome C= indophenol
only be done on aerobic, catalase + GPC
DO NOT USE with M. luteus (pig. interferes)
place disk on slide, inculate disk w/ bact., examine for 2 mins.
+: blue-purple/blue/brown color (Micrococcus)
-: no color change (Staph)

Question 28

Nitrate broth

Answer 28

bact. reduce nitrate-nitrite
NO3 + 2e + 2H=== NO2 + H2O
inculate nitrate medium with small loop from pure isolate, incubate 35-37*C for 18-24hrs. w/ loosened caps, examine for gas @ 18-24hrs. and @42-48hrs., after 24-48hrs. if gas test is + for nitrate===nitrogen gas, if not take 2mL of broth into clean tube, add 5 drops nitrate a and 5 drops nitrate b, shake
+ :pink/red color w/in 2 mins.
If no color in 2 mins. add small amount zinc dust, mix
if broth turns pink/red w/in 2 mins. nitrate is present so result is negative, if no color change result is positive
+: pink/red w/in 2 mins or after zinc no color change (E. coli)
-: no color change w/in 2mins or pink/red after zinc is added (Acinetobacter baumanii)

Question 29

LAP test

Answer 29

prod. of leucine aminopeptidase (LAP) disk spot test
disk has leucine-beta-naphthylamide hydrochloride, if LAP is present then substrate is hydrolyzed to release leucine and beta-naphthylamide (which combines w/ cinnamaldehyde to form pink/red color)
mositen disk a little, inoculate heavily, after 10 mins. add 1 drop developer, look for pink/orange-pink/cherry red color after 5 mins.
+ : pink/orange-pink/cherry red (Aerococcus viridans, Entercoccus sp., Gemella morbillorum, Pediococcus, Streptococcus)
- : yellow (Aerococcus urinae, Gemella haemolysans, Leuconostococcus)
weak + : pink

Question 30

VP test

Answer 30

voges-prokauer
detects acetylmethcarbinol (acetoin) produced as a result of glucose metabolism
prepare 2.0 mcfarland suspension of culture, incubate 35* C w/ loosened cap, at 24hrs. remove 1 mL to a tube, add 10 drops reagent A (5% alpha-naphthol), 5 drops reagent b (40% potassium hydroxide), shake for 30secs-1min, let sit for 15 mins look for pink-red color
+ : pink-red color (Enterobacter aerogenes)
- : yellow (E. coli)

Question 31

PDA

Answer 31

Phenylalanine, yeast extract, NaCl
Tests for deminase enzyme of PDA (phenylalanine deaminase)
Prod. Phenyl-pyruvic acid and ammonia
Add FeCl3===green color

Question 32

ONPG test

Answer 32

Ortho nitrophenol beta D galactopyranoside
Tests for beta galactosidase
Determines if late lactose fermenter

Question 33

KIA

Answer 33

Kilger iron agar
Tests for glucose and lactose fermentation and H2S prod.
1:10 glucose:lactose
H2S: ferrus sulfate and Na thiosulfate
Ak/Ak no fermentation
Ak/A only glucose fermented
A/A glucose and lactose fermented
Black: H2S prod.