Media/ Tests Flashcards
Trypticase soy agar
supportive media (non-fastidious)
BAP
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
BCYE
buffered charcoal yeast extract
enrichment media
contains: L-cysteine (enrichment)
Legionella pneumophila
CVA CAMPY
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
Chocolate Agar
enrichment
contains: hemin (x factor) and NAD (V factor), vit B12, Fe & Mg, Cysteine
Neisseria and Haemophilus
PEA
phenyl-ethyl alcohol agar
selective
contains: sheep BA, phenylethyl alcohol
isolates GPC from mixtures; inhibits GNR
MAC
MacConkey agar selective/differential contains: lactose (differential), bile salts (selective), crystal violet, neutral red indicator isolates GNR ferments lactose- pink non fermenter- colorless
S-MAC
Sorbitol MacConkey
differential
contains: lactose, bile salts, crystal violet, neutral red indicator
ID E. coli O157:H7 sorbitol negative (clear)
SXT
sulfamethoxazole/trimethoprim
selective/differential
contains: SXT (antimicrobial against normal throat flora alpha Strep)
isolate GAS
HIM
Hemophilus isolation media
enrichment/differential
contains: X (Hemin) and V (NAD) factors, horse blood,
ID Haemophilus
CNA
columbia colistin-naldixic acid
selective
contains: colistin, naldixic acid
selects for GP
Hektoen agar
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
XLD
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
Thayer Martin agar
enrichment/selective
contains: vancomycin (inhibit GPC), colistin (inhibit GNR), trimethoprim (stop Proteus swimming), nystatin (inhibits fungus)
Isolate Neisseria gonorrhoeae
Martin Lewis agar
enrichment/selective
contains: anisomycin (antifungal), vancomycin (more than Thayer Martin agar)
Neisseria isolates
V-agar
vaginalis agar
enrichment
contains: human blood, peptones, yeast extract
isolates Gardnerella vaginalis
MSA
mannitol salt agar
contains: peptones, beef extracts, 7.5% NaCl, mannitol, phenol red
ID Staphylococcus aureus (ferments mannitol= yellow)
Thioglycolate Broth
holding media (wounds & fluid cultures) supports aerobic (top)/anaerobic(bottom) growth contains: casein, soybean peptones, NaCl, Na thioglycollate
GN and Selenite Broth
support growth of Salmonella spp. & Shigella spp.
stool cultures subbed in this
good for small #s
Coagulase tube test
Staph rxts w/ coagulase-reacting factor (thrombin like thermostable molecule) to form complex that converts fibrinogen to fibrin
Rapid agglutination S. aureus
Use latex that detects clumping factor (w/ fibrinogen) and protein A (w/ IgG)
Coagulase slide test
Clumping factor causes agglutination in human/rabbit/pig plasma by converting fibrinogen to fibrin
sodium hippurate test
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
CAMP test
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
catalase test
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)
DNase test
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)
Microdase test
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)
Nitrate broth
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)
LAP test
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
VP test
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)
PDA
Phenylalanine, yeast extract, NaCl
Tests for deminase enzyme of PDA (phenylalanine deaminase)
Prod. Phenyl-pyruvic acid and ammonia
Add FeCl3===green color
ONPG test
Ortho nitrophenol beta D galactopyranoside
Tests for beta galactosidase
Determines if late lactose fermenter
KIA
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.
