Media Flashcards
1
Q
EYA
A
- Egg Yolk Agar (EYA)
- Type: enriched, nonselective, and differential medium
- Purpose: presumptive differentiation of Clostridium spp. and other obligate anaerobes.
- Purpose: Based on lecithinase, lipase, and proteolytic activity
- Components: casein, yeast extract, dextrose, and tryptophan. Hemin and vitamin K1 have been included to improve the growth of anaerobes
- Appearance: iridescent sheen (“oil on water”) on the surface of the colony is observed by lipase-positive organisms, due to the breakdown of free fats present in the egg yolk.
- Appearance: Clearing of the medium surrounding the colonies as a result of proteolytic organisms.
- Appearance: lipase opaque precipitation under agar
- Conditions:
- QC: Positive Organism - Fusobacterium necrophorum Lipase +
- Clostridium perfringens - Lecithinase +
-QC: Negative Organism - Grows most organisms
2
Q
CMGS
A
- Cooked Meat Glucose Starch Broth
- Type: enrichment and differential
- Purpose: medium for the enrichment and cultivation of anaerobic microorganisms, particularly obligate anaerobes. The differential in showing proteolytic action.
- Components: Solid meat cubes are digested by proteolytic bacteria
- Appearance: Turbidity around meat cubes
- Conditions: Incubate uninoculated representative tubes at 20 – 25 °C and 30 – 35 °C and examine after 7 days for microbial contamination. Anaerobically
-QC: Positive Organism - *Clostridium perfringens-Moderate to heavy growth
*Porphyromonas levii - Moderate to heavy growth
-QC: Negative Organism -
3
Q
TPGY
A
- Tryptone Peptone Glucose Yeast Extract Broth Base w/o Trypsin
- Type: Selective/Enrichment for toxins
- Purpose: is used to test toxicity type of Clostridium botulinum cultures for types A-G, Trypsin activates non-proteolytic toxin types so that can be added later to test toxin.
- Components: Tryptone Peptone Glucose Yeast Extract w/o trypsin
- Appearance: Strong Luxuriant growth
- Conditions: Cultural characteristics observed under anaerobic conditions, after incubation at 26-28°C for up to 7 days.
- QC: Positive Organism - Clostridium botulinum
- QC: Negative Organism -
4
Q
Thayer–Martin agar
A
- Thayer–Martin agar (or Thayer–Martin medium, or VPN agar) is a Mueller–Hinton agar with 5% chocolate sheep blood and antibiotics.
- Type: Selective
- Purpose: culturing and primarily isolating pathogenic Neisseria bacteria, including Neisseria gonorrhoeae and Neisseria meningitidis
- Components: Vancomycin, is able to kill most Gram-positive organisms, although some Gram-positive organisms such as Lactobacillus and Pediococcus are intrinsically resistant
- Components: Polymyxin, also known as colistin, is added to kill most Gram-negative organisms except Neisseria, although some other Gram-negative organisms such as Legionella are also resistant
- Components: Nystatin, which can kill most fungi
- Components: Trimethoprim inhibits swarming of Proteus spp
- Appearance: Small opaque, grayish-white to colorless, raised, glistening and smooth colonies are seen.
- Conditions: CO2-enriched (3%- 10%) environment and incubated at 35º-37ºC.
- QC: Positive Organism - Neisseria gonorrhea
- QC: Negative Organism - Escherichia coli
5
Q
Bismuth Sulfite Agar
A
- Type: selective and differential medium
- Purpose: Bismuth sulfite agar tests the ability to use ferrous sulfate and convert it to hydrogen sulfide is differential for salmonella from E. coli and Shigella
- Components: Brilliant Green and bismuth selective against gram-positive growth
- Appearance: Typical S. Typhi surface colonies are olive-green to black, surrounded by black or brown-black zone with or without a metallic sheen.
- Conditions: 35 ± 2°C after 40 - 48 hours
incubation. - QC: Positive Organism - Salmonella spp.
- QC: Negative Organism - Escherichia coli
6
Q
Simmons’ citrate agar
A
- Type: selective and differential medium
- Purpose: differentiating gram-negative bacteria on the basis of citrate utilization by selecting for organisms that use citrate.
- Purpose: that tests for an organism’s ability to use citrate as a sole carbon source and ammonium ions as the sole nitrogen source.
- Components: bromothymol blue, a pH indicator. Bromothymol blue is green at pH below 6.9 and then turns blue at a pH of 7.6 or greater.
- Components: contains sodium chloride, sodium citrate, ammonium dihydrogen phosphate, dipotassium phosphate, and magnesium sulfate. bromothymol blue
- Appearance: – citrate utilization = produces an alkaline reaction = the color of the medium changes from green to bright blue.
- Appearance: – no citrate utilization = the color of the medium remains unchanged(green)
- Conditions: 24–48 h or up to 4 days at 35 ± 2 °C in aerobic atmosphere.
- QC: Positive Organism - KLEBSIELLA,
- Positive Growth: Serratia, and the majority of the Enterobacter, Citrobacter, Klebsiella, Proteus, and Providencia species
- QC: Negative Organism - E. COLI,
- Negative Growth: Shigella, Yersinia, Edwardsiella species
7
Q
Bile Esculin Agar (BEA)
A
- Type: selective and differential
- Purpose: Bile Esculin Agar is used primarily to differentiate Enterococcus from Streptococcus
- Components: Bile salts are the selective ingredient, while esculin is the differential component. -
- Components: Enterococcus hydrolyze esculin to products that react with ferric citrate in the medium to produce insoluble iron salts, resulting in the blackening of the medium.
- Appearance: Brownish colonies with blackening of the medium
- Conditions: 24hr @ 35 ± 2 °C in an aerobic atmosphere.
- QC: Positive Organism - Enterococci
- QC: Negative Organism - S. pyogenes
8
Q
Motility GI Medium
A
- Type: differential
- Purpose: Differential organisms on the basis of motility
- Components: Standard agar sometimes with a dye
- Appearance: Motile organisms diffuse growth away from the line or spot of inoculation
- Appearance: Nonmotile organisms grow only along the line of inoculation.
- Conditions: Incubate at a temperature and duration appropriate for the suspected organism being tested.
- Positive organsim - Proteus mirabilis
- Negative Organism -Klebsiella pneumoniae
9
Q
CN/CIN AGAR
A
-Type: Selective
- Purpose: isolation and enumeration of Yersinia
spp. from food. - Components: sodium desoxycholate, crystal violet, cefsulodin, irgasan, and novobiocin, mannitol,
- Appearance: Yersiniae ferment mannitol with an intense, localized, acid production in the center of the colony which produces a red ‘bull’s eye’ appearance.
- Appearance: The ratio of the transparent border to red center varies with serotype and environmental strains may appear rough with an irregular edge. Red Colonies
- Conditions: incubated at 30 ± 1C for 18-24 hours.
- QC: Positive Organism - Yersinia enterocolitica
- QC: Negative Organism - E. coli, Enterococci
10
Q
GN BROTH
A
Gram-Negative Broth
- Type: Enrichment and Selective
- Purpose: cultivation of gram-negative enteric organisms.
- Purpose: enrichment medium for the recovery of Salmonella and Shigella from clinical specimens.
- Components: Mannitol and dextrose are sources of energy.
- Components: Sodium citrate and sodium desoxycholate are added to inhibit gram-positive and some gram-negative bacteria
- Components: Mannitol is provided in a higher concentration than dextrose
- Appearance: Growth in broth media is indicated by turbidity compared to an uninoculated control
- Conditions: Incubate the tubes with loosened caps at 35 °C and subculture onto selective and differential media after 6–8 h of incubation and again after 18–24 h of incubation.
- QC: Positive Organism - Escherichia coli, Salmonella
- QC: Negative Organism - Gram Positive
11
Q
(HE) agar
A
Hektoen enteric
- Black Colonies for Salmonella
- Positive organsim - Salmonella, Shigella
- Negative Organism- Escherichia coli, Enterococcus faecalis, Gram-Pos
- Type: selective and differential agar
- Purpose: inhibiting Gram-positive organisms and reducing the growth of some gram-negative organisms
- Purpose: isolation of Shigella and Salmonella.
- Components: bile salts
- Components: bromothymol blue, acid fuchsin, and ferric iron as an indicator of the formation of hydrogen sulfide from thiosulfate.
- Appearance: -Blue color change Peptone utilization by Shigella and Salmonella
- Appearance: Black Colonies for Salmonella by the formation of hydrogen sulfide from thiosulfate.
- Appearance: Sugar fermentation changes color red everything else
- Conditions: - Incubate @ 35° for 18 to 48 hrs
- QC: Positive Organism - Salmonella
- QC: Positive differential Organism: Shigella not black colonies
- QC: Negative Organism - Escherichia coli, Enterococcus faecalis, Gram-Pos
12
Q
(XLD) agar
A
xylose-lysine-deoxycholate agar
- Type: selective and differential
- Purpose: isolation of Salmonella and Shigella
- Components: indicator phenol red, xylose, sucrose, lactose, deoxycholate
- Appearance: Salmonella can ferment the sugar xylose to produce acid which turns indicator yellow
- Appearance: Salmonellae metabolize thiosulfate to produce hydrogen sulfide to produce red colonies with black centers
- Appearance: Shigella colonies cannot do this and therefore remain red at neutral pH
- Conditions: Incubate @ 35° for 18 to 24 hrs
- QC: Positive Organism - Salmonella, Shigella
- QC: Negative Organism - Escherichia coli, Enterococcus faecalis, Gram-Pos
13
Q
(SS) agar
A
Salmonella-Shigella Agar
- Type: moderately selective and differential medium
- Purpose: isolation, cultivation, and differentiation of Salmonella spp. and some strains of Shigella spp.
- Components: Bile Salts, Sodium Citrate and Brilliant Green serve to inhibit gram-positive, coliform organisms and inhibit swarming Proteus spp
- Components: Thiosulfate and Ferric Citrate permit detection of hydrogen sulfide by the production of colonies with black centers. Neutral Red. lactose
- Appearance: Neutral red turns red in the presence of an acidic pH, thus showing fermentation has occurred.
- Appearance: Salmonella will not ferment lactose but produce hydrogen sulfide (H2S) gas. The resulting bacterial colonies will appear colorless with black centers.
- Appearance: Shigella do not ferment lactose or produce hydrogen sulfide gas, so the resulting colonies will be colorless.
- Appearance: E. coli produces pink to red colonies and may have some bile precipitation.
-Conditions: incubated aerobically at 37 ± 1°C for
18 - 48 hours
- QC: Positive Organism - Salmonella enteriditis = Colorless colonies with black center
- QC: Positive Organism - Shigella flexneri = Colorless colonies
- QC: Negative Organism - Escherichia coli
- QC: Negative Organism - Enterococcus faecalis
14
Q
(SEL) F broth
A
Selenite Broth
- Type: selective enrichment
- Purpose: isolation of Shigella, Salmonella, and other Enterobacteriaceae.
- Components: Sodium selenite inhibits many species of gram-positive and gram-negative bacteria including enterococci and coliforms.
- Appearance: Colorless, Good Growth.
- Appearance: pink with bile precipitate, Inhibited or no growth.
- Conditions: incubated aerobically at 35 degrees for 8–12 h incubation
- QC: Positive Organism - Salmonella Typhimurium
- QC: Negative Organism - Escherichia coli
15
Q
(SBA) or BA
A
Sheep Blood Agar
- Type: Nutrient and differential
- Purpose: General growth medium with differentiates the organism’s ability to hemolyze RBC
- Components: 5% Sheep Blood Agar
- Appearance: Beta-hemolysis complete clearing of red agar
- Appearance: a-hemolytic is Partial hemolysis incomplete clearing sometimes green
- Appearance: no hemolysis occurs, this is termed gamma-hemolysis.
- Appearance: colonies of all shapes and sizes
- Conditions: 35 degrees for 18 to 24 hrs
- QC: Positive Organism - Grows almost all organisms
- QC: Negative Organism - Differential in hemolysis organisms
