Media To Know Flashcards
MacConkey
MacConkey- peptone base with lactose
Key characteristics
Lactose fermenting organism will have pink colonies
Non-lactose fermenters will have colorless colonies
Inhibit: gram positive (crystal violet, bile salts)
Indicator: natural red
Isolation and Differentiation: lactose fermenting and non-lactose fermenting enteric bacilli
Escherichia coli: pink colonies
Klebsiella pneumonia: pink colonies; mucoid colonies
Citrobacter freuundii: pink colonies
Proteus mirabilis: colorless
Shigella sonnei: colorless colonies: flat with jagged edges
Salmonella enteritidis: colorless colonies
Pseudomonas aeruginosa: colorless (mucoid)
Yersinia enterocolitica: colorless to peach (variable lactose fementation)
Hectoen enteric agar
Hectoen enteric agar- peptone base with bile salts, lactose, sucrose, salicin, and ferric ammonium citrate
Key Characteristics:
Enterics that ferment one or more of the carbohydrates will produce yellow to salmon colored colonies
Escherichia coli
Non-fermenters will produce blue-green colonies
H2S organisms will produce black or blue-green colonies
Indicators: bromthymol blue and acid fuchsin
Differential and Selective: Salmonella and Shigella from other gram negative enteric baccili
Escherichia coli: yellow colonies
Klebsiella pneumonia: yellow/orange colonies
Citrobacter freundii: colorless colonies
Proteus mirabilis: colorless
Shigella sonnei: blue-green colonies
Salmonella enteritidis: blue-green colonies w/ black centers
Xylose Lysine Desoxycholate (XLD)
Xylose lysine desoxycholate (XLD) agar- Yeast extracts with lysine, xylose, lactose, sucrose, and ferric ammonium citrate
Key Characteristics
Enterics that ferment lactose/sucrose produce yellow colonies
Salmonella produces red colonies, some with black centers (H2S positive)
Shigella produces colorless colonies
Inhibits: gram positive (sodium desoxycholate)c
Indicator: phenol red
Isolation and Differentiation: Salmonella and Shigella from other gram-negative enteric bacilli
Escherichia coli: yellow colonies
Klebsiella pneumonia: yellow colonies
Citrobacter freundii: red, yellow, or colorless w/ or w/o black centers
Proteus mirabilis: yellow/ colorless w/ or w/o black centers
Shigella sonnei: colorless colonies
Salmonella enteritidis: red colonies with black centers
MacConkey Sorbitol
MacConkey Sorbitol- MacConkey agar but with sorbitol instead of lacose
Selective and Differentiation: E.coli 0157:H7 in stool
Organisms:
Escherichia coli: only 0157:H7 will grow
Thiosulfate citrate-bile salts agar (TCBS)
Thiosulfate citrate-bile salts agar (TCBS)- peptone base with bile salts, yeast extract, citrate, sucrose, ferric acid, and thiosulfate.
Key Characteristics:
Non-Vibro H2S Organism produce small black colonies
Sucrose fermenting Vibros produce blue colonies
Other Vibros produce various colors of yellow, green, and blue
Indicator: bromythymol blue
Selective and Differential: Vibro spp.
Vibro cholerae
Cefsulodin-irgasen-novobiocin agar (CIN)
Cefsulodin-irgasan-novobiocin agar (CIN)- Peptone base with yeast extract, mannitol, and bile salts, supplemented with cefsulodin, irgasan, and novobiocin.
Key Characteristics:
No Growth of non-Yersinia organisms
Yesrsinia organism appear colorless to pink (may have zone of precipitate bile)
Inhibits: select organisms
Indicators: natural red and crystal violet
Selective: Yersinia spp (may be useful for isolation of Aeromonas)
Yersinia enterocolitica: dark red culls-eye colonies
Pyocyanin agar
Selective agar for pseudomonas
Salmonella-Shigella agar (SS agar)
Selective agar for Salmonella and Shigella
Tetrathionate broth
Tetrathionate broth- peptone base broth with enzyme tertethionate
Key Characteristics
Tetrathionate positive organisms will grow (Salmonella, Shigella, Proteus)
Tetrathionate negative organisms are inhibited (E. coli)
Inhibit: gram positive and Enterobacteria (iodine, potassium iodide, bile salts, sodium thiosulfate)
Selective: Salmonella and Shigella (except S. typi)
Proteus mirabilis: growth
Shigella sonnei: growth
Salmonella entertidis: growth
Selenite broth
Selective for Salmonella and Shigella
Centrimide agar
Selective for Pseudomonas
PC and OFPBL agar
selective for B. cepacia
Pyocyanin agar
Selective for pseudomonas