Mac conkey agar presentation

Mac conkey agar presentation

• 1.
  MacConkey Agar
• 2.
  What is MacConkeyAgar  MacConkey agar (MAC) was the first solid differential media to be formulated which was developed at 20th century by Alfred Theodore MacConkey.  MacConkey agar is a selective and differential media used for the isolation and differentiation of non- fastidious gram-negative rods, particularly members of the family Enterobacteriaceae and the genus Pseudomonas.  Neutral red is the PH indicator
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  Composition of MacConkeyAgar ingredients amount Peptone (pancreatic digest of gelatin ) 17 gm Proteose peptone (meat and casein ) 3gm Lactose monohydrate 1o gm Bile salts 1.5gm Sodium chloride 5gm Neutral red 0.03gm Crystal Violet 0.001g Agar 13.5gm Distilled Water Add to make 1 liter
• 5.
  USES OF MacConkeyAgar  MacConkey agar is used for the isolation of gram- negative enteric bacteria.  It is used in the differentiation of lactose fermenting from lactose non-fermenting gram-negative bacteria.  It is used for the isolation of coli forms and intestinal pathogens in water, dairy products and biological specimens.
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  Preparation of MacConkeyAgar 1. Suspend 49.53 grams of dehydrated medium in 1000 ml purified/distilled water. 2. Heat to boiling to dissolve the medium completely. 3. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. 4. Cool to 45-50°C. 5. Mix well before pouring into sterile Petri plates.
• 9.
  Result Interpretation onMacConkey Agar  Lactose fermenting strains grow as red or pink and may be surrounded by a zone of acid precipitated bile.  The red colour is due to production of acid from lactose, absorption of neutral red and a subsequent colour change of the dye when the pH of medium falls below 6.8.
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  CONTD… •Lactose non-fermenting strains, suchas Shigella and Salmonella are colourless and transparent and typically do not alter appearance of the medium. •Yersinia enterocolitica may appear as small, non- lactose fermenting colonies after incubation at room temperature.
• 12.
  Some lactose fermenting organism Somenon-lactose fermenting organism E.Coli Salmonella species Enterococci Shigella species K.Pneumoniae Proteus species Y.Enterocolitica NOTE Bacteria which do not grow on MacConkey agar include Streptococcus Pyogenes, Streptococcus Pneumoniae, Viridans streptococci , and Pasteurella species
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  Quality control  Thequality control is tested with at least one known organism to demonstrate growth or positive reaction and at least one organism to demonstrate inhibition or negative reaction
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  Contd… Control Organism ExpectedResults E. coli (ATCC 25922) Pink colonies Staphylococcus aureus (ATCC 25923) Growth Streptococcus faecalis (ATCC 29212) Growth with magenta pink Colonies Proteus mirabilis (ATCC 12453 ) No swarming Beta haemolytic Streptococcus No growth