Culture media Definition :- Routine culture media 1-Synthetic media : 2-Routine culture media: Routine culture media Common ingredients :- Dehydrated powders Bacteriological quality
Meat extract :- [Lab. Lemco] Peptone :- Nitrogen amino acids Animal & plant proteins [lean meat - soya bean] Proteolytic enzymes : Trypsin Meat extract :- [Lab. Lemco] Carbon Vitamins Mineral salt Evaporation of lean meat Mineral salts :- Sulphates Phosphates Sod.chloride Enzymes activity Isotonic Water :-
Complex inert long chain polysaccharide Agar :- Complex inert long chain polysaccharide Sea weeds New Zealand Japan Melting temp. : 90⁰c - 95 ⁰c Solidifying temp. : 39 ⁰c - 42 ⁰c Concentration in media : 1.2 - 2% [solid] 0.4 - 0.5 [semi solid]
Three forms according to the consistency :- 1-Solid :- Agar 1.2 up to 2% Plates or bottles Isolation from specimens 2-Semi – solid :- Agar < 1% [0.4 - 0.5%] Bottles & tubes Motility Some biochemical reactions Preservation Transport media 3- Fluid / Broth :- Blood culture bottles Enrichment media [ Carbohydrates fermentation ]
Types of routine culture media :- 1- Basic or simple media : Definition : Nutrient agar nutrient broth Non-fastidious organisms staphylococci E.coli
Blood agar Chocolate blood agar 2- Enriched media : Definition : Blood agar Chocolate blood agar Fastidious organisms Streptococcus pyogenes Niesseria
Fermentaion : indicator media 3- Differential media : Definition : Fermentaion : indicator media MacConkey agar : lactose & non-lactose fermenters Haemolysis : Blood agar α- and β hamolysis
4- Selective media : Definition : Dyes : 1) Adding substances 2) Changing the PH Dyes : Crystal violet blood agar [S.pyogenes] Malachite green L.J [Mycobacteria] Bile salts : Sodium deoxycholate [DCA] Salmonella & Shigella
Mineral salts : Sod.chloride [6.5%] Mannitol salt agar staphlococci Chemicals : Potassium tellurite Tellurite blood agar Corynebacteria
Antimicrobial agents : [Antibiotics] Neomycin blood agar [Clostridia] Thayer-Martin medium
Alkaline peptone water : Vibrios Changing the PH :- Alkaline peptone water : Vibrios Sabouraud medium : Fungi
5- Enrichment media :- Definition : Selenite F broth : Salmonella
6- Specialized media :- Definition : Identification media Antimicrobial Susceptibility Testing media
7- Transport media :- Definition : Preservation Buffers - Glycerol - Charcoal - Sod.thioglycolate Staurt - Amies - Cary - Blair
Preparation of media 1- Weighing & dissolving : Precautions Hygroscopic Dist. or diionized water Capacity of the container String or rotating
PH testing :- PH meter Sterilization :- Autoclave Narrow range PH paper Sterilization :- Autoclave Steaming Filetration
Addition of heat sensitive ingredients :- Waterbath 45⁰c - 50⁰c Dispensing :- Petri - dishes containers Quality control :- Control strains Storage :- Refrigerator 2⁰c - 8⁰c