Culture Media and Streaking method.pptx

Types of culture media and methods on plate streaking

1. Types of Culture Media & Streaking Method s Dr. Samira Fattah Hamid PhD Medical Bacteriology

2. Culture Media A culture is an in vitro technique of growing or cultivating microorganisms in a suitable nutrients medium called culture medium in the laboratory. The food materials on which the organism is grown is known as culture medium T he growth of organism is known as culture.

3. Different microorganisms require different nutrient materials. Thus , culture media vary in form and composition, depending upon the species to be cultivated. It must contain all the ingredients required by the organism and in certain proportions. Culture Media

4. Composition of culture media Water Energy source Carbon source Nitrogen source Mineral salts Special growth factors

5. Types of culture media Classification b ased on physical state a) Solid medium b) Semi solid medium c) L iquid medium

6. Classification based on the ingredients a) Simple media b) Complex media c) Synthetic or defined media d) Special media: Enriched media Selective media Differential media Transport media Anaerobic media Types of culture media

7. Agar Golden –yellow granular powder Prepared from seaweeds. Complex polysaccharide Generally not metabolized by microbes Melts at 98 o C & sets at 42 o C Used as solidifying agent for culture media

8. Common media in routine use Blood Agar Complex medium that contains Nutrient agar with 5% sheep blood D ifferential medium, identify hemolysis.

9. Chocolate Agar Prepared by heating blood agar . This medium is especially useful in growing Hemophilus , Neisseria and Gardnerella vaginalis . Common media in routine use

10. Common media in routine use Mannitol Salt Agar Both selective and differential medium. Used for the isolation and differentiation of Staphylococci Selective due to the presence of sodium chloride (7.5%) which inhibits most Gram negative and Gram positive bacteria . Differential based on the ability or not to ferment M annitol sugar . If there is fermentation, this induces acidification which leads, at pH levels below 6.9, to a yellow coloration of the medium in the presence of phenol red (pH indicator ).

11. Common media in routine use MacConkey Agar It is a selective and differential medium. used for the isolation and differentiation of gram-negative enteric bacteria Selective by bile salt and crystal violet that inhibit the growth of gram positive bacteria. Differential by L actose sugar fermentation.

12. Eosin methylene blue Selective and differential medium U sed for the isolation of gram-negative bacilli and enteric bacilli Selective because it contains two dyes, E osin and M ethylene blue which inhibit the growth of Gram-positive bacteria. Differential because it contains lactose sugar. Common media in routine use

13. Salmonella-Shigella Agar It is a selective and differential medium used to isolate Salmonella and Shigella species . Sodium thiosulfate and ferric citrate allows the detection of hydrogen sulphide production as indicated by colonies with black centers Common media in routine use

14. Xylose Lysine Deoxycholate Agar(XLD) Selective and differential medium for the isolation of Salmonella and Shigella spp. Sodium thiosulfate ( Na 2 S 2 O 3 )is included for the visualization of the hydrogen sulfide produced, resulting in the formation of colonies with black centers. Common media in routine use

15. Cystine Lactose Electrolyte Deficient Agar(CLED) Selective and differential medium used for the isolation and differentiation of urinary pathogens while inhibiting the growth of commensal bacteria . Bromothymol blue is the indicator used in the agar, it turns yellow in case of lactoses fermentation and acid production or turns dark blue in case of alkalization. Common media in routine use

16. Thiosulfate-Citrate-Bile S alts-Sucrose A gar(TCBS ) S elective and differential culture medium used for the isolation and cultivation of Vibrio cholera The high alkalinity of this medium largely inhibit the growth of Enterobacteriaceae. Ox bile and sodium cholate inhibit Gram-positive bacteria. Common media in routine use

17. Common media in routine use Mueller Hinton Agar Allows the growth of almost all types of organisms. U sed for Antimicrobial Susceptibility Testing. Starch is added to absorb any toxic metabolites produced .

18. Common media in routine use Blood Culture Bottle Detection of circulating microorganisms in bacteremia. C ontain agents which act as anticoagulants.

19. Streak Plate Methods

20. Streak Plate Methods

21. Quadrant streak