Enrichment media:

• Used to prevent the non-pathogenic or commensal bacteria from overgrowing the pathogenic bacteria.
• It is a liquid media to which certain substances are added which enhance the growth of pathogenic organism and suppress the unwanted bacteria.
• Selenite F-broth(Salmonella typhii), alkaline peptone water(Vibrio cholerae).

Selective media:

• Serve the same purpose as enrichment media but are solid in consistency. Eg. Wilson and Blair’s medium, Lowenstein Jensen’s medium.
• Used to cultivate Salmonella, Shigella, Mycobacteria

Transport media:

• Used in case of delicate organisms wherever there is delay in the transportation of the specimen to lab.
• Used to maintain viability of them and to prevent the multiplication of non-pathogenic bacteria.
• Stuart’s medium(Gonococci), Cary-Blair’s medium(V. cholerae), V-R medium(V. cholerae).