|
SELECTIVE MEDIA
Those culture media that permits the required bacterium to
grow and selectively inhibit unwanted commensals and contaminants are
termed selective media. When the same approach is employed for liquid
culture medium, it is called enrichment broth. Any medium can be made
selective by addition of some inhibitory substances or altering its
property. Some selective media also behave as indicator
media.
Various techniques are employed to make a medium
selective. These are:
- Addition of antibiotics
- Addition of chemicals
- Addition of dyes
- Altering the pH
- Combination of any of the above
Selective media containing antibiotics:
|
Name of
the medium
|
Selective
for
|
Antibiotics
|
|
Thayer
Martin Agar
|
N.gonorrhoeae
|
Vancomycin, Colistin, Nystatin
|
|
PNF Medium
|
β-hemolytic Streptococci
|
Polymyxin B, Neomycin, Fusidic Acid
|
|
Charcoal
Blood Agar
|
B.pertussis
|
Cephalexin
|
|
Modified New
York City Medium
|
N.gonorrhoeae
|
Colistin, Lincomycin, Trimethoprim and
Amphotericin B
|
|
Knisely’s
Medium (PLET)
|
B.anthracis
|
Polymyxin B
|
|
Kirchner
Medium
|
M.tuberculosis
|
Polymyxin B, Carbenicillin,
Trimethoprim and Amphotericin B
|
|
Skirrow’s
Medium
|
C.jejuni
|
Vancomycin, Polymyxin B, Trimethoprim
|
|
Selective Buffered Charcoal yeast
Extract Agar
|
Legionella pneumophila
|
Vancomycin, Polymyxin B
|
Selective media containing chemicals
|
Name of
the medium
|
Selective
for
|
Chemical
|
|
Mannitol
Salt Agar, Salt Milk Agar
|
S.aureus
|
10% NaCl
|
|
Potassium tellurite medium
(Hoyle’s,
Tinsdale)
|
C.diphtheriae
|
0.04% Potassium tellurite
|
|
McConkey’s
Agar (low selective)
|
Enterobacteriaceae
|
Bile salt
|
|
XLD Agar,
DCA
|
Salmonella,
Shigella
|
Bile salt
|
|
Pseudosel
Agar (Cetrimide Agar)
|
P.aeruginosa
|
Cetrimide
|
|
Pseudomonas
Isolation Agar
|
P.aeruginosa
|
Irgasan
|
|
Monsur’s Tellurite Taurocholate
Gelatin
Agar
|
V.cholerae
|
Potassium tellurite
|
|
Bile Esculin
Agar
|
Enterococci
|
Bile salt
|
Selective media containing dyes
|
Name of
the medium
|
Selective
for
|
Dye
|
|
Crystal
Violet Blood Agar
|
S.pyogenes
|
0.0002% crystal violet
|
|
Lowenstein
Jensen Medium
|
M.tuberculosis
|
Malachite green
|
|
Wilson & Blair’s Brilliant
Green
Bismuth Suphite Agar
|
S.typhi
|
Brilliant green
|
Selective media with altered pH
|
Name of
the medium
|
Selective
for
|
pH
|
|
TCBS Agar
|
V.cholerae
|
8.6
|
|
Monsur’s Tellurite Taurocholate
Gelatin
Agar
|
V.cholerae
|
8.5
|
|
Print This Page
