Culture media on the basis of physical state

March 15, 2018

Media exists in three different forms. They are:

Solid culture media.
Semisolid culture media.
Fluid culture media.

Solid culture media:

Mainly used in petri dishes as plate cultures.
Can also be used in bottles or tubes as stab (deep) or slope cultures.
Usually contain a concentration of 1-2% agar to yield a suitable gel.
Used to observe the colonial appearance, shape, size of colony, and the changes in the surrounding medium.
Helps to identify bacteria and differentiate commensals from pathogens.
Examples : nutrient agar, blood agar, chocolate agar, etc.

Medium	Main uses
Blood agar	Enriched medium for culturing wide range of pathogens. Detecting haemolytic bacteria. Notes: crystal violet blood agar for beta- haemolytic streptococci. Kanamycin and neomysin blood agar for anaerobes. Chocolate (heated blood) agar for Haemophilus influenzae and Neisseria species.
Butzler medium	Selective and enriched medium for isolating Campylobacter species from faeces.
Charcoal cephalexin blood agar (CCBA)	Selective and enriched medium for Bordetella species
Deoxycholate citrate agar (DCA)	Selective and differential medium for enteric pathogens.
DNase agar	Biochemical medium for identifying Staphylococcus aureus.
Dorset egg medium	Enriched medium for Corynebacterium diphtheria to show volutin granules.
Kligler iron agar (KIA)	Differential medium for Salmonella and Shigella species.
Lactose egg yolk milk agar	Identifying Clostridium perfringens
Loeffler serum medium	Enriched medium for Corynebacterium diptheriae to show volutin granules.
Lowenstein Jensen acid medium	Culturing Mycobacterium tuberculosis
Mac Conkey agar	Differentiating lactose and non-lactose fermenter.
Malt extract cycloheximide agar	Selective and enriched media for ringworm fungi.
Mannitol salt agar	Differential and selective media for Staphylococcus aureus.
Modified new york city medium (MNYC)	Selective and enriched medium for Neisseria gonorrhoea.
Modified Tinsdale medium (MTM)	Selective and differenetial medium for Corynebacterium diphtheriae.
Motility indole urea medium (MIU)	Motility medium for enterobacteriaceae.
Nutrient agar	Culturing bacteria which don’t have special nutrients requirements.
Phenylalanine agar	Differentiating Proteus and Providencia from other enterobacteriaceae except Yersinia enterocolitis.
Sabouraud agar	Culturing fungi
Tellurite blood agar	Selective medium for Corynebacterium diphtheria.
Thiosulphate citrate bile salt agar (TCBs)	Selective and differential medium for Vibrio cholera and other Vibrio species.
Tryptone soya medium (diphasic)	Culturing pathogens in blood.
Xylose lysine deoxycholate (XLD) agar	Differentiating Salmonella and Shigella species.

Semisolid culture media

Prepared by adding small amount of agar (0.2-0.5% W/V) to a fluid medium.
Mainly used as transport media and for motility testing.
Examples: Amies transport medium, Cary- Blair transport medium, etc

Medium	Main uses
Amies transport medium	For Neisseria gonorrhea and for other pathogens.
Cary- Blair transport medium	For pathogens (Salmonella, Shigella, Vibrio, Yersinia and Campylobacter)
Viral transport medium	Transport medium for viruses.
SIM medium	Test the sulphur reduction, indole production and motility for various pathogens.

Image source: microbeonline

Fluid culture media

Do not contain agar or solidifying agent.
Growth is shown by presence of turbidity in the medium.
Mainly used as enrichment media, biochemical testing media, and blood culture media.
Examples: tryptone broth, selenite F broth, nutrient broth, etc.

Medium	Main uses
Alkaline peptone water	Enrichment and transport medium for Vibrio cholerae
Christensen’s urea broth	For detecting urease activity of Proteus species.
Cooked meat medium (CMM)	Culturing anaerobes and maintaining control strains of bacteria.
Glucose phosphate peptone water	Culturing enterobateria in the Voges- Proskaeur test
Koser citrate medium	Detecting citrate utilization in differentiating enterobacteria from other bacteria
Litmus milk medium	Identifying enterococci and some other Clostridium species.
Nitrate broth	Detecting nitrate reduction in differentiating Mycobacterium species and Gram negative bacteria.
Peptone water sugars	Carbohydrate testing medium for differentiating enteric pathogens.
Selenite F broth	Enrichment medium for Salmonella species in faeces and urine.
Thioglycollate broth	Culturing anaerobes in blood.
Todd –Hewitt broth	Culturing beta- haemolytic Streptococci and other bacteria.
Tryptone water	Detecting indole production, especially of Escherichia coli.