Culture Media by Morphological Classification

Morphological Class

Protozoa

Culture Media

1 BACTEC This is not a traditional medium but a system for detecting the growth of M. tuberculosis by monitoring the release of C14O2 from C14 palmitic acid, which the bacteria metabolize. An increase in radioactive counts in the BACTEC instrument indicates the growth of bacteria.
2 Dubos’ Medium A liquid medium that contains a mixture of salts, fatty acids, and polysorbate. When M. tuberculosis grows in this medium, it causes the medium to become turbid.
3 Tarshis Medium A blood-based medium that can promote the growth of M. tuberculosis. The colonies appear similar to those on the LJ Medium.
4 Dorset Medium An egg-based medium. M. tuberculosis colonies appear similar to those on Petragnini Medium: small, round, buff-colored, and taking 3-4 weeks to develop.
5 Middlebrook 7H10 Agar A selective medium that contains oleic acid, albumin, dextrose, and catalase. The colonies of M. tuberculosis appear small, rough, and buff to white-colored, taking less time to appear compared to egg-based media.
6 Petragnini Medium An egg-based medium enriched with additional nutrients to promote the growth of Mycobacterium tuberculosis. Colonies of M. tuberculosis are small, round, buff-colored, and typically take 3-4 weeks to appear.
7 Triple Sugar Iron (TSI) Agar E. coli typically produces an acid butt, acid slant, and gas, with no H2S production, indicating it ferments lactose, sucrose, and glucose.
8 m-ENDO Agar E. coli colonies appear as green with a metallic sheen, indicating lactose fermentation.
9 Nutrient Agar (NA) A non-selective medium. E. coli colonies are usually large, circular, grayish-white, moist, and smooth.
10 Cornmeal Agar with Tween 80 It is used for the identification of Candida species by promoting the formation of chlamydospores, which is a characteristic of Candida albicans.
11 Potato Dextrose Agar (PDA) Potato Dextrose Agar (PDA) consists of a nutrient-rich substrate, made from dehydrated Potato Infusion and Dextrose, ideal for robust mycological propagation. Agar provides the solidifying medium. Acidification, typically using sterile tartaric acid, adjusts the pH to 3.5 +/- 0.1 to create a more selective environment by inhibiting bacterial proliferation. Additionally, Chloramphenicol is incorporated as an antimicrobial agent to further suppress bacterial contamination, thereby facilitating the selective isolation of fungi.
12 Nutrient Agar It is a general-purpose medium. However, E. faecalis grows poorly on nutrient agar, which means it does not proliferate as well on this medium compared to the others listed, indicating a negative or poor growth.

Mycobacteria

Culture Media

1 Blood Agar (BA) This is a nutrient-rich, differential medium that supports the growth of many organisms. S. aureus forms colonies that are round, smooth, and golden-yellow. This bacterium typically demonstrates β-hemolysis, which is complete lysis of red blood cells, resulting in a clear zone around the colonies. This hemolysis is due to the production of hemolysins by S. aureus.
2 Sula’s Medium A liquid medium containing glycerol, asparagine, and a variety of salts. The growth of M. tuberculosis results in turbidity.
3 Middlebrook 7H9 Broth This is a liquid medium that contains glycerol and Tween 80, which prevent clumping of mycobacteria. The growth of M. tuberculosis results in turbidity.
4 Middlebrook 7H11 Agar This is a nutrient-rich medium similar to 7H10 but includes additional pyruvate for energy source, promoting more luxurious growth. The colonies of M. tuberculosis appear small, slightly domed, and rough with a butyrous consistency.
5 Tryptic Soy Agar (TSA) A general purpose medium. E. coli colonies are medium to large, with a shiny moist appearance.
6 Brain-Heart Infusion (BHI) Broth or Agar This is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.
7 Tryptic Soy Broth or Agar (TSB/TSA) A general-purpose medium that supports the growth of a broad spectrum of bacteria. E. faecalis on TSA will typically form small, round, and white colonies, indicating a positive growth.

Fungi

Culture Media

1 BACTEC This is not a traditional medium but a system for detecting the growth of M. tuberculosis by monitoring the release of C14O2 from C14 palmitic acid, which the bacteria metabolize. An increase in radioactive counts in the BACTEC instrument indicates the growth of bacteria.
2 Pawlowsky Medium A potato-based medium. Growth of M. tuberculosis may be similar to that seen on the LJ Medium.
3 Middlebrook 7H11 Agar This is a nutrient-rich medium similar to 7H10 but includes additional pyruvate for energy source, promoting more luxurious growth. The colonies of M. tuberculosis appear small, slightly domed, and rough with a butyrous consistency.
4 Middlebrook 7H10 Agar A selective medium that contains oleic acid, albumin, dextrose, and catalase. The colonies of M. tuberculosis appear small, rough, and buff to white-colored, taking less time to appear compared to egg-based media.
5 Lowenstein-Jensen (LJ) Medium An egg-based medium that uses malachite green to suppress the growth of other bacteria and glycerol to stimulate the growth of Mycobacterium tuberculosis. The colonies of M. tuberculosis on LJ are non-pigmented, dry, rough, raised, irregular with a wrinkled surface, initially creamy-white, turning yellowish or buff-colored on further incubation.
6 Mueller Hinton Agar (MHA) Typically used for antibiotic susceptibility testing. E. coli colonies appear pale straw colored.
7 MacConkey Agar (MAC) This selective and differential medium distinguishes lactose fermenters from non-fermenters. E. coli colonies are circular, moist, smooth, and pink.
8 CHROMagar Candida This differential medium allows for the isolation and identification of Candida species based on colony color. Candida albicans usually forms green colonies on this medium.
9 Potato Dextrose Agar (PDA) Potato Dextrose Agar (PDA) consists of a nutrient-rich substrate, made from dehydrated Potato Infusion and Dextrose, ideal for robust mycological propagation. Agar provides the solidifying medium. Acidification, typically using sterile tartaric acid, adjusts the pH to 3.5 +/- 0.1 to create a more selective environment by inhibiting bacterial proliferation. Additionally, Chloramphenicol is incorporated as an antimicrobial agent to further suppress bacterial contamination, thereby facilitating the selective isolation of fungi.

Bacilli

Culture Media

1 Sauton’s Medium A liquid medium that lacks detergents, which helps in the formation of corded colonies. When M. tuberculosis grows in this medium, it results in turbidity.
2 Proskauer and Beck’s Medium A liquid medium. The growth of M. tuberculosis causes turbidity.
3 Middlebrook 7H9 Broth This is a liquid medium that contains glycerol and Tween 80, which prevent clumping of mycobacteria. The growth of M. tuberculosis results in turbidity.
4 Middlebrook 7H11 Agar This is a nutrient-rich medium similar to 7H10 but includes additional pyruvate for energy source, promoting more luxurious growth. The colonies of M. tuberculosis appear small, slightly domed, and rough with a butyrous consistency.
5 Middlebrook 7H10 Agar A selective medium that contains oleic acid, albumin, dextrose, and catalase. The colonies of M. tuberculosis appear small, rough, and buff to white-colored, taking less time to appear compared to egg-based media.
6 Simmons Citrate Agar Used for citrate utilization testing. E. coli usually can't utilize citrate as a sole carbon source, so no growth or color change would be expected.
7 Brain-Heart Infusion (BHI) Broth or Agar This is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.

Cocci

Culture Media

1 Sula’s Medium A liquid medium containing glycerol, asparagine, and a variety of salts. The growth of M. tuberculosis results in turbidity.
2 Middlebrook 7H10 Agar A selective medium that contains oleic acid, albumin, dextrose, and catalase. The colonies of M. tuberculosis appear small, rough, and buff to white-colored, taking less time to appear compared to egg-based media.
3 Lowenstein-Jensen (LJ) Medium An egg-based medium that uses malachite green to suppress the growth of other bacteria and glycerol to stimulate the growth of Mycobacterium tuberculosis. The colonies of M. tuberculosis on LJ are non-pigmented, dry, rough, raised, irregular with a wrinkled surface, initially creamy-white, turning yellowish or buff-colored on further incubation.
4 Simmons Citrate Agar Used for citrate utilization testing. E. coli usually can't utilize citrate as a sole carbon source, so no growth or color change would be expected.
5 Cystine Lactose Electrolyte-Deficient (CLED) Agar E. coli will give lactose-positive yellow colonies.
6 Mueller Hinton Agar (MHA) Typically used for antibiotic susceptibility testing. E. coli colonies appear pale straw colored.
7 CHROMagar Candida This differential medium allows for the isolation and identification of Candida species based on colony color. Candida albicans usually forms green colonies on this medium.
8 RPMI 1640 Medium It is a rich medium that contains inorganic salts, glucose, amino acids, vitamins, and other nutrients that promote the growth of yeast cells.
9 Tryptic Soy Broth or Agar (TSB/TSA) A general-purpose medium that supports the growth of a broad spectrum of bacteria. E. faecalis on TSA will typically form small, round, and white colonies, indicating a positive growth.

Spirillum

Culture Media

1 Middlebrook 7H9 Broth This is a liquid medium that contains glycerol and Tween 80, which prevent clumping of mycobacteria. The growth of M. tuberculosis results in turbidity.
2 Tarshis Medium A blood-based medium that can promote the growth of M. tuberculosis. The colonies appear similar to those on the LJ Medium.
3 Brain-Heart Infusion (BHI) Broth or Agar This is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.

Spirochetes

Culture Media

1 Sauton’s Medium A liquid medium that lacks detergents, which helps in the formation of corded colonies. When M. tuberculosis grows in this medium, it results in turbidity.
2 Pawlowsky Medium A potato-based medium. Growth of M. tuberculosis may be similar to that seen on the LJ Medium.
3 Tarshis Medium A blood-based medium that can promote the growth of M. tuberculosis. The colonies appear similar to those on the LJ Medium.
4 Dorset Medium An egg-based medium. M. tuberculosis colonies appear similar to those on Petragnini Medium: small, round, buff-colored, and taking 3-4 weeks to develop.
5 Middlebrook 7H11 Agar This is a nutrient-rich medium similar to 7H10 but includes additional pyruvate for energy source, promoting more luxurious growth. The colonies of M. tuberculosis appear small, slightly domed, and rough with a butyrous consistency.
6 RPMI 1640 Medium It is a rich medium that contains inorganic salts, glucose, amino acids, vitamins, and other nutrients that promote the growth of yeast cells.