Culture Media

Culture media are a combination of pre-defined ingredients that support the growth and proliferation of microorganisms in an artificial/in vitro environment. They are used for the isolation of organisms from various samples such as clinical specimens, food, or the environment.

Based on the consistency, culture media are further categorized as solid, semisolid, and liquid (broth). Functionally, culture media can be classified as differential, selective, enriched, enrichment, assay, transport, etc.

Czapek Dox Agar: Principle, Composition, Colony Characteristics

Czapek Dox Agar: Principle, Composition, Colony Characteristics

Czapek medium is also called Czapek’s agar (CZA) or Czapek-Dox medium. It is used to isolate the Aspergillus, Penicillium, Paecilomyces, and other fungi

Phenylethyl Alcohol Agar: Composition, Preparation, Uses

Phenylethyl Alcohol Agar: Composition, Preparation, Uses

Phenylethyl alcohol agar (PEA) is a selective medium used to cultivate Gram-positive cocci, from a sample containing a mixed flora.

Hydrogen Sulfide (H₂S) Production Test

Hydrogen Sulfide (H₂S) Production Test

Bacterial species capable of producing H₂S release sulfide which combines with iron present in the medium forming black precipitate.

Tinsdale Agar: Composition, Preparation, Uses

Tinsdale Agar: Composition, Preparation, Uses

Tinsdale Agar is used for the selective isolation and differentiation of C. diphtheriae from diphtheroids.

Amies Transport Medium

Amies Transport Medium

This semisolid medium is used for the transportation of swab specimens for preserving the viability of N. gonorrhoeae, H. influenzae, N. meningitidis.

Quality Control of Culture Media

Quality Control of Culture Media

Growth supporting characteristics, physical characteristics and sterility testing of the culture media has to be tested before putting them in use.

BHI Broth: Composition, Preparation, Uses

BHI Broth: Composition, Preparation, Uses

Brain Heart Infusion (BHI) broth is a general-purpose liquid medium for the cultivation and maintenance of a wide variety of microorganisms.

Kligler’s Iron Agar (KIA): Principle, Procedure, Results

Kligler’s Iron Agar (KIA): Principle, Procedure, Results

Kligler Iron Agar is used for the differentiation of microorganisms on the basis of glucose and lactose fermentation and H₂S production.

DCA Agar: Composition, Colony Characteristics

DCA Agar: Composition, Colony Characteristics

Deoxycholate citrate agar is used for the selective isolation and differentiation of Salmonella and Shigella species.

Selenite broth: Composition, Preparation Uses

Selenite broth: Composition, Preparation Uses

Selenite broth is an enrichment medium for the isolation of Salmonella and Shigella from stool, urine, water and food products.

Bird Seed Agar: Composition, Uses

Bird Seed Agar: Composition, Uses

Bird Seed Agar is a solid medium used for selective and differential isolation of Cryptococcus neoformans from clinical specimens.

Bismuth Sulfite Agar: Composition, Uses, Colony Morphology

Bismuth Sulfite Agar: Composition, Uses, Colony Morphology

Bismuth sulfite agar is a modification of original Wilson and Blair medium used for the isolation of Salmonella typhi and other salmonellae.

Chromogenic Culture Media: Principle, Composition, Results

Chromogenic Culture Media: Principle, Composition, Results

It contain chromogenic substrate which is utilized by the microorganisms to give colored colonies that is specific for each microorganism.

Tryptic Soy Agar (TSA): Composition, Preparation, Uses

Tryptic Soy Agar (TSA): Composition, Preparation, Uses

Tryptic Soy Agar (TSA) is a general purpose culture medium for  isolation and cultivation of a wide variety of organisms.

Thioglycollate broth: Composition, Principle, and Uses

Thioglycollate broth: Composition, Principle, and Uses

Thioglycollate broth supports the growth of anaerobes, aerobes, microaerophilic, and fastidious microorganisms.

Cary-Blair transport medium: Composition, Preparation, Uses

Cary-Blair transport medium: Composition, Preparation, Uses

Cary-Blair transport medium is used to transport clinical specimens suspected to contain enteric pathogens, including Shigella, Salmonella, Vibrio.

Alkaline Peptone Water (APW)

Alkaline Peptone Water (APW)

Alkaline Peptone Water (pH 8.4) is a suitable enrichment broth for the isolation of Vibrio cholerae and Vibrio species.

Salmonella-Shigella (SS) Agar

Salmonella-Shigella (SS) Agar

Salmonella-shigella (SS) agar is commonly used for the selective isolation and differentiation of Salmonella and Shigella.

Modified Thayer-Martin Agar: Preparation, Uses

Modified Thayer-Martin Agar: Preparation, Uses

Thayer-Martin agar is a selective medium used for the isolation of Neisseria gonorrheae from specimens containing a mixed flora of bacteria.

Nutrient Agar: Composition, Preparation, Uses

Nutrient Agar: Composition, Preparation, Uses

Nutrient agar is a general-purpose medium for the growth of a wide variety of non-fastidious microorganisms.

Sabouraud Agar (SDA): Composition, Uses, Colony Morphology

Sabouraud Agar (SDA): Composition, Uses, Colony Morphology

Originally formulated for dermatophyte growth and pigment production, SDA is used for growth and maintenance of fungi.

Potato Dextrose Agar (PDA): Principle, Composition, Colony Characteristics

Potato Dextrose Agar (PDA): Principle, Composition, Colony Characteristics

Potato Dextrose Agar (PDA) is an ideal medium for slide culture preparation. It promotes sporulation of moulds.

Baird-Parker Agar: Preparation, Composition, and Uses

Baird-Parker Agar: Preparation, Composition, and Uses

First reported by Baird–Parker, it is a selective medium for the enumeration of Staphylococcus aureus in foods.

Cetrimide Agar: Composition, Preparation, Uses

Cetrimide Agar: Composition, Preparation, Uses

Cetrimide agar test the ability of an organism to grow in the presence of cetrimide.

Xylose Lysine Deoxycholate (XLD) Agar

Xylose Lysine Deoxycholate (XLD) Agar

XLD Agar is a selective and differential medium for the isolation, cultivation, and differentiation of gram-negative enteric microorganisms.

CLED Agar: Composition, Uses, Colony Characteristics

CLED Agar: Composition, Uses, Colony Characteristics

Differential medium used for urine culture as it inhibits the swarming of Proteus and also supports the growth of gram-positive cocci.

Transport Media Used in Microbiology Lab

Transport Media Used in Microbiology Lab

Common transport media are Cary and Blair medium, amies medium, Staurt’s medium, and VTM for virus.

Hektoen Enteric (HE) Agar: Composition, Uses

Hektoen Enteric (HE) Agar: Composition, Uses

Hektoen Enteric Agar (HE) is a selective and differential medium to isolate and differentiate Salmonella and Shigella from other Enterobacteriaceae.

Common Fungal Culture Media: Their Uses

Common Fungal Culture Media: Their Uses

Fungal culture media contains high carbohydrate and nitrogen source. They may also contain cycloheximide and antibacterial agents to inhibit contaminants.

New York City Medium: Composition, Uses

New York City Medium: Composition, Uses

New York City medium is primarily designed for the isolation of pathogenic Neisseria. It also supports the growth of genital mycoplasmas.

TCBS Agar: Composition, Preparation, Uses

TCBS Agar: Composition, Preparation, Uses

TCBS agar is a selective as well as differential culture medium used for selective isolation and differentiation of Vibrio species.

Chocolate Agar: Composition, Preparation, Uses

Chocolate Agar: Composition, Preparation, Uses

Chocolate agar (heated blood agar) is an enriched medium used in clinical laboratories for cultivation of fastidious bacteria. e.g., Haemophilus influenzae.

Buffered Charcoal Yeast Extract (BCYE) Agar

Buffered Charcoal Yeast Extract (BCYE) Agar

Buffered Charcoal Yeast Extract (BCYE) Agar medium is recommended for use in the cultivation and primary isolation of Legionella spp.

Eosin Methylene Blue Agar (EMB Agar)

Eosin Methylene Blue Agar (EMB Agar)

Eosin methylene blue (EMB) agar is a selective and differential medium used to isolate fecal coliforms.

Blood Agar and Types of Hemolysis

Blood Agar and Types of Hemolysis

Blood agar is an enriched medium which supports growth of gram-positive cocci and differentiates them on the basis of hemolysis (α, β, or γ).

MacConkey Agar: Composition, Uses, Colony Characteristics

MacConkey Agar: Composition, Uses, Colony Characteristics

Selective (against gram-positive bacteria) and differential culture medium (LF and NLF), commonly used for the isolation of enterics.

Mannitol Salt Agar: Principle, Uses, and Results

Mannitol Salt Agar: Principle, Uses, and Results

Mannitol Salt Agar selects and differentiates Staphylococcus species. Staphylococcus aureus ferments mannitol and gives yellow colonies.

Mueller Hinton Agar (MHA): Composition, Preparation, Uses

Mueller Hinton Agar (MHA): Composition, Preparation, Uses

Best medium to use for routine susceptibility testing for non-fastidious bacteria.

Triple Sugar Iron (TSI) Agar: Principle, Results, and Interpretation

Triple Sugar Iron (TSI) Agar: Principle, Results, and Interpretation

TSI test determines whether a gram-negative rod utilizes glucose, and lactose or sucrose fermentatively and forms hydrogen sulfide.

Bacterial Culture Media: Classification, Types, Uses

Bacterial Culture Media: Classification, Types, Uses

Bacteria can be grown in an artificial medium in the laboratory. Growth medium can be broth, agar or biphasic. Medica can be categorized based on functions.