Transport Media: Principle, Uses, Types, Examples

Culture media are solid, semisolid, or liquid preparations containing essential nutrients and minerals vital for microorganisms’ survival and growth. They are also called growth media. They provide nutritional requirements and a place to grow the microorganisms in the laboratory. Based on physical state, culture media are classified as solid, semi-solid, and liquid culture media. Similarly, based on their function (intended use), they are classified as general purpose (supportive) media, selective media, differential (indicator) media, enriched media, enrichment media, sugar media, and transport media.

Transport Media

Transport media are those culture media that are used to maintain the viability of pathogenic microorganisms present in a clinical sample and to prevent the potential pathogens to be overgrown by other commensals or contaminants in the specimen during the transportation of the clinical specimen to the clinical/diagnostic laboratory.

Transport media are typically buffer solutions with minimum nutrients like carbohydrates, peptones, and salts, excluding growth factors. Some also contain selective inhibitory components. Due to this minimum nutrient and lack of carbon, nitrogen, and organic growth factors, microorganisms present in the specimen do not multiply but remain viable. 

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Principle of Transport Media

Transport media only contains enough energy sources like peptone and carbohydrates to maintain the viability of microorganisms potentially present in a specimen. They are well buffered and pH maintained so the present organisms do not suffer from chemical stress. 

No additional carbon, nitrogen, and other organic and inorganic (ions and minerals) growth factors are incorporated in the medium. Some may also contain inhibitory substances that selectively inhibit the growth and multiplication of microorganisms. Due to this, the microorganisms can’t multiply but remain viable for a certain duration under optimum physical conditions. Hence, the transport media tends to preserve the microbiome of the specimens in their original condition till they are processed in a lab. 

Uses of Transport Media

  • To maintain the specimen and its microbiome in their original state after specimen collection to the processing period.
  • To maintain the viability of specific pathogenic microorganisms potentially present in a clinical specimen.
  • To prevent commensals and contaminants from overgrowing the pathogenic microorganisms potentially present in a clinical specimen.

Types of Transport Media

  • Based on their physical state, transport media may be classified as semi-solid or liquid transport media. 
  • Based on their utility, they can be classified as bacterial transport media, viral transport media, and parasite transport media. Specimens for fungal culture are generally transported without any transport media.

Some Common Transport Medium and Intended Use

Transport MediaTypeIntended Use
Alkaline Peptone WaterLiquid bacterial transport mediumRecovery and transport of V. cholerae 
Amies Transport MediumLiquid or Semi-solid bacterial transport mediumRecovery of aerobes and anaerobes

Transport of swab specimens
Amies Charcol Transport MediumSemi-solid bacterial transport mediumRecovery of Neisseria gonorrhea

Recovery of anaerobesTransport of swabs 
Anaerobic Transport MediumSemi-solid bacterial transport mediumRecovery of anaerobic, microaerophilic, and facultative bacteria
Buffered Glycerol (Buffered Glycerol Saline) MediumLiquid bacterial transport mediumTransport of fecal and rectal samples for recovery of enteric pathogens

Recovery of Salmonella spp., Shigella spp., and E. coli in fecal sample
Cary-Blair MediumSemi-solid bacterial transport mediumTransport of fecal and rectal samples for recovery of enteric pathogens

Recovery of Vibrio cholerae, V. parahaemolyticus, Salmonella spp., Shigella spp., and E. coli O157:H7
Chlamydia Transport MediumLiquid bacterial and viral transport mediumTransport of swab for recovery of Chlamydia trachomatis and Herpes Simplex Virus
5% to 10% Formalin SolutionLiquid parasites transport mediumRecovery and transportation of intestinal parasites
Leibovitz Emory Transport MediumLiquid Viral Transport MediumRecovery and transport of viruses
Mycoplasma Transport BrothLiquid bacterial transport mediumTransportation of swabs or body fluid for recovery of Mycoplasma, Ureaplasma, Trichomonas vaginalis, Gardenerella vaginalis, etc. 
Stuart Transport MediumSemisolid bacterial transport mediumTransportation of swabs for recovery of fastidious, non-fastidious, and anaerobic bacteria 
Universal Transport MediumLiquid viral transport mediumTransport of specimens for recovery of viruses, Mycoplasma, Ureaplasma, and Ricketssiae. 
Viral Transport MediumLiquid viral transport mediumTransport of specimens for recovery of viruses

Applications of Transport Media

  • They are used for transferring clinical specimens from the collection center to diagnostic laboratories; especially from remote or resource-limited places to a laboratory. 
  • They are used to preserve clinical specimens if there is some delay in processing/culturing clinical specimens. 
  • They are used while sharing or transferring microbial cultures which are highly sensitive to environmental change. 
  • They are used to suppress the growth of contaminants and other microbial species of non-interest in clinical samples. 
  • They are used to maintain the viability of anaerobes and fastidious organisms and obligate pathogens in the specimen. 
  • They are also used in transporting food samples, water samples, and other biological samples for analysis. 

Limitations of Transport Media

  • As the transport mediums are limited in nutrients, they do not support the survival of organisms for a longer duration. 
  • Though the transport medium inhibits and prevents the overgrowth of many contaminants, some contaminants having similar metabolic, physical, and chemical requirements also remain viable. 
  • Physical conditions like temperature and pressure must be maintained. 
  • Specimens must be cultured in another culture medium for isolation and diagnosis.


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About Author

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Prashant Dahal

Prashant Dahal completed his bachelor’s degree (B.Sc.) Microbiology from Sunsari Technical College, affiliated with Tribhuvan University. He is interested in topics related to Antimicrobial resistance, the mechanism of resistance development, Infectious diseases (Pneumonia, tuberculosis, HIV, malaria, dengue), Host-pathogen interaction, Actinomycetes, fungal metabolites, and phytochemicals as novel sources of antimicrobials and Vaccines.

1 thought on “Transport Media: Principle, Uses, Types, Examples”

  1. Dear Author,
    Warm greetings from Manjari. I request you to please add an example in the transport media category.
    Universal Microbial Transport Media – BiomLife®
    Thank You!


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