Transport media contain sufficient energy sources such as peptones and carbohydrates to maintain the viability of microorganisms in specimens.
They are well-buffered and maintain pH to prevent chemical stress on organisms.
These media do not include additional carbon, nitrogen, organic compounds, ions, or minerals necessary for growth.
Some transport media may include selective inhibitory substances that prevent microorganism multiplication.
Due to these conditions, microorganisms in the specimen cannot proliferate but remain viable.
Transport media aim to preserve the microbiome of specimens in their original state until laboratory processing.
Uses of Transport Media
Preserve the specimen and its microbiome in their original state from collection to processing.
Maintain the viability of specific pathogenic microorganisms that may be present in clinical specimens.
Prevent commensal organisms and contaminants from outgrowing potential pathogenic microorganisms in clinical specimens.
Types of Transport Media
Based on physical state, transport media can be categorized as semi-solid or liquid.
Based on utility, they are classified as:
Bacterial transport media
Viral transport media
Parasite transport media
Specimens for fungal culture are typically transported without any specific transport media.
Some Common Transport Medium and Intended Use
Applications of Transport Media
Facilitate transfer of clinical specimens from collection centers to diagnostic laboratories, especially from remote or resource-limited areas.
Preserve clinical specimens in cases where there may be delays in processing or culturing.
Maintain the integrity of microbial cultures that are sensitive to environmental changes during sharing or transfer.
Suppress the growth of contaminants and non-target microbial species in clinical samples.
Preserve the viability of anaerobes, fastidious organisms, and obligate pathogens present in the specimen.
Used for transporting food samples, water samples, and various other biological samples for analytical purposes.
Limitations of Transport Media
Due to their nutrient limitation, transport media do not sustain organism viability for extended periods.
While transport media inhibit and prevent the overgrowth of many contaminants, some with similar metabolic, physical, and chemical needs can remain viable.
It's crucial to maintain specific physical conditions such as temperature and pressure.
Specimens require subsequent culture in another medium for isolation and diagnosis purposes.
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