TRANSPORT OF CLINICAL SPECIMENS

TRANSPORT OF CLINICAL SPECIMENS

• Specimens to be sent to other laboratories require special attention for safe packing of the material.
• For hand-carried transportation over a short distance, the specimen should be placed upright in appropriate racks.
• For long distance transportation, it should be placed in three containers.

a) A primary container which has the specimen and is leak proof with a screw-cap.

b) A secondary container which is durable, waterproof and made of metal or plastic with a screw-cap. It should have enough absorptive material to absorb the contents of the primary container should the latter break or leak. On its outside, the details of the specimen should be pasted.

c)  A tertiary container is usually made of wood or cardbox. It should be capable of withstanding the shocks and trauma of transportation. Dry ice can be kept between this and the secondary container along with sufficient absorbents and provision for the escape of carbon-di-oxide to prevent a pressure build-up inside.

GENERAL PRECAUTIONS FOR THE TRANSPORT OF CLINICAL SAMPLES

• Most specimens should be processed in the laboratory within 1 to 2 hours after collection.
• In practice, a 2 to 4 hour time limit is probably more practical during a normal working day.
• The laboratory must be organized to permit processing of the specimens as soon as they arrive, and the collection of most specimens should be limited to the working hours of the laboratory.
• Some arrangements must be made to allow for the initial handling of the few specimens that have to be collected outside of the laboratory’s working hours.
• A continuous effort must be made in order to ensure proper collection and transportation of clinical specimens.
• Full cooperation of nursing staff and others concerned with specimen collection is required and can be achieved once they are made aware of the principles involved and the significance of what they are being asked to do.

COMMONLY USED TRANSPORT MEDIUM

a) Cary and Blair Medium: Semi-solid, white colored transport medium for faeces that may contain Salmonella, Shigella, Vibrio or Cam­pylobacter.

b) Amies medium with charcoal: Charcoal helps eliminate metabolic products of bacterial growth, which may be especially useful in the isolation of fastidious organisms.

c) Amies medium without charcoal:  Are ideal for the isolation of Mycoplasma and Ureaplasma

d) Stuarts medium: Commonly used for transporting specimens suspected of having Gonococci. Also used for transporting Throat, vaginal, wound and skin swabs that may contain fastidious organisms.

e) Venkatraman Ramakrishnan (VR) medium: Used to transport feces from suspected cholera patients.

f)  Sach’s buffered glycerol saline: Used to transport feces from patients suspected to be suffering from bacillary dysentery.

g) Viral Transport Medium: Viral Transport Medium (VTM) is ideal for diagnosis of viral infection. Ocular, respiratory and tissue swabs can be submitted in this medium. Fluid samples such as tracheal wash specimens or peritoneal fluid should be submitted as is, in sterile vials which prevent desiccation. Bacterial transport medias are not appropriate for virology.

h) Anaerobic Transport Medium (ATM): Mineral salt base semi-solid media with reducing agents designed as a holding medium for maintaining viability of Anaerobic bacteria. It contains buffered mineral salts in a semi-solid media with sodium thioglycolate and cysteine added to provide a reduced environment. Resazurin may also be added as a redox indicator to reveal exposure to oxygen by turning pink. It provides an environment, which maintains viability of most microorganisms without significant multiplication and allows for dilution of inhibitors present in clinical material. Examples include Thioglycolate broth.