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.
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