Use of the Laboratory and Collection of Specimens

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Use of the Laboratory and Collection of Specimens
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Laboratory Functions

• Diagnostic- detection of infectious agents
• guidelines for treatment
• information for individual cases
• collated information for general use (e.g.
  antimicrobial susceptibility summaries)

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Laboratory Functions (contd)

• Epidemiological - information provided can be
  used to complement clinical information
• Track resistant isolates (e.g. MRSA)
• Follow trends in development of resistance
• Detect or confirm outbreaks related to infectious
  agents
• Support control efforts

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Advantages of being a Smart Laboratory User

• Lab results correspond to the initial clinical
  question
• Decreased frustration for patients and health
  care workers
• Most cost effective use of Lab resources
• Speediest results by eliminating delays

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Advantages of being a Smart Laboratory User
(contd)

• By providing information, specialized testing can
  be accessed for unusual circumstances
• Avoidance of liability of mislabelled specimens,
  or loss of specimens.

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How to be a Smart Laboratory User

• Send as good quality specimens as possible,
  avoiding contamination with normal flora as much
  as possible.
• Make sure both specimen and requisition are
  labeled with patient name, birth date and health
  number, specimen type, etc.
• Put relevant clinical information on the
  requisition.

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How to be a Smart Laboratory User (contd)

• Use the appropriate transport media.
• Get specimens to the laboratory rapidly
• When in doubt ask the laboratory (especially if
  a request is unusual or needs additional testing,
  or results are unclear, etc.)
• When problems arise, work with laboratory staff
  to fix them.

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Specimen Collection General Considerations

• Issues to consider when collecting specimens
• Whether the specimen will provide useful
  information.
• Choice of the type of specimen
• Instructions for collection by patient
• Need for transport media
• Time taken for the specimen to get to the
  laboratory

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Specimen Collection - General Considerations
(contd)

• Quality of the specimen
• Risk of false positive or false negative results
• How to interpret the results.
• Each hospital/lab may provide detailed
  instructions for specimen collection. The
  following is a guide for collection of good
  quality specimens, but deals only with the most
  commonly collected specimens, or types of
  specimen.

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Specimen Collection - Urinary Tract

• Specimens
• Mid stream urine
• In-out catheter urine
• Indwelling catheter urine

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Specimen Collection - Urinary Tract (contd)

• Patient instructions
• Mid Stream Urine
• Decrease skin contamination by parting labia,
  retracting foreskin.
• Cleanse the urethral opening using soapy water
  and rinse with sterile water.
• After passing a few milliliters collect the
  specimen in a clean sterile container.

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Specimen Collection - Urinary Tract (contd)

• Transport medium is not required if urine is
  transported to the lab within 2 hours or
  refrigerated at 4C and delivered within 24 hours.
  Preservatives can be used if delivery to a lab
  is likely to be delayed, or transport prolonged.
• Label the container with the patient name and
  specimen type.
• DO NOT collect urine from bedpans, urinals, or
  catheter bags

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Specimen Collection - Urinary Tract (contd)

• In/Out Catheters
• Use aseptic technique to introduce the catheter.
• Discard the first few ml of urine that pass.
• Collect the specimen and submit it as above.
• Indwelling Catheter
• Collect the specimen using a needle and syringe
  after cleaning the collection port with alcohol,
  and send as above.

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Specimen Collection - Respiratory Tract (contd)

• Specimen Types
• sputum
• induced sputum
• tracheal aspirate
• ? If TB is suspected, use precautions to prevent
  spreading infection.

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Specimen Collection - Respiratory Tract (contd)

• Patient instructions
• Sputum
• Decrease contamination by saliva by removing
  dentures, cleaning teeth (no toothpaste as the
  residue may be antibacterial), gargling and
  rinsing mouth with sterile water (not tap water -
  may be contaminated with Legionella or
  pseudomonas).
• Avoid collecting post nasal discharge.
• Deep cough from the chest

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Specimen Collection - Respiratory Tract (contd)

• Sputum (contd)
• Collect sputum in a dry sterile container
• Transport to the laboratory as soon as possible
  but at least within 24 hours.
• Refrigerate at 4C if there is delay in delivery.
• Degree of contamination with saliva can be
  detected in the lab by microscopy, by
  identification of squamous cells.

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Specimen Collection - Respiratory Tract (contd)

• Induced Sputum
• Induction of sputum using saline aerosols can be
  useful if patient cannot produce sputum.
• Sputum produced after bronchoscopy is a good
  specimen also.
• Collect and transport as above.
• Tracheal Aspirate
• Useful in intubated patients.
• Specimen collection traps are prone to leaking
  during transport.

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Specimen Collection - Enteric

• Specimen Types
• Stool
• Patient Instructions
• Stool
• Pass stool on clean dry surface (e.g. paper)
• Place an almond sized portion in the specimen
  container

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Specimen Collection - Enteric (contd)

• For Culture use Cary Blair Transport medium
• For parasites use SAF parasite preservative
• For cytotoxicity and virology testing use a dry
  sterile container
• Transport to lab as soon as possible or
  refrigerate at 4C
• Send stool rather than rectal swabs if possible

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Specimen Collection - Swabs

• Choice of specimens
• throat
• wounds
• urethra, etc.

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Specimen Collection - Swabs (contd)

• Instructions
• Use a swab only if there is insufficient quantity
  to collect in a syringe and send in a dry sterile
  container. Some material will be absorbed by the
  swab.
• Collect purulent material.
• Avoid contamination with surrounding normal flora
  on skin etc.

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Specimen Collection - Swabs (contd)

• Use an appropriate transport medium (we use a
  charcoal transport medium) to increase organism
  survival or for specific organisms (e.g.
  Neisseria gonorrhoeae, viruses, chlamydia).
• Avoid dry swabs for sending specimens.
• Anaerobic swabs are 20X the cost of aerobic
  swabs, and so should be used judiciously (e.g. on
  infected wounds but not on mucous membranes).

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Specimen Collection - Biopsies, Sterile Fluids

• Specimens
• tissue
• pleural fluid
• pericardial fluid
• CSF
• vitreous fluid, etc.

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Specimen Collection - Biopsies, Sterile Fluids
(contd)

• Instructions
• Collect in a dry sterile container and send to
  the lab without delay.
• CSF and eye fluids are considered emergencies and
  staff are called in to process these specimens.
• Labelling must be complete and correct.
• It is not necessary to add sterile water to
  biopsies unless they are very small and in danger
  of drying out.
• Microbiology specimens should never be put in
  formalin.

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Results

• Microscopy is usually available within 1 - 2
  hours of specimen receipt.
• Cultures may take from overnight to several weeks
  for some organisms (e.g. TB). Most are available
  within 3 days.
• Rapid testing (e.g. antigen detection) may be
  available on a same day basis.
• Susceptibility results usually require a further
  overnight incubation.