Swabs, Pus and Fluids

(Microbiology)

 

1.        Swabs must always be placed in the appropriate transport medium. Dry swabs do not yield useful information; virus transport medium contains antibiotics which kill bacteria and chlamydia; there are important differences between chlamydia and mycoplasma transport media; and Trichomonas medium may be used only for the purpose of detecting parasites and yeasts (not bacterial culture).

2.        If it is possible to sample whole pus or fluid (particularly in theatre),collection into a sterile dry container is far preferable to taking a swab of the material.

 

Investigation

Culture and sensitivity
Microscopy (e.g. Gram stain & WBC count depending upon the type of specimen).

Inform lab before sending

No (unless urgent microscopy is required))

Specimen type

See above

Ideal time to take speciemn

Ideally before antibiotic therapy is administered

Specimen container

For samples of pus - sterile leak proof container

For swabs - Blue capped Stuarts transport media

For biopsies - A sterile universal container with a few drops of sterile saline to prevent drying

Labelling requirements

click here

How to take specimen

For wound swabs - sample a representative part of the lesion under investigation; best to sample the deepest part of the wound after cleaning to remove superficial microflora.

Volume

For fluids 5 - 10ml
For samples of pus - ideally >2ml (sufficient volume in order to carry out all necessary investigations).

Transport to the laboratory

If transport is delayed then refridgerate sample. Delays of over 48 hours are undesirable

Turnround

48 hours (may be more depending on the type of specimen and clinical details

Additional information

Investigation of ulcers/pressure sores are not recommended but if they are taken then the debris covering the ulcer must be removed. The ulcer should then be cleaned with saline and preferably perform needle aspiration at the edge of the ulcer margin.

Joint aspirates- If CRYSTAL SYNOVITIS is suspected - polarising light microscopy for urate and pyrophosphate crystals will be performed. If SEPTIC ARTHRITIS is suspected then blood culture should also be taken

Specimen retention

Please ensure that any requests for additional investigations on the specimen are made within 7 days from the date of the original request