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COLLECTION OF CEREBROSPINAL FLUID

CSF is used in the diagnosis of viral, bacterial, parasitic and fungal meningitis. The specimen must be taken by a physician or a person experienced in the procedure.


MATERIALS

EQUIPMENT SUPPLIES REAGENTS
Water manometer

Lumbar puncture tray which includes

Sterile materials: gloves, cotton wool, towels or drapes

Two lumbar puncture needles, small bore with stylet

Six small sterile screw-cap tubes and tube rack.

Microscope slides and slide boxes

Local anaesthetic, needle, syringe



PROCEDURE

As only specially trained personnel should be involved in the collection of CSF samples, the method is not described in this document.

CSF is collected directly into the separate screw-cap tubes.

If the samples will not be promptly transported, separate tubes should be collected for bacterial and viral processing.



HANDLING AND TRANSPORT

In general, specimens should be delivered to the laboratory and processed as soon as possible.

CSF specimens for bacteriology are transported at ambient temperature, generally with transport media. They must NEVER be refrigerated as many of the relevant pathogens do not survive well at low temperatures

CSF specimens for virology do not need transport medium. They may be transported at 4-8oC for up to 48 hours, or at -70oC for longer periods.




COLLECTION OF FAECAL SAMPLES

Stool specimens are most useful for microbiological diagnosis if collected soon after onset of diarrhoea (for viruses < 48 hours for bacteria < 4 days), and preferably before the initiation of antibiotic therapy. If required, two or three specimens may be collected on separate days for bacterial diarrhoea. Stool is the preferred specimen for culture of bacterial, viral and parasitic diarrhoeal pathogens. Rectal swabs showing faeces may also be used from infants. In general, rectal swabs are not recommended for the diagnosis of viruses.


MATERIALS

SUPPLIES REAGENTS

Clean, dry, leak-proof screw cap container and tape.

Appropriate bacterial transport media for transport of rectal swabs from infants

Parasitology transport pack: 10% formalin in water, polyvinyl isopropyl alcohol (PVA).



PROCEDURE

A.  Method for collecting a stool specimen:

STEP ACTION
1

Collect freshly passed stool, 5ml liquid or 5g solid (pea-size), in a container.

2

Label the container


B.  Method of collecting a rectal swab from infants:

STEP ACTION
1

Moisten a swab in sterile saline

2

Insert that swab tip just past the anal sphincter and rotate gently

3

Withdraw the swab and examine to ensure that the cotton top is stained with faeces

4

Place the swab in sterile tube/container containing the appropriate bacterial or viral transport medium.

5

Break off the top part of the stick without touching the tube and tighten the screw cap firmly.

6

Label the vial with patient’s name type of specimen and date of collection



HANDLING AND TRANSPORT
  • Stool specimens should be transported at 4-8oC. Bacterial yields may fall significantly if specimens are not processed within 1-2 days of collection. Shigella is particularly sensitive to elevated temperatures.

  • Specimens to be examined for parasites should be mixed with 10% formalin or PVA (3 parts stool to 1 part preservative).

  • Transport at ambient temperature in containers sealed in plastic bags.



COLLECTION OF EYE SPECIMENS

Conjunctival and corneal swabs and smears are the usual specimens collected to diagnose acute bacterial or viral (kerato) conjunctivitis. Label all specimens as conjunctival or corneal and indicate whether the specimen was taken from the left or right eye. Strict aseptic technique is essential when collecting and processing these specimens. All medicines and droppers that come in contact with patients should be discarded.

While corneal scrapings may occasionally prove useful in improving the utility of corneal specimens for diagnosis of some infections, these are not generally infections which are epidemic-prone. Corneal scrapings must only be collected by an ophthalmologist or other trained persons. For these reasons, instructions for taking corneal scrapings will not be given here.


MATERIALS

SUPPLIES REAGENTS

Sterile gloves.

Glass slides, glass slide marker, slide holder box

Glove and protective goggles should be worn if epidemic keratoconjunctivitis is suspected

Sterile calcium alginate and/or cotton swabs. (Do not use calcium alginate swabs for virology specimens)

Vials containing sterile saline and viral transport media.



PROCEDURE

Method of collection of conjunctival swabs

STEP ACTION
1

Clean the skin around the eye with a mild antiseptic

2

Moisten a swab in sterile saline and roll over the conjunctiva in a circular manner

3

Insert the swab into a sterile screw-cap vial containing the appropriate transport media for bacteria.

4

Break off the top part of the stick without touching the tip of the tube and tighten the screw cap firmly

5

Repeat the procedure with a tube containing the appropriate viral transport medium

6

Label the vial with patient’s name type of specimen and date of collection


Method of preparation for microscopy smears

STEP ACTION
1

Prepare two smears onto clean glass slides with a fresh conjunctival swab.

This should be done on-site if possible. Otherwise, specimens may be sent to the laboratory in appropriate transport media for the preparation of smears.

Note that it is not possible to prepare smears from swabs transported in certain media, such as those containing charcoal.

For detection of Chlamydia, it is essential that smears be prepared on-site prior to transport.

2

Label the glass slides and put into a slide carrier or others appropriate box.

DO NOT refrigerate or freeze the slides.



HANDLING AND TRANSPORT

  • Specimens for detection of bacterial pathogens are transported at ambient temperature in appropriate bacterial transport medium

  • Specimens for viral detection are transported at 4-8oC in viral transport medium. Swabs in viral transport medium may also be frozen in liquid nitrogen.

  • Microscopic slides are air dried and transported at ambient temperature in a slide box.

Caribbean Public Health Agency © 2014