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COLLECTION OF POST-MORTEM TISSUE SAMPLES


MATERIALS

SUPPLIES REAGENTS

Barrier precautions: double gloves, sterile gown, eye goggles, mask

Aseptic surgical and biopsy instruments for collecting tissue specimens.

Sterile containers, sterile screw cap tubes or vials and slide box.

Fixatives: saline, appropriate viral and bacterial transport media.

Disinfectant such as household bleach 1:10.


For collecting blood and other fluids, refer to corresponding annex for materials.



PROCEDURE

STEP ACTION
1

Use a separate sterile instrument for each tissue specimen from affected sites (several fragments with 1-2 grams of each is sufficient).

Smaller, but adequate, specimens are taken with a biopsy needle.

2

Place difference tissues in separate sterile containers containing the relevant medium:

  • Fixatives for histopathology,
  • Sterile saline for preparation of tissues for immunofluorescence microscopy
  • Microbiological transport media for the isolation of bacterial and viral pathogens.
3

Label all containers and tighten the screw caps firmly.


  • Other specimens are collected as per the relevant annex

  • Blood may be taken from the heart cavities.

  • If cerebral malaria is suspected, make several smears from the cerebral cortex on glass slides to detect Plasmodium falciparum. Label the slides and transport in a slide box.


HANDLING AND TRANSPORT

  • Fixed specimens can be stored at ambient temperatures

  • Tissue specimens for isolation of bacterial pathogens can be transported at ambient temperature in transport media for up to 24 hours.

  • Transport tissue specimens for isolation or viral pathogens in viral transport medium or sterile saline at 4-8oC for 24-48 hours. For longer periods, freeze and store at -70oC.

  • If rabies is suspected and brain samples are collected, freeze unfixed specimens immediately after collection. Formalin fixed samples are also useful and may be transported at ambient temperature.


Post- Mortem Skin Biopsy

MATERIALS

SUPPLIES REAGENTS

Instruments: Punch biopsy tool or scissors and forceps

Screw-cap vial containing sterile saline.


PROCEDURE

STEP ACTION
1

Take out a vial containing the sterile saline. Lay out the instruments

2

Using a punch-biopsy tool

  • Place the open, sharp end on the skin and swivel into the skin, pressing firmly.
  • Remove the tool from the skin and lift the biopsy specimen out with forceps.
  • Cut free with scalpel or scissors.

Using a scissors to take the biopsy

  • Lift the skin to be sampled with forceps.
  • Cut a small piece of skin from the area.
  • Use the forceps to remove the skin specimen.
3

Place the specimen in a vial containing the sterile saline, and close the screw cap tightly

4

Label the specimen vial

5

Discard all instruments safely – do not re-use.


In the diagnosis of rabies, samples from the nape of the neck at the hairline are preferred as concentrations of virus are likely to be high


Post-mortem skin biopsy for diagnosis of pathogens with high infectious risks (e.g. viral haemorrhagic fever)

MATERIALS

All these materials are assembled in one kit.

For bio-safety reasons the protective clothing and gloves are for one-time use only, and should be incinerated after use.

SUPPLIES REAGENTS

Bucket, soap and water. Gown, latex gloves, heavy duty rubber gloves, plastic apron.

Masks and, where available, respirators for aerosol protection.

Instruments: punch biopsy tool or scissors, forceps

Screw-cap vial containing 10% buffered formalin fixative.

Disinfection solution.


PROCEDURE

STEP ACTION
1

Put on protective clothing beginning with gown followed by latex gloves, rubber gloves, facial mask, and plastic apron.

2

Open the vial containing the formalin fixative. Lay out the instruments.

3

Gently turn the head of the cadaver to expose the nape of the neck. This area is selected because it is less visible and is highly vascular

4

Using a punch-biopsy tool

  • Place the open, sharp end on the skin and swivel into the skin, pressing firmly.
  • Remove the tool from the skin and lift the biopsy specimen out with forceps.
  • Cut free with scalpel or scissors.

Using a scissors to take the biopsy

5

Place the specimen in the vial containing the formalin fixative, and close the screw cap tightly.

Dip the closed vial in the disinfectant for 1 minute and allow to dry.

6

Drop the instruments in the disinfectant.

When finished, remove the outer rubber gloves and drop them in the disinfectant.

Keep the latex gloves on while removing materials from the disinfectant.

7

Dispose of all protective clothing, rubber and latex gloves, and materials in a plastic bag and incinerate everything.

8

Wash your hands well and disinfect with 70% isopropyl alcohol or povidone iodine

9

Label the specimen vial.

10

Pack the specimen vial and ship at ambient temperature.


Once the sample has been fixed in formalin, the decontaminated vial may be safely transported to the receiving laboratory.




COLLECTION OF TB SAMPLES

CARPHA performs a PCR assay using the Xpert MTB/RIF test (for use with the Cepheid GeneXpert® System). This is a semi-quantitative nested real-time PCR in-vitro diagnostic test for:

  1. the detection of Mycobacterium tuberculosis complex DNA in sputum samples or concentrated sediments prepared from induced or expectorated sputa that are either acid-fast bacilli (AFB) smear positive or negative; and
  2. the detection of rifampin resistance associated mutations of the rpoB gene in samples from patients at risk for rifampin resistance.

The MTB/RIF test is intended for use with specimens from untreated patients for whom there is clinical suspicion of tuberculosis (TB). Use of Xpert MTB/RIF for detection of M. tuberculosis (MTB) or determination of rifampin susceptibility has not been validated for patients who are receiving treatment for tuberculosis.


PROCEDURE

A.  Method for collecting a stool specimen:

STEP ACTION
1

Select a sample container.

2

Instruct the patient to rinse his or her mouth with plain water twice before bringing up the sputum.

3

Open the lid of the sample container.

4

Have the patient inhale deeply 2-3 times.

Cough deeply from the chest, and then spit into the sputum container by bringing it closer to the mouth.

Care should be taken to avoid spoiling or soiling the soiling the outside of the container.

Secure the lid on the collection device.

5

Make sure the sputum sample is of good quality.

Check the sample for food particles, blood or substances that may inhibit PCR process.

The sample volume should be at least 1ml.



HANDLING AND TRANSPORT

  • Treat all sputum samples as potentially infectious material and use leak proof containers for sample collection and transportation.

  • Specimens should be held at 2oC- 8oC (The sample remains viable at this temperature for 4-10 days.)

  • Transport the sample to CARPHA at (2oC- 8oC)

Caribbean Public Health Agency © 2014