Home – Our services – Pathology – Pathology tests – Faecal investigations

Faecal investigations

Clinical Use

Identification of pathogenic faecal bacteria and parasites.

Background

Diarrhoea is a typical symptom of gastrointestinal infection and may be defined as passing loose, watery, unformed faeces. It may be associated with other symptoms such as abdominal cramps, nausea, and malaise, and with vomiting, fever and consequent dehydration. A wide range of bacterial pathogens, viruses and parasites can cause diarrhoea. Outbreaks may occur as a result of inter-personal infection, through ingestion of infected food and water, and from direct contact with animals.

Infectious gastroenteritis is a significant cause of morbidity and mortality worldwide. The primary causes of bacterial gastroenteritis include Campylobacter sp., Salmonella sp., Shigella sp. and Shiga-like toxin-producing Escherichia coli. Cryptosporidium and Giardia are the two leading causes of parasite-associated diarrhoeal disease.

Please refer to parasite investigations for all other parasitic infections.

Patient preparation

  1. Place a wide mouth container e.g., potty, or large empty container in the toilet bowl to prevent specimen falling into the toilet.
  2. Cover the potty/large container with clean plastic wrap.
  3. Pass the stool onto the potty.
  4. Using a spatula, half-fill the faeces container. Do not fill more than a third full if the specimen is liquid (minimum volume is 2ml).
  5. Flush the remainder of the stool sample down the toilet.
  6. Wash hands thoroughly.

Specimen requirements

  • Sterile universal (please do not use universals that have/have had boric acid crystals in as this invalidates all faecal tests in Microbiology).
  • Specimens should be free from toilet paper, nappy liners or any other foreign material used in collection.
  • It is important to note that since 1st October 2024, stool samples that are graded Bristol Stool Chart (BSC) 1-4 in the laboratory will not be processed by Microbiology for bacterial PCR and will be rejected with a comment.

Minimum volume

  • If liquid stool: 2ml
  • If formed or semi-formed: 1 – 2g

Limitations & restrictions

  • Ensure urine is not mixed with the stool sample. Patients should be encouraged to urinate prior to collection of faeces.
  • If patients have been admitted to hospital for more than three days, they will not be eligible for Bacterial Faecal PCR unless they are under the care of Haematology, Oncology or Infectious Diseases.
  • We are currently only able to test for the following organisms by PCR: Cryptosporidium sp., Giardia (lamblia) intestinalis, Salmonella sp., Shigella sp./Entero-Invasive E. coli (EIEC), Campylobacter sp., Shiga-like toxin producing E. coli.
  • By culture we are only able to test for Vibrio sp. and Yersinia sp., subject to clinical history/inclusion criteria.
  • If testing is still required by the medical team after rejection, this must be discussed with the Medical Microbiology team.

Turnaround time

5 days

Analysing laboratory

Microbiology Lab, James Cook University Hospital, Marton Road, TS4 3BW

Additional information

Please provide all relevant clinical history including:

  • Any foreign travel
  • Any indication of hazard group 3 organism
  • Date of symptom onset
  • Severe abdominal pain
  • Haemolytic uraemic syndrome (HUS)
  • Blood in stool / bloody diarrhoea
  • Current or recent antibiotic treatment
  • Mesenteric adenitis, terminal ileitis
  • Consumption of shellfish
  • Contact with farm animals/livestock