Tuberculosis : Specimen Collection for Laboratory Diagnosis

Specimen Collection

  • Pulmonary tuberculosis: threat to both patients and others so sample should be collected and handled in a safe manner.
  • Successful identification of pathogens depends on quality of the specimens and appropriate processing of samples.
  • Pulmonary secretion: sputum, gastric lavage, tracheal aspirate, bronchospcopic aspirations
  • Sputum: most important and frequently received
  • Container: wide mouth, sterile, clean, leak proof, labeling site and placed into bags to stop leakage
  • Specimen of choice: spontaneously induced sputum
  • Patients is instructed to take deep breath, hold for few seconds and then cough deeply and vigorously
  • Covering mouth during coughing to prevent spread of aerosols
  • Not to use oral antiseptics before collection
  • Rejected samples: saliva, nasal secretions, specimen containing food particles and other matters
  • Aerosol induction technique: saline aerosol induction procedure to induce sputum from those patients who can not produce sputum spontaneously.
  • Saline aerosol, causes irritation, when inhaled slowly, induces deep coughing and facilitates sputum collection
Gastric lavage specimen
  • Collected form those patients who have swallowed sputum during night
  • Procedure is limited to senile, non ambulatory and children younger than 3 years old
  • Levine collection tube is inserted through the nose , when fully inserted, a syringe is attached to the end of the tube and filtered distilled water is inserted through tube
  • 20-25 ml gastric lavage specimen is then collected
  • Series of specimen should be collected within 3 days

Urine samples

  • Early morning voided urine (EMU) sample should be collected
  • Whole sample should be sent for examination
  • Twenty four hour urine sample are undesirable because of excessive dilutions, higher contamination and difficulty in concentration

Body fluids

  • Tubercular meningitis, rather uncommon, may in immunocompromised patients
  • At least 10 ml of CSF and 10-15 ml of peritoneal, pericardial sample is collected
  • Pleural fluid and ascitic fluid tend to clot so should be collected in a tris sodium citrate container


  • Immunocompromised patient particularly co-infected with HIV may have disseminated mycobacterial infection
  • collected in a manner as for routine blood culture
  • Best recovery in BACTEC vial or isolator – centrifugation system


  • Clean, dry, wax free container without any diluents


  • Skin should be cleaned using alcohol
  • collected in a syringe or swab depending upon the volume


  • Specimen should be promptly delivered to laboratory and can be refrigerated if processing is delayed (only for sputum, gastric lavage and urine)
  • Should be labeled as HIGH RISK
  • Specimen should be opened in Class II containment

Binod G C

I'm Binod G C (MSc), a PhD candidate in cell and molecular biology who works as a biology educator and enjoys scientific blogging. My proclivity for blogging is intended to make notes and study materials more accessible to students.

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