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Standard Operative Procedure for collection, transport and
processing and inoculation of Extra-pulmonary specimens
1. Introduction:
Mycobacteria may not be suspected as the causative agent of an extra
pulmonary disease because the chest X-ray or the tuberculin test is negative or
both. However, based on clinical symptoms and because mycobacteria can
infect almost any organ in the body, the laboratory should expect to receive a
variety of extra pulmonary specimens such as body fluids, surgically excised
tissues, aspirates or draining pus and urine.
Extra pulmonary specimens are divided in to two groups based on the site and
mode of collection and the extent of contamination.
Aseptically collected specimens, usually free from other microorganisms
(sterile) fluids like spinal, pleural, pericardial, synovial, ascitic, blood, bone
marrow, tissues (lymph node, tissue biopsies) and fine needle aspirates
(FNAs)
Specimens contaminated by normal flora or specimens not collected
aseptically (not sterile) gastric lavage, bronchial washings, urine , pus and
stool (in case of disseminated TB in HIV infected patients and infants)
2. Collection of extra pulmonary specimens
Body fluids (spinal, pleural, pericardial, synovial, ascitic, bone-marrow) should be
aseptically collected in a sterile container by the physician using aspiration
techniques or surgical procedures. Specimens should be transported to the
laboratory as quickly as possible.
2.1 Pleural fluid
Considered a suboptimal specimen as tubercle bacilli are mainly in the pleural
wall and not within the fluid. The minimum volume for pleural fluid required for
processing for culture is 20 50ml. The fluid is collected using pleural tap or
thoracocentesis.
2.2 Pericardial fluid
Should be collected using ultra sonogram
2.3 Blood
Blood as a specimen for isolating
M. tuberculosis
should be generally
discouraged for the low diagnostic yield and high possibility of contamination with
respect to the technique required for its culture. However, if there are specific
indications when a physician suspects disseminated TB in a HIV infected patient,
blood can be collected provided, the culture systems for recovery of
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