Mycobacterium species (culture or PCR)
| About This Test |
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Department: Microbiology, Virology and Molecular Microbiology Requirement:
If sample volume is insufficient, culture is usually preferred to microscopy due to greater sensitivity. Turnaround Time: AAFB microscopy usually within 24 hours weekdays only, contact laboratory if urgent Mycobacterium culture 2-8 weeks (extended cultures are performed if clinically relevant and may extend to 12 weeks). Mycobacterium PCR available on request, results within 3-5 working days. |
Auramine stain for acid-alcohol fast bacilli (AAFB) , liquid and slope culture for Mycobacterium species.
PCR is available on specific request – please discuss with consultant microbiologist first
Other Comments:
Collection container:
CE marked leakproof container, send to laboratory in sealed plastic bag. NB Send citrate bottles for blood or bone marrow – see below.
Blood and Bone Marrow 2 x 5ml heparin blood tubes (green top). These samples MUST NOT be sent via the pod system.
Sputum specimens
Sputum specimens should be relatively fresh (less than 1 day old) to minimise contamination. Purulent specimens are best. Three samples of ≥5mL should be collected approximately 8-24 hours apart with at least one from early morning. Samples taken early morning (i.e. shortly after patient waking) have the greatest yield. When the cough is dry, physiotherapy, postural drainage or inhalation of nebulised saline (‘sputum induction’) before expectoration may be helpful. Minimum volume of sample 1ml
Bronchoalveolar lavage/bronchial washings/traps/brushes
These may be sent if spontaneous or induced sputum is unavailable or if such specimens are AAFB smear negative. Note: Contamination of the bronchoscope with tap water, which may contain environmental Mycobacterium species, should be avoided. Minimum sample size is preferably 5mL.
Urine specimens
Urine specimens should be collected in the early morning on three consecutive days in a CE marked leak proof container and placed in a sealed plastic bag. Do not use boric acid containers.
Fluids (e.g. CSF, ascitic fluid, pleural fluids) Collect aseptically as much sample as possible into a CE Marked leak proof container in a sealed plastic bag. Minimum sample volume 5ml CSF - If only a small volume is available after initial lumbar puncture, and the findings of cell counts and protein suggest TB meningitis, a second procedure should be considered to obtain a larger volume to improve chances of achieving positive cultures. Minimum sample volume ideally 6ml Pus/tissues/biopsies Collect aseptically as much sample as possible into a CE Marked leak proof container in a sealed plastic bag. Do not send in formalin or use containers that have contained formalin.
Specimen transport:
Specimens should be transported and received in the laboratory within one working day of collection. Requirements of individual testing laboratories should be referred to. If processing is delayed, refrigeration is preferable to storage at ambient temperature.
Note:
Positive cultures (new cases) are referred to the National Mycobacterium Reference Service - Central & North (MNRS, Birmingham) for identification and Whole Genome sequencing.