|Description||85% of clinical tuberculosis presents as pulmonary tuberculosis. Identification of the presence of mycobacteria provide diagnosis and treatment options. Initial indication of infection may be the identification of AAFB by microscopy. Culture for AAFB in the laboratory uses continuous automated bacterial culture but can take up to 8 weeks. Further identification and susceptibility testing are provided following referral to Birmingham PHL laboratory (currently the referral lab is not accredited for this test)
Three expectorated sputum samples on three consecutive days are the preferred samples for diagnosis. In most cases patients are able to expectorate sputum. Those too unwell to cough or with small lesions on chest x-ray might require a bronchoscopic broncho-alveolar lavage – see separate tests and tubes entries. Gastric aspirations in the morning using an NG tube can be another useful sampling technique.|
|Additional Info||Saliva and nasopharyngeal secretions are not suitable specimens. Optimal samples are obtained from a deep productive cough. If available sputum should always be sent even if the presenting condition is extra-pulmonary to assess anticipated infectiousness. Dry cough may require physiotherapy, postdural drainage or induced sputum by inhalation of saline.|
|Interpretation||Please remember that tuberculosis is notifiable even on grounds of clinical suspicion alone.
Preliminary microscopy results will be reported negative or positive with a quantitative indication.
Initial culture results will be reported as AAFB isolated with confirmation of final identification and sensitivities reported later.|
|Collection Conditions||Three early morning specimens, taken at least 8 hours apart and ideally with at least one sample taken on first waking, are recommended for AAFB culture, although collection later in the day is acceptable.
Well expectorated sputum is recommended. If induced sputum is required specimen collection should be performed in respiratory isolation ventilation conditions by trained staff. Please request clearly AAFB culture and microscopy on form|
|Min. Vol|| Ideally 5ml.|
|Freq.||once a day on 3 consecutive days|
|Ref. Range (Male)|| |
|Ref. Range (Female)|| |
|Ref. Range (Paed)|| |
|Ref. Range Notes||
|Units|| - Not Defined -|
|IP Acute TAT||See Turnaround Comment|
|IP Routine TAT||See Turnaround Comment|
|GP Acute TAT||See Turnaround Comment|
|GP Routine TAT||See Turnaround Comment|
|Turnround Comment||Microscopy for AAFB will be available within 24 hours for samples received Monday to Friday before 12pm. Microscopy TAT for samples received at weekends and bank holidays will be 3 days.
Culture 60 days
Turnaround time may be increased if prolonged incubation is clinically indicated.|
Originally edited by : Dr. Helmut Schuster. Review due on 30/11/2018 12:30:10. Published By K Roberts on 30/11/2017 12:30:10.