Abstract
BackgroundThe diagnosis of active pulmonary tuberculosis (TB) remains a challenge in clinic, especially for sputum negative pulmonary TB. Bronchoalveolar lavage fluid (BALF) has higher sensitivity than sputum for detection of Mycobacterium tuberculosis (Mtb). However, bronchoscopy is invasive and costly, and not suitable for all patients. In order to make TB patients get more benefit from BALF for diagnosis, we explore which indicator might be used to optimize the choice of bronchoscopy.MethodsA total of 1539 sputum-smear-negative pulmonary TB suspects who underwent bronchoscopy were recruited for evaluation. The sensitivity, specificity and accuracy of Mtb detection in sputum and BALF were compared. Odds ratios and 95% confidence intervals were used to assess variables that associated with positive acid-fast bacilli (AFB) smear, Mtb culture and nucleic acid amplification test (NAAT) of BALF in sputum-negative and non-sputum-producing pulmonary TB suspects.ResultsBALF has significantly higher sensitivity (63.4%) than sputum (43.5%) for Mtb detection by culture and NAAT. 19.7% (122/620) sputum-negative and 40.0% (163/408) non-sputum-producing suspects had positive bacteriological results in BALF. Among sputum-negative and non-sputum-producing pulmonary TB suspects, the positivity of Mtb detection in BALF is associated with a younger age, the presence of pulmonary cavities and a positive result of interferon-gamma release assay (IGRA). Sputum-negative patients under 35 years old with positive IGRA and pulmonary cavity had 84.8% positivity of Mtb in BALF.ConclusionsOur study indicated that combination of age, the presence of pulmonary cavity, and the result of IGRA is useful to predict the positivity of Mtb detection in BALF among sputum-negative and non-sputum producing pulmonary TB suspects. Those who are under 35 years old, positive for the presence of pulmonary cavity and IGRA, should undergo bronchoscopy to collect BAFL for Mtb tests, as they have the highest possibility to get bacteriologically confirmation of TB.
Highlights
The diagnosis of active pulmonary tuberculosis (TB) remains a challenge in clinic, especially for sputum negative pulmonary TB
Among 1539 suspect TB patients, 620 (40.3%) patients were negative for sputum Mycobacterium tuberculosis (Mtb) culture or nucleic acid amplification test (NAAT) test, 408 (26.5%) patients had no sputum
Factors associated with positive Bronchoalveolar lavage fluid (BALF) Mtb detection in sputum-negative and non-sputum-producing pulmonary TB patients In line with previous literature [14], our data demonstrated that BALF significantly improved Mtb detection in pulmonary TB patients
Summary
The diagnosis of active pulmonary tuberculosis (TB) remains a challenge in clinic, especially for sputum negative pulmonary TB. Bronchoalveolar lavage fluid (BALF) has higher sensitivity than sputum for detection of Mycobacterium tuberculosis (Mtb). In 2015, there were estimated 10.4 million new TB cases, and 1.8 million TB deaths Despite this large toll of mortality, majority of TB patients can be cured within 6 months with timely diagnosis and correct treatment [1]. Microbiological confirmation of TB and drug susceptibility testing are key factors ensuring that new TB suspects are accurately diagnosed and timely accessible to effective treatment. It remains as a challenge as up to 65% of TB patients were negative for Mtb detection in China [1]. There is a clear necessity to identity optimal methods for pulmonary TB diagnosis of bacteriologicallynegative patients, in high burden settings of multi-drug resistant TB (MDR-TB) like China
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