Liquid culture enhances diagnosis of patients with milder forms of non-tuberculous mycobacterial lung disease

Abstract

To evaluate the proportion and clinical characteristics of patients with non-tuberculous mycobacteria (NTM) lung disease diagnosed based on positive culture results in liquid medium only. We reviewed the medical records of 978 patients diagnosed with NTM lung disease. All clinical samples were cultured in both solid and liquid media. Of the 978 patients, 111 (11.3%) were culture-positive in liquid medium only (liquid culture group), and 867 (88.7%) (solid culture group) on solid medium, regardless of the culture results in liquid medium. At the time of diagnosis, the liquid culture group was less likely than the solid culture group to have haemoptysis (11.7% vs. 20.0%, P = 0.04), positive sputum smear for acid-fast bacilli (14.4% vs. 50.2%, P < 0.001) or the fibrocavitary form of NTM lung disease (3.6% vs. 14.6%, P = 0.001). During the median follow-up period of 28.9 months (interquartile range 19.1-41.6), the proportion of patients requiring antibiotic treatment was lower in the liquid culture group than in the solid culture group (44.1% vs. 61.6%, P < 0.001). Liquid media culture is helpful in the diagnosis of patients with less severe forms of NTM lung disease.