Efficacy of Induced Sputum for the Diagnosis of Pulmonary Tuberculosis in Adults Unable to Expectorate Sputum

Abstract

BackgroundInduced sputum (IS) has been used to collect airway secretions in subjects who have inadequate sputum production. The aim of this study was to investigate the efficacy of IS for the diagnosis of pulmonary tuberculosis (PTB) in adults unable to expectorate sputum.MethodsMedical records of 39 PTB patients who underwent IS due to absence of spontaneous sputum production between January 2011 and March 2014 at a tertiary hospital in South Korea were reviewed. Results of acid fast bacilli smear, Mycobacterium tuberculosis culture and polymerase chain reaction assay for M. tuberculosis (TB-PCR) of IS specimens from these patients were analyzed. Clinical and high-resolution computed tomography (HRCT) characteristics were also analyzed to find characteristics associated with IS culture positivity.ResultsOf the 39 IS specimens from PTB patients, 7 (17.9%) were smear positive and 31 (79.5%) were culture positive. Twenty-four IS specimens were tested for TB-PCR and 13 (54.2%) were positive on TB-PCR. Multivariate analysis showed that younger age (p=0.04) and presence of tree-in-bud appearance on HRCT (p=0.03) were independent predictors of IS culture positivity.ConclusionIS is useful for the diagnosis of PTB in adults unable to expectorate sputum. Younger age and tree-in-bud appearance on HRCT were associated with IS culture positivity in these patients.

Duration of Pulmonary Tuberculosis Infectiousness under Adequate Therapy, as Assessed Using Induced Sputum Samples

“…This is especially true when a patient's spontaneous sputum specimen is smear microscopy negative, the patient is unable to expectorate spontaneously, or when the produced sputum is inadequate in amount or quality192021. Anderson et al22 reported that the diagnostic accuracy of an IS specimen is equivalent to that of bronchoscopy for the diagnosis of smear-negative PTB.…”

Polymerase chain reaction test in induced sputum of patients with pulmonary tuberculosis

“…In this context, rapid diagnosis of TB relies on PCR test. Few studies evaluated the PCR role in IS samples for TB diagnosis, and most of them had small sample sizes and were not designed to evaluate the sensitivity and specificity of the test . Kawada et al compared the PCR with the conventional smear and culture method for the detection and identification of M. tuberculosis in only 25 IS samples from patients suspected of active pulmonary TB.…”

“…Few studies [16][17][18][19] evaluated the PCR role in IS samples for TB diagnosis, and most of them had small sample sizes and were not designed to evaluate the sensitivity and specificity of the test. [17][18][19] Kawada et al 17 compared the PCR with the conventional smear and culture method for the detection and identification of M. tuberculosis in only 25 IS samples from patients suspected of active pulmonary TB. Induced sputa were both PCR and culture positive in 10 patients, PCR positive and culture negative in 4 patients, and PCR negative and culture positive in 2 patients.…”

“…Only 38 patients were evaluated, and PCR was positive in 9, including cases of non‐tuberculous mycobacteria. A retrospective study from South Korea also reported the findings of 39 IS samples from pulmonary TB‐infected patients. Thirty‐one patients were culture positive.…”

“…In spontaneous sputum samples, PCR for TB provides high specificity, and the sensitivity varies from 36% to 97%, depending on the results of smears and cultures . However, few studies evaluated its role in IS samples. The aim of this study was, therefore, to determine the diagnostic yield of PCR for TB compared with culture in IS samples, among patients suspected of having pulmonary TB.…”