Induced sputum versus bronchial washings in the diagnosis of sputum negative pulmonary tuberculosis

Abstract

Introduction:Tuberculosis (TB) is one of the most important public health problems worldwide. Detecting patients with active pulmonary TB (PT) is an important component of TB control programs. However, at times in patients even with a compatible clinical picture, sputum smears do not reveal acid-fast bacilli (AFB) and smear-negative PT remains a common problem. This study compares the results of induced sputum (IS) and bronchial washings (BWs) in detecting sputum negative PT.Materials and Methods:A prospective study conducted from June 2014 to June 2015, comprising 120 patients fulfilling study criteria. Patients with respiratory symptoms and chest roentgenogram suspicious of PT with no previous history of antiTB treatment (ATT) and two spontaneous sputum smear samples negative for AFB were included in the study. Patients with active hemoptysis and sputum positive were excluded from the study. Sputum induction was done using 5–10 ml of 3% hypertonic saline through ultrasonic nebulizer taking safety precautions. All the patients underwent fiberoptic bronchoscopy after 6 h fasting on the same day. About 20 ml of normal saline instilled into the suspected pathology area and washings were taken with gentle suction. The sample processing and fluorescent staining for AFB were done in a designated microscopy laboratory.Results:Of 120 smear-negative PT patients, IS smear examination detected AFB in 76 patients (63.3%) and AFB detected from BWs in 94 patients (78.5%). Smear positivity higher in cavitary and infiltrative lesions compared to consolidation and infrahilar pattern disease.Conclusions:Even though both IS and BWs procedures were valuable for the diagnosis of smear-negative TB, sputum induction with hypertonic saline should be the initial procedure of choice, which can be repeated twice/thrice in a day or 2 consecutive days. If the patient remains IS smear-negative and if the clinical probability of TB is high, starting ATT and closely monitoring patient and reserving bronchoscopy to those patients who do not improve and to exclude alternative diagnosis seems to be a practically useful approach.

Is cough really necessary for TB transmission?

“…These small airways may also communicate with cavities in the lung parenchyma where bacilli are concentrated [39]. Further evidence comes from the consistently high sensitivity of broncho-alveolar lavage in TB, even in cases with negative sputum culture [40,41]. This suggests that viable Mtb bacilli are to be found in the lower airways.…”

Comparison of Induced Sputum and Fibre-Optic Bronchoscopy (Fob) in the Early Diagnosis of Sputum Smear Negative Suspected Cases of Pulmonary Tuberculosis under Rntcp Settings-A Study Conducted in Southern Part of Rajasthan

“…The various studies in this regard has reported the diagnostic yield varying from 35 to 95% [17]. There have been few studies reported in which the results of sputum induction and FOB related procedures have been compared and all have reported FOB superior to sputum induction [18][19][20]. But very few studies in this regard have been reported under RNTCP settings.…”

Hospital Practices for Respiratory Isolation for Patients With Suspected Tuberculosis and Potential Application of Prediction Models

“…In one study, patients with high clinical suspicion of PTB who were unable to generate adequate sputum or have smear-negative sputum may have a high probability of smear positivity on bronchoalveolar lavage (BAL) [ 25 ]. Another study found the added value of bronchoscopy over induced sputum to be 15% in identifying smear-positive TB in patients with previous smear-negative sputum [ 26 ]. In our study, it influenced management in only one patient.…”