The Yield of Acid-Fast Bacilli (AFB) and Tuberculosis (TB) Culture in the Microbiologic Diagnosis of Childhood Tuberculosis Using Sputum Induction: A Randomized Controlled Trial with Interrupted Time Series

  • Maria Cristina H. Lozada
  • Alexander O. Tuazon
Keywords: tuberculosis, children, sputum induction


Objectives. This study aims to determine the diagnostic yield and safety of sputum induction with hypertonic saline in the microbiologic confirmation of childhood tuberculosis (TB) in a tertiary hospital in the Philippines.

Methods. This is a randomized controlled trial with an interrupted time series in the control group. One hundred twelve (112) pediatric patients (4-18 years old) with clinical findings suggestive of TB were enrolled in the study. Patients were randomized into two groups composed of 56 patients each. Group A patients underwent sputum induction. Group B patients underwent spontaneous expectoration followed by sputum induction. The microbiologic yield for acid-fast bacilli and TB culture were determined and analyzed.

Results. Among the patients randomized to Group A, microbiologic confirmation for TB was 8/56 patients (14.3%) after sputum induction. For patients randomized to Group B, microbiologic yield was 4/56 patients (7.1%) from spontaneous expectoration; after sputum induction, the microbiologic yield increased to 5/56 patients (8.9%). There is insufficient evidence of statistical significance in microbiologic yield on parallel analysis of the two separate groups (p=0.22). Furthermore, for patients randomized to Group B, the increase in microbiologic yield after sputum induction compared to spontaneous expectoration did not reach statistical significance (p=1.000). The procedure was well-tolerated among children; no serious adverse events were observed.

Conclusion. Sputum induction is a feasible and safe method of specimen collection for microbiologic diagnosis of TB among children. While the microbiologic yield increased after sputum induction compared to spontaneous expectoration, the additional yield does not seem to be significant.