Early diagnosis of smear-negative childhood pulmonary tuberculosis and its substantial yield in gastric lavage/aspirates through cartridge-based nucleic acid amplification test (Xpert Mycobacterium tuberculosis/rifampicin assay)

Abstract

Introduction: Tuberculosis (TB) still remains the major public health threat in India. Early diagnosis is a priority as any delay may complicate the prognosis further leading to the failure of an effective control. India accounts for 6% incidence of pediatric TB cases in a population that has 40% as estimated latent TB cases. Gastric Lavage /aspirates were taken under study for pediatric patients as key population. Collection of sputum samples from the pediatric patients has been very difficult. The most common implementation of cartridge-based nucleic acid amplification tests (CBNAATs) in diagnosis of pediatric TB has augmented the detection rates. As a mandate for universal drug sensitivity, testing of smear-negative pediatric samples is set as a priority. The program included the smear-negative pulmonary samples contributing to high yield after sputum includes induced sputum, bronchoalveolar lavage, gastric aspirate, and gastric lavage. The study involves an analysis probing into the percentage contribution of these samples and the substantial yields of gastric lavage among these samples. Methods: Pulmonary pediatric samples were tested on CBNAAT by Xpert Mycobacterium tuberculosis/rifampicin (RIF) (Cepheid) based on the manufacturer's instruction. All necessary aseptic measures were taken. The data were captured in the Xpert software automatically during the tests and exported to the Microsoft Excel sheets for further analysis. A defined study design against each and every objective was set up. Results: From earlier studies, it was found that a point prevalence of 6%–7% of pediatric TB exists among the tested specimens every quarter. The periodic prevalence was found to be 5%, and the incidence rates ranged from 4.5% to 5%. RIF resistance detection showing a seasonal variation ranged from 13% to 15% among the CBNAAT-positive cases. Conclusions: The study concluded that more skilled collection centers for biological specimens are required to address the undetected pulmonary TB cases among the pediatric age group, especially below 6 months of age. About 5% prevalence and around 4.9% incidence is an alarming situation in the TB control scenario of West Bengal. Gastric lavage showed a major detection in children aged below 6 months of whom collecting sputum samples were difficult. This prompted suboptimal detection levels due to the dearth of sample collection modalities at the peripheries.

Keywords

• cartridge-based nucleic acid amplification test
• childhood pulmonary tuberculosis
• gastric lavage