Diagnostic yield of direct smear, concentrated smear, liquid culture, and GeneXpert by sputum induction in smear-negative pulmonary tuberculosis patients

Abstract

Background: Spontaneous sputum smear gave negative results in clinically and radiologically suspected pulmonary tuberculosis (TB) patients. Hence, the study aimed to evaluate the diagnostic yield of induced sputum with direct smear, concentrated smear, liquid culture, and GeneXpert. Materials and Methods: This cross-sectional study was conducted on clinically and radiographically suspected TB patients who were sputum smear-negative; 88 sputum smear-negative patients underwent sputum induction, and the samples were tested for direct smear, concentrated smear, liquid culture, and GeneXpert. Descriptive analysis was carried out for frequency and proportion for categorical variables and mean and standard deviation for quantitative variables. Diagnostic yield was calculated for each test. Data analyzed using coGuide software, V.1.03. Results: The mean age of the study population was 46.87 ± 15.09 years, and male participants were the majority. The diagnostic yield of induced sputum was 19.29% compared to a direct smear. Diagnostic yield was 59.25%, 80.70%, and 94.73% for concentrated smears, liquid culture, and GeneXpert, respectively. Conclusion: Induced sputum gave a high diagnostic yield in smear-negative pulmonary TB. With induced sputum, GeneXpert gave maximum yield compared to direct smear, concentrated smear, and liquid culture.

Keywords

• acid-fast bacilli
• genexpert
• induced sputum
• tuberculosis