Kin Wang To1, Kai Man Kam2, Denise Pui Chung Chan2, Wing Ho Yip1, Ka Pang Chan1, Rachael Lo1, Susanna Ng1, Jenny Ngai1, Shui Shan Lee3. 1. Respiratory Division, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong. 2. Stanley Ho Centre for Emerging Infectious Diseases, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong. 3. Stanley Ho Centre for Emerging Infectious Diseases, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong. Electronic address: sslee@cuhk.edu.hk.
Abstract
OBJECTIVES: To explore the clinical role of GeneXpert in managing pulmonary tuberculosis (TB) in an intermediate burden city. METHODS: Sputum acid-fast-bacilli (AFB) smear negative patients underwent bronchoscopy for bronchial alveolar lavage (BAL). Fluids collected were examined for AFB smear, TB culture, TB polymerase chain reaction (PCR) (Cobas Taqman) and for GeneXpert. RESULTS: From October 2015 to February 2017, 227 BAL samples were collected. Cough and haemoptysis were the presenting symptoms in 70.0% and 37.4%, respectively. Apical shadows on chest X-rays (CXR) and apical cavitations on computed tomography (CT) were commoner in GeneXpert positive cases (p = 0.01 and 0.02, respectively). Sensitivity and specificity of GeneXpert for TB diagnosis was 80% and 98% respectively. Positive and negative predictive value of the test was 92.3 and 95.1%, respectively. There were 9 false negative GeneXpert samples (8 were Cobas Taqman TB PCR negative): 6 were diagnosed by BAL culture, 2 by biopsy and one by Cobas Taqman TB PCR. There were 3 false positive cases with negative culture; 2 were put on empirical treatment with favourable clinical responses, while one defaulted follow-p. CONCLUSION: GeneXpert in BAL samples has high sensitivity and specificity. It enabled timely initiation of anti-TB treatment in clinical suspicious cases.
OBJECTIVES: To explore the clinical role of GeneXpert in managing pulmonary tuberculosis (TB) in an intermediate burden city. METHODS: Sputum acid-fast-bacilli (AFB) smear negative patients underwent bronchoscopy for bronchial alveolar lavage (BAL). Fluids collected were examined for AFB smear, TB culture, TB polymerase chain reaction (PCR) (Cobas Taqman) and for GeneXpert. RESULTS: From October 2015 to February 2017, 227 BAL samples were collected. Cough and haemoptysis were the presenting symptoms in 70.0% and 37.4%, respectively. Apical shadows on chest X-rays (CXR) and apical cavitations on computed tomography (CT) were commoner in GeneXpert positive cases (p = 0.01 and 0.02, respectively). Sensitivity and specificity of GeneXpert for TB diagnosis was 80% and 98% respectively. Positive and negative predictive value of the test was 92.3 and 95.1%, respectively. There were 9 false negative GeneXpert samples (8 were Cobas Taqman TB PCR negative): 6 were diagnosed by BAL culture, 2 by biopsy and one by Cobas Taqman TB PCR. There were 3 false positive cases with negative culture; 2 were put on empirical treatment with favourable clinical responses, while one defaulted follow-p. CONCLUSION: GeneXpert in BAL samples has high sensitivity and specificity. It enabled timely initiation of anti-TB treatment in clinical suspicious cases.
Authors: Olivia Sánchez-Cabral; Cira Santillán-Díaz; Ángel Paul Flores-Bello; Mildred Ivannia Herrera-Ortega; José Luis Sandoval-Gutiérrez; Patricio Santillán-Doherty; Dina Martínez-Mendoza Journal: Ann Transl Med Date: 2020-03