Diagnostic performance of GeneXpert MTB/RIF assay compared to conventional Mycobacterium tuberculosis culture for diagnosis of pulmonary and extrapulmonary tuberculosis, Nepal

Raina Chaudhary (Nepal Army Instituteof Health Science, Kathmandu, Nepal)
Sabita Bhatta (Nepal Army Instituteof Health Science, Kathmandu, Nepal)
Alina Singh (Nepal Army Instituteof Health Science, Kathmandu, Nepal)
Manoj Pradhan (Nepal Army Instituteof Health Science, Kathmandu, Nepal)
Brijendra Shrivastava (Nepal Army Instituteof Health Science, Kathmandu, Nepal)
Yengkokpam I. Singh (Nepal Army Instituteof Health Science, Kathmandu, Nepal)
Ranjit Sah (Tribhuvan University Teaching Hospital, Institute of Medicine, Kathmandu, Nepal National Public Health Laboratory, Kathmandu, Nepal)
Zareena Fathah (King’s College London, London, United Kingdom)
Rachana Mehta (National Public Health Laboratory, Kathmandu, Nepal)
Ali A. Rabaan (Molecular Diagnostic Laboratory, Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia)
Alfonso J. Rodriguez-Morales (Grupo de Investigación Biomedicina, Faculty of Medicine, Fundacion Universitaria Autonoma de las Americas, Pereira, Risaralda, Colombia School of Medicine, Universidad Privada Franz Tamayo (UNIFRANZ), Cochabamba, Bolivia)
Kuldeep Dhama (Division of Pathology, ICAR-Indian Veterinary Research Institute, Izatnagar, Uttar Pradesh, India)

Narra J
Vol. 1 No. 2 (2021): August 2021

Tuberculosis is an infectious disease caused by the Mycobacterium tuberculosis. It is a global health problem and major cause of death in resource-limited countries like Nepal. Timely diagnosis with sensitive testing methods could assist in early management of the disease. This study was conducted to compare the diagnostic performance of GeneXpert MTB/RIF and conventional acid-fast staining with M. tuberculosis culture. The study was carried out in the Department of Microbiology, Shree Birendra Army Hospital, Nepal. Samples (n=500) were tested with a GeneXpert MTB/RIF assay and acid-fast bacilli (AFB) smear microscopy. All samples were sent for M. tuberculosis conventional culture by the German-Nepal Tuberculosis Project, Kathmandu, Nepal (GENETUP). Out of a total 500 pulmonary and extrapulmonary samples tested, 97 samples were positive for M. tuberculosis by GeneXpert MTB/RIF assay. Out of the positive samples, only 95 samples were found positive by the culture method. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of AFB microscopy was 45.3%, 99.5%, 99.5% and 88.5%, respectively. The sensitivity, specificity, PPV and NPV of GeneXpert MTB/RIF was found to be 100%, 99.5%, 97.5% and 100%, respectively compared to the gold standard culture method. The GeneXpert MTB/RIF test was comparable with culture diagnosis of both pulmonary and extrapulmonary tuberculosis cases.