Original Research

Low-cost diagnostic test for susceptible and drug-resistant tuberculosis in rural Malawi

Annie Zhang, Enoch Jumbe, Robert Krysiak, Sabeen Sidiki, Holden V. Kelley, Elly K. Chemey, Chancy Kamba, Victor Mwapasa, Juan I. García, Alison Norris, Xueliang J. Pan, Carlton Evans, Shu-Hua Wang, Jesse J. Kwiek, Jordi B. Torrelles
African Journal of Laboratory Medicine | Vol 7, No 1 | a690 | DOI: https://doi.org/10.4102/ajlm.v7i1.690 | © 2018 Annie Zhang, Enoch Jumbe, Robert Krysiak, Sabeen Sidiki, Holden V Kelley, Elly K. Chemey, Chancy Kamba, Victor Mwapasa, Juan I. García, Alison Norris, Xueliang (Jeff) Pan, Carlton Evans, Shu-Hua Wang, Jesse Kwiek, Jordi B Torrelles | This work is licensed under CC Attribution 4.0
Submitted: 07 October 2017 | Published: 04 June 2018

About the author(s)

Annie Zhang, Department of Microbiology, College of Arts and Sciences, The Ohio State University, Columbus, Ohio, United States
Enoch Jumbe, Child Legacy International, Msundwe, Lilongwe, Malawi
Robert Krysiak, Department of Infectious Diseases, School of Medicine, University of North Carolina Project, Tidziwe Centre, Lilongwe, Malawi
Sabeen Sidiki, Department of Microbial Infection and Immunity, College of Medicine, The Ohio State University, Columbus, Ohio, United States
Holden V. Kelley, Department of Microbial Infection and Immunity, College of Medicine, The Ohio State University, Columbus, Ohio, United States
Elly K. Chemey, Child Legacy International, Msundwe, Lilongwe, Malawi
Chancy Kamba, District Tuberculosis Control Office, Ministry of Health, Lilongwe, Malawi
Victor Mwapasa, Department of Community Health, College of Medicine, Blantyre, Malawi
Juan I. García, Department of Pediatrics, Obstetrics, Gynecology and Preventive Medicine, Autonomous University of Barcelona, Barcelona, Spain
Alison Norris, College of Public Health, The Ohio State University, Columbus, Ohio, United States
Xueliang J. Pan, Center for Biostatistics, College of Medicine, The Ohio State University, Columbus, Ohio, United States
Carlton Evans, The Wellcome Centre for Clinical Tropical Medicine, Imperial College of London, London, United Kingdom; Department of Microbiology, Cayetano Heredia University, Lima, Peru
Shu-Hua Wang, Division of Infectious Diseases, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, Ohio, United States
Jesse J. Kwiek, Department of Microbiology, College of Arts and Sciences, The Ohio State University, Columbus, Ohio, United States
Jordi B. Torrelles, Department of Microbial Infection and Immunity, College of Medicine, The Ohio State University, Columbus, Ohio, United States


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Abstract

Background: Rural settings where molecular tuberculosis diagnostics are not currently available need easy-to-use tests that do not require additional processing or equipment. While acid-fast bacilli (AFB) smear is the most common and often only tuberculosis diagnosis test performed in rural settings, it is labour intensive, has less-than-ideal sensitivity, and cannot assess tuberculosis drug susceptibility patterns.

 

Objective: The objective of this study was to determine the feasibility of a multidrug-resistant (MDR) or extensively drug-resistant (XDR)-tuberculosis coloured agar-based culture test (tuberculosis CX-test), which can detect Mycobacterium tuberculosis growth and evaluate for drug susceptibility to isoniazid, rifampicin and a fluoroquinolone (i.e. ciprofloxacin) in approximately 14 days.

 

Method: In this study, 101 participants were enrolled who presented to a rural health clinic in central Malawi. They were suspected of having active pulmonary tuberculosis. Participants provided demographic and clinical data and submitted sputum samples for tuberculosis testing using the AFB smear and tuberculosis CX-test.

 

Results: The results showed a high level of concordance between the AFB smear (12 positive) and tuberculosis CX-test (13 positive); only one sample presented discordant results, with the molecular GeneXpert MTB/RIF® test confirming the tuberculosis CX-test results. The average time to a positive tuberculosis CX-test was 10 days. Of the positive samples, the tuberculosis CX-test detected no cases of drug resistance, which was later confirmed by the GeneXpert MTB/RIF®.

 

Conclusion: These findings demonstrate that the tuberculosis CX-test could be a reliable low-cost diagnostic method for active pulmonary tuberculosis in high tuberculosis burden rural areas.


Keywords

Tuberculosis; Mycobacterium tuberculosis;Diagnosis; Drug resistance

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