Accuracy of genotype MTBDRplus line probe assay in patients with tuberculous pleural effusion: comparison with clinical and culture based diagnosis

Abstract

Background: Pleural tuberculosis (TB) diagnosis is challenging due to paucibacillary disease. Diagnostic accuracy of GenoType MTBDRplus Line Probe Assay (MTBDRplus) has been evaluated in this study for pleural TB diagnosis.

Objective: To evaluate diagnostic accuracy of MTBDRplus for pleural TB diagnosis compared to clinical and microbiological diagnosis.

Methods: This prospective study was conducted at the Aga Khan University, Pakistan. Pleural fluid from 203 suspected pleural TB patients was collected and tested for smear, culture and MTBDRplus. Diagnostic accuracy of MTBDRplus was determined using clinical diagnosis and culture as the gold standard.

Results: Out of 203 TB suspect patients, MTBDRplus, culture and smear were positive in 14 (6. 9%), 27 (13.3%) and 4 (1.9%) cases, respectively. A total of 106/203 patients (27 culture positive and 79 culture negative) successfully completed TB treatment. Considering clinical diagnosis as gold standard, sensitivity of MTBDRplus was 13.2%; 95% CI (7.4–21.2%) and specificity was 100%; 95% CI (96.1–100%). The sensitivity and specificity of MTBDRplus in culture positive samples were 44.4%; 95% CI (25.5–64.7%) and 98.9%; 95% CI (95.9–99.9%), respectively. Excluding indeterminate results, MTBDRplus accurately detected isoniazid sensitivity in 5/6 and rifampicin sensitivity in 6/6 cases.

Conclusion: MTBDRplus had a low sensitivity of 13.2% in clinically diagnosed and 44% in culture-confirmed pleural TB patients and therefore could not be included in most diagnostic algorithms. Due to a higher sensitivity than smear, MTBDRplus may have a role in tuberculous pleural effusion diagnosis if it is positive pending culture results and pleural biopsy.

Keywords:

• Diagnosis
• line probe assay
• nucleic acid amplification
• pleural effusion
• tuberculosis

Acknowledgements

The authors acknowledge the hard work of their research associate Dr Hira Shahzad in data and sample collection.

This study has presented as poster in European Respiratory Society Annual Congress 2017, Milan –Italy and published as abstract in European Respiratory Journal supplement. (Irfan M, Jabeen K, Butt S, Zubairi ABS, Awan S, Hasan R. Sensitivity and specificity of Genotype MTBDRplus line probe assay in rapid diagnosis of tuberculous pleural effusion. Eur Respir J. 2017;50(Suppl. 61):PA2699. DOI:10.1183/1393003).

Initial preliminary data of 22 patients was presented in 1st Asian African congress of Mycobacteriology 2015, Iran and published as abstract in International Journal of Mycobacteriology. (Irfan M, Jabeen K, Ali HS, Zubairi AB, Hasnan R. Evaluation of sensitivity and specificity of GenoType MTBDRplus line probe assay in rapid diagnosis of tuberculous pleural effusion. Int J Mycobacteriol. 2015;4(1):111. DOI:10.1016/j.ijmyco.2014.11.003).

Disclosure statement

The authors report no conflict of interest.

Additional information

Funding

This study was funded by University Research Council (URC) grant of Aga Khan University, Karachi, Pakistan [131007MED]. The funding source had no role in study design, collection, data analysis and interpretation, in manuscript writing and in the decision to submit the article for publication.