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| Year : 2020 | Volume
: 12
| Issue : 4 | Page : 235-236 |
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| Comparison of conventional versus molecular semi-quantitative assay in presumptive pulmonary tuberculosis cases: A study from eastern India |
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Geetarani Purohit1, Baijayantimala Mishra1, Prasanta Raghab Mohapatra2
1 Department of Microbiology, All India Institute of Medical Sciences, Bhubaneswar, Odisha, India
2 Department of Pulmonary Medicine and Critical Care, All India Institute of Medical Sciences, Bhubaneswar, Odisha, India
Click here for correspondence address and email
| Date of Submission | 13-Jun-2020 |
| Date of Acceptance | 21-Jun-2020 |
| Date of Web Publication | 30-Nov-2020 |
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How to cite this article:
Purohit G, Mishra B, Mohapatra PR. Comparison of conventional versus molecular semi-quantitative assay in presumptive pulmonary tuberculosis cases: A study from eastern India. J Global Infect Dis 2020;12:235-6 |
How to cite this URL:
Purohit G, Mishra B, Mohapatra PR. Comparison of conventional versus molecular semi-quantitative assay in presumptive pulmonary tuberculosis cases: A study from eastern India. J Global Infect Dis [serial online] 2020 [cited 2021 Jan 26];12:235-6. Available from: https://www.jgid.org/text.asp?2020/12/4/235/302009 |
Sir,
India is one of the high tuberculosis (TB) burden countries. According to WHO global TB report 2018, India accounts for one-fourth of the global TB burden with an estimated 2.79 million incident cases.[1] Measurements of bacillary load have an important role in TB diagnostics. Semi-quantitative or quantitative measures of Mycobacterium tuberculosis bacilli present in pulmonary samples have been useful for determining severity of the disease, assessing risk of transmission or monitoring treatment response.[2],[3]
The present study aimed at comparative analysis of two assays used for semi-quantitation of bacillary load in presumptive pulmonary TB cases: Conventional (smear microscopy i.e., Ziehl Neelsen staining) and molecular (Xpert MTB/RIF assay). From February to July 2018, a total of 288 sputum samples were processed for both the assays. The Xpert MTB/RIF grading of very low (28 < Ct< 38), low (22 < Ct<28), medium (16 < Ct≤ 22) and high (Ct≤ 16) were compared with acid-fast bacilli (AFB) smear grading of negative and scanty, ≤1+, ≥1 + and ≥ 2+ respectively.[4] Spearman correlation test was used to calculate correlation between the two grading methods. P < 0.05 was considered significant.
Out of 288 sputum samples, four (1.4%) found to be Nontuberculous Mycobacteria by culture and MPT64 antigen detection method were excluded from the analysis. Out of 284 samples, M. tuberculosis was detected in 72 (25.3%) by the Xpert MTB/RIF assay, of which 47 (65.3%) could be detected by AFB smear microscopy.
The result for comparison of the Xpert MTB/RIF grading and AFB smear grading is described in [Table 1]. | Table 1: Comparison of the Xpert MTB/RIF grading with acid-fast bacilli smear grading
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The Xpert MTB/RIF grading was found to have strong correlation with AFB smear grading (correlation coefficient 0.73, P < 0.001).
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
 References | |  |
| 1. | World Health Organization. Global Tuberculosis Report. Geneva, Switzerland: World Health Organization; 2018.  |
| 2. | Palaci M, Dietze R, Hadad DJ, Ribeiro FK, Peres RL, Vinhas SA, et al. Cavitary disease and quantitative sputum bacillary load in cases of pulmonary tuberculosis. J Clin Microbiol 2007;45:4064-6. |
| 3. | Perrin FM, Woodward N, Phillips PP, McHugh TD, Nunn AJ, Lipman MC, et al. Radiological cavitation, sputum mycobacterial load and treatment response in pulmonary tuberculosis. Int J Tuberc Lung Dis 2010;14:1596-602. |
| 4. | Blakemore R, Nabeta P, Davidow AL, Vadwai V, Tahirli R, Munsamy V, et al. A multisite assessment of the quantitative capabilities of the Xpert MTB/RIF assay. Am J Respir Crit Care Med 2011;184:1076-84. |
Correspondence Address:
Dr. Baijayantimala Mishra
Department of Microbiology, All India Institute of Medical Sciences, Bhubaneswar - 751 019, Odisha
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jgid.jgid_179_20
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