Bulletin of the National Research Centre (Feb 2023)

Can resistance to either isoniazid or rifampicin predict multidrug resistance tuberculosis (MDR-TB)

  • Betty R. Mchaki,
  • Fauster X. Mgaya,
  • Peter P. Kunambi,
  • Mecky I. Matee

DOI
https://doi.org/10.1186/s42269-023-01001-4
Journal volume & issue
Vol. 47, no. 1
pp. 1 – 7

Abstract

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Abstract Background Previous studies have shown significant differences and lack clarity on whether resistance to either isoniazid or rifampicin can predict multidrug resistance tuberculosis (MDR-TB). Some consider rifampicin resistance to be a surrogate for MDR-TB. We, therefore, conducted this study to determine resistance to either isoniazid or rifampicin can predict MDR-TB. Results A total of 315 Mycobacteria tuberculosis isolates were tested for resistance against isoniazid, rifampicin, ethambutol and streptomycin using the phenotypic proportion method on Lowenstein–Jensen media. Results showed most isolates (88.9%, 280/315) were not resistant to any anti-TB tested, 5.7% (18/315) were resistant to both isoniazid and rifampicin, 2.5% (8/315) were resistant to rifampicin only and 1.3% (4/315) were resistant to all four first-line anti-tuberculosis. Prediction of MDR TB basing on rifampicin results showed sensitivity of 100.0%, specificity of 96.3%, diagnostic accuracy of 96.5%, and positive and negative predictive values of 62.1% and 100.0%, respectively. Isoniazid had sensitivity of 100.0%, specificity of 98.3%, diagnostic accuracy of 98.4%, and positive and negative predictive values of 78.3% and 100.0%, respectively. Prediction of rifampicin resistance based on isoniazid results had sensitivity of 62.1%, specificity of 98.3%, diagnostic accuracy of 94.9%, a positive predictive value of 78.3% and a negative predictive value of 96.2%. Conclusions Resistance to either rifampicin or isoniazid sub-optimally predicts MDR-TB. Despite having high sensitivity and specificity, the positive predictive value of rifampicin was only 62.1% and for isoniazid was 78.3%, suggesting that if either is tested in isolation both could result in false positives MDR-TB cases, resulting into patients being unnecessarily subjected to the more toxic and expensive second-line anti-TB drugs, which are less effective compared to first-line anti-TB drugs.

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