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Background <p>Rifampicin resistance has been assumed to be synonymous with multi-drug resistant tuberculosis (MDR-TB), but this approach could be exposing tuberculosis (TB) patients with rifampicin mono-resistance to unduly long and toxic treatment regimens. The current tuberculosis management algorithm in Nigeria recommends commencement of MDR-TB treatment on rifampicin resistance detection, based on GeneXpert results and subsequent phenotypic testing. With the current dearth of phenotypic drug susceptibility testing facilities in Nigeria, several rifampicin mono-resistant tuberculosis patients may be inappropriately placed on toxic second-line drugs used for MDR-TB treatment for prolonged periods before susceptibility results are available.</p> Methods <p>XpertMTB/Rif were performed on a total of 3,580 patient samples from 10 sites across Cross River State, Nigeria, as a prospective cross-sectional study. Rifampicin-resistant specimens were reprocessed and cultured on Lowenstein-Jensen medium. Indirect susceptibility testing following the microscopic observation drug susceptibility technique was performed using Rifampicin (1&#xa0;µg/ml), Isoniazid (0.4&#xa0;µg/ml), Fluoroquinolone (Ofloxacin-1.0&#xa0;µg), Capreomycin (2.5&#xa0;µg/ml), Amikacin (2&#xa0;µg/ml) and Kanamycin (5.0&#xa0;µg/ml).</p> Results <p><i>Mycobacterium tuberculosis</i> was detected in 21.3% (763) of the 3,580 presumptive tuberculosis cases recruited, of which 4.6% (35/763) were resistant to rifampicin. Culture yielded isolates from 89.6% (31/35) of these rifampicin resistant cases while susceptibility testing using first and second line antimicrobials, revealed 32.2% (10/31) and 64.5% (20/31) rifampicin mono-resistant and MDR-TB, respectively. When categorized into treatment groups, 25.7% (27/105) and 1.2% (8/658) of patients with rifampicin resistance belonged to retreatment and naïve patient groups respectively. There was no correlation between rifampicin mono-resistant and MDR-TB with gender (χ<sup>2</sup> = 0.793, <i>P</i> = 0.308) or HIV status (χ<sup>2</sup> = 0.416, <i>P</i> = 0.398). Patients who presented with first-line treatment failure were most likely to have MDR-TB (χ<sup>2</sup> = 9.121, <i>P</i> = 0.028).</p> Conclusion <p>Our finding that 32.2% of cases were rifampicin mono-resistant, underscores the critical need for phenotypic drug susceptibility testing. The MODS can fill in the gap created when there is a dearth of the more conventional (and costly) DST platforms in a resource-limited setting like Nigeria. More programmatic support and scale up of simpler susceptibility techniques are required in Nigeria and similar contexts.</p>

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Unmasking rifampicin mono-resistance in tuberculosis patients in Cross River State, Nigeria

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年9月4日

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  • Ernest Afu Ochang,
  • Ubong Aniefiok Udoh,
  • Akaninyene Asuquo Otu,
  • Atana Uket Ewa,
  • Chibuke Ibe,
  • David A. J. Moore

摘要

Background

Rifampicin resistance has been assumed to be synonymous with multi-drug resistant tuberculosis (MDR-TB), but this approach could be exposing tuberculosis (TB) patients with rifampicin mono-resistance to unduly long and toxic treatment regimens. The current tuberculosis management algorithm in Nigeria recommends commencement of MDR-TB treatment on rifampicin resistance detection, based on GeneXpert results and subsequent phenotypic testing. With the current dearth of phenotypic drug susceptibility testing facilities in Nigeria, several rifampicin mono-resistant tuberculosis patients may be inappropriately placed on toxic second-line drugs used for MDR-TB treatment for prolonged periods before susceptibility results are available.

Methods

XpertMTB/Rif were performed on a total of 3,580 patient samples from 10 sites across Cross River State, Nigeria, as a prospective cross-sectional study. Rifampicin-resistant specimens were reprocessed and cultured on Lowenstein-Jensen medium. Indirect susceptibility testing following the microscopic observation drug susceptibility technique was performed using Rifampicin (1 µg/ml), Isoniazid (0.4 µg/ml), Fluoroquinolone (Ofloxacin-1.0 µg), Capreomycin (2.5 µg/ml), Amikacin (2 µg/ml) and Kanamycin (5.0 µg/ml).

Results

Mycobacterium tuberculosis was detected in 21.3% (763) of the 3,580 presumptive tuberculosis cases recruited, of which 4.6% (35/763) were resistant to rifampicin. Culture yielded isolates from 89.6% (31/35) of these rifampicin resistant cases while susceptibility testing using first and second line antimicrobials, revealed 32.2% (10/31) and 64.5% (20/31) rifampicin mono-resistant and MDR-TB, respectively. When categorized into treatment groups, 25.7% (27/105) and 1.2% (8/658) of patients with rifampicin resistance belonged to retreatment and naïve patient groups respectively. There was no correlation between rifampicin mono-resistant and MDR-TB with gender (χ2 = 0.793, P = 0.308) or HIV status (χ2 = 0.416, P = 0.398). Patients who presented with first-line treatment failure were most likely to have MDR-TB (χ2 = 9.121, P = 0.028).

Conclusion

Our finding that 32.2% of cases were rifampicin mono-resistant, underscores the critical need for phenotypic drug susceptibility testing. The MODS can fill in the gap created when there is a dearth of the more conventional (and costly) DST platforms in a resource-limited setting like Nigeria. More programmatic support and scale up of simpler susceptibility techniques are required in Nigeria and similar contexts.