Prevalence and profile of isoniazid mono-resistant tuberculosis in Pakistan: Insights from a decade of surveillance.

BACKGROUND &

OBJECTIVE

Isoniazid monoresistance poses a growing concern in tuberculosis (TB) management, as it can compromise treatment outcomes and increase risk of multidrug-resistant TB. With limited data on its prevalence and characteristics in Pakistan, identifying its prevalence and factors associated is imperative. This study, therefore aimed to identify prevalence and resistance profile of isoniazid mono-resistance isolates and association of isoniazid mono-resistance with demographic, TB category and patient status.

METHODOLOGY: This retrospective study analyzed all Mycobacterium tuberculosis complex (MTBC) culture-positive samples received at the Indus Hospital & Health Network (IHHN) Microbiology Laboratory between 2015 to 2023. Samples with no growth or growth of organisms other than MTBC, were excluded. Data were analyzed using SPSS version 26.

RESULT: A total of 5,820 MTBC-positive cultures were evaluated. Among these, 140 (2.4%) were identified with isoniazid monoresistance. The prevalence fluctuated across the study period, with the highest rate observed in 2023 (3.5%). Most patients with isoniazid monoresistance had pulmonary TB (117; 83.6%) compared to extrapulmonary TB (23; 16.4%). The majority were newly enrolled cases (127; 90.7%). No statistically significant associations were found between isoniazid monoresistance and patient demographics or TB category.

CONCLUSION

The prevalence of isoniazid monoresistance remained relatively low but showed a rising trend, peaking in 2023. Most cases occurred in newly enrolled pulmonary TB patients. Continuous surveillance and early detection are essential to guide treatment strategies and prevent the emergence of multidrug resistance.