Prevalence and outcome of isoniazid-monoresistant tuberculosis at a university hospital in Saudi Arabia

OBJECTIVES: To determine the prevalence and outcome in patients with isoniazid-monoresistant Mycobacterium tuberculosis complex and compare them to those in patients with non-isoniazid-monoresistant Mycobacterium tuberculosis. METHODS: This cross-sectional analytical study was conducted at King Khalid University Hospital, Riyadh, Saudi Arabia. The data were retrospectively collected from the electronic medical records of patients who tested positive for Mycobacterium tuberculosis between May 2015 and April 2019. RESULTS: We identified 105 patients infected with Mycobacterium tuberculosis. The prevalence proportion of isoniazid-monoresistant tuberculosis was 8.6% (n=9). Five patients with isoniazid-monoresistant tuberculosis (55.6%) were successfully treated, while one patient died. In the nonresistant population, 51 (53.1%) patients were successfully treated. However, 12 (12.5%) patients with no isoniazid resistance had an unsuccessful treatment outcome. The resistant group had a longer treatment duration with a mean of 12 months compared to the non-isoniazid-resistant group, with a mean treatment duration of 9.5 months. Twenty-eight patients (26.7%) had adverse events, with the majority of them being in the non-isoniazid-resistant group. CONCLUSION: Isoniazid monoresistance is the most common form of drug resistance found in our population. Our study has not shown any significance in the outcome of isoniazid-resistant cases compared to non-isoniazid-resistant cases. This may be due to the low number of isoniazid-monoresistant cases in our population.