Abstract
BackgroundIsoniazid mono-resistance (IMR) is the most common form of mono-resistance; its world prevalence is estimated to range between 0.0 to 9.5% globally. There is no consensus on how these patients should be treated.ObjectiveTo describe the impact of IMR tuberculosis (TB) on treatment outcome and survival among pulmonary TB patients treated under programmatic conditions in Orizaba, Veracruz, Mexico.Materials and MethodsWe conducted a prospective cohort study of pulmonary TB patients in Southern Mexico. From 1995 to 2010 patients with acid-fast bacilli or culture proven Mycobacterium tuberculosis in sputum samples underwent epidemiological, clinical and microbiological evaluation. We included patients who harbored isoniazid mono-resistant (IMR) strains and patients with strains susceptible to isoniazid, rifampicin, ethambutol and streptomycin. All patients were treated following Mexican TB Program guidelines. We performed annual follow-up to ascertain treatment outcome, recurrence, relapse and mortality.ResultsBetween 1995 and 2010 1,243 patients with pulmonary TB were recruited; 902/1,243 (72.57%) had drug susceptibility testing; 716 (79.38%) harbored pan-susceptible and 88 (9.75%) IMR strains. Having any contact with a person with TB (adjusted odds ratio (aOR)) 1.85, 95% Confidence interval (CI) 1.15–2.96) and homelessness (adjusted odds ratio (aOR) 2.76, 95% CI 1.08–6.99) were associated with IMR. IMR patients had a higher probability of failure (adjusted hazard ratio (HR) 12.35, 95% CI 3.38–45.15) and death due to TB among HIV negative patients (aHR 3.30. 95% CI 1.00–10.84). All the models were adjusted for socio-demographic and clinical variables.ConclusionsThe results from our study provide evidence that the standardized treatment schedule with first line drugs in new and previously treated cases with pulmonary TB and IMR produces a high frequency of treatment failure and death due to tuberculosis. We recommend re-evaluating the optimal schedule for patients harboring IMR. It is necessary to strengthen scientific research for the evaluation of alternative treatment schedules in similar settings.
Highlights
Tuberculosis (TB) is one of the most important infectious diseases worldwide
Having any contact with a person with TB (adjusted odds ratio) 1.85, 95% Confidence interval (CI) 1.15–2.96) and homelessness (adjusted odds ratio 2.76, 95% CI 1.08–6.99) were associated with Isoniazid mono-resistance (IMR)
IMR patients had a higher probability of failure (adjusted hazard ratio (HR) 12.35, 95% CI 3.38–45.15) and death due to TB among HIV negative patients
Summary
The World Health Organization (WHO) estimated that during 2015 there were 10.4 million new cases, with a mortality of 1.4 million people;[1] Perhaps one of the most significant factors that impact on control is resistance to first and second line antimicrobials. The resistance among all tuberculosis cases to any drug has ranged from 0% to 70.4%, to isoniazid from 0% to 60.3% and to rifampicin 0% to 44.4%.[2] Isoniazid Mono-Resistance (IMR) is the most common form of mono resistance, and its world prevalence is estimated to range between 0.0 to 9.5% globally (0.0 to 12.8% among new cases and 0.0 to 30.8% among retreated cases).[2]. Isoniazid mono-resistance (IMR) is the most common form of mono-resistance; its world prevalence is estimated to range between 0.0 to 9.5% globally. There is no consensus on how these patients should be treated.
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