Primary bacillary resistance in multidrug-resistant tuberculosis and predictive factors associated with cure at a referral center in São Paulo, Brazil

Abstract

Objective: To identify transmitted or primary resistance among cases of multidrug-resistant tuberculosis and predictive factors for cure in multidrug-resistant tuberculosis after the first treatment. Method: Descriptive study of a cohort from 2006 to 2010, in a reference unit of tuberculosis in São Paulo, Brazil. The data were obtained by the revision of medical records. Clinical criteria were used to classify transmitted and acquired resistance. Extended primary resistance was also defined, in this study, as cases initially treated with a standardized scheme, but with no therapeutic success, and the pre-treatment drug susceptibility test (DST) showed presence of resistance. Results: 156 patients with multidrug-resistant tuberculosis and their respective sputum samples were eligible for the study. Only 7% of the patients were positive for the human immunodeficiency virus (HIV). Previous treatment occurred in 95% of the sample. The cure rate after the first treatment was 54%. The median bacteriological conversion time of those who healed was one month. Bacillary resistance was considered acquired resistance in 100 (64%) and transmitted resistance in 56 (36%). By logistic regression, patients who presented primary multidrug-resistant tuberculosis (odds ratio-OR = 6,29), without comorbidity (OR = 3,37) and with higher initial weight (OR = 1.04) were associated with cure after the first treatment. Conclusion: The early detection of bacillary resistance and appropriate treatment are in favor of healing. Thus, it is crucial to know exactly the primary resistance rate avoiding the use of inadequate treatments, amplification of bacillary resistance and its transmission.

Primary and acquired multidrug-resistant tuberculosis: Predictive factors for unfavorable treatment outcomes in Rio de Janeiro, 2000–2016

“…Regarding treatment outcome, the cases with primary MDR-TB had a higher therapeutic success rate than the cases with acquired resistance (69.7% and 53.3%, respectively). The superior performance of the primary resistance group was also observed in another study that showed 6.3-fold higher odds of cure ( 15 ). Higher socioeconomic status is associated with a nearly 3-fold increased risk of primary MDR-TB as compared with acquired resistance and, conversely, lower socioeconomic status is associated with increased risk of acquired MDR-TB ( 18 ).…”

“…With this same definition, a study conducted in São Paulo with 156 MDR-TB patients found 36% of primary resistance cases. Note that only 5% of patients reported not having undergone previous treatment for TB ( 15 ). Another study conducted in RJ showed that approximately 30% of XDR-TB cases had no previous treatment for multidrug resistance.…”

“…The characteristics of cases of the primary resistance group differ from those of the acquired resistance group. Probably, the former is likely to be composed of people who spend more time in contact with infected people, like in the household ( 15 ). More recently, epidemiology and genetics studies with MDR-TB patients in China identified 93 clusters, in which 69% of the cases had epidemiological links with people they knew.…”

Tuberculosis series 2019

“…In our tuberculosis series, the diagnosis of tuberculosis is addressed in four original articles. (5)(6)(7)(8) Since its introduction in 2010, the molecular test for Mycobacterium tuberculosis and its resistance to rifampin (Xpert MTB/RIF assay) is increasingly used as the initial diagnostic test for tuberculosis in many countries. (9,10) Two of the articles in our series addressed the use of the Xpert MTB/RIF assay.…”

“…(11) Improving the coverage and quality of diagnosis for individuals infected with drug-resistant tuberculosis is also relevant. In a cohort study conducted at a referral center for tuberculosis in the state of São Paulo, Brazil, between 2006 and 2010, (7) the authors found that early detection of infection with a drug-resistant strain of M. tuberculosis was associated with higher cure rates in patients without comorbidities and in patients with a higher body weight at the beginning of treatment (in comparison with the cure rates observed for those without comorbidities and for those with a lower body weight at the beginning of treatment). In another study conducted in the state of São Paulo, (8) the authors evaluated the diagnosis of multidrug-resistant tuberculosis (MDR-TB) using the GenoType MTBDRplus assay, version 2.0, which detects concomitant resistance to rifampin and isoniazid.…”