“Multidrug-resistant tuberculosis” may be nontuberculous mycobacteria

Abstract

Introduction Multidrug resistant tuberculosis (MDR-TB) presents a great challenge to public health, especially for developing countries. Some nontuberculous mycobacteria (NTM) cause the similar clinical and radiological characteristics with tuberculosis. We aimed to identify the frequency of NTM infections among subjects who were suspected to have MDR-TB due to lack of response to anti-TB treatment. Methods This retrospective study evaluated patients with suspected MDR-TB due to lack of sputum conversion after 2–3 months therapy with first line anti-TB treatment from 2009 through 2014. Cultures for mycobacteria were performed and identification was done to species level by phenotypic and molecular tests. The outcome of the patients with NTM disease and related risk factors for poor outcome were evaluated. Results Out of 117 consecutive strains isolated from suspected MDR-TB subjects, 35 (30%) strains were identified as NTM by using conventional and molecular approaches. Of these patients with positive NTM cultures, 32 (27%) patients met ATS/IDSA diagnostic criteria. Out of 32, 29 (90%) individuals with confirmed NTM diseases had underlying disorders including 8 subjects with malignancy, 5 with organ transplantations, and 4 with the human immunodeficiency virus. No known underlying disorder was found in 3 (9%) subjects. Treatment outcomes were available for 27 subjects, 17 (63%) of whom were cured and 10 (37%) had poor outcome including 6 (60%) who failed and 4 (40%) who died during treatment. Conclusion The high costs to the patient and society should lead health care providers to consider NTM in all patients suspected of having TB.

Gender susceptibility to mycobacterial infections in patients with non-CF bronchiectasis

“…Some studies suggest that the incidence of NTM is as high as 15.5 cases per 100,000 in persons over 50 years of age in the United States [2-4]. This increase has been attributed to improvements in investigative methodologies such as 16S rNA gene sequencing to detect the presence of mycobacteria and awareness of the importance of NTM species as human pathogens [5,6]. Several studies have attempted to define the phenotypic characteristics of patients with NTM.…”

Evaluation of a semi‐automated Seegene PCR workflow with MTB, MDR, and NTM detection for rapid screening of tuberculosis in a low‐prevalence setting

“…Indeed, clinical symptoms and radiological findings are considered a prerequisite for the diagnosis of NTM pulmonary disease (NTMPD) (2) As NTMPD and TB may be clinically indistinguishable but differ greatly in antimicrobial therapy, a significant added value of detecting NTM lies in the exclusion of TB (3,4). Several cases of MDR-TB misdiagnosis due to NTM infection have been described in areas where NTM are not routinely analyzed (5,6). In countries where they are routinely analyzed, NTM make up a significant share of all mycobacterial laboratory findings and rates are systematically increasing (7,8).…”

Leveraging Advances in Tuberculosis Diagnosis and Treatment to Address Nontuberculous Mycobacterial Disease

“…Studies conducted in Burkino Faso and Mali found that 18%–20% of patients suspected of having chronic TB were found to have NTM in their sputum ( 6 ). Similarly, a study in Iran showed that as many as 30% of suspected cases of multidrug-resistant TB were in fact NTMs, further suggesting the generalization of this phenomenon ( 7 ). Understanding the true prevalence of NTMs in the developing world is especially valuable considering that evidence suggests that NTM infection may interfere with the Bacille Calmette-Guérin vaccine, a widely used tool in preventing TB infections in the developing world ( 8 ).…”