Laboratory tests and analysis of drug resistance in non-tuberculous mycobacteria.

Background: This study analyzed the laboratory diagnosis results and drug resistance of patients infected with non-tuberculous mycobacterium (NTM). Methods: We collected information on patients with positive indicators of NTM infection at the Henan Provincial Chest Hospital from 2020 to 2022. Acid-fast smear, mycobacterium culture, QB-SPOT assay, GeneXpert MTB/RIF assay, immunoglobulin E test, tuberculosis antibody test, and microplate method for drug sensitivity test were analyzed using strain identification as the gold standard. Results: The 242 cases of NTM infection were predominantly detected with slow-growing mycobacteria (a detection rate of 87.19%), among which Mycobacterium intracellulare (66.53%), Mycobacterium avium (15.70%), and Mycobacterium chelonei/abscessus complex (11.16%) ranked the top three in terms of the isolation rate. Males patients accounted for a higher proportion (58.26%) than females (41.74%), and the majority of them were over 60 years (50.83%). Among laboratory tests for patients with NTM infection, mycobacterium culture showed a highest detected rate (87.20%) among laboratory tests. The results of the drug sensitivity test demonstrated that the resistance rate of NTM was generally high. Moreover, the Mycobacterium avium complex with the highest isolation rate showed 100% resistant to doxycycline and minocycline, but exhibited relatively high sensitivity to moxifloxacin (a resistance rate of 7.89%) and rifabutin (a resistance rate of 13.16%). The Mycobacterium chelonei/abscessus complex was 100% resistant to doxycycline and relatively sensitive to cefoxitin (29.17%) and clarithromycin (37.50%). Conclusion: The NTM species isolated by the Henan Provincial Chest Hospital is dominated by Mycobacterium intracellulare and the highest positive rate is detected by mycobacterium culture among laboratory tests. NTM infection generally exhibits a high rate of drug resistance. Accordingly, the accurate diagnosis of NTM diseases requires enhanced drug sensitivity testing to provide patients with targeted combination drug treatment.

Radiological and functional evidence of the bronchial spread of tuberculosis: an observational analysis.

BACKGROUND: Direct bronchial spread of tuberculosis was extensively described in pre-antibiotic human pathology literature but this description has been overlooked in the post-antibiotic era, in which most pathology data come from animal models that emphasise the granuloma. Modern techniques, such as [18F]2-fluoro-2-deoxy-D-glucose (FDG) PET-CT scans, might provide further insight. Our aim was to understand normal early tuberculosis resolution patterns on pulmonary PET-CT scans in treated patients with tuberculosis who were subsequently cured. METHODS: In this observational analysis, we analysed data from PredictTB, an ongoing, prospective, randomised clinical trial that examined sequential baseline and week 4 FDG-PET-CT scans from participants successfully treated (sputum culture negative 18 months after enrolment) for drug-susceptible pulmonary tuberculosis in South Africa and China. Participants who were aged 18-75 years, GeneXpert MTB/RIF positive for tuberculosis and negative for rifampicin resistance, had not yet started tuberculosis treatment, had not been treated for active tuberculosis within the previous 3 years, and met basic safety laboratory criteria were included and participants with diabetes, HIV infection, or with extrapulmonary tuberculosis including pleural tuberculosis were excluded. Scans were assessed by two readers for the location of tuberculosis lesions (eg, cavities and consolidations), bronchial thickening patterns, and changes from baseline to week 4 of treatment. FINDINGS: Among the first 124 participants (enrolled from June 22, 2017, to Sept 27, 2018) who were successfully treated, 161 primarily apical cavitary lesions were identified at baseline. Bronchial thickening and inflammation linking non-cavitary consolidative lesions to cavities were observed in 121 (98%) of 124 participants' baseline PET-CT scans. After 4 weeks of treatment, 21 (17%) of 124 participants had new or expanding lesions linked to cavities via bronchial inflammation that were not present at baseline, particularly participants with two or more cavities at baseline and participants from South Africa. INTERPRETATION: In participants with pulmonary tuberculosis who were subsequently cured, the location of cavitary and non-cavitary lesions at baseline and new lesions at week 4 of treatment suggest a cavitary origin of disease and bronchial spread through the lungs. Bronchial spread from cavities might play a larger role in the spread of pulmonary tuberculosis than has been appreciated. Elucidating cavity lesion dynamics and Mycobacterium tuberculosis viability within cavities might better explain treatment outcomes and why some patients are cured and others relapse. FUNDING: Bill & Melinda Gates Foundation, European and Developing Countries Clinical Trials Partnership, China Ministry of Science and Technology, National Natural Science Foundation of China, and National Institutes of Health. TRANSLATIONS: For the Chinese, Afrikaans and Xhosa translations of the abstract see Supplementary Materials section.

The within-host population dynamics of Mycobacterium tuberculosis vary with treatment efficacy.

BACKGROUND: Combination therapy is one of the most effective tools for limiting the emergence of drug resistance in pathogens. Despite the widespread adoption of combination therapy across diseases, drug resistance rates continue to rise, leading to failing treatment regimens. The mechanisms underlying treatment failure are well studied, but the processes governing successful combination therapy are poorly understood. We address this question by studying the population dynamics of Mycobacterium tuberculosis within tuberculosis patients undergoing treatment with different combinations of antibiotics. RESULTS: By combining very deep whole genome sequencing (~1000-fold genome-wide coverage) with sequential sputum sampling, we were able to detect transient genetic diversity driven by the apparently continuous turnover of minor alleles, which could serve as the source of drug-resistant bacteria. However, we report that treatment efficacy has a clear impact on the population dynamics: sufficient drug pressure bears a clear signature of purifying selection leading to apparent genetic stability. In contrast, M. tuberculosis populations subject to less drug pressure show markedly different dynamics, including cases of acquisition of additional drug resistance. CONCLUSIONS: Our findings show that for a pathogen like M. tuberculosis, which is well adapted to the human host, purifying selection constrains the evolutionary trajectory to resistance in effectively treated individuals. Nonetheless, we also report a continuous turnover of minor variants, which could give rise to the emergence of drug resistance in cases of drug pressure weakening. Monitoring bacterial population dynamics could therefore provide an informative metric for assessing the efficacy of novel drug combinations.