Epidemiology of Nontuberculous Mycobacteria in Tuberculosis suspects, Southwest of China, 2017-2022

Subspecies distribution and drug-resistance characteristics of Mycobacterium abscessus complex clinical isolates in South China

Mycobacterium abscessus complex (MABC) is the most common rapidly growing non-tuberculous mycobacterium (NTM) and a significant pathogen responsible for various infections. Subspecies of MABC exhibit differing levels of antibiotic resistance, potentially influencing patient prognosis. In this study, 196 MABC clinical isolates were collected from Guangzhou Chest Hospital and subjected to a drug sensitivity test (DST) followed by whole-genome sequencing. In our study, the most common subspecies was Mycobacterium abscessus subsp. abscessus, followed by M. abscessus subsp. massiliense, with M. abscessus subsp. bolletii being the least frequent. The isolates were most susceptible to tigecycline and amikacin, followed by clarithromycin and linezolid. Bedaquiline and clofazimine showed promising anti-bacterial activity, whereas doramapimod and capreomycin demonstrated limited efficacy. The erm(41) gene mutation at position 28 and the rrl gene at position 2270 were identified in clarithromycin-resistant isolates. Additionally, the rrs gene mutation at position 1375 may serve as an indicator of amikacin resistance. Regular molecular surveillance investigation of NTM and DST is recommended for improved management.IMPORTANCEAs Guangdong is a region with a high prevalence of NTM, this study investigates the epidemiological trends of MABC subspecies and their associated drug-resistance profiles, addressing a critical research gap. The findings are crucial for guiding hospital drug management and clinical decision making, enabling more accurate diagnoses and the formulation of personalized, effective treatment plans. Additionally, this study provides a valuable reference for the development of drug-resistance detection reagents and new anti-bacterial agents.

Clinical features of Talaromyces marneffei infection and colonization in HIV-negative patients: the role of mNGS in diagnosis

Background

Talaromycosis, caused by Talaromyces marneffei (T. marneffei), has become more common in HIV-negative and immunocompetent patients. The fungus colonizes the body through dormant spores, causing opportunistic infections. Early diagnosis is challenging. This study aims to analyze the clinical features, diagnosis, treatment, and prognosis of T. marneffei infections.

Methods

Patients diagnosed with T. marneffei infection or colonization at the People's Hospital of Ningbo University between August 2022 and July 2024 were included. Demographic characteristics, clinical data, diagnostic approaches, and treatment outcomes were analyzed.

Results

Seven patients were diagnosed with T. marneffei infection, and three with colonization. Productive cough and fever were the predominant symptoms in all patients. Nodules, cavitary lesions, and pleural effusions on chest imaging were observed exclusively in infected patients. The positivity rates for metagenomic next-generation sequencing (mNGS) and conventional microbiological testing were 100 and 10%, respectively. Of the seven infected patients, three had a single infection with T. marneffei, and four had co-infection with T. marneffei and Mycobacterium avium complex. All patients were treated with monotherapy or combination therapy using voriconazole. All but one recovered.

Conclusion

Early diagnosis and combination therapy are critical for T. marneffei infection. mNGS complements traditional methods, facilitating accurate diagnosis and guiding targeted treatment.

The effects of cyclic peptide [R4W4] in combination with first-line therapy on the survival of Mycobacterium avium

Background

Mycobacterium avium (M. avium) is a nontuberculous mycobacterium (NTM) that can cause pulmonary and extrapulmonary infections mostly in immunocompromised individuals, such as those with HIV and diabetes. Traditionally, rifampicin (RIF) and azithromycin (AZ) have been used for a 12-month duration as first-line antibiotics against M. avium. Due to the increased multidrug resistance, novel ways, such as enhancement of macrophages response, are needed to provide adequate immune response required to clear M. avium infection.

Methods and findings

In this study, we aim to study the effects of using THP-1 cells, which are monocyte-like cells, to induce a macrophage response and control M. avium infection when used in combination with traditional treatments such as RIF and AZ in free and liposomal forms. Traditional treatments' effects are studied when used alone and in combination therapy with cyclic peptide [R4W4] (liposomal encapsulated and liposomal combination). Colony-forming units (CFU) counts were assessed for all samples 3 hours, 4 days, and 8 days post-treatment. A significant reduction in the intracellular viability of M. avium was observed when THP-1 cells were treated with liposomal combination [R4W4]+RIF and liposomal combination [R4W4]+AZ compared to when treated with liposomal RIF or liposomal AZ alone, respectively.

Conclusion

Our findings show that liposomal combination [R4W4] is a promising adjuvant therapy to increase M. avium susceptibility to known antibiotics.

Analysis of non-tuberculous mycobacteria types in high tuberculosis endemic areas

BACKGROUND

The incidence of non-tuberculous mycobacteria (NTM) has been rising globally, posing significant challenges for diagnosis and treatment, particularly in regions with high tuberculosis (TB) incidence. This study aims to investigate the epidemiological, demographic, and clinical characteristics of non-tuberculous mycobacterial lung disease (NTM-PD) in areas with a high incidence of TB.

METHOD

This study was conducted at the Affiliated Hospital of Zunyi Medical University from January 2017 to December 2021. A total of 6259 culture-positive specimens were analyzed. Screening was based on acid-fast staining, colony morphology, and p-nitrobenzoic acid detection, which identified 107 suspected NTM strains. Gene sequencing confirmed 51 NTM-positive cases.

RESULTS

The predominant species identified were Mycobacterium abscessus (33.33%) and Mycobacterium intracellulare (27.45%). Several risk factors were associated with higher susceptibility to NTM-PD suspect, including bronchiectasis, low serum albumin levels (< 3.5 g/L), and male gender. The study found that although the isolation rate of NTM remained stable over the five-year period, drug resistance rates for the dominant species were notably high.

CONCLUSIONS

The findings highlight the need for clinicians in TB-endemic areas to carefully distinguish NTM infections from TB. The stable isolation rates of NTM, coupled with the high drug resistance of key species, underscore the importance of accurate diagnosis and tailored treatment strategies to manage NTM-PD effectively.

Analytical and clinical validation of a novel MeltPlus TB-NTM/RIF platform for simultaneous detection of Mycobacterium tuberculosis complex, Non-Tuberculous Mycobacteria and rifampicin resistance

Background

Rapid and accurate diagnosis of tuberculosis, particularly rifampin (RIF)-resistant tuberculosis (RR-TB) and Non-Tuberculous Mycobacteria (NTM), is essential for implementing appropriate proper therapy to benefit patients and improve TB/NTM patient management.

Methods

In this study, we developed a novel MeltPlus MTB-NTM/RIF platform, designed to simultaneously detect Mycobacterium tuberculosis complex (MTBC), NTM and RIF resistance. The platform was evaluated for its limit of detection (LOD) and specificity before clinical validation, followed by a prospective single-center study in patients with presumptive TB cases.

Results

The calculated LOD for MTBC, NTM and RIF susceptibility was found to be 10.31 CFU/mL, 57.55 CFU/mL and 48.584 CFU/mL, respectively. The assay showed a sensitivity of 98.76% (95% CI: 96.41-99.74%) and a specificity of 94.42% (95% CI: 90.82-96.92%) for MTBC detection compared to the bacteriological TB standard. For NTM detection, the assay demonstrated a sensitivity of 91.98% (95% CI: 76.32-98.14%) and a specificity of 99.59% (95% CI: 98.54-99.95%). RIF resistance detection showed a sensitivity of 90.24% (95% CI:76.87-97.28%) and specificity of 95.98% (95% CI: 91.89-98.37%), with a high level of diagnostic agreement (Kappa: 0.8338) compared to GeneXpert. Sanger sequencing revealed that novel assay correctly classifies 98.6% of study cases as RIF resistant or susceptible, slightly higher that of GeneXpert.

Discussion

These findings indicate that the novel MeltPlus MTB-NTM/RIF platform provides a rapid and accurate method for the simultaneously detecting MTBC, NTM, and RIF resistance, making it a promising tool for clinical TB/NTM diagnosis and management, further multi-center and field studies are recommended to validate its broader applicability.

Clinical Characteristics, Species Distribution, and Drug Resistance of Non-Tuberculous Mycobacteria Lung Disease in Qingdao, China

Objective

To analyze the clinical characteristics, species distribution and drug resistance of patients with non-tuberculous mycobacteria (NTM) lung disease in Qingdao, China.

Methods

Clinical data of patients with NTM lung disease and pulmonary tuberculosis (TB) treated at Qingdao Chest Hospital from July 2021 to July 2023 were retrospectively analyzed.

Results

The prevalence of NTM lung disease was 8.03%, with a high rate of drug resistance during the study period. Patients with NTM lung disease had higher rates of older age, bronchiectasis, malignancy, HIV infection and bronchial dilatation shadow and lower rates of hollow shadow compared to patients with pulmonary TB.

Conclusion

Comprehensive understanding of NTM lung disease, improved laboratory testing techniques and appropriate treatment regimens are essential for the management of NTM lung disease.

Southern African HIV Clinicians Society guideline on the management of non-tuberculous mycobacteria in people with HIV

No Abstract required

Non-tuberculous mycobacteria enhance the tryptophan-kynurenine pathway to induce immunosuppression and facilitate pulmonary colonization

The increasing prevalence of non-tuberculous mycobacterium (NTM) infections alongside tuberculosis (TB) underscores a pressing public health challenge. Yet, the mechanisms governing their infection within the lung remain poorly understood. Here, we integrate metagenomic sequencing, metabolomic sequencing, machine learning classifiers, SparCC, and MetOrigin methods to profile bronchoalveolar lavage fluid (BALF) samples from NTM/TB patients. Our aim is to unravel the intricate interplay between lung microbial communities and NTM/Mycobacterium tuberculosis infections. Our investigation reveals a discernible reduction in the compositional diversity of the lung microbiota and a diminished degree of mutual interaction concomitant with NTM/TB infections. Notably, NTM patients exhibit a distinct microbial community characterized by marked specialization and notable enrichment of Pseudomonas aeruginosa and Staphylococcus aureus, driving pronounced niche specialization for NTM infection. Simultaneously, these microbial shifts significantly disrupt tryptophan metabolism in NTM infection, leading to an elevation of kynurenine. Mycobacterium intracellulare, Mycobacterium paraintracellulare, Mycobacterium abscessus, and Pseudomonas aeruginosa have been implicated in the metabolic pathways associated with the conversion of indole to tryptophan via tryptophan synthase within NTM patients. Additionally, indoleamine-2,3-dioxygenase converts tryptophan into kynurenine, fostering an immunosuppressive milieu during NTM infection. This strategic modulation supports microbial persistence, enabling evasion from immune surveillance and perpetuating a protracted state of NTM infection. The elucidation of these nuanced microbial and metabolic dynamics provides a profound understanding of the intricate processes underlying NTM and TB infections, offering potential avenues for therapeutic intervention and management.

Analysis of Clinical Isolation Characteristics of Nontuberculous Mycobacteria and Drug Sensitivity of Rapidly Growing Mycobacteria in the General Hospital of Guangzhou, China

Purpose

The clinical distribution characteristics of nontuberculous mycobacteria (NTM) in general hospital were explored to guide the clinical diagnosis and treatment of NTM infection.

Methods

Samples with positive mycobacterium culture in the First Affiliated Hospital of Guangzhou Medical University were collected and identified through PCR. Phenotypic drug sensitivity experiments were conducted on 44 Mycobacteroides abscessus isolated from clinical departments with broth microdilution method, and rrl, rrs and erm (41) genes associated with drug resistance were detected.

Results

From September 2020 to July 2023, 314 mycobacterium-positive isolates were separated from patients in the First Affiliated Hospital of Guangzhou Medical University, with 147 (46.8%) NTM isolates were included in our study. The samples were respiratory tract specimens mainly, with 64% bronchoalveolar lavage fluid. Of 144 cases identified, samples were from 133 patients (60 males and 73 females; gender ratio of 0.82:1). NTM was mainly isolated from the people aged 40 and above, especially females (χ2 = 10.688, P = 0.014). M. abscessus (61, 42.36%), M. intracellulare (35, 24.31%) were the two most NTMs in this hospital. Clinical strains of M. abscessus exhibited high resistance to antibiotics, except for cefoxitin (31.8%), linezolid (25.0%), amikacin (0%), and clarithromycin (18.2%). Among 8 strains of M. abscessus with clarithromycin acquired resistance, just 4 strains (50.0%) showed mutations (A2270G, A2271G) in rrl gene, but a new mutation (C2750T) was detected in 1 strain. Among 14 strains of M. abscessus with clarithromycin-induced resistance, 13 (93.0%) strains had T28 erm (41) gene and 1 (7.0%) strain had C28 erm (41) gene.

Conclusion

M. avium-intracellulare complex was gradually becoming predominant strain in Guangzhou area. The resistant situation of M. abscessus in general hospital had shown severe. Potential mutation in rrl gene associated with clarithromycin acquired resistance of M. abscessus were found, but drug-resistant mechanism remained unclear.

Screening, epidemic trends and drug sensitivity analysis of nontuberculous mycobacteria in a local area of China

OBJECTIVE

To analyze the isolation rate, prevalence trends, species distribution, and drug sensitivity of non-tuberculous mycobacteria (NTM) in Anhui Province, providing a reference for diagnosis and treatment strategies.

METHODS

Specimens from suspected mycobacterial infection patients at Anhui Chest Hospital (including outpatients and inpatients) from January 2021 to December 2023 were cultured. Identified NTM strains were analyzed for species distribution and drug sensitivity.

RESULTS

Of 10,519 mycobacteria strains cultured, 1,589 were NTM (15.11%). The top four species were Mycobacterium intracellulare (75.36%), Mycobacterium abscessus (11.78%), Mycobacterium kansasii (7.09%), and Mycobacterium avium (2.85%). NTM strains showed high sensitivity to amikacin and clarithromycin (≥90%) and significant sensitivity to rifabutin, moxifloxacin, and rifampicin (89.03%-79.61%). They exhibited high resistance to imipenem/cilastatin, sulfamethoxazole, minocycline, and doxycycline (≥95%).

CONCLUSION

NTM isolation rates in Anhui have remained stable, with the predominant species being M. intracellulare, M. kansasii, M. abscessus, and M. avium. NTM strains are highly sensitive to amikacin, clarithromycin, rifabutin, moxifloxacin, and rifampicin. These findings can guide diagnosis, treatment strategies, and drug selection for NTM disease in Anhui Province.

Identification of Mycobacterium tuberculosis Resistance to Common Antibiotics: An Overview of Current Methods and Techniques

Multidrug-resistant tuberculosis (MDR-TB) is an essential cause of tuberculosis treatment failure and death of tuberculosis patients. The rapid and reliable profiling of Mycobacterium tuberculosis (MTB) drug resistance in the early stage is a critical research area for public health. Then, most traditional approaches for detecting MTB are time-consuming and costly, leading to the inappropriate therapeutic schedule resting on the ambiguous information of MTB drug resistance, increasing patient economic burden, morbidity, and mortality. Therefore, novel diagnosis methods are frequently required to meet the emerging challenges of MTB drug resistance distinguish. Considering the difficulty in treating MDR-TB, it is urgently required for the development of rapid and accurate methods in the identification of drug resistance profiles of MTB in clinical diagnosis. This review discussed recent advances in MTB drug resistance detection, focusing on developing emerging approaches and their applications in tangled clinical situations. In particular, a brief overview of antibiotic resistance to MTB was present, referred to as intrinsic bacterial resistance, consisting of cell wall barriers and efflux pumping action and acquired resistance caused by genetic mutations. Then, different drug susceptibility test (DST) methods were described, including phenotype DST, genotype DST and novel DST methods. The phenotype DST includes nitrate reductase assay, RocheTM solid ratio method, and liquid culture method and genotype DST includes fluorescent PCR, GeneXpert, PCR reverse dot hybridization, ddPCR, next-generation sequencing and gene chips. Then, novel DST methods were described, including metabolism testing, cell-free DNA probe, CRISPR assay, and spectral analysis technique. The limitations, challenges, and perspectives of different techniques for drug resistance are also discussed. These methods significantly improve the detection sensitivity and accuracy of multidrug-resistant tuberculosis (MRT) and can effectively curb the incidence of drug-resistant tuberculosis and accelerate the process of tuberculosis eradication.