Epidemiology of Nontuberculous Mycobacteria in Nanjing and MAB_0540 Mutations Associated with Clofazimine Resistance in Mycobacterium abscessus

TBAJ-587, a novel diarylquinoline, is active against Mycobacterium abscessus

Nontuberculous mycobacteria (NTM) infections are extremely difficult to treat due to a natural resistance to many antimicrobials. TBAJ-587 is a novel diarylquinoline, which shows higher anti-tuberculosis activity, lower lipophilicity, and weaker inhibition of hERG channels than bedaquiline (BDQ). The susceptibilities of 11 NTM reference strains and 194 clinical Mycobacterium abscessus isolates to TBAJ-587 were determined by the broth microdilution assay. The activity of TBAJ-587 toward the growth of M. abscessus in macrophages was also evaluated. Minimum bactericidal concentration and time-kill kinetic assays were conducted to distinguish between the bactericidal and bacteriostatic activities of TBAJ-587. The synergy between TBAJ-587 and eight clinically important antibiotics was determined using a checkerboard assay. TBAJ-587 was highly effective against M. abscessus by targeting its F-ATP synthase c chain. The antimicrobial activities of TBAJ-587 and BDQ toward intracellular M. abscessus were comparable. The in vivo activities of TBAJ-587 and BDQ in an immunocompromised mouse model were also comparable. TBAJ-587 expressed bactericidal activity and was compatible with eight anti-NTM drugs commonly used in clinical practice; no antagonism was discovered. As such, TBAJ-587 represents a potential candidate for the treatment of NTM infections.

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.

Employing Multicolor Melting Curve Analysis to Rapidly Identify Non-Tuberculous Mycobacteria in Patients with Bronchiectasis: A Study from a Pulmonary Hospital in the Fuzhou District of China, 2018-2022

Non-tuberculous mycobacteria (NTM) infection is common in bronchiectasis, with rising incidence globally. However, investigation into NTM in bronchiectasis patients in China remains relatively limited. This work aimed to identify and understand the features of NTM in bronchiectasis patient in Fuzhou district of China. The pulmonary samples were collected from 281 bronchiectasis patients with suspected NTM infection in Fuzhou, 2018-2022. MPB64 antigen detection was employed for the preliminary evaluation of NTM. Further NTM identification was realized using gene chip and gene sequencing. Among 281 patients, 172 (61.21%) patients were NTM-positive (58.72%) according to MPB64 antigen detection, with females (58.72%) outnumbering males (41.28%) and the highest prevalence in the age group of 46-65 years. In total, 47 NTM single infections and 3 mixed infections (1 Mycobacterium tuberculosis complex-M. intracellulare, 1 M. avium-M. intracellulare, and 1 M. abscessus-M. intracellulare) were identified through multicolor melting curve analysis (MMCA), which was compared with gene sequencing results. Both methods suggested Mycobacterium (M.) intracellulare, M. abscessus, and M. avium as the primary NTM species affecting bronchiectasis patients. M. intracellulare and M. abscessus were more frequent in females than males with the highest prevalence in the age group of 46-65 years according to MMCA. This research provides novel insights into the epidemiological and clinical features of NTM in bronchiectasis patients in Southeastern China. Significantly, M. intracellulare, M. abscessus, and M. avium were identified as the major NTM species, contributing to a better understanding and management of bronchiectasis accompanied by NTM infection.