Medical Management of Pulmonary Nontuberculous Mycobacterial Disease

Clinical Characteristics of Patients with Nontuberculous Mycobacterium Pulmonary Disease in Fuyang, China: A Retrospective Study

Objective

We retrospectively review consecutive patients with nontuberculous mycobacterium (NTM) pulmonary disease reported from a designated hospital for infectious diseases in the Fuyang district of China to determine the clinical characteristics of these patients.

Methods

This research enrolled 234 patients with NTM pulmonary disease between January 2018 and May 2023 in the Fuyang district of China. Data were collected from the electronic medical records. The NTM strain composition and clinical characteristics of NTM pulmonary disease were retrospectively analyzed.

Results

73 (31.20%) patients had previous tuberculosis (TB) or TB exposure history and bronchiectasis. Mixed NTM infection accounted for 12.39%. Mycobacterium intracellulare strain was detected in 132 patients (49.62%). Women were found to be more affected by Mycobacterium avium infection, and men by Mycobacterium abscessus infection. Mycobacterium avium (34.21%) and Mycobacterium abscessus (33.33%) strains were most common in people with previous TB or TB exposure history. Among respiratory tract-related diseases, patients with bronchiectasis had the highest isolation rate of Mycobacterium avium (55.36%). Women were susceptible to bronchiectasis (P <0.01). The median of mononuclear-to-lymphocyte ratio (MLR) was higher in men than in women (P < 0.01). The serum albumin (ALB) level was lower in patients with TB or TB exposure history than in those without TB history (P = 0.034). The prognostic nutritional index (PNI) was lower in patients with TB or TB exposure history than in those without tuberculosis history (P = 0.021). Patients with NTM lung disease were poorly treated.

Conclusion

Clinical symptoms of the disease were not species-specific. Mycobacterium intracellulare and Mycobacterium avium strains were predominant in the Fuyang district of China. Previous TB or TB exposure history immensely enhanced the risk of NTM disease.

Mycobacterium porcinum Infection of Hilar and Mediastinal Lymph Nodes: A Case Report and Literature Review

In the available reports on clinical medicine, the infection sites of Mycobacterium porcinum include wounds, bone marrow, respiratory tract, and catheters. A 61-year-old woman was admitted to our hospital; her hilar and mediastinal lymph nodes were found to be enlarged during health examination, but there was no specific discomfort. Initially, she had undergone a mediastinal lymph node biopsy and pathology, but the diagnosis was not confirmed. However, 16S rRNA gene sequencing revealed M. porcinum infection of hilar and mediastinal lymph nodes. Subsequently, she was treated with clarithromycin, amikacin, imipenem, and tigecycline. After 2 months, chest computed tomography showed a significant reduction in lymph nodes. M. porcinum infection was considered to be the cause of disease.

Synthesis of Novel Benzenesulfonamide-Bearing Functionalized Imidazole Derivatives as Novel Candidates Targeting Multidrug-Resistant Mycobacterium abscessus Complex

Infections caused by drug-resistant (DR) Mycobacterium abscessus (M. abscessus) complex (MAC) are an important public health concern, particularly when affecting individuals with various immunodeficiencies or chronic pulmonary diseases. Rapidly growing antimicrobial resistance among MAC urges us to develop novel antimicrobial candidates for future optimization. Therefore, we have designed and synthesized benzenesulfonamide-bearing functionalized imidazole or S-alkylated derivatives and evaluated their antimicrobial activity using multidrug-resistant M. abscessus strains and compared their antimycobacterial activity using M. bovis BCG and M. tuberculosis H37Ra. Benzenesulfonamide-bearing imidazole-2-thiol compound 13, containing 4-CF₃ substituent in benzene ring, showed strong antimicrobial activity against the tested mycobacterial strains and was more active than some antibiotics used as a reference. Furthermore, an imidazole-bearing 4-F substituent and S-methyl group demonstrated good antimicrobial activity against M. abscessus complex strains, as well as M. bovis BCG and M. tuberculosis H37Ra. In summary, these results demonstrated that novel benzenesulfonamide derivatives, bearing substituted imidazoles, could be further explored as potential candidates for the further hit-to-lead optimization of novel antimycobacterial compounds.

MGIT-seq for the Identification of Nontuberculous Mycobacteria and Drug Resistance: a Prospective Study

Because nontuberculous mycobacterial pulmonary disease is a considerable health burden, a simple and clinically applicable analytical protocol enabling the identification of subspecies and drug-resistant disease is required to determine the treatment strategy. We aimed to develop a simplified workflow consisting only of direct sequencing of mycobacterial growth indicator tube cultures (MGIT-seq). In total, 138 patients were prospectively enrolled between April 2021 and May 2022, and culture-positive MGIT broths were subjected to sequencing using MinION, a portable next-generation sequencer. Sequence analysis was conducted to identify species using core genome multilocus sequence typing and to predict macrolide and amikacin (AMK) resistance based on previously reported mutations in rrl, rrs, and erm(41). The results were compared to clinical tests for species identification and drug susceptibility. A total of 116 patients with positive MGIT cultures were included in the analysis. MGIT-seq yielded 99.1% accuracy in species-level identification and identified 98 isolates (84.5%) at the subspecies level. Macrolide and AMK resistance were detected in 19.4% and 1.9% of Mycobacterium avium complex (MAC) and Mycobacterium abscessus isolates. The predicted macrolide and AMK resistance was consistent with the results of conventional drug susceptibility tests, with specificities of 97.6% and 100.0%, respectively. Direct MGIT-seq has achieved comprehensive identification and drug resistance detection of nontuberculous mycobacteria, which could be applicable to determine the treatment strategy by a single test in clinical practice.

Rapid and Comprehensive Identification of Nontuberculous Mycobacteria

Next-generation sequencing is a powerful tool to accurately identify pathogens. The MinION sequencer is best suited for the rapid identification of bacterial species due to its real-time sequence output. In this chapter, we introduce a method to identify nontuberculous mycobacteria (NTM) in one sequencing analysis from culture isolates using the MinION sequencer. NTM disease is now recognized as a growing global health concern due to its increasing incidence and prevalence. There are over 200 NTM species, of which the major pathogens are further classified into many subspecies showing different antibiotic susceptibilities. Therefore, identifying the pathogens at the subspecies level of NTM is necessary to select an appropriate treatment regimen. The protocol described here includes DNA extraction by lysis using silica beads, library preparation, sequencing by the MinION sequencer, and analysis of multilocus sequence typing using the software "mlstverse" and enables rapid and comprehensive identification of 175 species of NTM at the subspecies level with high sensitivity and accuracy.

Pulmonary disease caused by a newly identified mycobacterium: Mycolicibacterium toneyamachuris: a case report

BACKGROUND

Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is becoming a significant health burden. Recent advances in analysis techniques have allowed the accurate identification of previously unknown NTM species. Here, we report a case of NTM-PD caused by a newly identified mycobacteria in an immunocompetent patient.

CASE PRESENTATION

A 44-year-old woman was referred to our hospital due to the frequent aggravation of her chronic respiratory symptoms, with NTM-PD-compatible computed tomography findings. Unidentified mycobacterium was repeatedly isolated from respiratory specimens and we diagnosed her as NTM-PD of unidentified mycobacterium. Subsequent whole-genome analysis revealed that the unidentified mycobacterium was a novel mycobacterium genetically close to Mycolicibacterium mucogenicum. We started combination therapy with clarithromycin, moxifloxacin, amikacin, and imipenem/cilastatin, referring to drug sensitivity test results and observed its effect on M. mucogenicum infection. Her symptoms and radiological findings improved significantly.

CONCLUSION

We report a case of NTM-PD caused by a newly identified mycobacteria, Mycolicibacterium toneyamachuris, genetically close to M. mucogenicum. This pathogenic mycobacterium showed different characteristics from M. mucogenicum about clinical presentation and drug sensitivity. The clinical application of genomic sequencing will advance the identification and classification of pathogenic NTM species, and enhance our understanding of mycobacterial diseases.

Opportunist Coinfections by Nontuberculous Mycobacteria and Fungi in Immunocompromised Patients

Nontuberculous mycobacteria (NTM) and many fungal species (spp.) are commonly associated with opportunistic infections (OPIs) in immunocompromised individuals. Moreover, occurrence of concomitant infection by NTM (mainly spp. of Mycobacterium avium complex and Mycobacterium abscessus complex) and fungal spp. (mainly, Aspergillus fumigatus, Histoplasma capsulatum and Cryptococcus neoformans) is very challenging and is associated with poor patient prognosis. The most frequent clinical symptoms for coinfection and infection by single agents (fungi or NTM) are similar. For this reason, the accurate identification of the aetiological agent(s) is crucial to select the best treatment approach. Despite the significance of this topic it has not been sufficiently addressed in the literature. This review aims at summarizing case reports and studies on NTM and fungi coinfection during the last 20 years. In addition, it briefly characterizes OPIs and coinfection, describes key features of opportunistic pathogens (e.g., NTM and fungi) and human host predisposing conditions to OPIs onset and outcome. The review could interest a wide spectrum of audiences, including medical doctors and scientists, to improve awareness of these infections, leading to early identification in clinical settings and increasing research in the field. Improved diagnosis and availability of therapeutic options might contribute to improve the prognosis of patients' survival.

Looking beyond Typical Treatments for Atypical Mycobacteria

The genus Mycobacterium comprises not only the deadliest of bacterial pathogens, Mycobacterium tuberculosis, but several other pathogenic species, including M. avium and M. abscessus. The incidence of infections caused by atypical or nontuberculous mycobacteria (NTM) has been steadily increasing, and is associated with a panoply of diseases, including pulmonary, soft-tissue, or disseminated infections. The treatment for NTM disease is particularly challenging, due to its long duration, to variability in bacterial susceptibility profiles, and to the lack of evidence-based guidelines. Treatment usually consists of a combination of at least three drugs taken from months to years, often leading to severe secondary effects and a high chance of relapse. Therefore, new treatment approaches are clearly needed. In this review, we identify the main limitations of current treatments and discuss different alternatives that have been put forward in recent years, with an emphasis on less conventional therapeutics, such as antimicrobial peptides, bacteriophages, iron chelators, or host-directed therapies. We also review new forms of the use of old drugs, including the repurposing of non-antibacterial molecules and the incorporation of antimicrobials into ionic liquids. We aim to stimulate advancements in testing these therapies in relevant models, in order to provide clinicians and patients with useful new tools with which to treat these devastating diseases.

Comprehensive subspecies identification of 175 nontuberculous mycobacteria species based on 7547 genomic profiles

The prevalence of nontuberculous mycobacteria (NTM) pulmonary diseases has been increasing worldwide. NTM consist of approximately 200 species and distinguishing between them at the subspecies level is critical to treatment. In this study, we sequenced 63 NTM genomes, 27 of which were newly determined, by hybrid assembly using sequencers from Illumina and Oxford Nanopore Technologies (ONT). This analysis expanded the available genomic data to 175 NTM species and redefined their subgenus classification. We also developed a novel multi-locus sequence typing (MLST) database based on 184 genes from 7547 assemblies and an identification software, mlstverse, which can also be used for detecting other bacteria given a suitable MLST database. This method showed the highest sensitivity and specificity amongst conventional methods and demonstrated the capacity for rapid detection of NTM, 10 min of sequencing of the ONT MinION being sufficient. Application of this methodology could improve disease epidemiology and increase the cure rates of NTM diseases.

Added diagnostic value of 16S rRNA gene pan-mycobacterial PCR for nontuberculous mycobacterial infections: a 10-year retrospective study

The diagnosis of mycobacterial infections has been dramatically improved by the introduction of molecular methods aimed to reduce the time to diagnosis as compared with culture. The broad range pan-mycobacterial PCR can detect all the mycobacterial species directly from clinical specimens. We aimed to evaluate its usefulness and its clinical added value for the diagnosis of nontuberculous mycobacterial (NTM) infections. We performed a retrospective study (2003-2013) including 952 samples taken from 639 patients with clinical suspicion of NTM infection. The performance of smear microscopy, PCR and culture was established using clinical data to investigate discrepant results. We also compared the time to microbial diagnosis between the direct PCR and culture. The sensitivity, specificity, positive and negative predictive values of the PCR were 61.6% (53.5-69.1), 99.1% (98.2-99.6), 92.8% (85.8-96.5) and 93.4% (91.6-94.9), respectively, when considering all specimens. When considering smear-positive specimens and smear-negative specimens, the sensitivity was 81.6% and 40%, respectively. The sensitivity for pulmonary and extra-pulmonary smear-positive specimens was 85.2% versus 72.7%. The median time to identification at species level was 35 days (SD, 17.67) for culture and 6 days (SD, 2.67) for the PCR (when positive), which represents a 29-day shorter time to results (p < 0.0001). The 16S rRNA gene pan-mycobacterial PCR displays a substantial benefit in terms of time to diagnose NTM infections when compared with culture. Despite an excellent specificity, its sensitivity is yet limited in particular for smear-negative specimens, which might be improved by relying onto real-time PCRs.

Characterization of non-tuberculous mycobacterial pulmonary disease in Nanjing district of China

BACKGROUND

Environmental bacteria, nontuberculous mycobacteria (NTM), are recognized as one of the major human infection pathogens. NTM are prone to be mistaken as multidrug-resistant Mycobacterium tuberculosis and challenge our fight against TB. In addition, treatment of NTM per se is intractable. Remarkably, the distribution of NTM pathogenic species is geographically specific. Thus, it is very important to summarize the prevalent features and clinical symptoms of NTM pulmonary disease. However, In Nanjing district, southeast China, there is no such a report.

METHODS

Through investigating electronic medical records and analyzing data of clinical examination system (Lis), we retrospectively summarized the NTM species from 6012 clinical isolates from May 2017 to August 2018, and analyzed the association between NTM species and clinical symptoms.

RESULTS

Of 6012 clinical specimens, 1461 (24.3%) could grow in the MGIT 960 broth. Among these positive isolates, 1213 (83%) were M. tuberculosis, 22 (1.5%) were M. bovis, and 226 (15.5%) were NTM. After deducting redundancy, those NTM specimens were confirmed from 154 patients, among which, 87 (56.5%) patients met the full ATS/IDSA NTM disease criteria. The most common etiologic agent was M. intracellulare (70.1%). NTM infection was associated with age, based on which 68.6% male patients and 77.8% female patients were over 50 years old. The older patients were more likely to have hemoptysis, but the younger patients were more likely to manifest chest congestion. Male patients were more likely to have shortness of breath and females were more likely to have hemoptysis. The most common radiographic presentation of NTM pulmonary disease was bronchiectasis, accounting for 39.1%. Remarkably, multiple and thin-walled cavities were outstanding. The most frequent comorbidity of NTM disease was previous tuberculosis (64%), followed by clinical bronchiectasis (19.5%), HIV (19.5%), and 6.9% chronic obstructive pulmonary disease (COPD). There was no association between NTM species and clinical symptoms.

CONCLUSION

This study retrospectively investigated the prevalence of NTM pulmonary disease in Nanjing district, southeast China. Similar to Beijing area, north China, M. intracellulare was the major pathogenic NTM species. Clinical symptoms of the disease were not species-specific. Previous TB and HIV infection immensely enhanced risk of NTM disease.