Whole-Blood Gene Expression in Pulmonary Nontuberculous Mycobacterial Infection.

The factors predisposing toward the development of pulmonary nontuberculous mycobacterial (pNTM) disease and influencing disease progression remain unclear. Impaired immune responses have been reported in individuals with pNTM disease, but data are limited and inconsistent. In this study, we sought to use gene expression profiling to examine the host response to pNTM disease. Microarray analysis of whole-blood gene expression was performed on 25 subjects with pNTM disease and 27 uninfected control subjects with respiratory disease. Gene expression results were compared with phenotypic variables and survival data. Compared with uninfected control subjects, pNTM disease was associated with downregulation of 213 transcripts enriched for terms related to T cell signaling, including IFNG. Reduced IFNG expression was associated with more severe computed tomography changes and impaired lung function. Mortality was associated with the expression of transcripts related to the innate immune response and inflammation, whereas transcripts related to T and B cell function were associated with improved survival. These findings suggest that pNTM disease is associated with an aberrant immune response, which may reflect an underlying propensity to infection or result from NTM infection itself. There were important differences in the immune response associated with survival and mortality in pNTM disease.

Diagnosis of Nontuberculous Mycobacteria Lung Disease.

The diagnosis of pulmonary nontuberculous mycobacteria (NTM) disease may be challenging, as their presence alone does not necessarily indicate disease and diagnosis requires the integration of clinical, radiological, and microbiological findings. The first step is to suspect NTM disease; however, clinical manifestations of NTM are nonspecific and it may not be possible to separate them from those caused by underlying respiratory disease. The radiological appearance generally falls into two patterns, fibrocavitary disease and nodular-bronchiectatic disease; consolidation, infiltrates, and solitary nodules are also described. The isolation of NTM from clinical samples is fundamental to the diagnosis and they may be cultured from sputum, bronchoalveolar lavage fluid, or tissue specimens. If sputum is used, more than one isolate is required for diagnosis due to the propensity of NTM to contaminate clinical samples. The correct identification of NTM is vital, as their clinical relevance varies widely between species, and treatment is dictated by the identity of the isolated organism. This review covers the clinical presentation of NTM disease, the interpretation of radiological findings, and issues surrounding the isolation and identification of mycobacteria.

Latent class analysis to define radiological subgroups in pulmonary nontuberculous mycobacterial disease.

BACKGROUND: Nontuberculous mycobacterial (NTM) pulmonary disease has conventionally been classified on the basis of radiology into fibrocavitary and nodular-bronchiectatic disease. Whilst being of great clinical utility, this may not capture the full spectrum of radiological appearances present. The aim of this study was to use latent class analysis (LCA) as an unbiased method of grouping subjects with NTM-pulmonary disease based on their CT features and to compare the clinical characteristics of these groups. METHODS: Individuals with NTM-pulmonary disease were recruited and a contemporaneous CT scan obtained. This was scored using an NTM-specific scoring system. LCA was used to identify groups with common radiological characteristics. The analysis was then repeated in an independent cohort. RESULTS: Three classes were identified in the initial cohort of 85 subjects. Group 1 was characterised by severe bronchiectasis, cavitation and aspergillomas, Group 2 by relatively minor radiological changes, and Group 3 by predominantly bronchiectasis only. These findings were reproduced in an independent cohort of 62 subjects. Subjects in Group 1 had a lower BMI and serum albumin, higher serum CRP, and a higher mortality. CONCLUSIONS: These findings suggest that NTM-pulmonary may be divided into three radiological subgroups, and that important clinical and survival differences exist between these groups.

Profiling mycobacterial communities in pulmonary nontuberculous mycobacterial disease.

The diagnosis of pulmonary non-tuberculous mycobacterial disease (pNTM) is dependent on the isolation of NTM in culture, which is prone to overgrowth and contamination and may not capture the diversity of mycobacteria present, including rare or unidentified species. This study aimed to develop a culture independent method of detecting and identifying mycobacteria from sputum samples using partial sequencing of the hsp65 gene. DNA was extracted from sputum samples from subjects with pNTM and disease controls. Multiplexed partial sequencing of the hsp65 gene was performed using the Illumina MiSeq and custom primers. A reference database of hsp65 sequences was created for taxonomy assignment. Sequencing results were obtained from 42 subjects (31 cases, 11 controls). Mycobacterial sequences were identified in all subjects. In 90.5% of samples more than one species was found (median 5.5). The species isolated in culture was detected by sequencing in 81% of subjects and was the most abundant species in 62%. The sequencing of NTM from clinical samples reveals a far greater diversity than conventional culture and suggests NTM are present as communities rather than a single species. NTM were found to be present even in the absence of isolation in culture or clinical disease.

Superior vena cava stent migration into the pulmonary artery causing fatal pulmonary infarction.

Migration of superior vena cava (SVC) stents is a well-recognised complication of their deployment, and numerous strategies exist for their retrieval. To our knowledge, only three cases of migration of an SVC stent to the pulmonary vasculature have previously been reported. None of these patients developed complications that resulted in death. We report a case of SVC stent migration to the pulmonary vasculature with delayed pulmonary artery thrombosis and death from pulmonary infarction. We conclude that early retrieval of migrated stents should be performed to decrease the risk of serious complications.