The clinical impact of pneumocystis and viral PCR testing on bronchoalveolar lavage in immunosuppressed patients

Utility of multimodal sampling and testing during advanced bronchoscopy for diagnosing atypical respiratory infections in a Coccidioides-endemic region

Background

The role of advanced diagnostic bronchoscopy (ADB) for assessing atypical respiratory infections is unclear. The purpose of this study was to ascertain: (I) the diagnostic utility of ADB-tissue sampling in patients with focal thoracic lesions due to atypical respiratory infections; (II) how multimodal bronchoscopic sampling and testing enhance diagnosis in a Coccidioides-endemic region.

Methods

A retrospective observational cohort study analyzing all ADBs performed over a 10-year period in patients with focal thoracic lesions diagnosed with a non-malignant disorder. Only cases which procured lower respiratory tract secretion and tissue samples by ADB, and had both cytohistology and culture results available were included.

Results

Among 403 subjects with non-malignant disease, 136 (33.7%) were diagnosed with atypical respiratory infections, with ADB contributing a diagnosis in 119 (87.5%) of these. Coccidioidal disease was independently associated with a cytohistologic diagnosis [odds ratio =7.64, 95% confidence interval (CI): 2.51-23.26; P<0.001]. Mycobacteria were more effectively identified by culture (overall yield of 8.4%, vs. 2.7% by cytohistology; P<0.001). Among subjects for which both respiratory secretion and tissue sampling were dual-tested with culture and cytology/cytohistology, adding ADB-guided transbronchial needle aspiration and/or forceps biopsy (TBNA/TBFB) to bronchoalveolar lavage and/or bronchial washings (BAL/BW) more than doubled the yield for dimorphic fungi, from 7.1% to 15.1% (increase of 8.0%, 95% CI: 5.2-11.9%). For lung lesions, adding tissue culture to dual TBNA/TBFB cytohistology-tested lung samples doubled the proportion diagnosed with atypical infection over using TBNA-cytohistology alone (increase of 15.8%, 95% CI: 10.4-23.1%). Adding lymph node to lung sampling increased the proportion diagnosed with coccidioidomycosis by 8.8% (95% CI: 4.8-15%). Among subjects with atypical respiratory infections, major ADB-related complications occurred in 1.5%.

Conclusions

ADB is useful for diagnosing atypical respiratory infections manifesting as focal thoracic lesions. A multimodal approach to both sampling and testing enhances yield, while maintaining a favorable procedure safety profile. Cytohistology testing and nodal sampling are beneficial for pulmonary coccidioidomycosis, and culture for mycobacterial disease. The approach to ADB-sampling should be adjusted according to clinical context and regional infection patterns.

A Novel MIP-1-Expressing Macrophage Subtype in BAL Fluid from Healthy Volunteers

Tissue availability remains an important limitation of single-cell genomic technologies for investigating cellular heterogeneity in human health and disease. BAL represents a minimally invasive approach to assessing an individual's lung cellular environment for diagnosis and research. However, the lack of high-quality, healthy lung reference data is a major obstacle to using single-cell approaches to study a plethora of lung diseases. Here, we performed single-cell RNA sequencing on over 40,000 cells isolated from the BAL of four healthy volunteers. Of the six cell types or lineages we identified, macrophages were consistently the most numerous across individuals. Our analysis confirmed the expression of marker genes defining cell types despite background signals because of the ambient RNA found in many single-cell studies. We assessed the variability of gene expression across macrophages and defined a distinct subpopulation of cells expressing a set of genes associated with Macrophage Inflammatory Protein 1 (MIP-1). RNA in situ hybridization and reanalysis of published lung single-cell data validated the presence of this macrophage subpopulation. Thus, our study characterizes lung macrophage heterogeneity in healthy individuals and provides a valuable resource for future studies to understand the lung environment in health and disease.

Bronchoalveolar lavage: role in the evaluation of pulmonary interstitial disease

INTRODUCTION

Bronchoalveolar lavage (BAL), a noninvasive, well-tolerated procedure is an important diagnostic tool that can facilitate the diagnosis of various lung diseases. This procedure allows the assessment of large alveolar compartments, by providing cells as well as non-cellular constituents from the lower respiratory tract. Alterations in BAL fluid and cells ratio reflects pathological changes in the lung parenchyma. In some cases, clinicians use BAL as a differential diagnosis guide for interstitial lung disease.

AREAS COVERED

In this review, we summarized the diagnostic criteria for BAL in interstitial lung diseases, pulmonary infections, lung cancer and other pathologies such as fat embolism, gastroesophageal reflux and collagen vascular disease. For this review, we have selected scientific papers published in the PubMed database in our area of interest. We aimed to highlight the usefulness of BAL in respiratory pathology.

EXPERT OPINION

Although BAL fluid analyzes has an essential role in the diagnostic work-up of many lung pathologies, it should be performed in selected patients. For accurate results, the BAL technique is very important to be standardized.