Dataset Information

Culture-Independent Analysis of Pediatric Bronchoalveolar Lavage Specimens.

ABSTRACT: RATIONALE:The clinical utility of culture-independent testing of pediatric BAL specimens is unknown. In addition, the variability of the pediatric pulmonary microbiome with patient characteristics is not well understood. OBJECTIVES:To compare testing with 16S rRNA gene-based sequencing to conventional cultures of BAL specimens in children Methods: Study subjects were not more than 22 years old and underwent BAL from May 2013 to August 2015 as part of clinical care. DNA extracted from BAL specimens was used for 16S rRNA gene-based analysis, and results were compared with routine cultures from the same samples. Indices of microbial diversity and relative taxon abundances were compared on the basis of subject characteristics (diagnosis and antibiotic use). RESULTS:From 81 participants (male, 51%; median age, 9 yr), 89 samples were collected. The 16S rRNA genes of 77 samples (86.5%) from 70 subjects were successfully analyzed. These 70 subjects included 23 with cystic fibrosis, 19 who were immunocompromised, and 28 who were nonimmunocompromised. Of 68 organisms identified in culture, 16S rRNA gene-based analyses detected corresponding taxa in 66 (97.1%) and also identified potentially clinically significant organisms missed by cultures (e.g., Staphylococcus, Legionella, and Pseudomonas). Taxa that varied significantly with diagnosis and antibiotic use included Veillonella, Corynebacterium, Haemophilus, and Streptococcus. The microbiota of cystic fibrosis samples was less diverse. A "core" group of 15 taxa present in all three diagnosis groups was identified. CONCLUSIONS:Culture-independent analysis was concordant with routine cultures and showed the potential to detect noncultured pathogens. Although culture-independent testing identified relative changes in organism abundance associated with clinical characteristics, distinct microbiome profiles associated with disease states were not identified.

SUBMITTER: Zachariah P

PROVIDER: S-EPMC6322044 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Culture-Independent Analysis of Pediatric Bronchoalveolar Lavage Specimens.

Zachariah Philip P Ryan Chanelle C Nadimpalli Sruti S Coscia Gina G Kolb Michelle M Smith Hannah H Foca Marc M Saiman Lisa L Planet Paul J PJ

Annals of the American Thoracic Society 20180901 9

<h4>Rationale</h4>The clinical utility of culture-independent testing of pediatric BAL specimens is unknown. In addition, the variability of the pediatric pulmonary microbiome with patient characteristics is not well understood.<h4>Objectives</h4>To compare testing with 16S rRNA gene-based sequencing to conventional cultures of BAL specimens in children Methods: Study subjects were not more than 22 years old and underwent BAL from May 2013 to August 2015 as part of clinical care. DNA extracted f ...[more]

PMID: 29877714

Similar Datasets

Project description:The diagnosis and management of pneumonia are limited by the use of culture-based techniques of microbial identification, which may fail to identify unculturable, fastidious, and metabolically active viable but unculturable bacteria. Novel high-throughput culture-independent techniques hold promise but have not been systematically compared to conventional culture. We analyzed 46 clinically obtained bronchoalveolar lavage (BAL) fluid specimens from symptomatic and asymptomatic lung transplant recipients both by culture (using a clinical microbiology laboratory protocol) and by bacterial 16S rRNA gene pyrosequencing. Bacteria were identified in 44 of 46 (95.7%) BAL fluid specimens by culture-independent sequencing, significantly more than the number of specimens in which bacteria were detected (37 of 46, 80.4%, P ≤ 0.05) or "pathogen" species reported (18 of 46, 39.1%, P ≤ 0.0001) via culture. Identification of bacteria by culture was positively associated with culture-independent indices of infection (total bacterial DNA burden and low bacterial community diversity) (P ≤ 0.01). In BAL fluid specimens with no culture growth, the amount of bacterial DNA was greater than that in reagent and rinse controls, and communities were markedly dominated by select Gammaproteobacteria, notably Escherichia species and Pseudomonas fluorescens. Culture growth above the threshold of 10(4) CFU/ml was correlated with increased bacterial DNA burden (P < 0.01), decreased community diversity (P < 0.05), and increased relative abundance of Pseudomonas aeruginosa (P < 0.001). We present two case studies in which culture-independent techniques identified a respiratory pathogen missed by culture and clarified whether a cultured "oral flora" species represented a state of acute infection. In summary, we found that bacterial culture of BAL fluid is largely effective in discriminating acute infection from its absence and identified some specific limitations of BAL fluid culture in the diagnosis of pneumonia. We report the first correlation of quantitative BAL fluid culture results with culture-independent evidence of infection.

Project description:BackgroundIt is now possible to comprehensively characterize the microbiota of the lungs using culture-independent, sequencing-based assays. Several sample types have been used to investigate the lung microbiota, each presenting specific challenges for preparation and analysis of microbial communities. Bronchoalveolar lavage fluid (BALF) enables the identification of microbiota specific to the lower lung but commonly has low bacterial density, increasing the risk of false-positive signal from contaminating DNA. The objectives of this study were to investigate the extent of contamination across a range of sample densities representative of BALF and identify features of contaminants that facilitate their removal from sequence data and aid in the interpretation of BALF sample 16S sequencing data.ResultsUsing three mock communities across a range of densities ranging from 8E+?02 to 8E+?09 16S copies/ml, we assessed taxonomic accuracy and precision by 16S rRNA gene sequencing and the proportion of reads arising from contaminants. Sequencing accuracy, precision, and the relative abundance of mock community members decreased with sample input density, with a significant drop-off below 8E+?05 16S copies/ml. Contaminant OTUs were commonly inversely correlated with sample input density or not reproduced between technical replicates. Removal of taxa with these features or physical concentration of samples prior to sequencing improved both sequencing accuracy and precision for samples between 8E+?04 and 8E+?06 16S copies/ml. For the lowest densities, below 8E+?03 16S copies/ml BALF, accuracy and precision could not be significantly improved using these approaches. Using clinical BALF samples across a large density range, we observed that OTUs with features of contaminants identified in mock communities were also evident in low-density BALF samples.ConclusionRelative abundance data and community composition generated by 16S sequencing of BALF samples across the range of density commonly observed in this sample type should be interpreted in the context of input sample density and may be improved by simple pre- and post-sequencing steps for densities above 8E+?04 16S copies/ml.

Project description:Objectives The aim of this study was to evaluate the diagnostic value of bronchoalveolar lavage fluid (BALF) metagenomic next-generation sequencing (mNGS) versus conventional microbiological tests (CMTs) for pediatric pneumonia. Methods This retrospective observational study enrolled 103 children who were diagnosed with pneumonia and hospitalized at Hubei Maternity and Child Health Care Hospital between 15 October 2020 and 15 February 2022. The pneumonia diagnosis was based on clinical manifestations, lung imaging, and microbiological tests. Pathogens in the lower respiratory tract were detected using CMTs and BALF mNGS (of DNA and RNA). The diagnostic performance of BALF mNGS was compared with that of CMTs. Results In 96 patients, pathogens were identified by microbiological tests. The overall pathogen detection rate of mNGS was significantly higher than that of CMTs (91.3% vs. 59.2%, p = 0.000). The diagnostic performance of mNGS varied for different pathogens; however, its sensitivity and accuracy for diagnosing bacterial and viral infections were both higher than those of CMTs (p = 0.000). For the diagnosis of fungi, the sensitivity of mNGS (87.5%) was higher than that of CMTs (25%); however, its specificity and accuracy were lower than those of CMTs (p < 0.01). For the diagnosis of Mycoplasma pneumoniae, the specificity (98.8%) and accuracy (88.3%) of mNGS were high; however, its sensitivity (42.1%) was significantly lower than that of CMTs (100%) (p = 0.001). In 96 patients with definite pathogens, 52 cases (50.5%) were infected with a single pathogen, while 44 cases (42.7%) had polymicrobial infections. Virus–bacteria and virus–virus co-infections were the most common. Staphylococcus aureus, Haemophilus influenzae, rhinovirus, cytomegalovirus, parainfluenza virus, and fungi were more likely to be associated with polymicrobial infections. Conclusions BALF mNGS improved the detection rate of pediatric pneumonia, especially in mixed infections. The diagnostic performance of BALF mNGS varies according to pathogen type. mNGS can be used to supplement CMTs. A combination of mNGS and CMTs may be the best diagnostic strategy.

Project description:We developed a rapid thermocycling, real-time detection (also known as real-time PCR) method for the detection of Legionella species directly from clinical specimens. This method uses the LightCycler (Roche Molecular Biochemicals, Indianapolis, Ind.) and requires approximately 1 to 2 h to perform. Both a Legionella genus PCR assay and Legionella pneumophila species-specific PCR assay were designed. A total of 43 archived specimens from 35 patients were evaluated, including 19 bronchoalveolar lavage (BAL) specimens and 24 formalin-fixed, paraffin-embedded open lung biopsy specimens. Twenty-five of the specimens were culture-positive for Legionella (9 BAL specimens and 16 tissue specimens). BAL specimens were tested by LightCycler PCR (LC-PCR) methods and by a direct fluorescent antibody (DFA) assay, which detects L. pneumophila serogroups 1 to 6 and several other Legionella species. Tissue sections were tested by the two LC-PCR methods, by DFA, by an in situ hybridization (ISH) assay, specifically designed to detect L. pneumophila, and by Warthin-Starry (WS) staining. The results were compared to the "gold standard" method of bacterial culture. With BAL specimens the following assays yielded the indicated sensitivities and specificities, respectively: Legionella genus detection by Legionella genus LC-PCR, 100 and 100%; Legionella genus detection by DFA assay, 33 and 100%; and L. pneumophila detection by L. pneumophila species-specific LC-PCR, 100 and 100%. With open lung biopsy specimens the following assays yielded the indicated sensitivities and specificities, respectively: Legionella genus detection by LC-PCR 68.8 and 100%; Legionella genus detection by DFA assay, 44 and 100%; Legionella genus detection by WS staining, 63 and 100%; L. pneumophila species-specific detection by LC-PCR, 17 and 100%; and L. pneumophila species-specific detection by ISH, 100 and 100%. The analytical sensitivity of both LC-PCR assays was <10 CFU/reaction. LC-PCR is a reliable method for the direct detection of Legionella species from BAL specimens. The Legionella genus LC-PCR assay could be performed initially; if positive, L. pneumophila species-specific LC-PCR could then be performed (if species differentiation is desired). The speed with which the LC-PCR procedure can be performed offers significant advantages over both culture-based methods and conventional PCR techniques. In contrast, for the methods evaluated, culture was the best for detecting multiple Legionella species in lung tissue. WS staining, Legionella genus LC-PCR, and L. pneumophila species-specific ISH were useful as rapid tests with lung tissue.

Dataset Information

Culture-Independent Analysis of Pediatric Bronchoalveolar Lavage Specimens.

Publications

Culture-Independent Analysis of Pediatric Bronchoalveolar Lavage Specimens.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets