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Comparison of two aspiration techniques of bronchoalveolar lavage in children.

ABSTRACT: Although bronchoalveolar lavage (BAL) via flexible bronchoscopy is an essential diagnostic tool, its technique is not standardized in children. Our objective was to compare two different aspiration techniques of BAL in children (continuous wall suction vs. handheld syringe suction) in regards to the percentage of fluid recovered and the odds of performing a technically acceptable procedure (i.e., >40% of volume return).We conducted a review of all pediatric flexible bronchoscopies with BAL conducted at our institution over a 2-year period. To minimize the differences between groups at baseline and reduce the possibility of bias, we used one-to-one propensity score (PS) caliper matching with no replacement for statistical analyses.We identified 539 procedures that met pre-specified criteria. There were considerable covariate imbalances between procedures in the handheld syringe group (n?=?147) and those in the continuous wall group (n?=?392); however, these imbalances were substantially reduced after the PS matching. In the matched sample (n?=?236), children in the handheld syringe group had ?7% higher volume return (95% CI?=?3.4-11.0, P?

SUBMITTER: Rosas-Salazar C

PROVIDER: S-EPMC3999312 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Comparison of two aspiration techniques of bronchoalveolar lavage in children.

Rosas-Salazar Christian C Walczak Stephen A SA Winger Daniel G DG Kurland Geoffrey G Spahr Jonathan E JE

Pediatric pulmonology 20131024 10

<h4>Background</h4>Although bronchoalveolar lavage (BAL) via flexible bronchoscopy is an essential diagnostic tool, its technique is not standardized in children. Our objective was to compare two different aspiration techniques of BAL in children (continuous wall suction vs. handheld syringe suction) in regards to the percentage of fluid recovered and the odds of performing a technically acceptable procedure (i.e., >40% of volume return).<h4>Methods</h4>We conducted a review of all pediatric fle ...[more]

PMID: 24155175

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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.

Dataset Information

Comparison of two aspiration techniques of bronchoalveolar lavage in children.

Publications

Comparison of two aspiration techniques of bronchoalveolar lavage in children.

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