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Ann Lab Med. 2018 Mar;38(2):110-118. English. Original Article. https://doi.org/10.3343/alm.2018.38.2.110
Sung JY , Hwang Y , Shin MH , Park MS , Lee SH , Yong D , Lee K .
Research Institute of Bacterial Resistance and Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea. DEYONG@yuhs.ac
Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, Korea.
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Department of Internal Medicine, Seoul National University College of Medicine, Division of Pulmonary and Critical Care Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
Abstract

Background

Diverse microbiota exist in the lower respiratory tract. Although next generation sequencing (NGS) is the most widely used microbiome analysis technique, it is difficult to implement NGS in clinical microbiology laboratories. Therefore, we evaluated the performance of conventional culture methods together with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in identifying microbiota in bronchoalveolar lavage (BAL) fluid.

Methods

BAL fluid samples (n=27) were obtained from patients undergoing diagnostic bronchoscopy for lung mass evaluation. Bacterial and fungal culture was performed with conventional media used in clinical microbiology laboratories. On an average, 20 isolated colonies were picked from each agar plate and identified by MALDI-TOF MS. Microbiome analysis using 16S rRNA NGS was conducted for comparison.

Results

Streptococcus spp. and Neisseria spp. were most frequently cultured from the BAL fluid samples. In two samples, Enterobacteriaceae grew predominantly on MacConkey agar. Actinomyces and Veillonella spp. were commonly identified anaerobes; gut bacteria, such as Lactobacillus, Bifidobacterium, and Clostridium, and fungi were also isolated. NGS revealed more diverse bacterial communities than culture, and Prevotella spp. were mainly identified solely by NGS. Some bacteria, such as Staphylococcus spp., Clostridium spp., and Bifidobacterium spp., were identified solely by culture, indicating that culture may be more sensitive for detecting certain bacteria.

Conclusions

Culture and NGS of BAL fluid samples revealed common bacteria with some different microbial communities. Despite some limitations, culture combined with MALDI-TOF MS might play a complementary role in microbiome analysis using 16S rRNA NGS.

Copyright © 2019. Korean Association of Medical Journal Editors.