Original Article Microbiota profiling of bronchial fluids of elderly patients with pulmonary carcinoma Naoko Ishida a,b , Takuichi Sato a,n , Yasushi Hoshikawa c , Naoko Tanda d , Keiichi Sasaki b , Takashi Kondo c , Nobuhiro Takahashi a a Division of Oral Ecology and Biochemistry, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan b Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan c Department of Thoracic Surgery, Institute of Development, Aging, and Cancer, Tohoku University, Sendai 980-8575, Japan d Division of Preventive Dentistry, Tohoku University Hospital, Sendai 980-8575, Japan article info Article history: Received 10 September 2014 Received in revised form 10 November 2014 Accepted 17 November 2014 Keywords: 16S ribosomal RNA Bronchial fluids Microbiota The elderly abstract Objectives: The source of the bacteria involved in silent aspiration remains to be completely defined. This study aimed to obtain reliable evidence on silent aspiration of oral bacteria in elderly patients. Methods: After obtaining informed consent, the cough and swallowing reflexes of patients were assessed. Bronchial fluids from patients undergoing lung resections were collected with a micro- sampling probe, and α-amylase activity of bronchial fluids was measured to estimate the degree of silent aspiration. The bronchial fluids were cultured aerobically and anaerobically on blood agar plates, and colonies were identified by 16S rRNA gene sequencing. Additionally, whole saliva bacterial amounts and composition were analyzed. Results: Six patients (72.2 75.8 years) exhibited an impaired swallowing reflex and 5 (75.4 77.9 years) had a normal swallowing reflex, while all patients had a normal cough reflex. α-Amylase activity was detected in bronchial fluids of both the impaired and normal reflex groups. The amount of anaerobic bacteria in bronchial fluids in the impaired reflex group [(3.0 73.5)  10 4 ] was higher than in the normal reflex group [(2.5 75.3)  10 4 ], although the difference was not significant. Actinomyces, Gemella, Streptococcus, Rothia, Mogibacterium, and Campylobacter were the predominant bacterial species in bronchial fluids of the impaired reflex group, while Streptococcus, Lactobacillus, Veillonella, and Actinomyces were predominant in the normal reflex group. Conclusions: Our results suggest that bacteria in bronchial fluids associated with silent aspiration are derived from saliva, and that the bronchial fluids of elderly patients with an impaired swallowing reflex may have a characteristic microbiota. & 2014 Japanese Association for Oral Biology. Published by Elsevier B.V. All rights reserved. 1. Introduction To date, pneumonia has a high mortality rate in Japanese adults; 90% of pneumonia-associated deaths are observed in elderly people ( Z65 years). Therefore, it is important to prevent pneumonia in elderly people. Aspiration pneumonia, in particular in elderly patients, has been suggested to be a crucial issue. Indeed, silent aspiration was observed, using indium-111 chloride scanning, in approximately 70% of elderly patients during the hours of sleep [1]. Furthermore, oral bacteria have been found in bronchoalveolar lavage fluids of elderly patients with community-acquired pneumo- nia [2–4] and in intraoperative bronchial fluids of elderly patients with pulmonary carcinoma [5], suggesting that silent aspiration of oral bacteria frequently occurs in elderly patients. Yamasaki et al. [4] reported that oral bacteria, e.g., Fusobacterium, Prevotella, Streptococcus, Neisseria, and Veillonella, are frequently detected in bronchoalveolar lavage fluids of patients with community-acquired pneumonia. Hasegawa et al. [5] have found indigenous oral bacteria, i.e., Streptococcus, Veillonella, Gemella, Porphyromonas, Olsenella, and Eikenella, in intraoperative bronchial fluids. Based on these findings, it has been suggested that the bacteria involved in silent aspiration may come from the oral cavity, although definite proof for this hypothesis is currently lacking. In order to obtain more reliable evidence on silent aspiration of oral bacteria in elderly patients, we measured α-amylase activity in bronchial fluids to estimate the degree of silent aspiration. We compared bacterial amounts and composition in intraoperative bronchial fluids and saliva of the patients. Because the protective Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/job Journal of Oral Biosciences http://dx.doi.org/10.1016/j.job.2014.11.001 1349-0079/& 2014 Japanese Association for Oral Biology. Published by Elsevier B.V. All rights reserved. n Corresponding author. Tel.: þ81 22 717 8295; fax: þ81 22 717 8297. E-mail address: tak@m.tohoku.ac.jp (T. Sato). Please cite this article as: Ishida N, et al. Microbiota profiling of bronchial fluids of elderly patients with pulmonary carcinoma. J Oral Biosci (2015), http://dx.doi.org/10.1016/j.job.2014.11.001i Journal of Oral Biosciences ∎ (∎∎∎∎) ∎∎∎–∎∎∎