Search

Yoichi Nishii,1 Kazuki Furuhashi,1 Saki Nakamura,1 Miho Nishio,1 Yuki Nakamura,1 Kengo Ushiro,1 Kentaro Ito,1 Tadashi Sakaguchi,1 Yuta Suzuki,1 Kentaro Fujiwara,1 Taro Yasuma,2 Tetsu Kobayashi,3 Corina D’Alessandro-Gabazza,2 Esteban C Gabazza,2 Osamu Taguchi,1 Osamu Hataji1 1Respiratory Center, Matsusaka Municipal Hospital, Matsusaka, Mie, Japan; 2Department of Immunology, Faculty and Graduate School of Medicine, Mie University, Tsu-city, Mie, Japan; 3Department of Pulmonary and Critical Care Medicine, Faculty and Graduate School of Medicine, Mie University, Tsu-city, Mie, JapanCorrespondence: Esteban C GabazzaDepartment of Immunology, Mie University Graduate School of Medicine, Edobashi 2-174, Tsu-city, Mie, 514-8507, JapanTel +81 59 231 5017Fax +81 59 231 5225Email gabazza@doc.medic.mie-u.ac.jpIntroduction: Many patients with nontuberculous mycobacteria pulmonary disease are asymptomatic. The disease diagnosis is confirmed in only a small proportion of patients with radiological findings suspicious for nontuberculous mycobacteria pulmonary disease. Thus, many patients remained undiagnosed. Here, we evaluated the diagnostic value of digital polymerase chain reaction (PCR) in nontuberculous mycobacteria pulmonary disease.Methods: We prospectively evaluated 123 patients with radiological findings suspicious for nontuberculous mycobacteria pulmonary disease. Digital PCR was performed using bronchial lavage fluid, sputum, saliva, blood, and urine.Results: The culture of bronchial washing fluid was positive for nontuberculous mycobacteria in 53 patients and negative in 70. The positive detection rate of nontuberculous mycobacteria by digital PCR in patients with positive culture (n = 53) was as follows: bronchial lavage fluid 100%, sputum 62.9%, saliva 41.5%, blood 7.5%, and urine 3.8%. All patients with two or more positive partitions for nontuberculous mycobacteria in the digital PCR of bronchial lavage fluid showed nontuberculous mycobacteria growth in the bronchial lavage fluid culture. The digital PCR analysis of the bronchial lavage fluid showed a high sensitivity (100%), specificity (85.7%), positive predictive value (84.1%), negative predictive value (100%), and a high concordance rate (91.9%) with the bronchial lavage fluid culture results. In addition, the culture of bronchial lavage fluid was positive for nontuberculous mycobacteria in patients with two or more positive partitions in the digital PCR of sputum and saliva with a combined positive predictive value of 81.1%.Conclusion: Digital PCR analysis of nontuberculous mycobacteria in bronchial lavage fluid shows a high concordance rate with the bronchial lavage fluid culture results and a high positive predictive value using both sputum and saliva, suggesting the potential usefulness of dPCR for diagnosis of nontuberculous mycobacteria pulmonary disease in clinical practice.Keywords: digital PCR, nontuberculous mycobacteria pulmonary disease, diagnosis, bronchial lavage fluid culture, bronchoscopy

The surfactant precipitation and recovery method (SPR method) consist of a precipitation step, that is precipitation of protein-surfactant complex by the addition of aqueous surfactant solution to aqueous protein solution, and a recovery step, that is dissolution of precipitate in polar organic solvent and protein recovery by addition of trace amount of aqueous salt solution. When the denaturant was not included, the precipitation ratio of lysozyme increased as the AOT/lysozyme molar ratio increased, and after reaching 100%, the precipitation ratio decreased due to the redissolution of the precipitation. It was shown that lysozyme denatured by urea and GuHCl can be recovered by the SPR method. Lysozyme denatured with urea had a precipitation ratio and recovery ratio of almost 100% up to a urea concentration of 4 kmol/m3 at an AOT/lysozyme molar ratio of 28.6. As the urea concentration increased, the precipitation ratio and the recovery ratio decreased. Lysozyme denatured with GuHCl had a precipitation ratio and recovery ratio of about 75% at an AOT/lysozyme molar ratio of 71.5 and a GuHCl concentration of 0.6 kmol/m3. The specific activity and the secondary conformation of the recovered lysozyme were confirmed to be almost the same as those of the native lysozyme by measuring the enzyme activity and CD spectrum. It was shown that lysozyme denatured with urea and GuHCl can be recovered by the SPR method as lysozyme has native properties.