Masanori YAMASHITA

Publications (4)7.86 Total impact

• Article: Rapid Detection of the Mycobacterium tuberculosis Complex by Use of Quenching Probe PCR (geneCube).

  Yukio Hida, Kyoko Hisada, Akihiro Shimada, Masanori Yamashita, Hideki Kimura, Haruyoshi Yoshida, Hiromichi Iwasaki, Masayuki Iwano
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  ABSTRACT: Early detection of tuberculosis (TB) is essential for infection control. The geneCube (Toyobo) is a novel fully automated gene analyzer that can amplify target DNAs within 60 min. In this study, we evaluated the ability of the geneCube to directly detect Mycobacterium tuberculosis complex (MTBC) and Mycobacterium avium complex (MAC) in clinical specimens. The results were then compared with those obtained using conventional culture, microscopy, and the Cobas Amplicor assay (Roche). We examined a total of 516 frozen samples from 69 patients who showed culture-positive infection (73 samples; 39 MTBC, 32 MAC, and 2 mixed infections) and from 354 patients who were culture negative (443 samples). Assays using the geneCube had a sensitivity of 85.4% and a specificity of 99.8% for detection of MTBC and a sensitivity of 85.3% and a specificity of 99.8% for detection of MAC. These results are similar to those obtained using the Amplicor system but were obtained much more rapidly (1 h with the geneCube versus 5.5 h with the Amplicor system). The geneCube thus enables a significant shortening of the assay time with no loss of sensitivity or specificity.
  Journal of clinical microbiology 08/2012; 50(11):3604-8. · 4.16 Impact Factor
• Article: A specific serum IgA antibody discriminates pneumonia from colonization state in patients with Pseudomonas aeruginosa in sputum culture.

  Masanori Yamashita, Yukio Hida, Hidehiro Sugimoto, Naoki Takahashi, Hideki Kimura, Yasuo Nakatomi, Haruyoshi Yoshida, Takeshi Ishizaki
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  ABSTRACT: We attempted to develop a new specific antibody detection method for discriminating infection state from colonization state in hospitalized immunocompromised patients with a positive sputum culture for Pseudomonas aeruginosa. Serum samples from 65 patients with P. aeruginosa in sputum culture (total PA patients), including 24 patients with P. aeruginosa-related pulmonary infections (PA infection group) and 21 patients without pulmonary infections (PA colonization group), as well as samples from 20 patients positive for other bacteria in blood culture (non-PA infection group) and 38 healthy controls were examined and compared for IgG and IgA anti-P. aeruginosa antibodies by a newly developed enzyme-linked immunosorbent assay (ELISA). Both IgG and IgA antibody ELISA showed satisfactory reproducibility with low coefficient of variation (CV) percent, and western blotting analysis showed two protein bands as the corresponding antigens common to both antibodies. The serum levels of both antibodies in all the PA patients were higher than those in the healthy controls with high significance (p<0.0001). The PA infection group showed significantly higher mean levels of both IgG and IgA class antibodies than the PA colonization group, non-PA infection group and healthy controls (each, p<0.0001). In receiver operating characteristic (ROC) curves analysis to differentiate between total PA infections and the PA colonization group, the area under curve (AUC) of the IgA antibody (0.848) was significantly larger than the AUC of the IgG antibody (0.677) (p=0.019). At the optimal IgA antibody cutoff value for differentiation of 1.37 units/mL, the sensitivity and specificity of IgA anti-P. aeruginosa ELISA were 83.3% and 85.7%, respectively. These findings suggest that IgA antibody ELISA, rather than IgG antibody ELISA, may be useful for differentiating P. aeruginosa-related pneumonia from latent colonization in immunocompromised patients with a positive sputum culture.
  Journal of microbiological methods 09/2010; 82(3):198-204. · 2.43 Impact Factor
• Article: Frequent detection of multidrug-resistant pneumonia-causing bacteria in the pneumonia lung tissues of patients with hematological malignancies.

  Kunihiro Inai, Hiromichi Iwasaki, Sakon Noriki, Satoshi Ikegaya, Masanori Yamashita, Yoshiaki Imamura, Nobuo Takimoto, Hisataka Kato, Takanori Ueda, Hironobu Naikia
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  ABSTRACT: Pneumonia is a critical issue during the agonal phase, and often becomes lethal in the absence of pathogen detection. Autopsy is a powerful tool for analyzing the cause of a patient's death, progression of the disease, and the therapeutic response. However, it is frequently limited to the identification of bacterial strains. To elucidate the pathogenesis during the agonal phase of pneumonia, intrapulmonary sputum was harvested by directly inserting a swab into a resected lung, and the bacterial composition was analyzed using both pathological and microbiological techniques from 15 patients with hematological malignancies, and the results were compared with those from 25 patients with other medical and surgical diseases. Among the 54 bacteria strains isolated from the 40 patients, multidrug-resistant strains were significantly more prevalent in hematological group than in other diseases (16/21 versus 11/33, P = .002). Enterococcus faecium was preferentially isolated from the hematological patients, whereas the methicillin-resistant Staphylococcus aureus was predominantly found in the nonhematological group. Two coagulase-negative Staphylococcus epidermidis strains in hematological diseases may be diagnosed as causative bacteria of pneumonia by both bacterial and pathological techniques. Although the results of this study may not be directly applicable for clinical diagnosis, this approach has a potential to become not only a diagnostic method for bacterial pneumonia, but may be also useful for the analysis of multidrug-resistant pathogens.
  International Journal of Hematology 11/2007; 86(3):225-32. · 1.27 Impact Factor
• Article: 福井大学医学部附属病院における臨床分離菌の薬剤感受性

  政宣 山下, 征男 飛田, 治義 吉田, 慎吾 飴嶋, 武志 石崎, Masanori YAMASHITA, Yukio Hida, Haruyoshi Yoshida, Shingo Ameshima, Takeshi Ishizaki