Biomedical subjects
Publications and source records attributed to Mitsuaki Nagasawa.
Fetal bovine serum (FBS) and adult bovine serum (BS) exhibited bactericidal activity against Helicobacter pylori at various levels, which were higher in BS than in FBS. The bactericidal activity was inactivated by heat treatment at 56 degrees C for 30 min. Our results demonstrated that heat-treated BS is a useful serum source of H. pylori culture medium.
The effectiveness of antibacterial agents against 70 strains of clinically isolated multiple-drug resistant Pseudomonas aeruginosa (MDRP) was measured by the micro dilution method. Fifty of all strains (71%) produced metallo-beta-lactamase and the IMP-1 gene was detected by polymerase chain reaction (PCR). The MIC90 (the minimum inhibitory concentration of an antibiotic necessary to inhibit the growth of 90% of bacterial strains) values of biapenem (BIPM), meropenem (MEPM), tazobactam/piperacillin (TAZ/PIPC), sulbactam/ cefoperazone (SBT/CPZ), cefepime (CFPM), ciprofloxacin (CPFX), pazufloxacin (PZFX), amikacin (AMK) and aztreonam (AZT) were found to be 265, 512, 256, 512, 512, 64, 128, 128 and 128 microg/mL, respectively. The in vitro combination effects of antibacterial agents were examined against 62 strains of MDRP and the synergy or additive effects were evaluated by fractional inhibitory concentration (FIC) index calculated by the checkerboard method. The combination of AMK and AZT showed synergy effects on 15/59 (25.4%) strains of MDRP. The synergy and additive effects on the MDRP strains were also found by the other antibacterial agents combination such as TAZ/PIPC and AMK, CFPM and AMK, and SBT/CPZ and AZT. These results suggested the necessity of further investigation of clinical usefulness.
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Amplicor Mycobacterium Kit (Roch Diagnostics: Japan) is the most widely used kit in Japan for the diagnosis of mycobacteria infections, especially those caused by Mycobacterium tuberculosis, Mycobacterium avium and Mycobacterium intracellulare. We evaluated the reliability of the kit in co-operation with 331 laboratories using the kit in routine examination. We distributed specially prepared 4 test samples to each laboratories. The negative sample was NALC-NaOH treated sputum which showed "negative" when tested by this kit and positive samples were NALC-NaOH treated sputum containing M. bovis or M. intracellurare. False-positive results were reported in 6 out of 331 laboratories (1.8%) and false-negative results were reported from 7 laboratories (2.1%). (The details were 1 out of 331 labs for TB-H sample, 5 out of 331 labs for TB-L sample and 1 out of 316 in MIN sample.) Statistical significance between MWP method and COBAS method was not significant. After receiving and evaluating the test results on the 4 samples, the follow up questionnaires were sent out to 22 laboratories which reported incorrect results and low optical density (O.D.) on positive control. Results of this questionnaire suggested that it was important to follow the package insert instructions and to follow the correct procedures for PCR assay. These results suggested that Amplicor Mycobacterium Kit is reliable for rapid diagnosis of Mycobacteria infections.