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西出 景子ニシデ ケイコ

所属部署医学研究科高度医療教育研究センター
職名講師(診療担当)
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Last Updated :2020/06/03

研究者基本情報

基本情報

    科研費研究者番号:00402561
    ORCID ID:0000-0003-4510-0948

学位

  • 医学博士, 名古屋大学
  • 薬学修士, 大阪大学

経歴

  •   2018年04月 - 現在, 名古屋市立大学, 大学院医学研究科, 講師

研究活動情報

研究分野

  • ライフサイエンス, 医療薬学
  • その他, その他, 病態検査学
  • ライフサイエンス, 細菌学

論文

  • Erythromycin-susceptible but clindamycin-resistant phenotype of ermB-PCR-positive clinical group B streptococci having IS1216E-inserted ermB, Japanese Journal of Infectious Diseases,   2019年, 査読有り
  • High isolation rate and multidrug resistance tendency of penicillin-susceptible group B Streptococcus with reduced ceftibuten susceptibility in Japan., Banno H, Kimura K, Seki T, Jin W, Wachino JI, Yamada K, Nagano N, Arakawa Y, European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology,   2018年05月, 査読有り
  • Analysis of multidrug resistant group B streptococci with reduced penicillin susceptibility forming small, less hemolytic colonies, Hirotsugu Banno, Kouji Kimura, Yosuke Tanaka, Tsuyoshi Sekizuka, Makoto Kuroda, Wanchun Jin, Jun-ichi Wachino, Keiko Yamada, Keigo Shibayama, Yoshichika Arakawa, PLOS ONE, 12, (8) ,   2017年08月, 査読有り, Group B streptococci (GBS; Streptococcus agalactiae) are the leading cause of neonatal invasive diseases and are also important pathogens for elderly adults. Until now, nearly all GBS with reduced penicillin susceptibility (PRGBS) have shown beta-hemolytic activity and grow on sheep blood agar. However, we have previously reported three PRGBS clinical isolates harboring a CylK deletion that form small less hemolytic colonies. In this study, we examined the causes of small, less hemolytic colony formation in these clinical isolates. Isogenic strains were sequenced to identify the mutation related to a small colony size. We identified a 276_277insG nucleic acid insertion in the thiamin pyrophosphokinase (tpk) gene, resulting in premature termination at amino acid 103 in TPK, as a candidate mutation responsible for small colony formation. The recombinant strain Delta tpk, which harbored the 276_277insG insertion in the tpk gene, showed small colony formation. The recombinant strain.cylK, which harbored the G379T substitution in cylK, showed a reduction in hemolytic activity. The phenotypes of both recombinant strains were complemented by the expression of intact TPK or CylK, respectively. Moreover, the use of Rapid ID 32 API and VITEK MS to identify strains as GBS was evaluated clinical isolates and recombinant strains. VITEK MS, but not Rapid ID 32 API, was able to accurately identify the strains as GBS. In conclusion, we determined that mutations in tpk and cylK caused small colonies and reduced hemolytic activity, respectively, and characterized the clinical isolates in detail.
  • High rate of slowly-killed-by-ampicillin phenotype among group B streptococci with reduced penicillin susceptibility, Rina Taniguchi, Kouji Kimura, Akira Miyazaki, Hirotsugu Banno, Wanchun Jin, Keiko Yamada, Jun-ichi Wachino, Yoshichika Arakawa, JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY, 72, (3) 941 - 942,   2017年03月, 査読有り
  • In vitro reduction of antibacterial activity of tigecycline against multidrug-resistant Acinetobacter baumannii with host stress hormone norepinephrine, Masato Inaba, Naoyuki Matsuda, Hirotsugu Banno, Wanchun Jin, Jun-ichi Wachino, Keiko Yamada, Kouji Kimura, Yoshichika Arakawa, INTERNATIONAL JOURNAL OF ANTIMICROBIAL AGENTS, 48, (6) 680 - 689,   2016年12月, 査読有り, The host stress hormone norepinephrine (NE), also called noradrenaline, is reported to augment bacterial growth and pathogenicity, but few studies have focused on the effect of NE on the activity of antimicrobials. The aim of this study was to clarify whether NE affects antimicrobial activity against multidrug-resistant Acinetobacter baumannii (MDR-AB). Time-kill studies of tigecycline (TIG) and colistin (COL) against MDR-AB as well as assays for factors contributing to antibiotic resistance were performed using MDR-AB clinical strains both in the presence and absence of 10 mu M NE. In addition, expression of three efflux pump genes (adeB, adeJ and adeG) in the presence and absence of NE was analysed by quantitative reverse transcription PCR. Viable bacterial cell counts in TIG-supplemented medium containing NE were significantly increased compared with those in medium without NE. In contrast, NE had little influence on viable bacterial cell counts in the presence of COL. NE-supplemented medium resulted in an ca. 2 log increase in growth and in bacterial cell numbers adhering on polyurethane, silicone and polyvinylchloride surfaces. Amounts of biofilm in the presence of NE were ca. 3-fold higher than without NE. Expression of the adeG gene was upregulated 4-6-fold in the presence of NE. In conclusion, NE augmented factors contributing to antibiotic resistance and markedly reduced the in vitro antibacterial activity of TIG against MDR-AB. These findings suggest that NE treatment may contribute to the failure of TIG therapy in patients with MDR-AB infections. (C) 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.
  • Effectual detection of group B streptococci with reduced penicillin susceptibility (PRGBS) by commercially available methicillin-resistant-Staphylococcus aureus (MRSA)-selective agar, Shinako Fukigai, Makiko Morimoto, Kouji Kimura, Yo Doyama, Akira Miyazaki, Chitose Kamiya, Hirotsugu Banno, Eriko Morishima, Tomohiro Onoda, Noriyuki Nagano, Wanchun Jin, Jun-ichi Wachino, Keiko Yamada, Yoshichika Arakawa, DIAGNOSTIC MICROBIOLOGY AND INFECTIOUS DISEASE, 85, (3) 309 - 312,   2016年07月, 査読有り, We evaluated the feasibility and efficacy of a commercially available methicillin-resistant Staphylococcus aureus (MRSA)-selective agar, chromID (TM) MRSA, to detect group B streptococci with reduced penicillin susceptibility (PRGBS) in this study. The results showed 72.4% (21/29) sensitivity and 98.4% (60/61) specificity to detect PRGBS using this method. (C) 2016 Elsevier Inc. All rights reserved
  • A Highly Macrolide-Resistant Campylobacter jejuni Strain with Rare A2074T Mutations in 23S rRNA Genes, Hiroe Ohno, Jun-ichi Wachino, Ryoichi Saito, Wanchun Jin, Keiko Yamada, Kouji Kimura, Yoshichika Arakawa, ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, 60, (4) 2580 - 2581,   2016年04月, 査読有り
  • Molecular Epidemiological Characteristics of Klebsiella pneumoniae Associated with Bacteremia among Patients with Pneumonia, Ryota Ito, Yuichiro Shindo, Daisuke Kobayashi, Masahiko Ando, Wanchun Jin, Jun-ichi Wachino, Keiko Yamada, Kouji Kimura, Tetsuya Yagi, Yoshinori Hasegawa, Yoshichika Arakawa, JOURNAL OF CLINICAL MICROBIOLOGY, 53, (3) 879 - 886,   2015年03月, 査読有り, Some important virulence factors have been elucidated in Klebsiella pneumoniae infections. We investigated the relationship between virulence factors and multilocus sequence types (STs) and assessed the risk factors for bacteremia in patients with pneumonia due to K. pneumoniae. From April 2004 through April 2012, a total of 120 K. pneumoniae isolates from patients with pneumonia (23 with bacteremia and 97 without bacteremia) were collected from 10 medical institutions in Japan. Additionally, 10 strains of K. pneumoniae serotype K2 that were isolated >30 years ago were included in this study. These isolates were characterized using multilocus sequence typing (MLST), and the characteristics of their virulence factors, such as hypermucoviscosity phenotype and RmpA and aerobactin production between patients with and without bacteremia, were examined. MLST analysis was performed on the 120 isolates from patients with pneumonia, and some sequence type groups were defined as genetic lineages (GLs). GL65 was more prevalent among patients with bacteremia (21.7%) than in those without bacteremia (7.2%). The majority of the strains with serotype K2 were classified into GL14 or GL65, and rmpA and the gene for aerobactin were present in all GL65-K2 strains but absent in all GL14-K2 strains. In a multivariate analysis, the independent risk factors for bacteremia included GL65 (adjusted odds ratio [AOR], 9.46; 95% confidence interval [CI], 1.81 to 49.31), as well as neoplastic disease (AOR, 9.94; 95% CI, 2.61 to 37.92), immunosuppression (AOR, 17.85; 95% CI, 1.49 to 214.17), and hypoalbuminemia (AOR, 4.76; 95% CI, 1.29 to 17.61). GL65 was more prevalent among patients with bacteremia and was associated with the virulence factors of K. pneumoniae.
  • Rapid, highly sensitive, and simultaneous detection of staphylococcal enterotoxins in milk by using immuno-pillar devices, Kasama T, Ikami M, Jin W, Yamada K, Kaji N, Atsumi Y, Mizutani M, Murai A, Okamoto A, Namikawa T, Ohta M, Tokeshi M, Baba Y, Analytical Methods, 7, (12) 5092 - 5095,   2015年, 査読有り
  • High isolation rate of MDR group B streptococci with reduced penicillin susceptibility in Japan, Seki T, Kimura K, Reid M.E, Miyazaki A, Banno H, Jin W, Wachino J-I, Yamada K, Arakawa Y, Journal of Antimicrobial Chemotherapy, 70, (10) 2725 - 2728,   2015年, 査読有り
  • Genetic Profiles of Fluoroquinolone-Nonsusceptible Klebsiella pneumoniae among Cephalosporin-Resistant K. pneumoniae, Nagasaka Y, Kimura K, Yamada K, Wachino J.-I, Jin W, Notake S, Yanagisawa H, Arakawa Y, Microbial Drug Resistance, 21, (2) 224 - 233,   2015年, 査読有り
  • Effect of incubation atmosphere on the production and composition of staphylococcal biofilms, Asai K, Yamada K, Yagi T, Baba H, Kawamura I, Ohta M, Journal of Infection and Chemotherapy, 21, (1) 55 - 61,   2015年, 査読有り
  • Comparative analysis of penicillin-susceptible and non-susceptible isolates of group B streptococci by multilocus sequence typing, Yamada R, Kimura K, Nagano N, Nagano Y, Suzuki S, Jin W, Wachino J.-I, Yamada K, Shibayama K, Arakawa Y, Japanese Journal of Infectious Diseases, 68, (4) 326 - 329,   2015年, 査読有り
  • Characterization of piperacillin/tazobactam-resistant Klebsiella oxytoca recovered from a nosocomial outbreak, Fujita A, Kimura K, Yokoyama S, Jin W, Wachino J.-I, Yamada K, Suematsu H, Yamagishi Y, Mikamo H, Arakawa Y, PLoS ONE, 10, (11) ,   2015年, 査読有り
  • Ceftibuten-containing agar plate for detecting group B streptococci with reduced penicillin susceptibility (PRGBS), Kamiya C, Kimura K, Doyama Y, Miyazaki A, Morimoto M, Banno H, Nagano N, Jin W, Wachino J.-I, Yamada K, Arakawa Y, Diagnostic Microbiology and Infectious Disease, 82, (4) 269 - 273,   2015年, 査読有り
  • Rapid, highly sensitive, and simultaneous detection of staphylococcal enterotoxins in milk by using immuno-pillar devices, Kasama T, Ikami M, Jin W, Yamada K, Kaji N, Atsumi Y, Mizutani M, Murai A, Okamoto A, Namikawa T, Ohta M, Tokeshi M, Baba Y, Analytical Methods, 7, (12) 5092 - 5095,   2015年, 査読有り
  • 801Molecular Epidemiological Characteristics of Klebsiella pneumoniae Associated with Bacteremia among Patients with Pneumonia., Ito R, Shindo Y, Kobayashi D, Jin W, Wachino J, Yamada K, Kimura K, Yagi T, Hasegawa Y, Arakawa Y, Open forum infectious diseases,   2014年12月, 査読有り
  • Evaluation of Disk Potentiation Test Using Kirby-Bauer Disks Containing High-Dosage Fosfomycin and Glucose-6-Phosphate To Detect Production of Glutathione S-Transferase Responsible for Fosfomycin Resistance, Jun-ichi Wachino, Kouji Kimura, Keiko Yamada, Wanchun Jin, Yoshichika Arakawa, JOURNAL OF CLINICAL MICROBIOLOGY, 52, (10) 3827 - 3828,   2014年10月, 査読有り
  • Practical Agar-Based Disk Potentiation Test for Detection of Fosfomycin-Nonsusceptible Escherichia coli Clinical Isolates Producing Glutathione S-Transferases, Genki Nakamura, Jun-ichi Wachino, Natsumi Sato, Kouji Kimura, Keiko Yamada, Wanchun Jin, Keigo Shibayama, Tetsuya Yagi, Kumiko Kawamura, Yoshichika Arakawa, JOURNAL OF CLINICAL MICROBIOLOGY, 52, (9) 3175 - 3179,   2014年09月, 査読有り, The number of reports concerning Escherichia coli clinical isolates that produce glutathione S-transferases responsible for fosfomycin resistance (FR-GSTs) has been increasing. We have developed a disk-based potentiation test in which FR-GST producers expand the growth inhibition zone around a Kirby-Bauer disk containing fosfomycin in combination with sodium phosphonoformate (PPF). PPF, an analog of fosfomycin, is a transition-state inhibitor of FosA(PA), a type of FR-GST from Pseudomonas aeruginosa. Considering its mechanism of action, PPF was expected to inhibit a variety of FR-GSTs. In the presence of PPF, zone enlargement around the disk containing fosfomycin was observed for FosA3-, FosA4-, and FosC2-producing E. coli clinical isolates. Moreover, the growth inhibition zone was remarkably enlarged when the Mueller-Hinton (MH) agar plate contained 25 mu g/ml glucose-6-phosphate (G6P). When we retrospectively tested 12 fosfomycin-resistant (MIC, >= 256 mu g/ml) E. coli clinical isolates from our hospital with the potentiation test, 6 FR-GST producers were positive phenotypically by potentiation disk and were positive for FR-GST genes: 5 harbored fosA3 and 1 harbored fosA4. To identify the production of FR-GSTs, we set the provisional cutoff value, 5-mm enlargement, by adding PPF to a fosfomycin disk on the MH agar plates containing G6P. Our disk-based potentiation test reliably identifies FR-GST producers and can be performed easily; therefore, it will be advantageous in epidemiological surveys and infection control of fosfomycin-resistant bacteria in clinical settings.
  • Invasive Infection Caused by Carbapenem-Resistant Acinetobacter soli, Japan, Hiromitsu Kitanaka, Masa-aki Sasano, Satoru Yokoyama, Masahiro Suzuki, Wanchun Jin, Masami Inayoshi, Mitsuhiro Hori, Jun-ichi Wachino, Kouji Kimura, Keiko Yamada, Yoshichika Arakawa, EMERGING INFECTIOUS DISEASES, 20, (9) 1574 - 1576,   2014年09月, 査読有り
  • Novel Integron-Mediated Fosfomycin Resistance Gene fosK, Hiromitsu Kitanaka, Jun-ichi Wachino, Wanchun Jin, Satoru Yokoyama, Masa-aki Sasano, Mitsuhiro Hori, Keiko Yamada, Kouji Kimura, Yoshichika Arakawa, ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, 58, (8) 4978 - 4979,   2014年08月, 査読有り
  • Characterization of Multidrug-Resistant Group B Streptococci with Reduced Penicillin Susceptibility Forming Small Non-Beta-Hemolytic Colonies on Sheep Blood Agar Plates, Hirotsugu Banno, Kouji Kimura, Yosuke Tanaka, Hiromitsu Kitanaka, Wanchun Jin, Jun-ichi Wachino, Keiko Yamada, Keigo Shibayama, Yoshichika Arakawa, JOURNAL OF CLINICAL MICROBIOLOGY, 52, (6) 2169 - 2171,   2014年06月, 査読有り, We isolated and characterized three multidrug-resistant clinical isolates of group B streptococci with reduced penicillin susceptibility (PRGBS) that formed small non-beta-hemolytic colonies on sheep blood agar plates but grew well on chocolate agar plates. They can be overlooked in the bacterial identification step, leading to clinical misdiagnosis and treatment failure.
  • New plasmid-mediated aminoglycoside 6′-N-acetyltransferase, AAC(6′)-Ian, and ESBL, TLA-3, from a Serratia marcescens clinical isolate, Jin W, Wachino J.-I, Kimura K, Yamada K, Arakawa Y, Journal of Antimicrobial Chemotherapy, 70, (5) 1331 - 1337,   2014年, 査読有り
  • Have group A streptococci with reduced penicillin susceptibility emerged?, Suzuki T, Kimura K, Suzuki H, Banno H, Jin W, Jun-ichi Wachino, Yamada K, Arakawa Y, Journal of Antimicrobial Chemotherapy, 70, (4) 1258 - 1259,   2014年, 査読有り
  • Complete Genome Sequence of Bacillus cereus NC7401, Which Produces High Levels of the Emetic Toxin Cereulide, Akira Takeno, Akira Okamoto, Keizo Tori, Kenshiro Oshima, Hideki Hirakawa, Hidehiro Toh, Norio Agata, Keiko Yamada, Naotake Ogasawara, Tetsuya Hayashi, Tohru Shimizu, Satoru Kuhara, Masahira Hattori, Michio Ohta, JOURNAL OF BACTERIOLOGY, 194, (17) 4767 - 4768,   2012年09月, 査読有り, We report the complete and annotated genome sequence of Bacillus cereus NC7401, a representative of the strain group that causes emetic-type food poisoning. The emetic toxin, cereulide, is produced by a nonribosomal protein synthesis (NRPS) system that is encoded by a gene cluster on a large resident plasmid, pNCcld.
  • Application of both high-performance liquid chromatography combined with tandem mass spectrometry shotgun and 2-D polyacrylamide gel electrophoresis for streptococcal exoproteins gave reliable proteomic data, Akira Okamoto, Tadao Hasegawa, Keiko Yamada, Michio Ohta, MICROBIOLOGY AND IMMUNOLOGY, 55, (2) 84 - 94,   2011年02月, 査読有り, Streptococci secrete a large number of exoproteins including virulence-associated toxins and enzymes. To construct a reliable database of streptococcal exoproteins, we integrated the results that were derived from two approaches: LC-based shotgun proteomic analysis and 2-D PAGE-based proteomic analysis. We identified 74 and 82 proteins by LC-based and gel-based analysis, respectively. Forty-five proteins were identified by both methods. In addition, two proteins, one identified by both methods and the other only by LC-based shotgun analysis, were newly annotated. We therefore found the importance of combinational analysis by the two methods for the construction of a more reliable database.
  • A New Microarray System to Detect Streptococcus pneumoniae Serotypes, Yuka Tomita, Akira Okamoto, Keiko Yamada, Testuya Yagi, Yoshinori Hasegawa, Michio Ohta, JOURNAL OF BIOMEDICINE AND BIOTECHNOLOGY, 2011,   2011年, 査読有り, Streptococcus pneumoniae, one of the most common gram-positive pathogens to colonize the human upper respiratory tract, is responsible for many severe infections, including meningitis and bacteremia. A 23-valent pneumococcal vaccine is available to protect against the 23 S. pneumoniae serotypes responsible for 90% of reported bacteremic infections. Unfortunately, current S. pneumoniae serotype testing requires a large panel of expensive antisera, assay results may be subjective, and serotype cross-reactions are common. For this study, we designed an oligonucleotide-based DNA microarray to identify glycosyltransferase gene sequences specific to each vaccine-related serotype. Out of 56 isolates representing different serotypes, only one isolate, representing serotype 23A, was not detected correctly as it could not be distinguished from serotype 23F. Our data suggest that the microarray provides a more cost-effective and reliable way of monitoring pneumococcal capsular types.
  • Detection of invasive protein profile of Streptococcus pyogenes M1 isolates from pharyngitis patients, Tadao Hasegawa, Akira Okamoto, Takuya Kamimura, Ichiro Tatsuno, Shin-Nosuke Hashikawa, Mitsutaka Yabutani, Masakado Matsumoto, Keiko Yamada, Masanori Isaka, Masaaki Minami, Michio Ohta, APMIS, 118, (3) 167 - 178,   2010年03月, 査読有り, Streptococcal toxic shock syndrome (STSS) is a re-emerging infectious disease in Japan and many other developed countries. Epidemiological studies have revealed that the M1 serotype of Streptococcus pyogenes is the most dominant causative isolate of STSS. Recent characterization of M1 isolates revealed that the mutation of covS, one of the two-component regulatory systems, plays an important role in STSS by altering protein expression. We analyzed the M1 S. pyogenes clinical isolates before or after 1990 in Japan, using two-dimensional gel electrophoresis (2-DE) and pulsed-field gel electrophoresis (PFGE). PFGE profiles were different between the isolates before and after 1990. Markedly different profiles among isolates after 1990 from STSS and pharyngitis patients were detected. Sequence analysis of two-component regulatory systems showed that covS mutations were detected not only in STSS but also in three pharyngitis isolates, in which proteins from the culture supernatant displayed the invasive type. The mutated CovS detected in the pharyngitis isolates had impaired function on the production of streptococcal pyrogenic exotoxin B (SpeB) analyzed by 2-DE. These results suggest that several covS mutations that lead to the malfunction of the CovS protein occurred even in pharyngeal infection.
  • Evaluation of selection media for the detection of borderline MRSA, Keiko Yamada, Kazuhisa Inuzuka, Norio Tatsumi, Ikuyo Sanzen, Teruko Ohkura, Akira Okamoto, Tadao Hasegawa, Michio Ohta, JOURNAL OF INFECTION AND CHEMOTHERAPY, 16, (1) 19 - 24,   2010年02月, 査読有り, Recently, hospital-associated as well as community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains showing a low level of resistance to oxacillin have emerged worldwide, and as a result, a highly sensitive method to detect MRSA has become more important. To prevent MRSA being overlooked, some selection agar media have recently been developed. We evaluated six commercially available selection agar media in regard to the detection of 35 borderline MRSA (BOMRSA) strains which were mecA-positive but showed low resistance to oxacillin. The MIC values of oxacillin differed between the broth dilution method and the agar dilution method, and 11 of the 35 BOMRSA strains were judged as sensitive by the broth dilution method and 14 of the 35 strains were judged as sensitive by the agar dilution method. Thirty-two of the 35 strains were also judged as sensitive by an oxacillin disk diffusion test. Moreover, there was no consistent pattern of resistance to the tested beta-lactams among the BOMRSA strains. Some commercially available selection media designed for the detection of MRSA contain a beta-lactam antibiotic; oxacillin, ceftizoxime, or cefoxitin, and we evaluated media containing each of these agents. The detection sensitivities of cefoxitin-based agar media, such as CHROMagar MRSA and MRSA ID, for BOMRSA were 100% at 24-h culture. On the other hand, the media containing oxacillin or ceftizoxime gave lower results at 24 h, suggesting that, possibly, BOMRSA strains may not to be able to grow on these media. These results suggest that cefoxitin-based agar media should be recommended for the first-round screening of BOMRSA.
  • Effect of cyclic bis(3′-5′)diguanylic acid and its analogs on bacterial biofilm formation, Ishihara Y, Hyodo M, Hayakawa Y, Kamegaya T, Yamada K, Okamoto A, Hasegawa T, Ohta M, FEMS Microbiology Letters, 301, (2) 193 - 200,   2009年12月, 査読有り
  • Nationwide epidemiological study revealed the dissemination of meticillin-resistant Staphylococcus aureus carrying a specific set of virulence-associated genes in Japanese hospitals, Teruko Ohkura, Keiko Yamada, Akira Okamoto, Hisashi Baba, Yasuyoshi Ike, Yoshichika Arakawa, Tadao Hasegawa, Michio Ohta, JOURNAL OF MEDICAL MICROBIOLOGY, 58, (10) 1329 - 1336,   2009年10月, 査読有り, To study comprehensive toxin profiles and the chromosomal diversity of current Japanese hospital-associated meticillin-resistant Staphylococcus aureus (HA-MRSA) strains, we conducted PCR-based identification of 28 toxin genes, and staphylococcal cassette chromosome mec (SCCmec) typing and PFGE analysis of 208 MRSA strains isolated from 100 hospitals throughout Japan. Of the tested HA-MRSA strains, 80.3 % were tst-positive. The most frequent toxin gene profile was characterized by the carriage of 13 genes, tst, sec, seg, sei, sel, sem, sen, seo, lukED, hla, hlb, Not and hlg-2. Ninety of the 208 strains had this profile, which was named pattern A. Among the 118 non-pattern A strains, 100 had similar toxin gene profiles, the concordance rates to pattern A of which were more than 80 %. Consequently, 91.3 % of the examined HA-MRSA strains carried similar toxin profiles, although PFGE patterns showed a wide variation. These strains belonged to SCCmec type II, agr II and coagulase type II. We concluded that, unlike MRSA from many other countries, most of the Japanese HA-MRSA strains belonged to, or were related to, a specific group carrying the set of 13 toxin genes, irrespective of chromosomal diversity. In addition, among the 13 toxin genes, the coexistence rates of tst, sec and sel, and those of seg, sei, sem, sen and seo, were higher than for the other toxin genes. High coexistence rates of tst, sec and sel genes suggested the presence of the pathogenicity island SaPIn1 in these strains.
  • Variations in amount of TSST-1 produced by clinical methicillin resistant Staphylococcus aureus (MRSA) isolates and allelic variation in accessory gene regulator (agr) locus, Miki Nagao, Akira Okamoto, Keiko Yamada, Tadao Hasegawa, Yoshinori Hasegawa, Michio Ohta, BMC MICROBIOLOGY, 9,   2009年03月, 査読有り, Background: Staphylococcus aureus (S. aureus) is an important pathogen associated with both nosocomial and community-acquired infections and its pathogenicity is attributed to its potential to produce virulence factors. Since the amount of toxin produced is related to virulence, evaluating toxin production should be useful for controlling S. aureus infection. We previously found that some strains produce relatively large amounts of TSST-1; however, no reports have described the amount of TSST-1 produced by clinical isolates. Methods: Amounts of TSST-1 produced by clinical methicillin resistant S. aureus (MRSA) isolates were measured by Western blotting. We determined their accessory gene regulator (agr) class by PCR and investigated whether TSST-1 production correlates with variations in the class and structure of the agr. Results: We found that 75% of surveyed MRSA isolates (n = 152) possessed the tst gene and that 96.7% belonged to agr class 2. The concentrations of TSST-1 secreted into culture supernatants by 34 strains measured by Western blotting differed 170-fold. Sequencing the entire agr locus (n = 9) revealed that some had allelic variations regardless of the amount of TSST-1 produced whereas sequencing the sar, sigma factor B and the tst promoter region revealed no significant changes. Conclusion: The amounts of TSST-1 produced by clinical MRSA isolates varied. The present results suggest that TSST-1 production is not directly associated with the agr structure, but is instead controlled by unknown transcriptional/translational regulatory systems, or synthesized by multiple regulatory mechanisms that are interlinked in a complex manner.
  • Immuno-pillar chip: Multiplex detection of proteins in real samples, Kawakami A, Ikami M, Okamoto Y, Kaji N, Wanchun J, Yamada K, Ohata M, Tazawa H, Ebata T, Tokeshi M, Baba Y, Proceedings of Conference, MicroTAS 2009 - The 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences, 436 - 438,   2009年, 査読有り
  • Microchip electrophoresis for specific gene detection of the pathogenic bacteria V. cholerae by circle-to-circle amplification, Mahmoudian L, Melin J, Mohamadi M.R, Yamada K, Ohta M, Kaji N, Tokeshi M, Nilsson M, Baba Y, Analytical Sciences, 24, (3) 327 - 332,   2008年, 査読有り
  • Analysis of twin-arginine translocation pathway homologue in Staphylococcus aureus, Keiko Yamada, Ikuyo Sanzen, Teruko Ohkura, Akira Okamoto, Keizo Torii, Tadao Hasegawa, Michio Ohta, CURRENT MICROBIOLOGY, 55, (1) 14 - 19,   2007年07月, 査読有り, Staphylococcus aureus releases a large number of exoproteins, including membrane-active proteins and toxins with superantigenic activity involved in pathogenicity. However, the export pathways of exoproteins in S. aureus have not been reported. We analyzed the function of the staphylococcal twin-arginine translocation (Tat) pathway homologue, the presence of which was recently discovered according to the genome database. The amino-acid sequences of the Tat homologues of S. aureus do not have a high similarity with those of Escherichia coli and other bacteria. Constructed tatC-deficient mutants from distinct parent strains showed the same patterns of exoproteins compared with those of parent strains on two-dementional gel electrophoresis, and the amounts of secreted staphylococcal enterotoxins and toxic shock syndrome toxin-1, of which signal peptides have some features often seen in signal sequences of Tat-dependent proteins, did not change with Western blotting analyses. Therefore, it seems that the Tat pathway does not play a major role in the secretion system of S. aureus, but other export pathways may play an important role in toxin secretion. This is the first experimental report showing the influence of the Tat pathway on the secretion of S. aureus.
  • A new phylogenetic cluster of cereulide-producing Bacillus cereus strains, Maria Vassileva, Keizo Torii, Megumi Oshimoto, Akira Okamoto, Norio Agata, Keiko Yamada, Tadao Hasegawa, Michio Ohta, JOURNAL OF CLINICAL MICROBIOLOGY, 45, (4) 1274 - 1277,   2007年04月, 査読有り, Phenotypic and molecular studies have established that cereulide-producing strains of Bacillus cereus are a distinct and probably recently emerged clone within the Bacillus population. We analyzed a set of B. cereus strains, both cereullide producers and nonproducers, by multilocus sequence typing. Consistent with earlier reports, nonproducers demonstrated high heterogeneity. Most cereullide-producing strains and all flagellar antigen type H1 strains were allocated to the known sequence type of exclusively emetic B. cereus strains. Several cereulide-producing strains, however, were recovered at a new phyllogenetic location, all of which were serotype H3 or H12. We hypothesize that the group of cereulide producers is diversifying progressively, probably by lateral transfer of the corresponding gene complex.
  • Microchip electrophoresis for detection of circle-to-circle amplification products towards sensitive and rapid DNA analysis, Laili Mahmoudian, Jonas Melin, Mohamad Reza Mohamadi, Keiko Yamada, Michio Ohta, Noritada Kaji, Manabu Tokeshi, Mats Nilsson, Yoshinobu Baba, CHEMISTRY LETTERS, 36, (3) 396 - 397,   2007年03月, 査読有り, A new method for fast and precise analysis of circle-to-circle amplification (C2CA) products by microchip electrophoresis has been developed. Stable C2CA products were produced by applying a new enzymatic step to C2CA. Detection was carried out within 55s with RSD of migration time of 3.6% (it = 6) enabling reproducibility and high speed. A real sample of bacterial pathogen (V. Cholerae) at single nucleotide level was detected successfully based on this method.
  • Growth phase-dependent effect of clindamycin on production of exoproteins by Streptococcus pyogenes, Jun Sawai, Tadao Hasegawa, Takuya Kamimura, Akira Okamoto, Daisuke Ohmori, Nobuyuki Nosaka, Keiko Yamada, Keizo Torii, Michio Ohta, ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, 51, (2) 461 - 467,   2007年02月, 査読有り, The administration of high-dose clindamycin plus benzylpenicillin has been recommended for the treatment of streptococcal toxic shock-like syndrome caused by Streptococcus pyogenes, and clindamycin has been found to be more effective than beta-lactams in retrospective analyses of human cases. Although therapeutic doses of clindamycin have also been shown to be effective against experimental infections and clindamycin has great efficacy against the production of bacterial exoproteins, we recently reported that the level of production of some exoproteins was unchanged or even increased by a subinhibitory dose of clindamycin when it is added upon the initiation of bacterial culture and the treated cultures were analyzed by two-dimensional gel electrophoresis. In this study we further examined the effect of clindamycin on the production of exoproteins by adding it to Streptococcus pyogenes cultures during various growth phases. We found that the levels of production of some proteins, NAD(+) glycohydrolase, streptolysin 0, and streptococcal inhibitor of complement, were increased when clindamycin was added at early-log-phase growth, which was the result that was seen when clindamycin was added at the beginning of culture. However, clindamycin inhibited the production of most types of proteins when it was administered to Streptococcus pyogenes cultures at mid-log-phase growth. In csrS- or mga-knockout bacterial strains, the increase in exoproteins seen in parental strains was considerably inhibited. Our study indicates that the in vitro effect of clindamycin on the production of exoproteins greatly depends on the growth phase of bacteria and some regulatory factors of Streptococcus pyogenes that are involved in this phenomenon.
  • Two cases of sucrose-fermenting Vibrio vulnificus infection in which 16S rDNA sequencing was useful for diagnosis, M Nagao, Y Shimizu, Y Kawada, H Baba, K Yamada, K Torii, M Ohta, JAPANESE JOURNAL OF INFECTIOUS DISEASES, 59, (2) 108 - 110,   2006年04月, 査読有り, Vibrio vulnificus is a Gram-negative bacterium which is associated with severe infections in humans. We experienced two cases of sucrose-fermenting V. vulnificus infection. The causative agents in both cases were unidentifiable by conventional identification systems because of their unique characteristics, and sequencing of 16S rDNA was found to be useful for diagnosis.
  • Phylogenetic analysis of Bacillus cereus isolates from severe systemic infections using multilocus sequence typing scheme, Maria Vassileva, Keizo Torii, Megumi Oshimoto, Akira Okamoto, Norio Agata, Keiko Yamada, Tadao Hasegawa, Michio Ohta, MICROBIOLOGY AND IMMUNOLOGY, 50, (9) 743 - 749,   2006年, 査読有り, Bacillus cereus strains from cases of severe or lethal systemic infections, including respiratory symptoms cases, were analyzed using multilocus sequence typing scheme of B. cereus MLST database. The isolates were evenly distributed between the two main clades, and 60% of them had allele profiles new to the database. Half of the collection's strains clustered in a lineage neighboring Bacillus anthracis phylogenetic origin. Strains from lethal cases with respiratory symptoms were allocated in both main clades. This is the first report of strains causing respiratory symptoms to be identified as genetically distant from B. anthracis. The phylogenetic location of the presented here strains was compared with all previously submitted to the database isolates from systemic infections, and were found to appear in the same clusters where clinical isolates from other studies had been assigned. It seems that the pathogenic strains are forming clusters on the phylogenetic tree.

講演・口頭発表等

  • ベッドサイドにおける抗がん剤の曝露調査 〜外来化学療法室全体の曝露状況を考える〜, 奥苑朱加, 青木有希, 林孝弘, 西出景子, 近藤祐樹, 片岡智哉, 山本由香, 田代雄祐, 竹本将士, 鬼頭典子, 佐橋朋代, 成瀬久美, 黒田純子, 木村和哲, 第 26 回日本医療薬学会年会


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