Kayo Shimada

National Institute of Infectious Diseases, Tokyo, Edo, Tōkyō, Japan

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Publications (13)46.7 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Background:Metallo-β-lactamase, an IMP-type enzyme, has been reported in different geographical areas in various Gram-negative bacteria. However, risk factors and epidemiology pertaining to IMP-producing E. cloacae have not been systematically evaluated.Methods:We conducted a retrospective, matched case-control study in addition to thorough molecular analyses on clinically isolated IMP-type-metallo-β-lactamase-producing-E. cloacae (IMP-E. cloacae). Unique cases with IMP-E. cloacae isolation were included. Patients with IMP-E. cloacae were matched to uninfected controls at a ratio of 1:3.Results:Fifteen IMP-E. cloacae cases were identified, with five from blood, and they were matched to 45 uninfected controls. All (100%) patients with isolation of IMP-E. cloacae had indwelling devices at the time of IMP-E. cloacae isolation compared with one (2.2%) uninfected control. Independent predictors for IMP-E. cloacae isolation were identified as cephalosporin exposure and invasive procedures within 3 months. Although in-hospital mortality rates were similar between cases and controls (14.3% vs 13.3%), the in-hospital mortality of IMP-E. cloacae bacteremia cases was significantly higher (40%) than in controls. IMP-E. cloacae isolates were frequently positive for other resistant determinants. Minimum inhibitory concentrations (MICs) of meropenem and imipenem were not elevated; 10 (67%) and 12 (80%) out of 15 IMP-E. cloacae isolates had an MIC ≤1 mg/L. A phylogenetic tree showed a close relation among IMP-E. cloacae samples.Conclusions:Indwelling devices, exposure to cephalosporin, and history of invasive procedures were associated with isolation of IMP-E. cloacae. Screening for carbapenemase production is important to apply appropriate clinical management and infection control measures.
    Antimicrobial Agents and Chemotherapy 04/2014; · 4.57 Impact Factor
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    ABSTRACT: New Delhi metallo-β-lactamase-3 (NDM-3) was identified in a multidrug-resistant Escherichia coli isolate, NCGM77, obtained from the feces of a patient in Japan. The enzymatic activities of NDM-3 against β-lactams were similar to those of NDM-1, although NDM-3 showed slightly lower kcat/Km ratios for all the β-lactams tested except doripenem. The genetic context surrounding blaNDM-3 was tnpA-blaNDM-3-bleMBL-trpF-dsbC-tnpA-sulI-qacEdeltaI-aadA2-dfrA1, which was present on an approximately 250-kilobase plasmid.
    Antimicrobial Agents and Chemotherapy 03/2014; · 4.57 Impact Factor
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    ABSTRACT: Forty-nine clinical isolates of multidrug-resistant Acinetobacter baumannii were obtained from 12 hospitals in 7 prefectures throughout Japan. Molecular phylogenetic analysis revealed the clonal spread of A. baumannii ST208 and ST455 isolates harboring armA and ST512 harboring armA and blaOXA-72. These findings show that A. baumannii isolates harboring armA are disseminated throughout Japan, as well as being the first report to show that A. baumannii strains harboring blaOXA-72 and armA are emerging in hospitals in Japan.
    Antimicrobial Agents and Chemotherapy 02/2014; · 4.57 Impact Factor
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    ABSTRACT: Drug-resistant Providencia rettgeri producing metallo-beta-lactamase and 16S rRNA methylase has been reported in several countries. We analyzed P. rettgeri clinical isolates with resistance to carbapenems and aminoglycosides in a hospital in Nepal. Five clinical isolates of multidrug-resistant P. rettgeri were obtained in a hospital in Nepal. Antimicrobial susceptibilities were determined using the microdilution method and entire genomes were sequenced to determine drug-resistant genes. Epidemiological analysis was performed by pulsed-field gel electrophoresis. Four of the 5 isolates were resistant to carbapenems (imipenem and meropenem), with MICs >=16 mg/L, with the remaining isolate showing intermediate resistance to imipenem, with an MIC of 2 mg/L and susceptibility to meropenem with an MIC <=1 mg/L. All 5 isolates had blaVEB-1. Of the 4 carbapenem-resistant strains, 3 had blaNDM-1 and 1 had blaOXA-72. All isolates were highly resistant to aminoglycosides (MICs >=1,024 mg/L) and harbored armA. As the result of pulsed-field gel electrophoresis pattern analysis in the 5 P. rettgeri isolates, 4 had identical PFGE patterns and the fifth showed 95.7% similarity. This is the first report describing multidrug-resistant P. rettgeri strains harboring blaNDM-1 or blaOXA-72 and armA isolated from patients in Nepal.
    BMC Infectious Diseases 02/2014; 14(1):56. · 3.03 Impact Factor
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    ABSTRACT: Spondylodiscitis caused by Parvimonas micra, a rarely reported infection, might be under-detected using conventional methods. This report of the detection and treatment of two cases of spondylodiscitis due to P. micra and review of the literature indicates that the use of gene sequencing methods might improve the accuracy of diagnosing this infection.
    International journal of infectious diseases: IJID: official publication of the International Society for Infectious Diseases 01/2014; · 2.17 Impact Factor
  • International journal of antimicrobial agents 08/2013; · 3.03 Impact Factor
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    ABSTRACT: Two novel IMP-type metallo-β-lactamase variants, IMP-43 and IMP-44, were identified in multidrug-resistant Pseudomonas aeruginosa isolates obtained in medical settings in Japan. Analysis of their predicted amino acid sequences revealed that IMP-43 had an amino acid substitution (Val67Phe) compared with IMP-7 and that IMP-44 had two substitutions (Val67Phe and Phe87Ser) compared with IMP-11. The amino acid residue at position 67 is located at the end of a loop close to the active site, consisting of residues 60 to 66 in IMP-1, and the amino acid residue at position 87 forms a hydrophobic patch close to the active site with other amino acids. Escherichia coli expressing blaIMP-43 was more resistant to doripenem and meropenem but not to imipenem than that expressing blaIMP-7. E. coli expressing blaIMP-44 was more resistant to doripenem, imipenem and meropenem than that expressing blaIMP-11. IMP-43 had more efficient catalytic activities against all three carbapenems than IMP-7, indicating that substitution of Val67Phe contributed to increased catalytic activities against carbapenems. IMP-44 had more efficient catalytic activities against all carbapenems tested than IMP-11, as well as increased activities compared with IMP-43, indicating that the substitutions at both Val67Phe and Phe87Ser contributed to increased catalytic activities against carbapenems.
    Antimicrobial Agents and Chemotherapy 07/2013; · 4.57 Impact Factor
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    ABSTRACT: Pseudomonas aeruginosa NCGM1588 has a novel chromosomal class 1 integron, In151, which includes the aac(6' )-Iaj gene. The encoded protein, AAC(6' )-Iaj, was found to consist of 184 amino acids, with 70% identity to AAC(6' )-Ia. Escherichia coli transformed with a plasmid containing the aac(6' )-Iaj gene acquired resistance to all aminoglycosides tested except gentamicin. Of note, aac(6' )-Iaj contributed to the resistance to arbekacin. Thin-layer chromatography revealed that AAC(6' )-Iaj acetylated all aminoglycosides tested except gentamicin. These findings indicated that AAC(6' )-Iaj is a functional acetyltransferase that modifies the amino groups at the 6' positions of aminoglycosides and contributes to aminoglycoside resistance of P. aeruginosa NCGM1588, including arbekacin.
    Antimicrobial Agents and Chemotherapy 10/2012; · 4.57 Impact Factor
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    ABSTRACT: To detect aminoglycoside 6'-N-acetyltransferase-Ib [AAC(6')-Ib]-producing, Pseudomonas aeruginosa isolates which are a frequent cause of nosocomial infections in Japan, an immunochromatographic assay was developed using two kinds of monoclonal antibodies (mAbs) recognizing AAC(6')-Ib. The results of the assessment were fully consistent with those of aac(6')-Ib PCR analyses.
    Journal of microbiological methods 05/2012; 91(1):114-6. · 2.43 Impact Factor
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    ABSTRACT: The emergence of multidrug-resistant (MDR) Pseudomonas aeruginosa isolates producing IMP-type metallo-β-lactamases (MBLs) and aminoglycoside 6'-N-acetyltransferase [AAC(6')-Iae] has become a serious problem in medical settings in Japan. A total of 217 MDR P. aeruginosa isolates were obtained from August 2009 to April 2010 from patients at 144 hospitals in Japan, of which 145 (66.8%) were positive for IMP-type MBLs and AAC(6')-Iae when tested with an immunochromatographic assay. Polymerase chain reaction (PCR) showed that these isolates were also positive for blaIMP and aac(6')-Iae genes. When these IMP-type MBL- and AAC(6')-Iae-producing isolates were analysed by pulsed-field gel electrophoresis (PFGE), two clusters (I and II) were detected. Most of the isolates (88.3%; 128/145) were grouped under cluster I and had multilocus sequence type ST235 and serotype O11, except for one isolate that was ST991 and serotype O3. The isolates were mainly isolated from the urinary tract (82/145; 56.6%) and respiratory tract (58/145; 40.0%). The epidemiological properties of the isolates belonging to cluster I were similar to those of MDR P. aeruginosa isolates that have been previously reported in Japan. The remaining 16 isolates belonged to cluster II, had identical PFGE patterns and were multilocus sequence type ST991 and serotype O18; all of these isolates were isolated from the respiratory tract. The properties of isolates belonging to cluster II have not been previously described, indicating that a novel IMP-type MBL- and AAC(6')-Iae producing P. aeruginosa strain is emerging in Japan. Isolates belonging to both clusters were isolated from different parts of the country.
    International journal of antimicrobial agents 04/2012; 39(6):518-21. · 3.03 Impact Factor
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    ABSTRACT: A method for rapid identification of antiseptic- and methicillin-resistant Staphylococcus aureus (MRSA) based on 3 loop-mediated isothermal amplification (LAMP) assays was developed. LAMP targeting the femB gene identified S. aureus with 100% specificity, and LAMP targeting the mecA gene associated with methicillin resistance identified methicillin-resistant staphylococci with 100% specificity. LAMP targeting the qacA/B gene encoding an efflux pump responsible for antiseptic resistance identified high-acriflavine-resistant (MIC≥100 mg/L) MRSA (92.5% positive) and acriflavine-susceptible (MIC<25 mg/L) MRSA (100% negative). They were performed under the same reaction conditions within 60 min at 63 °C. The combined LAMP assays will be useful for rapid identification of S. aureus isolates and determination of their antibiotic and antiseptic resistance patterns with regard to methicillin and organic cationic substrates.
    Journal of microbiological methods 02/2011; 84(2):251-4. · 2.43 Impact Factor
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    ABSTRACT: To develop an easy-to-use method for the rapid detection of antibiotic-resistant bacteria. Here, a new immunochromatographic assay specific for aminoglycoside 6'-N-acetyltransferase AAC(6')-Iae was designed. AAC(6')-Iae is a significant marker molecule for multidrug-resistant (MDR) Pseudomonas aeruginosa isolates in Japan. Monoclonal antibodies specific for AAC(6')-Iae were used to construct the assay. The assessment of the assay was performed using 116 P. aeruginosa clinical isolates obtained from hospitals in the Kanto area of Japan where little was known about AAC(6')-Iae producers. PCR analyses of the aac(6')-Iae and class 1 integron, antimicrobial susceptibility testing and PFGE analysis were performed to characterize positive strains. The detection limit of the assay was 1.0 x 10(5) cfu. Of 116 clinical isolates, 60 were positive for AAC(6')-Iae using the assay. The results of assessment with clinical isolates were fully consistent with those of aac(6')-Iae PCR analyses, showing no false positives or negatives. All positive strains detected by the assay showed MDR phenotypes that were resistant to several classes of antibiotic. PFGE analysis showed that 59 of 60 positive strains tightly clustered, and these included clonal expansions. The developed assay is an easy-to-use and reliable detection method for AAC(6')-Iae-producing MDR P. aeruginosa. This approach may be applicable for screening and investigation of antibiotic-resistant bacteria as an alternative to PCR analysis.
    Journal of Antimicrobial Chemotherapy 07/2010; 65(7):1382-6. · 5.34 Impact Factor
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    ABSTRACT: A colorimetric loop-mediated isothermal amplification (LAMP) assay with hydroxy naphthol blue was designed to amplify a region in the outer membrane lipoprotein (oprL) gene of Pseudomonas aeruginosa. The LAMP assay showed 100% specificity for the serogroup and other bacteria, and the sensitivity was 10-fold higher than that of the PCR assays. The LAMP assay could detect P. aeruginosa inoculated in mouse feces at 130 colony-forming units (CFU)/0.1g feces (3.25 CFU/reaction). The assay was completed within 2h from DNA extraction. In a field trial, the LAMP assay revealed that none of the 27 samples was obtained from 2 specific pathogen-free (SPF) mouse facilities that were monitoring infection with P. aeruginosa; 1 out of 12 samples from an SPF mouse facility that was not monitoring infection with P. aeruginosa and 2 out of 7 samples from a conventional mouse facility were positive for P. aeruginosa. In contrast, P. aeruginosa was not detected in any of the samples by a conventional culture assay. Thus, this colorimetric LAMP assay is a simple and rapid method for P. aeruginosa detection.
    Journal of microbiological methods 03/2010; 81(3):247-52. · 2.43 Impact Factor

Publication Stats

27 Citations
46.70 Total Impact Points


  • 2012–2014
    • National Institute of Infectious Diseases, Tokyo
      Edo, Tōkyō, Japan
  • 2010–2012
    • National Center for Global Health and Medicine in Japan
      • Disease Control and Prevention Center
      Edo, Tōkyō, Japan
  • 2011
    • Iwate Medical University
      Morioka, Iwate, Japan