Faculty Profiles - SHIBAYAMA Keigo

Papers - SHIBAYAMA Keigo

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Reduction in chlorhexidine efficacy against multi-drugresistant Acinetobacter baumannii international clone II Reviewed

M. Hayashi, K. Kawamura, M. Matsui, M. Suzuki, S. Suzuki, K. Shibayama, Y. Arakawa

JOURNAL OF HOSPITAL INFECTION Vol. 95 ( 3 ) page： 318 - 323 2017.3

Language：English Publishing type：Research paper (scientific journal) Publisher：W B SAUNDERS CO LTD

Background: Nosocomial infections caused by Acinetobacter baumannii international clone II (IC II) can cause severe clinical outcomes. Aim: Differential evaluation of bactericidal efficacy of chlorhexidine gluconate (CHX) and benzethonium chloride (BZT) disinfectants against IC II and non-IC II isolates.
Methods: Minimum inhibitory concentrations (MICs) of CHX and BZT were determined for 137 A. baumannii IC II, 99 non-IC II and 69 non-baumannii isolates, further classified according to MIC values into disinfectant-reduced susceptible (DRS) and disinfectantsusceptible (DS) groups. Time-kill curves and minimum bactericidal concentrations (MBCs) were evaluated for representative isolates in each group.
Results: CHX and BZT MIC(90)s for IC II isolates were 100 and 175 mg/L, respectively, but those for non-IC II and non-baumannii isolates were < 100 mg/L. Nevertheless, time-kill curves indicated that CHX and BZT reduced live bacterial cell number by 5 log(10) for IC II and non-IC II isolates within 30 s when used at 1000 mg/L, comparable to practical use concentrations. CHX MBC at 30 s was 1000 mg/L for IC II and non-IC II isolates, and was not influenced by addition of 3% bovine serum albumin (BSA); BZT MBC at 30 s was 100 mg/L without BSA and increased up to 500 mg/L upon addition of BSA. No significant differences in BSA were found between DRS and DS isolates.
Conclusion: CHX and BZT were effective against Acinetobacter spp. including IC II at a concentration of 1000 mg/L and exposure for at least 30 s, but their concentrations should be considered carefully to ensure sufficient effects in both clinical and healthcare settings.(C) 2016 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jhin.2016.12.004

Emergence of New Delhi metallo-beta-lactamase 1 and other carbapenemase-producing Acinetobacter calcoaceticus-baumannii complex among patients in hospitals in Ha Noi, Viet Nam Reviewed Open Access

D. N. Tran, H. H. Tran, M. Matsui, M. Suzuki, S. Suzuki, K. Shibayama, T. D. Pham, T. T. Van Phuong, D. A. Dang, H. S. Trinh, C. T. Loan, L. T. V. Nga, H. R. Van Doorn, H. F. L. Wertheim

EUROPEAN JOURNAL OF CLINICAL MICROBIOLOGY & INFECTIOUS DISEASES Vol. 36 ( 2 ) page： 219 - 225 2017.2

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

Acinetobacter baumannii is an important cause of multidrug-resistant hospital acquired infections in the world. Here, we investigate the presence of NDM-1 and other carbapenemases among carbapenem-resistant A. baumannii isolated between August 2010 and December 2014 from three large hospitals in Hanoi, Vietnam. We identified 23/582 isolates (4 %) (11 from hospital A, five from hospital B, and seven from hospital C) that were NDM-1 positive, and among them 18 carried additional carbapenemase genes, including seven isolates carrying NDM-1, IMP-1, and OXA-58 with high MICs for carbapenems. Genotyping indicated that NDM-1 carrying A. baumannii have expanded clonally in these hospitals. Five new STs (ST1135, ST1136, ST1137, ST1138, and ST1139) were identified. One isolate carried NDM-1 on a plasmid belonging to the N-repA replicon type; no NDM-1-positive plasmids were identified in the other isolates. We have shown the extent of the carbapenem resistance and the local clonal spread of A. baumannii carrying NDM-1 in these hospitals; coexistence of NDM-1 and IMP-1 is reported for the first time from Vietnam here, and this will further seriously limit future therapeutic options.

DOI： 10.1007/s10096-016-2784-8

Evaluation of a commercial loop-mediated isothermal amplification assay for diagnosis of Bordetella pertussis infection Reviewed

Kazunari Kamachi, Takumi Moriuchi, Yukihiro Hiramatsu, Nao Otsuka, Keigo Shibayama

JOURNAL OF MICROBIOLOGICAL METHODS Vol. 133 page： 20 - 22 2017.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We evaluated a commercial loop-mediated isothermal amplification (LAMP) assay kit for Bordetella pertussis detection. The LAMP primers were designed to target the pbcP1 allele of the pertussis toxin promoter, but the assay could detect B. pertussis ptxP3 and ptxP8 strains in addition to ptxPl strains, with high analytical sensitivity. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.mimet.2016.12.009

Inter- and intra-strain variability of tandem repeats in Mycoplasma pneumoniae based on next-generation sequencing data Reviewed Open Access

Jing Zhang, Xiaohong Song, Marella J. Ma, Li Xiao, Tsuyoshi Kenri, Hongmei Sun, Travis Ptacek, Shaoli Li, Ken B. Waites, T. Prescott Atkinson, Keigo Shibayama, Kevin Dybvig, Yanmei Feng

FUTURE MICROBIOLOGY Vol. 12 ( 2 ) page： 119 - 129 2017.2

Language：English Publishing type：Research paper (scientific journal) Publisher：FUTURE MEDICINE LTD

Aim: To characterize inter-and intra-strain variability of variable-number tandem repeats (VNTRs) in Mycoplasma pneumoniae to determine the optimal multilocus VNTR analysis scheme for improved strain typing. Methods: Whole genome assemblies and next-generation sequencing data from diverse M. pneumoniae isolates were used to characterize VNTRs and their variability, and to compare the strain discriminability of new VNTR and existing markers. Results: We identified 13 VNTRs including five reported previously. These VNTRs displayed different levels of inter-and intra-strain copy number variations. All new markers showed similar or higher discriminability compared with existing VNTR markers and the P1 typing system. Conclusion: Our study provides novel insights into VNTR variations and potential new multilocus VNTR analysis schemes for improved genotyping of M. pneumoniae.

DOI： 10.2217/fmb-2016-0111

Utilizing the Carba NP test as an indicator of expression level of carbapenemase genes in Enterobacteriaceae Reviewed

Takaya Segawa, Mari Matsui, Masato Suzuki, Atsuko Tsutsui, Makoto Kuroda, Keigo Shibayama, Satowa Suzuki

JOURNAL OF MICROBIOLOGICAL METHODS Vol. 133 page： 35 - 39 2017.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The Carba NP test was developed to detect carbapenemase-producing Enterobacteriaceae, and uses imipenem as the reaction substrate. In Japan, IMP-6 metallo-beta-lactamase (MBL) producers, which are usually resistant to meropenem but susceptible to imipenem, and IMP-1 MBL producers, which are usually resistant to both carbapenems are prevalent. We performed the Carba NP test with IMP-6 and IMP-1 MBL producers, and both types were detected by the Carba NP test with high sensitivity. All IMP-1 MBL producers were detected by the Carba NP test, but the minimum inhibitory concentrations (MICs) of imipenem varied from 0.25 to >32 mu g/mL, and the time to positivity varied from 0 to 30 min. Time to positivity was significantly correlated with expression levels of bla(IMP-1), but not with MICs of imipenem. These results suggested that the Carba NP test can be used as a screening assay for carbapenemase gene expression levels among producers of the same type of carbapenemase. Using this approach, it is possible to determine whether the carbapenem resistance of each carbapenemase-producing Enterobacteriaceae isolate is primarily due to carbapenemase production, or to another mechanism such as outer membrane impermeability. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.mimet.2016.12.015

The proline residue at position 319 of BvgS is essential for BvgAS activation in Bordetella pertussis Reviewed Open Access

Yukihiro Hiramatsu, Shuji Yoshino, Yoshiko Yamamura, Nao Otsuka, Keigo Shibayama, Mineo Watanabe, Kazunari Kamachi

PATHOGENS AND DISEASE Vol. 75 ( 1 ) 2017.1

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Bordetella pertussis is the etiological agent of pertussis and produces various virulence factors, including pertussis toxin (PT), filamentous hemagglutinin (FHA) and pertactin (PRN), most of which are positively regulated by the BvgAS two-component sensory transduction system. Here, we describe a B. pertussis isolate not expressing PT, FHA and PRN recovered from a pertussis patient. Sequencing revealed that the bvgS gene of this isolate contains a spontaneous mutation (C> A at position 955) causing the proline residue at position 319 of the BvgS protein to be substituted by threonine. Moreover, loss of PT, FHA and PRN expression was completely restored by complementation with a wild-type bvgAS locus, indicating that this non-synonymous substitution in bvgS leads to impaired BvgS function. Our findings indicate that the proline residue at position 319 in this protein plays an essential role in activation of the BvgAS system and, therefore, subsequent expression of Bvg-regulated virulence factors in B. pertussis.

DOI： 10.1093/femspd/ftx011

Complete genome sequences of the p1 gene type 2b and 2c strains Mycoplasma pneumoniae KCH-402 and KCH-405 Reviewed

Tsuyoshi Kenri, Masato Suzuki, Atsuko Horino, Tsuyoshi Sekizuka, Makoto Kuroda, Hiroyuki Fujii, Toru Hashimoto, Hiroshi Nakajima, Hitomi Ohya, Keigo Shibayama

Genome Announcements Vol. 5 ( 24 ) 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：American Society for Microbiology

Here, we present the complete genome sequences of Mycoplasma pneumoniae KCH-402 and KCH-405, which are p1 gene type 2b and 2c strains, respectively. These strains harbor variations in the orf6 gene, which encodes the cytadherence-related proteins P40 and P90.

DOI： 10.1128/genomeA.00513-17

Genome sequence of Clostridium botulinum strain Adk2012 associated with a foodborne botulinum case in Tottori, Japan, in 2012 Reviewed

Hiroshi Asakura, Shiori Yamamoto, Yoshika Momose, Haru Kato, Masaaki Iwaki, Keigo Shibayama

Genome Announcements Vol. 5 ( 34 ) 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：American Society for Microbiology

We report here a draft genome sequence of Clostridium botulinum Adk2012 responsible for a foodborne botulism case that occurred in Tottori, Japan, in 2012. Its genome size was 2,904,173 bp, with 46 rRNAs and 54 tRNAs, at a coverage of 14.5X.

DOI： 10.1128/genomeA.00872-17

Mycobacterium avium infection induces the resistance of the interferon-γ response in mouse spleen cells at late stages of infection Reviewed International journal Open Access

Atsuko Masumi, Keiko Mochida, Kazuya Takizawa, Takuo Mizukami, Madoka Kuramitsu, Momoka Tsuruhara, Shigetarou Mori, Keigo Shibayama, Kazunari Yamaguchi, Isao Hamaguchi

Inflammation and Regeneration Vol. 36 ( 1 ) page： 21 - 21 2016.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Background: Bacterial infections cause an increase in the population of hematopoietic stem cells (HSCs). To investigate the downstream factors associated with hematopoietic stem cells, mice are infected with Mycobacterium avium (M. avium). Results: Mycobacterium avium (M. avium) infection induces the enlargement of the spleen and changes in histopathology, including changes to the lineage populations. A dramatic expansion of Lin-c-kit+Sca-1+ (KSL) cells in mouse bone marrow cells and spleen cells was detected 4 weeks after infection with M. avium; however, there was no difference in the engraft activity between infected and un-infected mouse bone marrow cells. We tested the cytokine and cytokine-related gene expression after M. avium infection and found that IFN-γ expression increased and peaked at 4 weeks in both bone marrow and spleen cells. The expression of Sca-1 gene peaked at 4 weeks in the bone marrow but peaked at 2 weeks in spleen cells, although the Sca-1 surface marker peaked at 4 weeks after infection in both bone marrow and spleen cells. Interferon regulatory factor-2 (IRF-2) expression did not change in the bone marrow cells, whereas it decreased in spleen cells at 4 weeks and IRF-1 expression was up-regulated in both bone marrow and spleen cells after infection. However, the up-regulation of IRF-1 was not correlated with IFN-γ expression in the M. avium-infected mouse spleen cells. Conclusions: This finding suggests that the IFN-γ production mediated by M. avium infection alters the population of KSL cells during host defense, and the down-regulation of the IFN-γ response in spleen cells occurs at the late stage after M. avium infection.

DOI： 10.1186/s41232-016-0024-3

A genome-wide association study identifies a horizontally transferred bacterial surface adhesin gene associated with antimicrobial resistant strains Reviewed Open Access

Masato Suzuki, Keigo Shibayama, Koji Yahara

SCIENTIFIC REPORTS Vol. 6 page： 37811 2016.11

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Carbapenems are a class of last-resort antibiotics; thus, the increase in bacterial carbapenem-resistance is a serious public health threat. Acinetobacter baumannii is one of the microorganisms that can acquire carbapenem-resistance; it causes severe nosocomial infection, and is notoriously difficult to control in hospitals. Recently, a machine-learning approach was first used to analyze the genome sequences of hundreds of susceptible and resistant A. baumannii strains, including those carrying commonly acquired resistant mechanisms, to build a classifier that can predict strain resistance. A complementary approach is to explore novel genetic elements that could be associated with the antimicrobial resistance of strains, independent of known mechanisms. Therefore, we carefully selected A. baumannii strains, spanning various genotypes, from public genome databases, and conducted the first genome-wide association study (GWAS) of carbapenem resistance. We employed a recently developed method, capable of identifying any kind of genetic variation and accounting for bacterial population structure, and evaluated its effectiveness. Our study identified a surface adhesin gene that had been horizontally transferred to an ancestral branch of A. baumannii, as well as a specific region of that gene that appeared to accumulate multiple individual variations across the different branches of carbapenem-resistant A. baumannii strains.

DOI： 10.1038/srep37811

gamma-Glutamyltranspeptidase is an endogenous activator of Toll-like receptor 4-mediated osteoclastogenesis Reviewed Open Access

Sawako Moriwaki, Takeshi Into, Keiko Suzuki, Mutsumi Miyauchi, Takashi Takata, Keigo Shibayama, Shumpei Niida

SCIENTIFIC REPORTS Vol. 6 page： 35930 2016.10

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Chronic inflammation-associated bone destruction, which is observed in rheumatoid arthritis (RA) and periodontitis, is mediated by excessive osteoclastogenesis. We showed previously that gamma-glutamyltranspeptidase (GGT), an enzyme involved in glutathione metabolism, acts as an endogenous activator of such pathological osteoclastogenesis, independent of its enzymatic activity. GGT accumulation is clinically observed in the joints of RA patients, and, in animals, the administration of recombinant GGT to the gingival sulcus as an in vivo periodontitis model induces an increase in the number of osteoclasts. However, the underlying mechanisms of this process remain unclear. Here, we report that Toll-like receptor 4 (TLR4) recognizes GGT to activate inflammation-associated osteoclastogenesis. Unlike lipopolysaccharide, GGT is sensitive to proteinase K treatment and insensitive to polymyxin B treatment. TLR4 deficiency abrogates GGT-induced osteoclastogenesis and activation of NF-kappa B and MAPK signaling in precursor cells. Additionally, GGT does not induce osteoclastogenesis in cells lacking the signaling adaptor MyD88. The administration of GGT to the gingival sulcus induces increased osteoclastogenesis in wild-type mice, but does not induce it in TLR4-deficient mice. Our findings elucidate a novel mechanism of inflammation-associated osteoclastogenesis, which involves TLR4 recognition of GGT and subsequent activation of MyD88-dependent signaling.

DOI： 10.1038/srep35930

Draft Genome Sequence of Helicobacter suis Strain SNTW101, Isolated from a Japanese Patient with Nodular Gastritis. Reviewed International journal

Hidenori Matsui, Tetsufumi Takahashi, Somay Y Murayama, Ikuo Uchiyama, Katsushi Yamaguchi, Shuji Shigenobu, Masato Suzuki, Emiko Rimbara, Keigo Shibayama, Anders Øverby, Masahiko Nakamura

Genome announcements Vol. 4 ( 5 ) page： e00934 2016.9

Language：English Publishing type：Research paper (scientific journal)

We present here the draft whole-genome shotgun sequence of an uncultivated strain SNTW101 of Helicobacter suis, which has been maintained in the stomachs of mice. This strain was originally isolated from gastric biopsy specimens of a urea breath test-negative Japanese patient suffering from nodular gastritis.

DOI： 10.1128/genomeA.00934-16

Pelvic abscess due to <i>Mycoplasma hominis</i> following caesarean section. Reviewed International journal

Mori N, Takigawa A, Kagawa N, Kenri T, Yoshida S, Shibayama K, Aoki Y

JMM case reports Vol. 3 ( 4 ) page： e005059 2016.8

Language：English Publishing type：Research paper (scientific journal)

INTRODUCTION: Mycoplasma hominis is associated with genito-urinary tract infection and adverse pregnancy outcomes. However, whether the species is a true pathogen or part of the genito-urinary tracts natural flora remains unclear. CASE PRESENTATION: A 41-year-old pregnant woman was admitted to our hospital at 38 weeks and 5 days of gestation owing to premature rupture of the membranes. The patient delivered by caesarean section. Subsequently, the patient complained of lower abdominal pain and had persistent fever. Enhanced computed tomography revealed pelvic abscesses. Gram staining of pus from the abscess and vaginal secretions indicated presence of polymorphonuclear leucocytes but no pathogens. Cultures on blood agar showed growth of pinpoint-sized colonies in an anaerobic environment within 48 h. Although administration of carbapenem and metronidazole was ineffective and we could not fully drain the abscess, administration of clindamycin led to clinical improvement. The isolates 16S rRNA gene and yidC gene sequences exhibited identity with those of M. hominis. CONCLUSION: Physicians should consider M. hominis in cases of pelvic abscesses where Gram staining yields negative results, small colonies are isolated from the abscess and treatment with β-lactam antibiotics is ineffective.

DOI： 10.1099/jmmcr.0.005059

Correction for Rimbara et al., Draft Genome Sequence of Helicobacter fennelliae Strain MRY12-0050, Isolated from a Bacteremia Patient. Reviewed International journal

Emiko Rimbara, Mari Matsui, Shigetarou Mori, Satowa Suzuki, Masato Suzuki, Hyun Kim, Tsuyoshi Sekizuka, Makoto Kuroda, Keigo Shibayama

Genome announcements Vol. 4 ( 4 ) 2016.7

BipA Is Associated with Preventing Autoagglutination and Promoting Biofilm Formation in Bordetella holmesii Reviewed Open Access

Yukihiro Hiramatsu, Momoko Saito, Nao Otsuka, Eri Suzuki, Mineo Watanabe, Keigo Shibayama, Kazunari Kamachi

PLOS ONE Vol. 11 ( 7 ) page： e0159999 2016.7

Language：English Publishing type：Research paper (scientific journal) Publisher：PUBLIC LIBRARY SCIENCE

Bordetella holmesii causes both invasive and respiratory diseases in humans. Although the number of cases of pertussis-like respiratory illnesses due to B. holmesii infection has increased in the last decade worldwide, little is known about the virulence factors of the organism. Here, we analyzed a B. holmesii isolate that forms large aggregates and precipitates in suspension, and subsequently demonstrated that the autoagglutinating isolate is deficient in Bordetella intermediate protein A (BipA) and that this deletion is caused by a frame-shift mutation in the bipA gene. A BipA-deficient mutant generated by homologous recombination also exhibited the autoagglutination phenotype. Moreover, the BipA mutant adhered poorly to an abiotic surface and failed to form biofilms, as did two other B. holmesii autoagglutinating strains, ATCC 51541 and ATCC 700053, which exhibit transcriptional down-regulation of bipA gene expression, indicating that autoagglutination indirectly inhibits biofilm formation. In a mouse intranasal infection model, the BipA mutant showed significantly lower levels of initial lung colonization than did the parental strain (P<0.01), suggesting that BipA might be a critical virulence factor in B. holmesii respiratory infection. Together, our findings suggest that BipA production plays an essential role in preventing autoagglutination and indirectly promoting biofilm formation by B. holmesii.

DOI： 10.1371/journal.pone.0159999

A Novel IgM-capture enzyme-linked immunosorbent assay using recombinant Vag8 fusion protein for the accurate and early diagnosis of Bordetella pertussis infection Reviewed Open Access

Nao Otsuka, Kensei Gotoh, Naoko Nishimura, Takao Ozaki, Yukitsugu Nakamura, Kiyohito Haga, Makoto Yamazaki, Fumio Gondaira, Kenji Okada, Yusuke Miyaji, Hiromi Toyoizumi-Ajisaka, Keigo Shibayama, Yoshichika Arakawa, Kazunari Kamachi

MICROBIOLOGY AND IMMUNOLOGY Vol. 60 ( 5 ) page： 326 - 333 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

An ELISA that measures anti-PT IgG antibody has been used widely for the serodiagnosis of pertussis; however, the IgG-based ELISA is inadequate for patients during the acute phase of the disease because of the slow response of anti-PT IgG antibodies. To solve this problem, we developed a novel IgM-capture ELISA that measures serum anti-Bordetella pertussis Vag8 IgM levels for the accurate and early diagnosis of pertussis. First, we confirmed that Vag8 was highly expressed in all B. pertussis isolates tested (n = 30), but little or none in other Bordetella species, and that DTaP vaccines did not induce anti-Vag8 IgG antibodies in mice (i.e. the antibody level could be unaffected by the vaccination). To determine the immune response to Vag8 in B. pertussis infection, anti-Vag8 IgM levels were compared between 38 patients (acute phase of pertussis) and 29 healthy individuals using the anti-Vag8 IgM-capture ELISA. The results revealed that the anti-Vag8 IgM levels were significantly higher in the patients compared with the healthy individuals (P < 0.001). ROC analysis also showed that the anti-Vag8 IgM-capture ELISA has higher diagnostic accuracy (AUC, 0.92) than a commercial anti-PT IgG ELISA kit. Moreover, it was shown that anti-Vag8 IgM antibodies were induced earlier than anti-PT IgG antibodies on sequential patients' sera. These data indicate that our novel anti-Vag8 IgM-capture ELISA is a potentially useful tool for making the accurate and early diagnosis of B. pertussis infection.

DOI： 10.1111/1348-0421.12378

A Epidemiological Investigation of a Nosocomial Outbreak of Multidrug-Resistant Acinetobacter baumannii in a Critical Care Center in Japan, 2011-2012 Reviewed

Hiroto Ushizawa, Yuichiro Yahata, Takeo Endo, Tomoko Iwashima, Michiyo Misawa, Makoto Sonobe, Takuya Yamagishi, Hajime Kamiya, Kazutoshi Nakashima, Tamano Matsui, Mari Matsui, Satowa Suzuki, Keigo Shibayama, Mikio Doi, Fujiko Irie, Shinichi Yamato, Yasuhiro Otomo, Kazunori Oishi

JAPANESE JOURNAL OF INFECTIOUS DISEASES Vol. 69 ( 2 ) page： 143 - 148 2016.3

Language：English Publishing type：Research paper (scientific journal) Publisher：NATL INST INFECTIOUS DISEASES

In 2011, a multidrug-resistant Acinetobacter baumannii (MDRAB) outbreak occurred at a Japanese critical care center (CCC) in a tertiary care hospital. Multidrug-resistance in Japan is defined as resistance to the antimicrobials amikacin, carbapenem, and fluoroquinolone. We conducted a retrospective epidemiological investigation of this outbreak to identify the risk factors for MDRAB respiratory tract acquisition in this hospital. Cases were defined as hospitalized patients with MDRAB-positive cultures at least 3 days post admission to the CCC between June 1, 2011 and April 20, 2012. Fifteen MDRAB cases were identified, including 3 with infection and 12 with colonization. This case-control study demonstrated that hypoalbuminemia along with carbapenem administration were associated with MDRAB respiratory tract acquisition. Pulsed-field gel electrophoresis analysis and multilocus sequence typing using MDRAB isolates suggested a clonal dissemination of MDRAB strains with sequence type 74 occurred primarily among patients admitted to the CCC. From April 16, 2012, a decreased isolation rate of MDRAB in the hospital occurred after the implementation of the following infection control measures: closing the emergency room, discontinuing admission to the CCC, isolating patients with MDRAB colonization or infection to single room status, and conducting environmental cleaning. No MDRAB cases were detected between March 23 and April 20, 2012.

DOI： 10.7883/yoken.JJID.2015.049

A novel experimental platform for toxigenic and non-toxigenic Corynebacterium ulcerans infection in mice Reviewed Open Access

Yu Mochizuki, Honami Saeki, Masaaki Iwaki, Hitrotaka Takagi, Keigo Shibayama, Hiromi Amao, Akihiko Yamamoto

PATHOGENS AND DISEASE Vol. 74 ( 2 ) 2016.3

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Corynebacterium ulcerans is a zoonotic pathogen that can produce diphtheria toxin and causes an illness categorized as diphtheria in the European Union because its clinical appearance is similar to that of diphtheria caused by Corynebacterium diphtheriae. Despite the importance of the pathogen in public health, the organism's mechanism of infection has not been extensively studied, especially in experimental animal models. Therefore in the present study we constructed an intranasal infection system for mice. Mice are insensitive to diphtheria toxin and this has the advantage of excluding the cytotoxic effect of the toxin that might interfere with the analysis of the early stage of infection. Both the toxigenic and non-toxigenic C. ulcerans strains were capable of killing mice within 3 days after inoculation at 107 colony-forming units per mouse. In experimentally infected animals, C. ulcerans was detected in the respiratory tract but not in the intestinal tract. The bacterium was also detected in peripheral blood and it disseminated into the lung, kidney and spleen to produce a systemic infection. This experimental infection system provides a platform for analyzing the virulence of C. ulcerans in future studies.

DOI： 10.1093/femspd/ftv109

Linezolid-resistant Staphylococcus epidermidis associated with long-term, repeated linezolid use in a pediatric patient Reviewed

Naruhiko Ishiwada, Akiko Takaya, Asahi Kimura, Masaharu Watanabe, Moeko Hino, Hidemasa Ochiai, Mari Matsui, Keigo Shibayama, Tomoko Yamamoto

JOURNAL OF INFECTION AND CHEMOTHERAPY Vol. 22 ( 3 ) page： 187 - 190 2016.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We report an 8-year-old patient with catheter-related bacteremia caused by linezolid-resistant Staphylococcus epidermidis that was isolated after the long-term, repeated use of linezolid. Three S. epidermidis strains isolated from this patient were bacteriologically analyzed. While the strain isolated prior to linezolid initiation was susceptible to linezolid, two strains after linezolid therapy displayed low-level linezolid susceptibility (MIC, 4 mg/L) and linezolid resistance (MIC, 16 mg/L). T2500A mutation in two copies and G2575T mutations in three copies of 23S rRNA were detected in the low-susceptible strain and the resistant strain, respectively. Linezolid-resistant S. epidermidis infection is rare, but may occur with the long-term administration of linezolid. (C) 2015, Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jiac.2015.10.004

Analyses of short-term antagonistic evolution of Pseudomonas Aeruginosa strain PAO1 and phage KPP22 (Myoviridae family, PB1-like virus genus) Reviewed Open Access

Jumpei Uchiyama, Masato Suzuki, Koji Nishifuji, Shin ichiro Kato, Reina Miyata, Tadahiro Nasukawa, Kotoe Yamaguchi, Iyo Takemura-Uchiyama, Takako Ujihara, Hidekatsu Shimakura, Hironobu Murakami, Noriaki Okamoto, Yoshihiko Sakaguchi, Keigo Shibayama, Masahiro Sakaguchi, Shigenobu Matsuzaki

Applied and Environmental Microbiology Vol. 82 ( 15 ) page： 4482 - 4491 2016

Language：English Publishing type：Research paper (scientific journal)

© 2016, American Society for Microbiology. Pseudomonas aeruginosa causes serious intractable infections in humans and animals. Bacteriophage (phage) therapy has been applied to treat P. aeruginosa infections, and phages belonging to the PB1-like virus genus in the Myoviridae family have been used as therapeutic phages. To achieve safer and more effective phage therapy, the use of preadapted phages is proposed. To understand in detail such phage preadaptation, the short-term antagonistic evolution of bacteria and phages should be studied. In this study, the short-term antagonistic evolution of bacteria and PB1-like phage was examined by studying phage-resistant clones of P. aeruginosa strain PAO1 and mutant PB1-like phages that had recovered their infectivity. First, phage KPP22 was isolated and characterized; it was classified as belonging to the PB1-like virus genus in the Myoviridae family. Subsequently, three KPP22-resistant PAO1 clones and three KPP22 mutant phages capable of infecting these clones were isolated in three sets of in vitro experiments. It was shown that the bacterial resistance to phage KPP22 was caused by significant decreases in phage adsorption and that the improved infectivity of KPP22 mutant phages was caused by significant increases in phage adsorption. The KPP22-resistant PAO1 clones and the KPP22 mutant phages were then analyzed genetically. All three KPP22-resistant PAO1 clones, which were deficient for the O5 antigen, had a common nonsense mutation in the wzy gene. All the KPP22 mutant phage genomes showed the same four missense mutations in the open reading frames orf060, orf065, and orf086. The information obtained in this study should be useful for further development of safe and efficient phage therapy.

DOI： 10.1128/AEM.00090-16

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