Faculty Profiles - SHIBAYAMA Keigo

Papers - SHIBAYAMA Keigo

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

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

Japanese Journal of Infectious Diseases Vol. 69 ( 4 ) page： 356 - 356 2016

Authorship：Lead author,　Last author,　Corresponding author Publishing type：Research paper (scientific journal) Publisher：国立感染症研究所 Japanese Journal of Infectious Diseases 編集委員会

Volume 69, no. 2, p. 143–148, 2016. Page 143, Title should appear as shown below.<br><br>An Epidemiological Investigation of a Nosocomial Outbreak of Multidrug-Resistant <i>Acinetobacter baumannii</i> in a Critical Care Center in Japan, 2011–2012

DOI： 10.7883/yoken.JJID.2016.E002

Genome sequence of an Acinetobacter baumannii strain carrying three acquired carbapenemase genes Reviewed

Ken-Ichi Oinuma, Masato Suzuki, Kanako Sato, Kiyotaka Nakaie, Makoto Niki, Etsuko Takizawa, Mamiko Niki, Keigo Shibayama, Koichi Yamada, Hiroshi Kakeya, Yukihiro Kaneko

Genome Announcements Vol. 4 ( 6 ) page： e01290-16 2016

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

The emergence of multiple-carbapenemase-producing Acinetobacter strains has been a serious concern during the past decade. Here, we report the draft genome sequence of an Acinetobacter baumannii strain isolated from a Japanese patient with three acquired carbapenemase genes: blaNDM-1, blaTMB-1, and blaOXA-58.

DOI： 10.1128/genomeA.01290-16

Genome sequence of the psychrophilic bacterium Tenacibaculum ovolyticum strain da5A-8 isolated from deep seawater Reviewed

Maki Teramoto, Zhenyu Zhai, Ayumi Komatsu, Keigo Shibayama, Masato Suzuki

Genome Announcements Vol. 4 ( 3 ) 2016

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

Some bacterial species of the genus Tenacibaculum, including Tenacibaculum ovolyticum, have been known as fish pathogens in the sea. So far, the only published genome sequence for this genus is for Tenacibaculum dicentrarchi, which could also be a fish pathogen. Strain da5A-8, showing 100% identity to the 16S rRNA gene sequence of T. ovolyticum DSM 18103T, was isolated from seawater at a depth of 344min Kochi, Japan, and grew optimally at 10 to 20ï¿½C. The genome sequence of strain da5A-8 revealed the possible virulence genes commonly observed in the genus Tenacibaculum.

DOI： 10.1128/genomeA.00644-16

Simple and rapid detection method for qepA1 by loop-mediated isothermal amplification Reviewed

YAMANE Kunikazu, HORINO Atsuko, SUZUKI Satowa, SHIBAYAMA Keigo, FUSHIMI Shigeko, KATSUYAMA Hironobu

Kawasaki medical journal Vol. 42 ( 1 ) page： 25 - 29 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：Kawasaki Medical School

Although fluoroquinolone (FQ) has been used for the treatment of various bacterial infectious diseases, its continued use has been problematic given the appearance of FQ-resistant bacteria. However, the recent discovery of four plasmid-mediated quinolone resistance (PMQR) genes comprising qnr, aac(6')Ib-cr, qepA and OqxAB since 1998 has provided insights in the area of FQ-resistance. For practical detection of qepA in microbiology laboratory, a specific, simple, rapid and cost-effective isothermal amplification method designated as LAMP is the good candidate to use. In this study, the development of a new detection method using LAMP to identify qepA1, one variant of the qepA gene, was tried. As the results, the LAMP method using a qepA1-specific LAMP primer set comprising five primerscould detect all four qepA1-positive strains in addition to 17 qepA1-negative strains. The LAMP method is clearly much more advantageous for use in clinical laboratories. Furthermore, the time and accuracy benefits allow for the selection of antibiotics in a clinical setting.

DOI： 10.11482/KMJ-E42(1)25

Other Link： http://id.nii.ac.jp/1162/00000578/

Laboratory-based surveillance of pertussis using multitarget real-time PCR in Japan: Evidence for Bordetella pertussis infection in preteens and teens Reviewed

K. Kamachi, S. Yoshino, C. Katsukawa, N. Otsuka, Y. Hiramatsu, K. Shibayama

New Microbes and New Infections Vol. 8 page： 70 - 74 2015.11

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

Between January 2013 and December 2014, we conducted laboratory-based surveillance of pertussis using multitarget real-time PCR, which discriminates among Bordetella pertussis, Bordetella parapertussis, Bordetella holmesii and Mycoplasma pneumoniae. Of 355 patients clinically diagnosed with pertussis in Japan, B. pertussis, B. parapertussis and M. pneumoniae were detected in 26% (n = 94), 1.1% (n = 4) and 0.6% (n = 2), respectively, whereas B. holmesii was not detected. It was confirmed that B. parapertussis and M. pneumoniae are also responsible for causing pertussis-like illness. The positive rates for B. pertussis ranged from 16% to 49%, depending on age. Infants aged ≤ 3 months had the highest rate (49%), and children aged 1 to 4 years had the lowest rate (16%, p &lt
0.01 vs. infants aged ≤ 3 months). Persons aged 10 to 14 and 15 to 19 years also showed high positive rates (29% each)
the positive rates were not statistically significant compared with that of infants aged ≤ 3 months (p ≥ 0.06). Our observations indicate that similar to infants, preteens and teens are at high risk of B. pertussis infection.

DOI： 10.1016/j.nmni.2015.10.001

Predominance of PCR-ribotypes, 018 (smz) and 369 (trf) of Clostridium difficile in Japan: a potential relationship with other global circulating strains? Reviewed

Mitsutoshi Senoh, Haru Kato, Tadashi Fukuda, Akiko Niikawa, Yoshiko Hori, Hideharu Hagiya, Yoichiro Ito, Hiroshi Miki, Yoshifumi Abe, Kiyoshi Furuta, Hideki Takeuchi, Hirokazu Tajima, Harumi Tominaga, Hideyuki Satomura, Hideaki Kato, Sayuri Morita, Ai Tanada, Toshinori Hara, Miki Kawada, Yuka Sato, Masahiko Takahashi, Akiko Higuchi, Tomoko Nakajima, Yukiko Wakamatsu, Masahiro Toyokawa, Akiko Ueda, Paul Roberts, Fabio Miyajima, Keigo Shibayama

JOURNAL OF MEDICAL MICROBIOLOGY Vol. 64 ( 10 ) page： 1226 - 1236 2015.10

Language：English Publishing type：Research paper (scientific journal) Publisher：SOC GENERAL MICROBIOLOGY

Global spread and evolutionary links of an epidemic Clostridium difficile strain (PCR-ribotype 027) have been noted in recent decades. However, in Japan, no outbreaks caused by type 027 have been reported to date. A total of 120 C. difficile isolates from patients at 15 hospitals during non-outbreak seasons between 2011 and 2013 as well as 18 and 21 isolates collected from two hospitals in 2010 and 2009, respectively, in outbreak periods in Japan, were examined. Among these 120 isolates, Japan-ribotypes smz and ysmz (subtype variant of smz) were the most predominant (39.2 %) followed by Japan-ribotype trf (15.8 %). Types smz/ysmz and trf were also concurrently predominant at two hospitals in the outbreak settings. Out of the five binary toxin-positive isolates observed, only one was PCR-ribotype 027 and another PCR-ribotype 078. Type smz was later found to correspond to PCR-ribotype 018. High rates of resistance against gatifloxacin, moxifloxacin, erythromycin and clindamycin were observed in the PCR-ribotype 018 isolates. Interestingly, all trf isolates were toxin A-negative, toxin B-positive, but they did not correspond to PCR-ribotype 017, thus being assigned a new ribotype (PCR-ribotype 369). In conclusion, PCR-ribotypes 018 (smz) and 369 (trf) were identified as major circulating strains in both outbreak and non-outbreak settings in Japan. Given their epidemiological relevance, molecular investigations are warranted to clarify potential evolutionary links with related strains found elsewhere, such as PCR-ribotypes 018 and 017 from Europe and North America.

DOI： 10.1099/jmm.0.000149

Development of a novel chromogenic method, Penta-well test, for rapid prediction of beta(-)lactamase classes produced in clinical Enterobacteriaceae isolates Reviewed

Tatsuki Mura, Kumiko Kawamura, Jun-ichi Wachino, Keigo Shibayama, Yoshichika Arakawa

DIAGNOSTIC MICROBIOLOGY AND INFECTIOUS DISEASE Vol. 83 ( 1 ) page： 25 - 29 2015.9

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

We developed a novel chromogenic method, Penta-well test, which enables the rapid detection and classification of beta-lactamases in clinical Enterobacteriaceae isolates. This test is based on a combination of nitrocefin and 3 beta-lactamase inhibitors specific to classes A. B, and/or C, with nitrocefin hydrolysis by beta-lactamases being assessed by optical density measurements at 490 nm. When the cutoff value for each beta-lactamase class was determined (0.09, 0.4, and 0.55 for class A, class B, and class C beta-lactamase producers, respectively), the sensitivity and specificity of classification were 93.5% and 68.8% for class A, 93.8% and 100% for class B, and 86.7% and 100% for class C. respectively. Moreover, this method allowed accurate beta-lactamase classification in 20 of 23 (87.0%) isolates producing plural class of beta-lactamases. Thus, the Penta-well test can provide information that would be useful in the accurate detection and classification of beta-lactamases produced by causative bacteria. (C) 2015 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.diagmicrobio.2015.06.002

The determinant of periodicity in Mycoplasma pneumoniae incidence: an insight from mathematical modelling Reviewed

Ryosuke Omori, Yukihiko Nakata, Heidi L. Tessmer, Satowa Suzuki, Keigo Shibayama

SCIENTIFIC REPORTS Vol. 5 page： 14473 2015.9

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

Until the early 1990s, incidences of Mycoplasma pneumoniae (MP) infection showed three to five year epidemic cycles in multiple countries, however, the mechanism for the MP epidemic cycle has not been understood. Here, we investigate the determinant of periodicity in MP incidence by employing a mathematical model describing MP transmission dynamics. Three candidates for the determinant of periodicity were evaluated: school-term forcing, minor variance in the duration of immunity, and epidemiological interference between MP serotypes. We find that minor variation in the duration of immunity at the population level must be considered essential for the MP epidemic cycle because the MP cyclic incidence pattern did not replicate without it. Minor variation, in this case, is a less dispersed distribution for the duration of immunity than an exponential distribution. Various lengths of epidemic cycles, including cycles typically found in nature, e.g. three to five year cycles, were also observed when there was minor variance in the duration of immunity. The cyclic incidence pattern is robust even if there is epidemiological interference due to cross-immune protection, which is observed in the epidemiological data as negative correlation between epidemics per MP serotype.

DOI： 10.1038/srep14473

The Other Helicobacters. Reviewed International journal

Bram Flahou, Emiko Rimbara, Shigetarou Mori, Freddy Haesebrouck, Keigo Shibayama

Helicobacter Vol. 20 Suppl 1 page： 62 - 7 2015.9

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

In the past year, a substantial number of (putative) novel Helicobacter species have been described, including Helicobacter himalayensis colonizing the Himalayan marmot and Helicobacter apodemus, colonizing the Korean striped field mouse. In addition, a putative novel gastric Helicobacter species was identified in wild gorillas and chimpanzees, for which the name "Candidatus H. homininae" was proposed. A high incidence of gastric non-H. pylori Helicobacter infection was described in China and multiple case reports have described the involvement of enterohepatic Helicobacter species, especially Helicobacter cinaedi, in a wide range of diseases. Several studies in rodent models further elucidated the mechanisms underlying the development of gastric mucosa-associated lymphoid tissue lymphoma during infection with gastric non-H. pylori Helicobacters. The effects of infection with gastric Helicobacters on the development of neuroinflammation were investigated and several enterohepatic Helicobacter species were shown to affect the composition of the gut microbiota, to influence vaccine efficiency as well as the progression of cancer in distant sites of the body.

DOI： 10.1111/hel.12259

Purification and functional characterization of diadenosine 5',5‴-P(1),P(4)-tetraphosphate phosphorylases from Mycobacterium smegmatis and Mycobacterium avium. Reviewed International journal

Naoko Honda, Hyun Kim, Emiko Rimbara, Atsushi Kato, Keigo Shibayama, Shigetarou Mori

Protein expression and purification Vol. 112 page： 37 - 42 2015.8

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

We recently demonstrated that the Rv2613c protein from Mycobacterium tuberculosis H37Rv is a novel diadenosine 5',5‴-P(1),P(4)-tetraphosphate (Ap4A) phosphorylase (MtAPA) that forms a tetramer. Mycobacterium avium and Mycobacterium smegmatis express proteins named MAV_3489 and MSMEG_2932, respectively, that are homologous to MtAPA. Here we showed that the MAV_3489 and MSMEG_2932 proteins possess Ap4A phosphorylase activity and enzymatic properties similar to those of MtAPA. Furthermore, gel-filtration column chromatography revealed that MAV_3489 and MSMEG_2932 assembled into homotetramers in solution, indicating that they may also form unique Ap4A-binding sites composed of tetramers.

DOI： 10.1016/j.pep.2015.04.010

Comparative Analysis of Penicillin-Susceptible and Non-Susceptible Isolates of Group B Streptococci by Multilocus Sequence Typing Reviewed

Ryoko Yamada, Kouji Kimura, Noriyuki Nagano, Yukiko Nagano, Satowa Suzuki, Wanchun Jin, Jun-ichi Wachino, Keiko Yamada, Keigo Shibayama, Yoshichika Arakawa

JAPANESE JOURNAL OF INFECTIOUS DISEASES Vol. 68 ( 4 ) page： 326 - 329 2015.7

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

Since Group B Streptococcus (GBS, Streptococcus agalactiae) clinical isolates are believed to be uniformly susceptible to beta-lactams, penicillin G has been used as the first-line agent for the prevention and treatment of GBS infections. However, the existence and characteristics of GBS isolates with reduced penicillin susceptibility (PRGBS) have recently been reported in Japan. Moreover, the sequence type (ST) 458 is predominant among the PRGBS in Japan. Although the majority of the PRGBS isolates in Japan have been recovered from respiratory specimens of adults, no information on the genotype of these isolates is available. Therefore, whether ST458 predominates among GBS isolates obtained from such specimens is not known. In this study, we characterized the STs of 38 penicillin-susceptible GBS isolates (PSGBS) recovered from respiratory specimens and compared them to the reported PRGBS STs. ST458, the predominant ST among the PRGBS isolates studied (10/19, 53%), was not found in the PSGBS isolates. Thirty-six PSGBS isolates belonged to the ST1/19/10 group (includes 6 different STs), and the remaining 2 isolates belonged to that of ST23. Further, the PRGBS isolates were divided into the ST1 (3 STs), and ST23 (2 STs) groups. ST458 was not predominant among the PSGBS isolates recovered from respiratory specimens in Japan and may therefore be specific to the PRGBS. Thus, the ST distribution of the PRGBS isolates does not reflect that of the PSGBS.

DOI： 10.7883/yoken.JJID.2014.387

[A Study on the Clinical Course and Antimicrobial Susceptibility of Mycoplasma pneumoniae in a Community Hospital]. Reviewed

Sakai T, Ishida T, Arita M, Tachibana H, Yoshioka H, Noyama M, Tokioka F, Ito A, Furuta K, Nishiyama A, Hashimoto T, Fujii H, Nakajima H, Kenri T, Shibayama K

Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases Vol. 89 ( 4 ) page： 458 - 464 2015.7

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japanese Association for Infectious Diseases

Recently, reports of macrolide-resistant strains of <i>Mycoplasma pneumoniae </i>have been increasing. We examined the antimicrobial susceptibility and clinical significance in patients with <i>M. pneumoniae</i>. Seventy patients in whom <i>M. pneumoniae </i>was detected from 2008 to 2012 were included in the study, and compared with patients between 2003 and 2006. There were no macrolide-resistant strains detected in the 38 strains from 2003 to 2006, but from 2008 to 2012, out of the 70 strains 46 (65.7％) were positive for the macrolide resistant 23SrRNA gene mutant (A2063G), which is consistent with recent trends. Comparison between cases of macrolide resistant strains and those with macrolide sensitive strains did not reveal a significant difference in the hospitalization period. The approximate duration of fever was 7 days ; for both cases : those who received effective antimicrobials as the initial therapy, and for those with macrolide sensitive strains. It seems that the duration of fever depends on susceptibility to the initial antimicrobials regardless of macrolide resistance. There were some patients that improved without use of quinolone or minocycline, though macrolide resistant strains were detected. These patients did not reveal extension of the hospital stay nor aggravation of pneumonia. This suggests that a macrolide drug might be the first choice drug for <i>M. pneumoniae </i>even now, and a change of drug should be considered when fever duration is long.

DOI： 10.11150/kansenshogakuzasshi.89.458

Common isolation of New Delhi metallo-beta-lactamase 1-producing Enterobacteriaceae in a large surgical hospital in Vietnam Reviewed

H. H. Tran, S. Ehsani, K. Shibayama, M. Matsui, S. Suzuki, M. B. Nguyen, D. N. Tran, V. P. Tran, D. L. Tran, H. T. Nguyen, D. A. Dang, H. S. Trinh, T. H. Nguyen, H. F. L. Wertheim

EUROPEAN JOURNAL OF CLINICAL MICROBIOLOGY & INFECTIOUS DISEASES Vol. 34 ( 6 ) page： 1247 - 1254 2015.6

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

This study sought to monitor the presence of carbapenem-resistant Enterobacteriaceae (CRE) and the proportion New Delhi metallo-beta-lactamase 1 (NDM-1)-producing bacteria between August 2010 and December 2012 in a surgical hospital in Vietnam. We identified 47 CRE strains from a total of 4,096 Enterobacteriaceae isolates (1.1 %) that were NDM-1-positive from 45 patients admitted to 11 different departments, with the majority being from the urology department. The NDM-1 gene was found in seven different species. Genotyping revealed limited clonality of NDM-1-positive isolates. Most of the isolates carried the NDM-1 gene on a plasmid and 17.8 % (8/45) of those were readily transferable. We found five patients at admission and one patient at discharge with NDM-1-positive bacteria in their stool. From 200 screening environmental hospital samples, five were confirmed to be NDM-1-positive and included Acinetobacter species (n = 3) and Enterobacter aerogenes (n = 2). The results reveal that NDM-1-producing Enterobacteriaceae are commonly isolated in patients admitted to a Vietnamese surgical hospital and are also detected in the hospital environment.

DOI： 10.1007/s10096-015-2345-6

Molecular epidemiology of Bordetella pertussis in the Philippines in 2012-2014 Reviewed

Salvacion Rosario L. Galit, Nao Otsuka, Yuki Furuse, Daryl Joy V. Almonia, Lydia T. Sombrero, Rosario Z. Capeding, Socorro P. Lupisan, Mariko Saito, Hitoshi Oshitani, Yukihiro Hiramatsu, Keigo Shibayama, Kazunari Kamachi

INTERNATIONAL JOURNAL OF INFECTIOUS DISEASES Vol. 35 page： 24 - 26 2015.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

Objectives: The present study was designed to determine the genotypes of circulating Bordetella pertussis in the Philippines by direct molecular typing of clinical specimens.
Methods: Nasopharyngeal swabs (NPSs) were collected from 50 children hospitalized with pertussis in three hospitals during 2012-2014. Multilocus variable-number tandem repeat analysis (MLVA) was performed on the DNA extracts from NPSs. B. pertussis virulence-associated allelic genes (ptxA, prn, and fim3) and the pertussis toxin promoter, ptxP, were also investigated by DNA sequence-based typing.
Results: Twenty-six DNA extracts yielded a complete MLVA profile, which were sorted into 10 MLVA types. MLVA type 34 (MT34), which is rare in Australia, Europe, Japan, and the USA, was the predominant strain (50%). Seven MTs (MT29, MT32, MT33, and MT283-286, total 42%) were single-locus variants of MT34, while two (MT141 and MT287, total 8%) were double-locus variants of MT34. All MTs had the combination of virulence-associated allelic genes, ptxP1-ptxA1-prn1-fim3A.
Conclusions: The B. pertussis population in the Philippines comprises genetically related strains. These strains are markedly different from those found in patients from other countries where acellular pertussis vaccines are used. The differences in vaccine types between these other countries and the Philippines, where the whole-cell vaccine is still used, may select for distinct populations of B. pertussis. (C) 2015 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.

DOI： 10.1016/j.ijid.2015.04.001

Genome Sequence of a Carbapenem-Resistant Strain of Ralstonia mannitolilytica. Reviewed International journal

Masato Suzuki, Hisaaki Nishio, Kohsuke Asagoe, Kaneyuki Kida, Satowa Suzuki, Mari Matsui, Keigo Shibayama

Genome announcements Vol. 3 ( 3 ) 2015.5

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

Ralstonia mannitolilytica, a Gram-negative aerobic bacterium, is an opportunistic human pathogen that is becoming more common in cases of nosocomial infections. We report for the first time the whole-genome sequence analysis of R. mannitolilytica strain MRY14-0246, which carries the intrinsic OXA-443/OXA-22-like and OXA-444/OXA-60-like β-lactamase genes and is resistant to meropenem.

DOI： 10.1128/genomeA.00405-15

Inhibition of adhesion of Clostridium difficile to human intestinal cells after treatment with serum and intestinal fluid isolated from mice immunized with nontoxigenic C-difficile membrane fraction Reviewed

Mitsutoshi Senoh, Masaaki Iwaki, Akihiko Yamamoto, Haru Kato, Tadashi Fukuda, Keigo Shibayama

MICROBIAL PATHOGENESIS Vol. 81 page： 1 - 5 2015.4

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD

Diarrhea and pseudomembrane colitis caused by Clostridium difficile infection is a global health concern because of the high recurrence rate after standard antibiotic therapy. Vaccination presents a powerful countermeasure against disease recurrence. In this study, mice vaccinated with the nontoxigenic Clostridium difficile membrane fraction generated a marked immune response to the antigen, as demonstrated by the serum IgG and intestinal fluid IgA levels. Significantly, pretreatment with harvested IgG- and IgA-containing fluids was sufficient to prevent in vitro adhesion of Clostridium difficile to human Caco-2 intestinal cells. These results highlight the potential of nontoxigenic Clostridium difficile membrane fraction as a vaccine candidate for Clostridium difficile infection. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.micpath.2015.03.001

Molecular characterization of linezolid-resistant CoNS isolates in Japan Reviewed

Akiko Takaya, Asahi Kimura, Yoshiharu Sato, Naruhiko Ishiwada, Masaharu Watanabe, Mari Matsui, Keigo Shibayama, Tomoko Yamamoto

JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY Vol. 70 ( 3 ) page： 658 - 663 2015.3

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

Objectives: Linezolid has been reported to remain active against 98% of staphylococci with resistance identified in 0.05% of Staphylococcus aureus and 1.4% of CoNS. The objective of this study was to characterize the linezolid-resistance mechanisms in the linezolid-resistant CoNS strains isolated in Japan.
Methods: Staphylococcus capitis strains exhibiting linezolid MICs >8 mg/L isolated from inpatients between 2012 and 2014 were screened for cfr and mutations in 23S rRNA, L3 and L4 by PCR/sequencing. Isolates were also examined for mutations in the rlmN gene.
Results: S. capitis had six 23S rRNA alleles. Five S. capitis isolates displayed linezolid MICs of 8, 16 and 32 mg/L. G2576U mutations were detected in three, four or five copies of 23S rRNA in all isolates. In two isolates exhibiting the highest linezolid MIC (32 mg/L) there was a large deletion in a single copy of 23S rRNA. Repeated 10 bp sequences were found in both 16S and 23S rRNAs, suggesting deletion by recombination between the repeats. One isolate had the mutation Ala-142 -> Thr in the ribosomal protein L3. All linezolid-resistant isolates also demonstrated mutations in the gene encoding RlmN methyltransferase, leading to Thr-62 -> Met and Gly-148 -> Ser.
Conclusions: Multiple mechanisms appeared to be responsible for the elevated linezolid resistance in S. capitis isolates: a G2576U mutation in different numbers of copies of 23S rRNA, loss of a single copy of 23S rRNA and a mutation in the ribosomal protein L3, suggesting the accumulation of independent mutational events.

DOI： 10.1093/jac/dku443

Crystal Structure of IMP-2 Metallo-beta-lactamase from Acinetobacter spp.: Comparison of Active-Site Loop Structures between IMP-1 and IMP-2 Reviewed

Yamaguchi Yoshihiro, Matsueda Satoshi, Matsunaga Kazuyo, Takashio Nobutoshi, Toma-Fukai Sachiko, Yamagata Yuriko, Shibata Naohiro, Wachino Jun-ichi, Shibayama Keigo, Arakawa Yoshichika, Kurosaki Hiromasa

BIOLOGICAL & PHARMACEUTICAL BULLETIN Vol. 38 ( 1 ) page： 96 - 101 2015.1

Crystal Structure of IMP-2 Metallo-beta-lactamase from Acinetobacter spp.: Comparison of Active-Site Loop Structures between IMP-1 and IMP-2 Reviewed

Yoshihiro Yamaguchi, Satoshi Matsueda, Kazuyo Matsunaga, Nobutoshi Takashio, Sachiko Toma-Fukai, Yuriko Yamagata, Naohiro Shibata, Jun-ichi Wachino, Keigo Shibayama, Yoshichika Arakawa, Hiromasa Kurosaki

BIOLOGICAL & PHARMACEUTICAL BULLETIN Vol. 38 ( 1 ) page： 96 - 101 2015.1

Language：English Publishing type：Research paper (scientific journal) Publisher：PHARMACEUTICAL SOC JAPAN

IMP-2, a subclass B1 metallo-beta-lactamase (MBL), is a Zn(II)-containing hydrolase. This hydrolase, involved in antibiotic resistance, catalyzes the hydrolysis of the C-N bond of the beta-lactam ring in beta-lactam antibiotics such as benzylpenicillin and imipenem. The crystal structure of IMP-2 MBL from Acinetobacter spp. was determined at 2.3 angstrom resolution. This structure is analogous to that of subclass B1 MBLs such as IMP-1 and VIM-2. Comparison of the structures of IMP-1 and IMP-2, which have an 85% amino acid identity, suggests that the amino acid substitution at position 68 on a beta-strand (beta 3) (Pro in IMP-1 versus Ser in IMP-2) may be a staple factor affecting the flexibility of loop 1 (comprising residues at positions 60-66; EVNGWGV). In the IMP-1 structure, loop 1 adopts an open, disordered conformation. On the other hand, loop 1 of IMP-2 forms a closed conformation in which the side chain of Trp64, involved in substrate binding, is oriented so as to cover the active site, even though there is an acetate ion in the active site of both IMP-1 and IMP-2. Loop 1 of IMP-2 has a more flexible structure in comparison to IMP-1 due to having a Ser residue instead of the Pro residue at position 68, indicating that this difference in sequence may be a trigger to induce a more flexible conformation in loop 1.

DOI： 10.1248/bpb.b14-00594

Helicobacter cinaedi-associated Vertebral Osteomyelitis in an Immunocompetent Patient. Reviewed

Satoshi Murata, Hiromichi Suzuki, Setsu Sakamoto, Takamitsu Miki, Emiko Rimbara, Keigo Shibayama, Shinobu Koyama, Kiyoko Tamai, Yuji Yaguchi, Masaki Tada

Internal medicine (Tokyo, Japan) Vol. 54 ( 24 ) page： 3221 - 4 2015

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japanese Society of Internal Medicine

A 56-year-old previously healthy man was hospitalized due to a 10-day history of neck pain and an elevated C-reactive protein level. Gram-negative spiral bacilli were isolated from his blood, and Helicobacter cinaedi was confirmed using 16S rRNA sequencing. The infectious focus was not identified by initial cervical magnetic resonance imaging (MRI); however, repeated MRI demonstrated prominent high signal intensity in the entire region of the C6-C7 vertebrae and C6/C7 disc space. Furthermore, fluorodeoxyglucose-positron emission tomography/computed tomography showed no significant uptake, other than in the C6-C7 region. The patient was successfully treated with ceftriaxone for six weeks without sequelae.

DOI： 10.2169/internalmedicine.54.4574

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