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Carriage of Escherichia coli Producing CTX-M-Type Extended-Spectrum β-Lactamase in Healthy Vietnamese Individuals.

Bui TM, Hirai I, Ueda S, Bui TK, Hamamoto K, Toyosato T, Le DT, Yamamoto Y

Antimicrobial agents and chemotherapy ( Antimicrobial Agents and Chemotherapy )  59 ( 10 ) 6611 - 4   2015年10月

掲載種別: 研究論文（学術雑誌）

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Characteristics of Extended-Spectrum β-Lactamase-Producing Escherichia coli in Retail Meats and Shrimp at a Local Market in Vietnam.

Le QP, Ueda S, Nguyen TN, Dao TV, Van Hoang TA, Tran TT, Hirai I, Nakayama T, Kawahara R, Do TH, Vien QM, Yamamoto Y

Foodborne pathogens and disease   12 ( 8 ) 719 - 25   2015年08月

掲載種別: 研究論文（学術雑誌）

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Evaluation of a Method Using Three Genomic Guided Escherichia coli Markers for Phylogenetic Typing of E. coli Isolates of Various Genetic Backgrounds.

Hamamoto K, Ueda S, Yamamoto Y, Hirai I

Journal of clinical microbiology ( Journal of Clinical Microbiology )  53 ( 6 ) 1848 - 53   2015年06月

掲載種別: 研究論文（学術雑誌）

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Wide dissemination of extended-spectrum β-lactamase-producing Escherichia coli in community residents in the Indochinese peninsula.

Nakayama T, Ueda S, Huong BT, Tuyen le D, Komalamisra C, Kusolsuk T, Hirai I, Yamamoto Y

Infection and drug resistance ( Infection and Drug Resistance )  8   1 - 5   2015年

掲載種別: 研究論文（学術雑誌）

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Limited transmission of bla(CTX-M-9)-type-positive Escherichia coli between humans and poultry in Vietnam.

Ueda S, Ngan BT, Huong BT, Hirai I, Tuyen le D, Yamamoto Y

Antimicrobial agents and chemotherapy ( Antimicrobial Agents and Chemotherapy )  59 ( 6 ) 3574 - 7   2015年

掲載種別: 研究論文（学術雑誌）

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A highly conserved region between amino acids 221 and 266 of dengue virus non-structural protein 1 is a major epitope region in infected patients.

Omokoko MD, Pambudi S, Phanthanawiboon S, Masrinoul P, Setthapramote C, Sasaki T, Kuhara M, Ramasoota P, Yamashita A, Hirai I, Ikuta K, Kurosu T

The American journal of tropical medicine and hygiene ( AMER SOC TROP MED & HYGIENE )  91 ( 1 ) 146 - 55   2014年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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The immune response to dengue virus (DENV) infection generates high levels of antibodies (Abs) against the DENV non-structural protein 1 (NS1), particularly in cases of secondary infection. Therefore, anti-NS1 Abs may play a role in severe dengue infections, possibly by interacting (directly or indirectly) with host factors or regulating virus production. If it does play a role, NS1 may contain epitopes that mimic those epitopes of host molecules. Previous attempts to map immunogenic regions within DENV-NS1 were undertaken using mouse monoclonal Abs (MAbs). The aim of this study was to characterize the epitope regions of nine anti-NS1 human monoclonal Abs (HuMAbs) derived from six patients secondarily infected with DENV-2. These anti-NS1 HuMAbs were cross-reactive with DENV-1, -2, and -3 but not DENV-4. All HuMAbs bound a common epitope region located between amino acids 221 and 266 of NS1. This study is the first report to map a DENV-NS1 epitope region using anti-DENV MAbs derived from patients.

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Detection of chromosomal blaCTX-M-15 in Escherichia coli O25b-B2-ST131 isolates from the Kinki region of Japan.

Hirai I, Fukui N, Taguchi M, Yamauchi K, Nakamura T, Okano S, Yamamoto Y

International journal of antimicrobial agents   42 ( 6 ) 500 - 6   2013年12月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Escherichia coli O25b-B2-ST131 isolates harbouring blaCTX-M-15 are distributed worldwide. The blaCTX-M-15 transposition unit has often been found on plasmids and the genetic contexts have been examined however, less is known about the frequency and contexts of the bla CTX-M-15 transposition unit on the chromosome. This study was performed to determine the chromosomal location of the blaCTX-M-15 transposition unit and to analyse the molecular structure of the region surrounding the blaCTX-M-15 transposition unit in E. coli O25b-B2-ST131 isolates. Twenty-two E. coli O25b-B2-ST131 strains harbouring blaCTX-M-15 that had been isolated from university hospital patients and nursing home residents in the Kinki region of Japan were examined. Inverse PCR (iPCR) targeting blaCTX-M-15 was performed to classify the molecular structure of the region surrounding the blaCTX-M-15 transposition unit. The isolates were classified into nine types (types A-I) considering the iPCR results type A was the most prevalent type (13/22 isolates). Sequences of the iPCR-amplified DNA fragments showed that the blaCTX-M-15 transposition unit consisted of ISEcp1, bla CTX-M-15 and orf477Δ. A homology search of the obtained sequences showed that the blaCTX-M-15 transposition unit was inserted into different chromosomal regions in eight of the nine classified types. Although 21 of the 22 E. coli isolates possessed chromosomally located bla CTX-M-15 transposition units, clonal spread was not evident on pulsed-field gel electrophoresis (PFGE) analysis. Taken together, these data indicate that certain E. coli O25b-B2-ST131 strains harbouring chromosomal blaCTX-M-15 have emerged and spread in the Kinki region of Japan. © 2013 Elsevier B.V. and the International Society of Chemotherapy.

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Dengue virus neutralization and antibody-dependent enhancement activities of human monoclonal antibodies derived from dengue patients at acute phase of secondary infection.

Sasaki T, Setthapramote C, Kurosu T, Nishimura M, Asai A, Omokoko MD, Pipattanaboon C, Pitaksajjakul P, Limkittikul K, Subchareon A, Chaichana P, Okabayashi T, Hirai I, Leaungwutiwong P, Misaki R, Fujiyama K, Ono K, Okuno Y, Ramasoota P, Ikuta K

Antiviral research ( ELSEVIER SCIENCE BV )  98 ( 3 ) 423 - 31   2013年06月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Public health concern about dengue diseases, caused by mosquito-borne infections with four serotypes of dengue virus (DENV-1-DENV-4), is escalating in tropical and subtropical countries. Most of the severe dengue cases occur in patients experiencing a secondary infection with a serotype that is different from the first infection. This is believed to be due to antibody-dependent enhancement (ADE), by which one DENV serotype uses pre-existing anti-DENV antibodies elicited in the primary infection to facilitate entry of a different DENV serotype into the Fc receptor-positive macrophages. Recently, we prepared a number of hybridomas producing human monoclonal antibodies (HuMAbs) by using peripheral blood lymphocytes from Thai patients at acute phase of secondary infection with DENV-2. Here, we characterized 17 HuMAbs prepared from two patients with dengue fever (DF) and one patient with dengue hemorrhagic fever (DHF) that were selected as antibodies recognizing viral envelope protein and showing higher neutralization activity to all serotypes. In vivo evaluation using suckling mice revealed near perfect activity to prevent mouse lethality following intracerebral DENV-2 inoculation. In a THP-1 cell assay, these HuMAbs showed ADE activities against DENV-2 at similar levels between HuMAbs derived from DF and DHF patients. However, the F(ab')(2) fragment of the HuMAb showed a similar virus neutralization activity as original, with no ADE activity. Thus, these HuMAbs could be one of the therapeutic candidates against DENV infection. (C) 2013 Elsevier B.V. All rights reserved.

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Jurkat cell proliferation is suppressed by Chlamydia (Chlamydophila) pneumoniae infection accompanied with attenuation of phosphorylation at Thr389 of host cellular p70S6K.

Hirai I, Ebara M, Nakanishi S, Yamamoto C, Sasaki T, Ikuta K, Yamamoto Y

Immunobiology   218 ( 4 ) 527 - 32   2013年04月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Chlamydia (Chlamydophila) pneumoniae infects T lymphocytes and multiplies within them. Our previous studies have indicated that C. pneumoniae infection suppresses proliferation of peripheral blood mononuclear cells stimulated with Staphylococcus-enterotoxin B however, the mechanism of suppression was unclear. In this study, we explored the molecular mechanism involved in C. pneumoniae infection by using human acute T cell leukemia cell line, Jurkat E6-1. Proliferation of Jurkat cells was suppressed in an m.o.i.-dependent manner by C. pneumoniae infection. The suppression by the infection was particularly evident during the initial 24. h of the infection, and down modulation of cyclin D3 protein levels were observed at the same time period by immunoblot analysis. The suppression of the Jurkat cell proliferation and the down modulation of cyclin D3 protein level were only induced by viable C. pneumoniae infection, not by exposure to UV-killed or heat-killed C. pneumoniae. Phosphorylations at Thr308 and Ser473 of AKT were induced by C. pneumoniae infection however, phosphorylation at Thr389 of the downstream kinase, p70S6K was inhibited by unidentified mechanism associated with C. pneumoniae infection. Taking into account that G1 arrest of the C. pneumoniae infected Jurkat cells were not observed and that p70S6K is one of the most important regulators of protein synthesis, it was suggested that the suppression of Jurkat cell proliferation by C. pneumoniae was at least in part mediated by down modulation of protein synthesis through attenuation of Thr389 phosphorylation of p70S6K. © 2012 Elsevier GmbH.

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Human monoclonal antibodies to neutralize all dengue virus serotypes using lymphocytes from patients at acute phase of the secondary infection (vol 423, pg 867, 2012)

Chayanee Setthapramote, Tadahiro Sasaki, Orapim Puiprom, Kriengsak Limkittikul, Pannamthip Pitaksajjakul, Chonlatip Pipattanaboon, Mikiko Sasayama, Pornsawan Leuangwutiwong, Weerapong Phumratanaprapin, Supat Chamnachanan, Teera Kusolsuk, Akanitt Jittmittraphap, Azusa Asai, Juan Fernando Arias, Itaru Hirai, Motoki Kuhara, Yoshinobu Okuno, Takeshi Kurosu, Pongrama Ramasoota, Kazuyoshi Ikuta

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS ( ACADEMIC PRESS INC ELSEVIER SCIENCE )  432 ( 1 ) 200 - 201   2013年03月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Chlamydophila pneumoniae in human immortal Jurkat cells and primary lymphocytes uncontrolled by interferon-γ.

Ishida K, Kubo T, Saeki A, Yamane C, Matsuo J, Yimin, Nakamura S, Hayashi Y, Kunichika M, Yoshida M, Takahashi K, Hirai I, Yamamoto Y, Shibata K, Yamaguchi H

Microbes and infection ( ELSEVIER SCIENCE BV )  15 ( 3 ) 192 - 200   2013年03月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Lymphocytes are a potential host cell for Chlamydophila pneumoniae, although why the bacteria must hide in lymphocytes remains unknown. Meanwhile, interferon (IFN)-gamma is a crucial factor for eliminating chlamydiae from infected cells through indoleamine 2,3-dioxygenase (IDO) expression, resulting in depletion of tryptophan. We therefore assessed if lymphocytes could work as a shelter for the bacteria to escape IFN-gamma. C. pneumoniae grew normally in human lymphoid Jurkat cells, even in the presence of IFN-gamma or under stimulation with phorbol myristate acetate plus ionomycin. Although Jurkat cells expressed IFN-gamma receptor CD119, their lack of IDO expression was confirmed by RT-PCR and western blotting. Also, C. pneumoniae survived in enriched human peripheral blood lymphocytes, even in the presence of IFN-gamma. Furthermore, C. pneumoniae in spleen cells obtained from IFN-gamma knockout mice with C57BL16 background was maintained in a similar way to wild-type mice, supporting a minimal role of]FN-gamma-related response for eliminating C. pneumoniae from lymphocytes. Thus, we concluded that IFN-gamma did not remove C. pneumoniae from lymphocytes, possibly providing a shelter for C. pneumoniae to escape from the innate immune response, which has direct clinical significance. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

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Fecal carriage of CTX-M β-lactamase-producing Enterobacteriaceae in nursing homes in the Kinki region of Japan.

Luvsansharav UO, Hirai I, Niki M, Nakata A, Yoshinaga A, Yamamoto A, Yamamoto M, Toyoshima H, Kawakami F, Matsuura N, Yamamoto Y

Infection and drug resistance   6   67 - 70   2013年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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The detection rate of CTX-M-type β-lactamase-producing Enterobacteriaceae in Japan has significantly increased. Nursing homes may be a reservoir of antibiotic-resistant bacteria. Therefore, we determined the prevalence of, and risk factors associated with, fecal carriage of CTX-M-type β-lactamase-producing Enterobacteriaceae among nursing home residents. A total of 225 stool samples were collected for phenotypic and genotypic identification of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. Multivariate analysis was performed to identify the risk factors associated with fecal carriage of CTX-M producers. The prevalence of CTX-M-type ESBL-producing Enterobacteriaceae, as confirmed by phenotypic and genotypic methods, was 19.6% (44 of 225 samples). Escherichia coli was the predominant CTX-M-type ESBL-producing bacterium among these isolates (41 of 44 isolates). Genotyping of blabla gene-positive isolates showed that 30 (68.2%), 13 (29.5%), and 1 (2.3%) of 44 samples belonged to groups CTX-M-9, CTX-M-1 and CTX-M-2, respectively. Among the CTX-M-type ESBL-producing Enterobacteriaceae found in nursing homes, 95.5% (42 of 44 isolates) were co-resistant to quinolone antibiotics. In multivariate logistic regression analysis, inability to turn over in bed, diabetes, and invasive procedures within the last 2 years were the only variables independently associated with fecal carriage of CTX-M-type ESBL producers. Nursing home residents in Japan exhibit a high prevalence of CTX-M-type ESBL-producing Enterobacteriaceae carriage, with a high level of co-resistance to quinolones. © 2013 Luvsansharav et al, publisher and licensee Dove Medical Press Ltd.

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Human monoclonal antibodies to neutralize all dengue virus serotypes using lymphocytes from patients at acute phase of the secondary infection.

Setthapramote C, Sasaki T, Puiprom O, Limkittikul K, Pitaksajjakul P, Pipattanaboon C, Sasayama M, Leuangwutiwong P, Phumratanaprapin W, Chamnachanan S, Kusolsuk T, Jittmittraphap A, Asai A, Arias JF, Hirai I, Kuhara M, Okuno Y, Kurosu T, Ramasoota P, Ikuta K

Biochemical and biophysical research communications ( ACADEMIC PRESS INC ELSEVIER SCIENCE )  423 ( 4 ) 867 - 72   2012年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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The global spread of the four dengue virus serotypes (DENV-1 to -4) has made this virus a major and growing public health concern. Generally, pre-existing neutralizing antibodies derived from primary infection play a significant role in protecting against subsequent infection with the same serotype. By contrast, these pre-existing antibodies are believed to mediate a non-protective response to subsequent heterotypic DENV infections, leading to the onset of dengue illness. In this study, we prepared hybridomas producing human monoclonal antibodies (HuMAbs) against DENV using peripheral blood mononuclear cells (PBMCs) from patients in the acute phase (around 1 week after the onset of illness) or the convalescent phase (around 2 weeks after the onset of illness) of secondary infection. Interestingly, a larger number of hybridoma clones was obtained from patients in the acute phase than from those in the convalescent phase. Most HuMAbs from acute-phase infections were cross-reactive with all four DENV serotypes and showed significant neutralization activity to all four DENV serotypes. Thus, secondary DENV infection plays a significant role in stimulating memory cells to transiently increase the number of antibody-secreting plasma cells in patients in the early phase after the secondary infection. These HuMAbs will enable us to better understand the protective and pathogenic effects of DENV infection, which could vary greatly among secondarily-infected individuals. (C) 2012 Elsevier Inc. All rights reserved.

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Chlamydia trachomatis serovar L2 infection model using human lymphoid Jurkat cells.

Kubo T, Ishida K, Matsuo J, Nakamura S, Hayashi Y, Sakai H, Yoshida M, Takahashi K, Hirai I, Yamamoto Y, Yamaguchi H

Microbial pathogenesis ( ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD )  53 ( 1 ) 1 - 11   2012年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Chlamydia trachomatis L2 invasively attacks lymphatic and subepithelial tissues of the genital tract during the formation of primary lesions. This subsequently results in lymphadenopathy, and suggests a greater propensity for systemic dissemination. However, whether lymphocytes are a potential vehicle cell for the dissemination of this infection remains unknown. We therefore assessed the growth properties of C trachomatis L2 in lymphoid Jurkat cells compared with those observed in epithelial HeLa cells. Both cells supported the growth of C trachomatis with a similar increase in infective progenies. Enriched human-blood lymphocytes also supported the C trachomatis growth as well as Jurkat cells. Bacteria infecting the Jurkat cells were more susceptible to antibiotics (doxycycline, azithromycin, ofloxacin) than those in HeLa cells. Of the sphingomyelin biosynthesis inhibitors tested, both myriocin and fumonisin B1 significantly inhibited bacterial growth in both cells types. A Jurkat cell mutant that impaired bacterial growth was established using ethylmethanesulfonate treatment. DNA microarray analysis with real-time reverse transcription-polymerase chain reaction revealed that the mutant cells over-expressed granzyme K gene. Immunofluorescence staining also indicated that granzyme K irregularly over-expressed among the mutant cells as compared with that of the wild cells, suggesting a possible mechanism refractory to C. trachomatis infection. Thus, we concluded that C. trachomatis 12 could infect Jurkat cells with lymphoid properties, providing a new tool for studying C. trachomatis dissemination to tissues via lymphocyte movement. (C) 2012 Elsevier Ltd. All rights reserved.

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Prevalence of and risk factors associated with faecal carriage of CTX-M β-lactamase-producing Enterobacteriaceae in rural Thai communities.

Luvsansharav UO, Hirai I, Nakata A, Imura K, Yamauchi K, Niki M, Komalamisra C, Kusolsuk T, Yamamoto Y

The Journal of antimicrobial chemotherapy ( OXFORD UNIV PRESS )  67 ( 7 ) 1769 - 74   2012年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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To determine the prevalence of CTX-M -lactamase-producing Enterobacteriaceae and to study the risk factors associated with faecal carriage in asymptomatic rural Thai people. In all, 417 stool samples were obtained from rural Thai people and screened for extended-spectrum -lactamases (ESBLs) using MacConkey agar supplemented with 2 mg/L cefotaxime. Results were confirmed using cefotaxime and ceftazidime with and without clavulanic acid. The bla(CTX-M) genes were identified and genotyped using PCR with bacterial DNA samples. Multivariate analysis was performed to investigate risk factors associated with the faecal carriage of CTX-M producers. The prevalence of CTX-M-type ESBL-producing Enterobacteriaceae was 65.7. The CTX-M-9 group (60.6) was dominant, followed by the CTX-M-1 group (38.7). Most of the bacteria were Escherichia coli (85.4) and Klebsiella pneumoniae (4.7). Of a total of 234 E. coli strains, 48.7 belonged to phylogenetic group A, 28.6 to group B1, 15.8 to group D and 6.8 to group B2. Most CTX-M producers were susceptible to carbapenems and amikacin, but resistant to tetracycline and gentamicin. In a multivariate logistic regression model, better education status (OR 2.245; 95 CI 1.2973.884), history of hospitalization (OR 1.643; 95 CI 1.0362.603) and the use of antibiotics within the last 3 months (OR 1.883; 95 CI 1.2212.903) were independently associated with faecal carriage. Faecal carriage of CTX-M-type ESBL-producing Enterobacteriaceae among asymptomatic individuals in rural Thailand remains alarmingly high, and previous antibiotic use and a history of hospitalization may contribute to its dissemination.

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Epidemiology of Escherichia coli, Klebsiella species, and Proteus mirabilis strains producing extended-spectrum β-lactamases from clinical samples in the Kinki Region of Japan.

Nakamura T, Komatsu M, Yamasaki K, Fukuda S, Miyamoto Y, Higuchi T, Ono T, Nishio H, Sueyoshi N, Kida K, Satoh K, Toda H, Toyokawa M, Nishi I, Sakamoto M, Akagi M, Nakai I, Kofuku T, Orita T, Wada Y, Zikimoto T, Koike C, Kinoshita S, Hirai I, Takahashi H, Matsuura N, Yamamoto Y

American journal of clinical pathology ( AMER SOC CLINICAL PATHOLOGY )  137 ( 4 ) 620 - 6   2012年04月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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In the present study, nonduplicate, clinical isolates of extended-spectrum beta-lactamase (ESBL)-producing Escherichia colt, Klebsiella spp, and Proteus mirabilis were collected during a 10-year period from 2000 to 2009 at several hospitals in the Kinki region, Japan. The detection rate of E coli markedly increased from 0.24% to 7.25%. The detection rate of Klebsiella pneumoniae increased from 0% to 2.44% and that of P mirabilis from 6.97% to 12.85%. The most frequently detected genotypes were the CTX-M9 group for E coli, the CTX-M2 group for K pneumoniae, and the CTX-M2 group for P mirabilis. E coli clone O25:H4-ST131 producing CTX-M-15, which is spreading worldwide, was first detected in 2007. The most common replicon type of E coli was the IncF type, particularly FIB, detected in 466 strains (69.7%). Of the K pneumoniae strains, 47 (55.3%) were of the IncN type; 77 P mirabilis strains (96.3%) were of the IncT type. In the future, the surveillance of various resistant bacteria, mainly ESBL-producing Enterobacteriaceae, should be expanded to prevent their spread.

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Extended-spectrum β-lactamase-producing Escherichia coli strains in the feces of carriers contribute substantially to urinary tract infections in these patients.

Niki M, Hirai I, Yoshinaga A, Ulzii-Orshikh L, Nakata A, Yamamoto A, Yamamoto M, Yamamoto Y

Infection ( SPRINGER HEIDELBERG )  39 ( 5 ) 467 - 471   2011年10月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Introduction The current increase in the incidence of urinary tract infections (UTIs) worldwide caused by extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli may be due to the high number of ESBL-producing Enterobacteriaceae carriers in the community. However, whether ESBL-producing bacteria can cause UTIs in carriers remains uncertain. Materials and methods In this study, 21 fecal carriers of ESBL-producing Enterobacteriaceae were assessed for UTIs caused by ESBL-producing E. coli. Bacterial isolates obtained from patients' urine and stool specimens were phenotypically and genotypically examined. Clonal similarities of isolates were assessed by multilocus sequence typing (MLST) and random amplified polymorphic DNA (RAPD) fingerprinting. Results The study revealed that 9 of 21 carriers developed UTIs, and genetic analysis showed that 44% of the UTIs developed were caused by the same ESBL-producing E. coli as that found in the feces of the patients. Conclusions The ESBL-producing E. coli in carriers can cause UTIs.

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Prevalence of fecal carriage of extended-spectrum β-lactamase-producing Enterobacteriaceae among healthy adult people in Japan.

Luvsansharav UO, Hirai I, Niki M, Nakata A, Yoshinaga A, Moriyama T, Yamamoto Y

Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy ( SPRINGER TOKYO )  17 ( 5 ) 722 - 5   2011年10月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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In Japan, the prevalence of extended-spectrum beta-lactamase (ESBL) producers in hospital settings has shown an increasing trend. In the present study, we investigated the prevalence of the fecal carriage of ESBL-producing Enterobacteriaceae among healthy adults. Stool samples were collected for the phenotypic and genotypic identification of ESBL-producing Enterobacteriaceae. We found the prevalence of ESBL producers to be 6.4% by phenotypic identification, and 92.9% of them possessed the bla(CTX-M) gene. Among the CTX-M ESBL-producing Enterobacteriaceae, we identified 11 Escherichia coli and 2 Klebsiella pneumonia strains. The findings suggest that the fecal carriage of CTX-M-type ESBL producers by healthy people is rapidly increasing in Japan. This may be one of the causes of the increased spread of ESBL-producing bacteria in hospitals.

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Chlamydophila pneumoniae attachment and infection in low proteoglycan expressing human lymphoid Jurkat cells.

Kobayashi M, Ishida K, Matsuo J, Nakamura S, Nagasawa A, Motohashi K, Yao T, Hirai I, Yamamoto Y, Suzuki H, Shimizu C, Matsuno K, Yamaguchi H

Microbial pathogenesis ( ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD )  51 ( 3 ) 209 - 16   2011年09月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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This study investigated the proteoglycan (PG)-dependent mechanism of Chlamydophila pneumoniae attachment to lymphocytic cells. Lymphoid Jurkat cells and epithelial HEp-2 cells were statically infected with C. pneumoniae (TW183). Transmission electron microscopy and assessment of inclusion-forming units indicated that the bacteria grew normally in Jurkat cells and were capable of producing secondary infection; however, they grew at a slower rate than in HEp-2 cells. RT-PCR analysis indicated that HEp-2 cells strongly expressed PG-core protein encoding genes, thereby sustaining glycosaminoglycans (GAGs), such as heparin, on the cellular surface. Similar gene expression levels were not observed in Jurkat cells, with the exception of glypican-1. Immunofluorescence analysis also supported strong heparin expression in HEp-2 cells and minimal expression in Jurkat cells, although heparan sulfate pretreatment significantly inhibited bacterial attachment to both cell types. Immunofluorescent co-staining with antibodies against chlamydial LPS and heparin did not identify bacterial and heparin co-localization on Jurkat cells. We also confirmed that when C. pneumoniae was statically infected to human CD4(+) peripheral blood lymphocytes known not expressing detectable level of heparin, the bacteria attached to and formed inclusion bodies in the cells. Thus, the attachment mechanism of C pneumoniae to Jurkat cells with low PG expression is unique when compared with HEp-2 cells and potentially independent of GAGs such as heparin. (C) 2011 Elsevier Ltd. All rights reserved.

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Analysis of risk factors for a high prevalence of extended-spectrum {beta}-lactamase-producing Enterobacteriaceae in asymptomatic individuals in rural Thailand.

Luvsansharav UO, Hirai I, Niki M, Sasaki T, Makimoto K, Komalamisra C, Maipanich W, Kusolsuk T, Sa-Nguankiat S, Pubampen S, Yamamoto Y

Journal of medical microbiology ( SOC GENERAL MICROBIOLOGY )  60 ( Pt 5 ) 619 - 624   2011年05月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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The prevalence of and risk factors associated with extended-spectrum beta-lactamase (ESBL)-producing micro-organisms have not been well studied in healthy individuals. The aim of this study was to determine this in healthy individuals in Thailand. Stool samples and questionnaires obtained from 445 participants from three provinces in Thailand were analysed. The antimicrobial susceptibility of the isolates was assessed using phenotypic and genotypic methods. PCR analysis was performed to detect and group the bla(CTX-M) genes. The prevalence of CTX-M-type ESBL-producing Enterobacteriaceae in the three provinces was as follows: 29.3% in Nan (43/147), 29.9% in Nakhon Si Thammarat (43/144) and 50.6% in Kanchanaburi (78/154) (P<0.001). Of the 445 samples, 33 (7.4%), 1 (0.2%) and 127 (28.5%) isolates belonged to the bla(CTX-M) gene groups I, Ill and IV, respectively. Escherichia coli was the predominant member of the Enterobacteriaceae producing CTX-M-type ESBLs (40/43, 39/43 and 70/78 isolates in Nan, Nakhon Si Thammarat and Kanchanaburi, respectively). No statistically significant association was observed between the presence of ESBL-producing bacteria and gender, age, education, food habits or antibiotic usage. However, the provinces that had the highest prevalence of ESBL-producing Enterobacteriaceae also had the highest prevalence of use and purchase of antibiotics without a prescription. Thus, this study revealed that faecal carriage of ESBL-producing Enterobacteriaceae is very high in asymptomatic individuals in Thailand, with some variations among the provinces. This high prevalence may be linked to antibiotic abuse.

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