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  • Chen, Te-Li  (4)
  • 2010-2014  (4)
  • Medicine  (4)
  • 1
    Online Resource
    Online Resource
    Sheltering Effect and Indirect Pathogenesis of Carbapenem-Resistant Acinetobacter baumannii in Polymicrobial Infection
    American Society for Microbiology ; 2014
    In:  Antimicrobial Agents and Chemotherapy Vol. 58, No. 7 ( 2014-07), p. 3983-3990
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 58, No. 7 ( 2014-07), p. 3983-3990
    Abstract: The role of carbapenem-resistant Acinetobacter baumannii (CRAb) in polymicrobial infection remains elusive. Having observed the ability of CRAb to shelter other susceptible bacteria from carbapenem killing, we sought to determine the factors contributing to this sheltering effect by transforming different recombinant plasmids into recipient A. baumannii cells. The sheltering effects of CRAb were reproduced in recipient A. baumannii cells that highly expressed carbapenem-hydrolyzing class D β-lactamases (CHDLs) through their associated strong promoter. With the use of Western blot analysis and a bioassay, the highly expressed CHDLs were found to be extracellularly released and led to hydrolysis of carbapenem. The level of extracellular CHDLs increased after challenge with a higher concentration of CHDL substrates, such as carbapenem and ticarcillin. This increased CHDL may, in part, be attributed to cell lysis, as indicated by the presence of extracellular gyrase. In the planktonic condition, the sheltering effect for the cocultured susceptible bacteria might represent an indirect and passive effect of the CRAb self-defense mechanism, because coculture with the susceptible pathogen did not augment the amount of the extracellular CHDLs. Polymicrobial infection caused by CRAb and a susceptible counterpart exerted higher pathogenicity than monomicrobial infection caused by either pathogen alone in mice receiving carbapenem therapy. This study demonstrated that CHDL-producing CRAb appears to provide a sheltering effect for carbapenem-susceptible pathogens via the extracellular release of CHDLs and, by this mechanism, can enhance the pathogenesis of polymicrobial infection in the presence of carbapenem therapy.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.02636-13
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2014
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Emergence and Distribution of Plasmids Bearing the bla OXA-51 -Like Gene with an Upstream IS Aba1 in Carbapenem-Resistant Acinetobacter baumannii Isolates in Taiwan
    American Society for Microbiology ; 2010
    In:  Antimicrobial Agents and Chemotherapy Vol. 54, No. 11 ( 2010-11), p. 4575-4581
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 54, No. 11 ( 2010-11), p. 4575-4581
    Abstract: The bla OXA-51 -like gene with an upstream IS Aba1 (IS Aba1 - bla OXA-51 -like gene) was originally found on the chromosomes of carbapenem-resistant or -susceptible Acinetobacter baumannii isolates. However, a plasmid-borne IS Aba1 - bla OXA-51 -like gene has recently been identified in Acinetobacter genomic species 13TU and several A. baumannii isolates in Taiwan, and all of the isolates are carbapenem resistant. This study aimed to characterize the plasmids bearing the IS Aba1 - bla OXA-51 -like gene and their significance in A. baumannii . Among the 117 IS Aba1 - bla OXA-51 -like-harboring isolates collected from 10 hospitals in Taiwan, 58 isolates (49.6%) from 24 clones had the genes located on plasmids that likely originated from a common progenitor. Among the 58 isolates, four had additional copy of the IS Aba1 - bla OXA-51 -like gene on their chromosomes. Based on the analysis of these four isolates, the plasmid-located IS Aba1 - bla OXA-51 -like gene appeared to be acquired via one-ended transposition (Tn 6080 ). The isolates with a plasmid bearing the IS Aba1 - bla OXA-51 -like gene had higher rates of resistance to imipenem (98% versus 46.6%; P 〈 0.001) and meropenem (98% versus 69%; P = 0.019) than those with the genes chromosomally encoded, which is most likely due to increased gene dosage provided by the higher copy number of associated plasmids. Transformation with a recombinant plasmid harboring only the IS Aba1 - bla OXA-51 -like gene was enough to confer a high level of carbapenem resistance to A. baumannii , eliminating the possible contribution of other factors on the original plasmids. This study demonstrated that the carbapenem resistance-associated plasmids carrying the IS Aba1 - bla OXA-51 -like gene are widespread in A. baumannii strains in Taiwan.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.00764-10
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2010
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Contribution of a Plasmid-Borne bla OXA-58 Gene with Its Hybrid Promoter Provided by IS 1006 and an IS Aba3 -Like Element to β-Lactam Resistance in Acinetobacter Genomic Species 13TU
    American Society for Microbiology ; 2010
    In:  Antimicrobial Agents and Chemotherapy Vol. 54, No. 8 ( 2010-08), p. 3107-3112
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 54, No. 8 ( 2010-08), p. 3107-3112
    Abstract: The contribution of the bla OXA-58 gene and its promoter to β-lactam resistance has not been validated in Acinetobacter spp. other than Acinetobacter baumannii . We identified a multidrug-resistant (including carbapenem resistance) Acinetobacter genomic species 13TU in which bla OXA-58 was the only detected carbapenemase gene. The bla OXA-58 gene was plasmid located, flanked by IS Aba3 (downstream) and an IS Aba3- like element (upstream). An IS 1006 element was inserted into IS Aba3 -like (IS 1006 -ΔIS Aba3 -like) to generate a hybrid promoter for bla OXA-58 , with a −35 promoter located in IS 1006 and a −10 promoter in IS Aba3 -like. The reference strain of Acinetobacter genomic species 13TU, ATCC 17903, revealed higher MICs of amoxicillin, ticarcillin, and piperacillin and heteroresistance to imipenem and meropenem when it was transformed with a shuttle vector containing a fragment encompassing ΔIS Aba3 -like- bla OXA-58 , compared to the same host containing only bla OXA-58 . When the fragment was changed from ΔIS Aba3 -like- bla OXA-58 to IS 1006 -ΔIS Aba3 -like- bla OXA-58 , the ATCC 17903 transformant revealed a markedly higher level of bla OXA-58 transcription (12-fold), increased cefuroxime and piperacillin-tazobactam MICs, and homoresistance to imipenem and meropenem. Different roles of the insertion elements preceding the bla OXA-58 gene in Acinetobacter genomic species 13TU are demonstrated. The IS Aba3 -like- -bla OXA-58 construct can mediate resistance to penicillin derivatives but only heteroresistance to carbapenems. The insertion of IS 1006 into IS Aba3 -like, generating a hybrid promoter, could further enhance the transcription of bla OXA-58 and mediate homoresistance to carbapenems and also enhanced resistance to piperacillin-tazobactam.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.00128-10
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2010
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Association Between Recent Use of Fluoroquinolones and Rhegmatogenous Retinal Detachment: A Population-Based Cohort Study
    Oxford University Press (OUP) ; 2014
    In:  Clinical Infectious Diseases Vol. 58, No. 2 ( 2014-1-15), p. 197-203
    Details
    In: Clinical Infectious Diseases, Oxford University Press (OUP), Vol. 58, No. 2 ( 2014-1-15), p. 197-203
    Type of Medium: Online Resource
    ISSN: 1537-6591 , 1058-4838
    URL: Article
    DOI: 10.1093/cid/cit708
    RVK:
    XA 10000
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2014
    detail.hit.zdb_id: 2002229-3
    Location Call Number Limitation Availability
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