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Please use this identifier to cite or link to this item: http://hdl.handle.net/10564/3764

Title: Comparison of the inoculum size effects of antibiotics on IMP-6 β-lactamase-producing Enterobacteriaceae co-harboring plasmid-mediated quinolone resistance genes.
Other Titles: プラスミド性キノロン耐性遺伝子を保有するIMP-6産生腸内細菌科細菌でのイノカラムサイズ効果の比較
Authors: Ogawa, Yoshihiko
Nakano, Ryuichi
Kasahara, Kei
Mizuno, Tomoki
Hirai, Nobuyasu
Nakano, Akiyo
Suzuki, Yuki
Kakuta, Naoki
Masui, Takashi
Yano, Hisakazu
Mikasa, Keiichi
Issue Date: 13-Nov-2019
Publisher: Public Library of Science
Citation: PloS one Vol.14 No.11 Article No.e0225210 (2019 Nov)
Abstract: Almost all cases of carbapenemase-producing Enterobacteriaceae infections in Japan are caused by blaIMP-positive Enterobacteriaceae (especially blaIMP-6) and infections caused by other types of carbapenemase-producing Enterobacteriaceae are quite rare. We examined drug resistance genes co-harboring with blaIMP-6 and their inoculum size effects. We screened β-lactamase genes, plasmid-mediated quinolone resistance (PMQR) genes, and aminoglycoside-modifying enzyme genes by PCR and performed sequencing for 14 blaIMP-6-positive Enterobacteriaceae. Further, all PMQR-positive isolates were submitted to conjugation and inoculum effect evaluation. Our data showed that 13 of the 14 isolates harbored CTX-M-2 and one co-harbored CTX-M-2 and CTX-M-1 as extended-spectrum β-lactamases. All isolates carried one or more PMQRs; aac(6’)-Ib-cr was the most prevalent (92.8%), and was followed by oqxA (64.3%), qnrS (50%), oqxAB (21.4%), and qnrB (14.3%). However, Klebsiella pneumoniae contains chromosomal OqxAB. Inoculum size effects were significant in all strains for meropenem, 13 strains for imipenem, 7 for levofloxacin, and 3 for amikacin. We observed that 11 of the experimental strains (100%), 8 strains (72.7%), and 1 strain showed inoculum size effects for meropenem, imipenem, and amikacin, respectively. However, four strains harbored qnr genes and two strains harbored qnr genes and QRDR mutations concurrently; no inoculum size effect was seen for levofloxacin. The blaIMP-6-positive Enterobacteriaceae that we studied was found to harbor at least one plasmid-mediated drug resistance gene. The inoculum size effect for carbapenems was thought to be mainly due to IMP-6-type metallo-β-lactamase; however qnrB and qnrS also had a minimal impact on the inoculum size effect for levofloxacin.
Description: 博士(医学)・乙第1463号・令和2年6月30日
Copyright: © 2019 Ogawa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License(https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
URI: http://hdl.handle.net/10564/3764
ISSN: 19326203
Academic Degrees and number: 24601B1463
Degree-granting date: 2020-06-30
Degree name: 博士(医学)
Degree-granting institutions: 奈良県立医科大学
Appears in Collections:2020年度

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