ESBLs産生グラム陰性桿菌の疫学調査におけるゲノム型の有用性 SIGNIFICANCE OF MOLECULAR EPIDEMIOLOGY OF ESBLs PRODUCING GRAM NEGATIVE RODS BY ANALYZING THE GENOME TYPE

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Abstract

昭和大学病院において2001年2月から7月の6カ月間にMIC測定とクラブラン酸抑制試験により検出された<I>E. coli</I>205株のうち5株 (2.4%) , <I>K.pneumoniae</I>93株のうち3株 (3.2%) と<I>K. oxytoca</I>52株のうち2株 (3.8%) がESBLs産生と判定された.ESBLs産生と判定された<I>E. coli, K. pneumoniae</I>および<I>K. oxytoca</I>のSpe I消化後のパルスフィールド電気泳動パターンによる分子疫学解析を行ったところ, <I>E. coli</I>の2株, <I>K. pneumoniae</I>の2株, および<I>K.oxytoca</I>の2株が同一のゲノム型であった.しかし, 同一ゲノム型であっても<I>E.coli</I>と<I>K. oxytoca</I>はそれぞれ異なるMICパターンを示した.さらに, これら分離菌のTEM型β-1actamase遺伝子の存在をPCRで確認したところ, 同一ゲノム型を示した<I>E.coli</I>の2株と, <I>K.pneumoniae</I>の1株で検出された.これらTEM型β-lactamase遺伝子の塩基配列解析の結果, これらは既知のESBL変異とは一致しておらず, さらに, 3株由来のTEM型β-lactamase遺伝子配列は同一ではなかった.<BR>ESBLs産生グラム陰性桿菌は, 耐性責任遺伝子が多数あるため, MICパターンや, 耐性責任遺伝子解析では感染経路に関わる十分な情報が得られない.このため, ESBLs産生グラム陰性桿菌による院内感染防止のための疫学解析にはゲノム型解析が必須といえる.

Among the clinical isolates from February to July, 2001 at Showa University Hospital, 5 of 205<I>E. coli</I> (2.4%), 3 of 93<I>K. pneumoniae</I> (3.2%) and 2 of 52<I>K. oxytoca</I> (3.8%) were extended spectrum β-lactamase (ESBLs) -producing strains identified by a combination of minimal inhibitory concentration (MIC) detection and clavulanic acid inhibition tests. After Spe I digestion of the genome DNA from the above ESBL-producing isolates, pulsed field gel electrophoretic analysis revealed that 2 of the 5 <I>E. coli</I>, 2 of the 3 <I>K. pneumoniae</I>and 2 of the 2<I>K.oxytoca</I>strains had identical genome types, respectively. Despite the identical genome type, however, MIC patterns of the 2 <I>E. coli</I> strains and of the 2<I>K.oxytoca</I>were quite different. By PCR analysis, the presence of the TEM type β-lactamase gene was confirmed in the 2 strains of<I>E. coli</I>and 1 of 2 strains of<I>K. pneumoniae</I>, although the 2 stains of<I>K. pneumonia</I>showed a similar MIC pattern and an identical genome type. Sequence analysis showed that the sequences of the TEM type β-lactamase gene from the three positive strains were not identical. The nucleotides of the gene had mutations in the<I>E. coli</I>and<I>K. pneumoniae</I> strains, and the mutations would result in amino acid substitutions. These mutations seem to be unique because they are different from the well-known mutations of the gene reported previously. The above results indicate that detection of the MIC pattern or analysis of the resistant gene is not enough to trace the routes of infection. Identification of the genome type may also be essential for epidemiological analysis of such nosocomial infections as ESBL-producing Gram-negative rods.

Journal

  • Journal of The Showa Medical Association

    Journal of The Showa Medical Association 64(4), 332-339, 2004

    The Showa University Society

Cited by:  1

Codes

  • NII Article ID (NAID)
    130001819207
  • NII NACSIS-CAT ID (NCID)
    AN00117027
  • Text Lang
    UNK
  • Article Type
    Journal Article
  • ISSN
    0037-4342
  • NDL Article ID
    026099220
  • NDL Call No.
    Z19-373
  • Data Source
    CJPref  NDL  J-STAGE 
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