Nosocomial spread of cephem-resistant Escherichia coli strains carrying multiple toho-1-like beta-lactamase genes
Nosocomial spread of cephem-resistant Escherichia coli strains carrying multiple toho-1-like beta-lactamase genes
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DOI：
10.1128/aac.41.12.2606
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发表时间：
1997-12-01
影响因子：
4.9
通讯作者：
Arakawa, Y
中科院分区：
文献类型：
--
作者：
Yagi, T;Kurokawa, H;Arakawa, Y
1991年从一位住院病人的咽拭子中分离出大肠杆菌HKY 56，它对除碳青霉烯类外的多种β-内酰胺类抗生素都表现出耐药性。从HKY 56到E. coli CSH 2的表达失败。3株耐头孢噻肟E.从HKY 56中获得含有质粒pMRE 001、pMRE 002或pMRE 003的大肠杆菌克隆，每一个质粒分别带有3.4-、5.8-或6.2-kb的EcoRI片段插入物。虽然限制性内切酶分析表明它们的来源不同，但这些克隆对各种β-内酰胺类抗生素的抗性表现出相似的特征。对从大肠杆菌中纯化的β-内酰胺酶N端10个氨基酸残基进行了序列测定。coli HB 101（pMRE 001）中的表达产物与Toho-1中的表达产物相同。该酶能有效水解头孢哌酮和头孢噻肟，但不能水解头孢霉素。将Toho-1特异性DNA探针与来自菌株HKY 56的染色体DNA的三个不同的EcoRI片段杂交，这些片段分别对应于pMRE 001、pMRE 002和pMRE 003携带的DNA插入物。PCR和Southern杂交分析表明，所有6株头孢抗性E. 1996年在同一所医院分离的菌株HKY 56中的菌株HKY 273、HKY 285、HKY 288、HKY 305、HKY 316和HKY 335也具有多个Toho-1样β-内酰胺酶（TLB）基因，用Toho-1特异性探针获得的杂交图谱在这6个菌株中非常相似。脉冲场凝胶电泳观察到的DNA指纹图谱显示，在E。大肠杆菌分离株的遗传背景基本一致。这些结果表明，E.携带染色体倍增TLB基因的大肠杆菌菌株可能已经在同一家医院的患者中增殖和传播。
Escherichia coli HKY56, which demonstrated resistance to various beta-lactams except carbapenems, was isolated from the throat swab of an inpatient in 1991. Conjugal transfer of cephem resistance from HKY56 to E. coli CSH2 was not successful. Three cefotaxime-resistant E. coli clones harboring plasmid pMRE001, pMRE002, or pMRE003, each of which carried a 3.4-, 5.8-, or 6.2-kb EcoRI fragment insert, respectively, were obtained from HKY56. Although restriction analysis suggested their different origins, these clones showed similar profiles of resistance to various beta-lactams. The sequence of 10 amino acid residues at the N terminus of beta-lactamase purified from E. coli HB101(pMRE001) was identical to that of Toho-1. This Toho-1-like beta-lactamase-1 (TLB-1) was able to hydrolyze cefoperazone and cefotaxime efficiently, but it failed to hydrolyze cephamycins. A Toho-1-specific DNA probe was hybridized with three distinct EcoRI fragments derived from the chromosomal DNA of strain HKY56, and these fragments corresponded to DNA inserts carried by pMRE001, pMRE002, and pMRE003, respectively. PCR and Southern hybridization analysis suggested that all six cephem-resistant E. coli strains, strains HKY273, HKY285, HKY288, HKY305, HKY316, and HKY335, which were isolated in 1996 at the same hospital where strain HKY56 had been isolated, also possessed multiple Toho-1-like beta-lactamase (TLB) genes, and the hybridization patterns obtained with the Toho-1-specific probe were quite similar among these six isolates. The DNA fingerprinting patterns observed by pulsed-field gel electrophoresis revealed that among the E. coli isolates tested, all isolates except HKY56 possessed a similar genetic background. These findings suggested that E. coli strains that carry chromosomally multiplied TLB genes may have been proliferating and transmitted among patients in the same hospital.