Department of Laboratory Medicine, Korea University College of Medicine, Seoul, Republic of Korea.
Department of Laboratory Medicine, Hallym University College of Medicine, Seoul, Republic of Korea.
J Med Microbiol. 2012 Jan;61(Pt 1):94-100. doi: 10.1099/jmm.0.032573-0. Epub 2011 Aug 26.
In this study of the diversity of AmpC β-lactamase in clinical isolates of Enterobacter spp., a strain was found carrying the plasmid-mediated AmpC β-lactamase ACT-1 gene on its chromosome. The strain was identified as Enterobacter hormaechei using phylogenetic analysis of 16S rRNA and hsp60 genes. In addition, the species was confirmed by DNA-DNA hybridization. The genetic environment of the bla(ACT-1) gene was characterized, including the ampR and ampG genes, using a two-step PCR. The amino acid sequences of AmpR at serine 35, arginine 86, glycine 102, aspartic acid 135 and tyrosine 264 were conserved. Measurement of the transcription level of the bla(ACT-1) gene using real-time quantitative PCR showed that it increased 1.98-fold following cefoxitin induction. These results suggest that the plasmid-mediated bla(ACT-1) gene originated from the chromosome of E. hormaechei.
在这项研究中，我们研究了临床分离的肠杆菌属菌株中 AmpC β-内酰胺酶的多样性，发现一株携带染色体介导的 AmpC β-内酰胺酶 ACT-1 基因的菌株。该菌株通过 16S rRNA 和 hsp60 基因的系统发育分析鉴定为霍氏肠杆菌。此外，通过 DNA-DNA 杂交进一步确认了该物种。采用两步 PCR 法对 bla(ACT-1)基因的 ampR 和 ampG 基因等遗传环境进行了特征分析。AmpR 的丝氨酸 35、精氨酸 86、甘氨酸 102、天冬氨酸 135 和酪氨酸 264 处的氨基酸序列是保守的。使用实时定量 PCR 测量 bla(ACT-1)基因的转录水平表明，头孢西丁诱导后其转录水平增加了 1.98 倍。这些结果表明，质粒介导的 bla(ACT-1)基因来源于霍氏肠杆菌的染色体。
