Okamoto R, Okubo T, Inoue M
Department of Microbiology, Kitasato University School of Medicine, Kanagawa, Japan.
Antimicrob Agents Chemother. 1996 Nov;40(11):2550-4. doi: 10.1128/AAC.40.11.2550.
Four beta-lactamase-producing clinical isolates (WH245, WH257, CH570, and DEL) of Enterococcus faecalis were examined for the presence of the staphylococcal beta-lactamase regulatory genes (blaR1 and blaI) by PCR using six primer pairs. All isolates produced small amounts of beta-lactamase constitutively. In WH245, CH570, and DEL, the corresponding regions of the regulatory genes have lost sequences of various lengths. However, the regulatory genes in WH257 appeared to be the same as those in staphylococcal plasmid pI258. The beta-lactamase genes could be transferred to enterococcal and staphylococcal recipients from WH257 and DEL by conjugation or transformation with selection for gentamicin resistance. After transformation, the expression of beta-lactamase from DEL was still constitutive, whereas the gene from WH257 showed inducible expression in Staphylococcus aureus. The gene coding for inducible beta-lactamase production from pI258 showed constitutive expression in E. faecalis. These findings suggest that constitutive beta-lactamase production in E. faecalis is due not only to the absence of functional regulatory genes but to some other factor(s) as well.
使用六对引物通过聚合酶链反应（PCR）检测了粪肠球菌的四株产β-内酰胺酶临床分离株（WH245、WH257、CH570和DEL）是否存在葡萄球菌β-内酰胺酶调节基因（blaR1和bla I）。所有分离株均组成性产生少量β-内酰胺酶。在WH245、CH570和DEL中，调节基因的相应区域丢失了不同长度的序列。然而，WH257中的调节基因似乎与葡萄球菌质粒pI258中的调节基因相同。通过接合或转化并选择庆大霉素抗性，β-内酰胺酶基因可从WH257和DEL转移至肠球菌和葡萄球菌受体。转化后，DEL的β-内酰胺酶表达仍为组成性，而WH257的基因在金黄色葡萄球菌中表现为诱导性表达。编码来自pI258的诱导性β-内酰胺酶产生的基因在粪肠球菌中表现为组成性表达。这些发现表明，粪肠球菌中组成性β-内酰胺酶的产生不仅是由于缺乏功能性调节基因，还与其他一些因素有关。
