Kernodle D S, McGraw P A, Stratton C W, Kaiser A B
Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Antimicrob Agents Chemother. 1990 Mar;34(3):420-5. doi: 10.1128/AAC.34.3.420.
We previously have shown that extracts of S. aureus isolates which produce the recognized serotypes of staphylococcal beta-lactamase (A, B, C, D) differ in the rates at which they hydrolyze selected cephalosporins, exhibiting substrate profiles which are distinctive for each serotype. In an effort to simplify the methods employed in identifying the different staphylococcal beta-lactamases, we evaluated whether distinctive substrate profiles could be obtained by using whole-cell suspensions of 115 beta-lactamase-producing isolates of S. aureus. Compared with extracts from the same strains, the whole-cell bacterial suspensions not only were simpler to prepare but enabled beta-lactamase typing of a higher proportion of the evaluated strains (86 versus 97%, respectively). Furthermore, the use of whole-cell bacterial suspensions enabled the simultaneous quantitation of the beta-lactamase activity exhibited by each strain. Additionally, by comparing the quantitative activity of beta-lactamase-induced and -uninduced preparations of the same strain, induction ratios (i.e., induced/uninduced activity) could be derived, yielding information regarding the regulation of beta-lactamase production by each strain. We believe that the utilization of whole-cell methods, such as those employed in this study, will facilitate the investigation of qualitative and quantitative differences in beta-lactamase production among clinical and reference isolates of S. aureus.
我们之前已经表明，产生公认葡萄球菌β-内酰胺酶血清型（A、B、C、D）的金黄色葡萄球菌分离株提取物，在水解所选头孢菌素的速率上存在差异，呈现出每种血清型独特的底物谱。为了简化鉴定不同葡萄球菌β-内酰胺酶所采用的方法，我们评估了使用115株产β-内酰胺酶的金黄色葡萄球菌分离株的全细胞悬液是否能获得独特的底物谱。与来自相同菌株的提取物相比，全细胞细菌悬液不仅制备更简单，而且能对更高比例的评估菌株进行β-内酰胺酶分型（分别为86%和97%）。此外，使用全细胞细菌悬液能够同时定量每个菌株所表现出的β-内酰胺酶活性。另外，通过比较同一菌株的β-内酰胺酶诱导制剂和未诱导制剂的定量活性，可以得出诱导率（即诱导活性/未诱导活性），从而获得有关每个菌株β-内酰胺酶产生调控的信息。我们认为，利用全细胞方法，如本研究中所采用的方法，将有助于研究金黄色葡萄球菌临床分离株和参考分离株之间β-内酰胺酶产生的定性和定量差异。
