Geldart Kathryn, Borrero Juan, Kaznessis Yiannis N
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA.
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
Appl Environ Microbiol. 2015 Jun;81(11):3889-97. doi: 10.1128/AEM.00227-15. Epub 2015 Apr 3.
Antibiotic-resistant enterococcal infections are a major concern in hospitals where patients with compromised immunity are readily infected. Enterococcus faecium bacteria are of particular interest as these pathogens account for over 80% of vancomycin-resistant enterococcal infections. Antimicrobial peptides (AMPs) produced at the site of infection by engineered bacteria may offer a potential alternative to traditional antibiotics for the treatment of resistant bacteria such as E. faecium. For this mode of delivery to be effective, it is essential to identify a suitable protein expression system that can be used in the desired delivery bacterium. In this study, we describe a promising chloride-inducible promoter and its application in the bacterial delivery of AMPs from Lactococcus lactis to reduce counts of E. faecium bacteria in vitro. Reporter gene studies show that at chloride concentrations found within the human intestines, the chloride-inducible promoter exhibits high levels of protein expression compared to those of the commonly used nisin-inducible promoter. These results indicate that this system is powerful and would not require the exogenous administration of an inducer molecule. In its application for AMP production against E. faecium in vitro, L. lactis producing AMPs under the chloride promoter rapidly decreased E. faecium counts by nearly 10,000-fold. As an extension of this application, we also demonstrate the potential in using this type of delivery system in combination with traditional antibiotics to slow the development of resistance. Collectively, this study shows the promise of using a chloride-inducible promoter for the bacterial delivery of AMPs in the body for the treatment of vancomycin-resistant enterococci (VRE) and other antibiotic-resistant bacteria.
耐抗生素肠球菌感染是医院中的一个主要问题，免疫力受损的患者很容易受到感染。粪肠球菌尤其值得关注，因为这些病原体占耐万古霉素肠球菌感染的80%以上。工程菌在感染部位产生的抗菌肽（AMPs）可能为治疗诸如粪肠球菌等耐药菌提供一种替代传统抗生素的潜在方法。为了使这种递送方式有效，必须鉴定出一种可用于所需递送细菌的合适蛋白质表达系统。在本研究中，我们描述了一种有前景的氯化物诱导型启动子及其在从乳酸乳球菌向体外递送AMPs以减少粪肠球菌数量方面的应用。报告基因研究表明，在人体肠道内发现的氯化物浓度下，与常用的乳链菌肽诱导型启动子相比，氯化物诱导型启动子表现出高水平的蛋白质表达。这些结果表明该系统很强大，且不需要外源施用诱导分子。在其体外用于生产抗粪肠球菌的AMPs的应用中，在氯化物启动子控制下产生AMPs的乳酸乳球菌使粪肠球菌数量迅速减少了近10000倍。作为该应用的扩展，我们还证明了将这种类型的递送系统与传统抗生素联合使用以减缓耐药性发展的潜力。总的来说，本研究显示了使用氯化物诱导型启动子在体内通过细菌递送AMPs来治疗耐万古霉素肠球菌（VRE）和其他耐药菌的前景。
