PDF(Pubmed)
Abstract：
As Klebsiella pneumoniae (KP) has acquired high levels of resistance to multiple antibiotics, it is considered a worldwide pathogen of concern, and substitutes for traditional antibiotics are urgently needed. 3-Phenyllactic acid (PLA) has been reported to have antimicrobial activity against food-borne bacteria. However, there was no experiment evidence for the exact antibacterial effect and mechanism of PLA kills pathogenic KP. In this study, the Oxford cup method indicated that PLA is effective to KP with a minimum inhibitory concentration of 2.5 mg/mL. Furthermore, PLA inhibited the growth and biofilm formation of in a time- and concentration-dependent manner. In vivo, PLA could significantly increase the survival rate of infected mice and reduce the pathological tissue damage. The antibacterial mode of PLA against KP was further explored. Firstly, scanning electron microscopy illustrated the disruption of cellular ultrastructure caused by PLA. Secondly, measurement of leaked alkaline phosphatase demonstrated that PLA disrupted the cell wall integrity of KP and flow cytometry analysis with propidium iodide staining suggested that PLA damaged the cell membrane integrity. Finally, the results of fluorescence spectroscopy and agarose gel electrophoresis demonstrated that PLA bound to genomic DNA and initiated its degradation. The anti-KP mode of action of PLA was attributed to the destruction of the cell wall, membrane, and genomic DNA binding. These findings suggest that PLA has great potential applications as antibiotic substitutes in feed additives against KP infection in animals.
摘要：
由于肺炎克雷伯菌(KP)对多种抗生素具有较高的耐药性,它被认为是全球关注的病原体，迫切需要传统抗生素的替代品。已报道3-苯基乳酸(PLA)具有抗食源性细菌的抗微生物活性。然而,没有实验证据表明PLA杀死致病性KP的确切抗菌作用和机制。在这项研究中,牛津杯法表明，PLA对KP有效，最小抑制浓度为2.5mg/mL。此外，PLA以时间和浓度依赖性方式抑制生长和生物膜形成。在体内,PLA能显著提高感染小鼠的存活率，减轻病理组织损伤。进一步探索了PLA对KP的抗菌模式。首先,扫描电子显微镜显示了PLA引起的细胞超微结构的破坏。其次,泄漏的碱性磷酸酶的测量表明PLA破坏了KP的细胞壁完整性，碘化丙啶染色的流式细胞术分析表明PLA破坏了细胞膜的完整性。最后,荧光光谱和琼脂糖凝胶电泳结果表明，PLA与基因组DNA结合并引发其降解。PLA的抗KP作用模式归因于细胞壁的破坏，膜,和基因组DNA结合。这些发现表明，PLA作为抗生素替代品在动物中对抗KP感染的饲料添加剂中具有巨大的潜在应用。
