Photodynamic and Antibiotic Therapy Impair the Pathogenesis of Enterococcus faecium in a Whole Animal Insect Model
Photodynamic and Antibiotic Therapy Impair the Pathogenesis of Enterococcus faecium in a Whole Animal Insect Model
复制标题
DOI：
10.1371/journal.pone.0055926
复制
发表时间：
2013-02-14
期刊：
影响因子：
3.7
通讯作者：
Mylonakis, Eleftherios
中科院分区：
文献类型：
--
作者：
Chibebe Junior, Jose;Fuchs, Beth B.;Mylonakis, Eleftherios
屎肠球菌由于其对包括万古霉素在内的多种抗生素的内在和获得性耐药性，已成为全球医疗保健相关感染中最重要的病原体之一。抗微生物光动力疗法（aPDT）是目前正在研究的用于控制和治疗感染的替代治疗平台。PDT是基于使用光敏染料分子，广泛称为光敏剂（PS）。PS在用可见光照射时产生活性氧物质，其可以破坏脂质和蛋白质，导致细胞死亡。我们采用大蜡螟（Galleria mellonella）毛虫感染E. faecium来开发可用于研究抗微生物PDT（单独或与抗生素组合）的无脊椎动物宿主模型系统。在建立E. faecium在G. mellonella，我们发现G.大蜡螟的死亡率与注入血腔的细菌细胞数有关。屎肠球菌菌株能感染并杀死G.梅隆内拉用氨苄青霉素、庆大霉素或氨苄青霉素和庆大霉素联合用药治疗感染E.屎肠（P = 0.0003、P = 0.0001和P = 0.0001）。在光动力疗法的研究中，我们证实了注射亚甲基蓝（MB）后全身光照能延长毛虫的存活时间（P = 0.0192）。有趣的是，联合治疗感染万古霉素耐药大肠杆菌的幼虫。与单独使用抗生素PDT（P = 0.0095）或万古霉素（P = 0.0025）相比，先用抗生素PDT再用万古霉素（P = 0.0025）处理粪肠球菌，显著延长了毛虫的存活时间，表明aPDT使万古霉素耐药的E.屎肠菌株对万古霉素作用更敏感。综上所述，G. Mellonella为研究抗微生物PDT和探索基于aPDT的组合治疗提供了无脊椎动物模型宿主。
Enterococcus faecium has emerged as one of the most important pathogens in healthcare-associated infections worldwide due to its intrinsic and acquired resistance to many antibiotics, including vancomycin. Antimicrobial photodynamic therapy (aPDT) is an alternative therapeutic platform that is currently under investigation for the control and treatment of infections. PDT is based on the use of photoactive dye molecules, widely known as photosensitizer (PS). PS, upon irradiation with visible light, produces reactive oxygen species that can destroy lipids and proteins causing cell death. We employed Galleria mellonella (the greater wax moth) caterpillar fatally infected with E. faecium to develop an invertebrate host model system that can be used to study the antimicrobial PDT (alone or combined with antibiotics). In the establishment of infection by E. faecium in G. mellonella, we found that the G. mellonella death rate was dependent on the number of bacterial cells injected into the insect hemocoel and all E. faecium strains tested were capable of infecting and killing G. mellonella. Antibiotic treatment with ampicillin, gentamicin or the combination of ampicillin and gentamicin prolonged caterpillar survival infected by E. faecium (P = 0.0003, P = 0.0001 and P = 0.0001, respectively). In the study of antimicrobial PDT, we verified that methylene blue (MB) injected into the insect followed by whole body illumination prolonged the caterpillar survival (P = 0.0192). Interestingly, combination therapy of larvae infected with vancomycin-resistant E. faecium, with antimicrobial PDT followed by vancomycin, significantly prolonged the survival of the caterpillars when compared to either antimicrobial PDT (P = 0.0095) or vancomycin treatment alone (P = 0.0025), suggesting that the aPDT made the vancomycin resistant E. faecium strain more susceptible to vancomycin action. In summary, G. mellonella provides an invertebrate model host to study the antimicrobial PDT and to explore combinatorial aPDT-based treatments.