Teixeira-Santos Rita, Ricardo Elisabete, Branco Ricardo J, Azevedo Maria M, Rodrigues Acácio G, Pina-Vaz Cidália
Department of Microbiology, Faculty of Medicine, University of Porto Porto, Portugal.
Department of Microbiology, Faculty of Medicine, University of PortoPorto, Portugal; CINTESIS - Center for Research in Health Technologies and Information Systems, Faculty of Medicine, University of PortoPorto, Portugal.
Front Microbiol. 2016 Sep 13;7:1439. doi: 10.3389/fmicb.2016.01439. eCollection 2016.
Patients with multiple comorbidities are often administered simultaneously or sequentially antifungals and antibacterial agents, without full knowledge of the consequences of drug interactions. Considering the clinical relevance of liposomal amphotericin B (L-AMB), the association between L-AMB and six antibacterial agents was evaluated against four clinical isolates and one type strain of Candida spp. and two clinical isolates and one type strain of Aspergillus fumigatus. In order to evaluate such combined effects, the minimal inhibitory concentration (MIC) of L-AMB was determined in the presence of 0.5-, 1-, 2-, and 4-fold peak plasma concentrations of each of the antibacterial drugs. Since the L-AMB/colistin (CST) association was the most synergic, viability assays were performed and the physiological status induced by this association was characterized. In addition, computational molecular dynamics studies were also performed in order to clarify the molecular interaction. The maximum synergistic effect with all antibacterial agents, except CST, was reached at fourfold the usual peak plasma concentrations, resulting in 2-to 8-fold L-AMB MIC reduction for Candida and 2-to 16-fold for Aspergillus. For CST, the greatest synergism was registered at peak plasma concentration (3 mg/L), with 4-to 8-fold L-AMB MIC reduction for Candida and 16-to 32-fold for Aspergillus. L-AMB at subinhibitory concentration (0.125 mg/L) combined with CST 3 mg/L resulted in: a decrease of fungal cell viability; an increase of cell membrane permeability; an increase of cellular metabolic activity soon after 1 h of exposure, which decreased until 24 h; and an increase of ROS production up to 24 h. From the molecular dynamics studies, AMB and CST molecules shown a propensity to form a stable molecular complex in solution, conferring a recognition and binding added value for membrane intercalation. Our results demonstrate that CST interacts synergistically with L-AMB, forming a stable complex, which promotes the fungicidal activity of L-AMB at low concentration.
患有多种合并症的患者常常会同时或先后接受抗真菌药和抗菌药治疗，却并不完全了解药物相互作用的后果。考虑到脂质体两性霉素B（L-AMB）的临床相关性，我们评估了L-AMB与六种抗菌药对四种念珠菌临床分离株、一株念珠菌标准菌株以及两种烟曲霉临床分离株、一株烟曲霉标准菌株的联合作用。为了评估这种联合效应，在每种抗菌药物的血浆峰浓度的0.5倍、1倍、2倍和4倍浓度存在的情况下，测定了L-AMB的最低抑菌浓度（MIC）。由于L-AMB/黏菌素（CST）的联合作用具有最强的协同性，因此进行了生存能力测定，并对这种联合作用所诱导的生理状态进行了表征。此外，还进行了计算分子动力学研究以阐明分子相互作用。除CST外，与所有抗菌药的最大协同效应在通常血浆峰浓度的4倍时达到，导致念珠菌的L-AMB MIC降低2至8倍，烟曲霉降低2至16倍。对于CST，最大协同作用在血浆峰浓度（3 mg/L）时出现，念珠菌的L-AMB MIC降低4至8倍，烟曲霉降低16至32倍。亚抑菌浓度（0.125 mg/L）的L-AMB与3 mg/L的CST联合使用导致：真菌细胞活力下降；细胞膜通透性增加；暴露1小时后细胞代谢活性立即增加，直至24小时降低；以及活性氧产生增加直至24小时。从分子动力学研究来看，AMB和CST分子在溶液中倾向于形成稳定的分子复合物，为膜插入赋予识别和结合附加值。我们的结果表明，CST与L-AMB协同相互作用，形成稳定的复合物，从而在低浓度下促进L-AMB的杀菌活性。
