Gulías Òscar, McKenzie Giselle, Bayó Miquel, Agut Montserrat, Nonell Santi
Institut Químic de Sarrià, Universitat Ramon Llull, 08017 Barcelona, Spain.
Laboratori d'anàlisis M. Bayó, 08221Terrassa, Spain.
Antibiotics (Basel). 2020 Feb 25;9(3):98. doi: 10.3390/antibiotics9030098.
The emergence of multidrug-resistant bacteria is a growing problem and alternative therapies are being sought to effectively address this issue. The aim of this study is to assess a range of strains' susceptibility to Methylene Blue-mediated antimicrobial photodynamic therapy and determine if this is affected by their antibiotic-resistance profile. Two reference and twenty-four uropathogenic clinical strains were used in this study. All were tested in vitro for antimicrobial susceptibility against sixteen antibiotics. Strains underwent photodynamic treatments using the photosensitizer Methylene Blue with red light and tested in both planktonic and biofilm state. It was found that reference strain ATCC 25922 was susceptible to all tested antibiotics whereas reference strain ATCC 35218 showed resistance only to Ampicillin. With the exception of strains number 16 and 22, all of the isolated strains were multidrug-resistant according to the criteria established by the European Centre for Disease Prevention and Control and the Centre for Disease Control and Prevention, where acquired non-susceptibility to at least one agent in three or more antimicrobial categories is outlined. Photodynamic therapy induced more than 3 log colony-forming units' reduction to all strains in planktonic state. Whereas when tested in biofilm state, two and a half times the original dose of methylene blue was necessary to cause a 3 log antimicrobial effect. There were statistically significant differences in susceptibility among the strains tested in both the planktonic and biofilm experiments. Nevertheless, antimicrobial photodynamic therapy could inactivate all multidrug-resistant strains in the planktonic and biofilm state.
多重耐药菌的出现是一个日益严重的问题，人们正在寻求替代疗法来有效解决这一问题。本研究的目的是评估一系列菌株对亚甲蓝介导的抗菌光动力疗法的敏感性，并确定这是否受其抗生素耐药谱的影响。本研究使用了两株参考菌株和二十四株致病性尿路临床菌株。所有菌株均在体外针对十六种抗生素进行了抗菌药敏试验。菌株使用光敏剂亚甲蓝和红光进行光动力治疗，并在浮游状态和生物膜状态下进行测试。结果发现，参考菌株ATCC 25922对所有测试抗生素敏感，而参考菌株ATCC 35218仅对氨苄西林耐药。根据欧洲疾病预防控制中心和疾病控制与预防中心制定的标准，除16号和22号菌株外，所有分离菌株均为多重耐药菌，该标准概述了对三种或更多抗菌类别中至少一种药物获得性不敏感的情况。光动力疗法使所有浮游状态的菌株菌落形成单位减少超过3个对数。而在生物膜状态下进行测试时，需要两倍半的亚甲蓝原始剂量才能产生3个对数的抗菌效果。在浮游和生物膜实验中测试的菌株之间，敏感性存在统计学上的显著差异。然而，抗菌光动力疗法可以使所有浮游和生物膜状态下 的多重耐药菌株失活。
