Abstract

Background: Increasing antimicrobial resistance to antibiotics is a substantial health threat. Bioactive glass S53P4 (BAG) has an antimicrobial effect that can reduce the use of antibiotics. The aim of this study was to evaluate the antimicrobial efficacy of BAG in vitro on staphylococci in biofilm and in planktonic form. Secondary aims were to investigate whether supernatant fluid primed from BAG retains the antibacterial capacity and if ciprofloxacin enhances the effect.

Methods: BAG-S53P4 granules, <45 µm, primed in tryptic soy broth (TSB) were investigated with granules present in TSB (100 mg/mL) and after removal of granules (100, 200, and 400 mg/mL). The efficacy of BAG to eradicate Staphylococcus aureus biofilm in vitro was tested using 10 different clinical strains and 1 reference strain in three test systems: the biofilm-oriented antiseptic test based on metabolic activity, the biofilm bactericidal test based on culturing surviving bacteria, and confocal laser scanning microscopy (CLSM) combined with LIVE/DEAD staining.

Results: Exposure to 48 h primed BAG granules (100 mg/mL) produced bactericidal effects in 11/11 strains (p = 0.001), and CLSM showed reduction of viable bacteria in biofilm (p = 0.001). Supernatant primed 14 days, 400 mg/mL, reduced metabolic activity (p < 0.001), showed bactericidal effects for 11/11 strains (p = 0.001), and CLSM showed fewer viable bacteria (p = 0.001). The supernatant primed for 48 h, or in concentrations lower than 400 mg/mL at 14 days, did not completely eradicate biofilm.

Conclusion: Direct exposure to BAG granules, or primed supernatant fluid, effectively eradicated S. aureus in biofilm. The anti-biofilm effect is time- and concentration-dependent. When BAG had reached its full antimicrobial effect, ciprofloxacin had no additional effect.

摘要

背景：增加对抗生素的抗药性是对健康的重大威胁。生物活性玻璃S53P4（BAG）具有抗菌作用，可以减少抗生素的使用。这项研究的目的是评估BAG在体外对生物膜和浮游形式葡萄球菌的抗菌作用。次要目的是研究从BAG灌注的上清液是否保留抗菌能力，以及环丙沙星是否增强该作用。

方法：使用在TSB中存在的颗粒（100 mg / mL）以及在除去颗粒（100、200和400 mg / mL）后，对在胰蛋白酶大豆肉汤（TSB）中引发的<45 µm BAG-S53P4颗粒进行了研究。在三个测试系统中，使用10个不同的临床菌株和1个参考菌株测试了BAG在体外根除金黄色葡萄球菌生物膜的功效：基于代谢活性的面向生物膜的抗菌测试，基于存活细菌培养的生物膜杀菌测试以及共聚焦激光扫描显微镜（CLSM）结合LIVE / DEAD染色。

结果：暴露于48小时底漆的BAG颗粒（100 mg / mL）可对11/11菌株产生杀菌作用（p  = 0.001），CLSM显示生物膜中的活菌减少（p  = 0.001）。上清液在14天后以400 mg / mL的剂量引发，代谢活性降低（p  <0.001），显示出对11/11菌株的杀菌作用（p  = 0.001），CLSM显示出的活菌较少（p  = 0.001）。灌注48小时或在14天时浓度低于400 mg / mL的上清液没有完全根除生物膜。

结论：直接暴露于BAG颗粒或灌注的上清液中可有效根除生物膜中的金黄色葡萄球菌。抗生物膜作用是时间和浓度依赖性的。当BAG达到完全的抗菌作用时，环丙沙星没有其他作用。