Objectives: Staphylococcus epidermidis (S. epidermidis) is a Gram-positive opportunistic pathogen that often causes hospital infections. With the abuse of antibiotics, the resistance of S. epidermidis gradually increases, and drug repurposing has become a research hotspot in the treating of refractory drug-resistant bacterial infections. This study aims to study the antimicrobial and antibiofilm effects of simeprevir, an antiviral hepatitis drug, on S. epidermidis in vitro.
Methods: The micro-dilution assay was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of simeprevir against S. epidermidis. Crystal violet staining assay was used to detect the biofilm inhibitory effect of simeprevir. The antimicrobial activity of simeprevir against S. epidermidis and its biofilm were explored by SYTO9/PI fluorescent staining. The combined effect between simeprevir and gentamycin was assessed by checkerboard assay and was confirmed by time-inhibition assay.
Results: Simeprevir showed significant antimicrobial effects against S. epidermidis type strains and clinical isolates with the MIC and MBC at 2-16 μg/mL and 4-32 μg/mL, respectively. The antimicrobial effects of simeprevir were confirmed by SYTO9/PI staining. Simeprevir at MIC could significantly inhibit and break the biofilm on cover slides. Similarly, simeprevir also significantly inhibit the biofilm formation on the surface of urine catheters either in TSB [from (0.700±0.020) to (0.050±0.004)] (t=54.03, P<0.001), or horse serum [from (1.00±0.02) to (0.13±0.01)] (t=82.78, P<0.001). Synergistic antimicrobial effect was found between simeprevir and gentamycin against S. epidermidis with the fractional inhibitory concentration index of 0.5.
Conclusions: Simeprevir shows antimicrobial effect and anti-biofilm activities against S. epidermidis.
目的: 表皮葡萄球菌是一种常引起院内感染的革兰阳性氏条件致病菌。抗生素的不合理使用导致其耐药性逐渐增高，药物再利用已成为难治性耐药菌感染治疗的研究热点。本研究拟探讨抗病毒性肝炎药物西咪匹韦对表皮葡萄球菌及其生物膜的体外抑制作用。方法: 通过微量肉汤稀释实验检测西咪匹韦对表皮葡萄球菌的最低抑菌浓度(minimal inhibitory concentration，MIC)和最低杀菌浓度(minimal bactericidal concentration，MBC)；采用结晶紫染色检测西咪匹韦对表皮葡萄球菌生物膜形成的抑制作用；SYTO9/PI双荧光染色检测西咪匹韦对表皮葡萄球菌及其生物膜内活菌的杀菌作用；棋盘稀释实验检测西咪匹韦联用庆大霉素的抗菌活性，并通过绘制时间-抑菌曲线进一步验证其协同抗菌活性。结果: 西咪匹韦对表皮葡萄球菌具有明显的抗菌活性，其对标准菌株和临床菌株的MIC和MBC分别为2~16 μg/mL和4~32 μg/mL。SYTO9/PI荧光染色进一步证明西咪匹韦对表皮葡萄球菌的杀菌作用。4 μg/mL的西咪匹韦可显著减少表皮葡萄球菌盖玻片上生物膜的形成并破坏生物膜的正常结构。MIC的西咪匹韦还可抑制TSB肉汤中导尿管表面表皮葡萄球菌的黏附作用，使黏附量从0.700±0.020减少到0.050±0.004(t=54.03，P<0.001)，并可使马血清培养基中导尿管表面的黏附量从1.00±0.02减少到0.13±0.01(t=82.78，P<0.001)。此外，西咪匹韦与庆大霉素联用还具有明显的协同抗菌作用，其协同抑菌指数为0.5。结论: 西咪匹韦对表皮葡萄球菌具有显著的抗菌作用，且能有效抑制其生物膜的形成。.
Keywords: Staphylococcus epidermidis; biofilm; drug repurposing; simeprevir; synergistic effect.