Objective: To investigate the effect of accessory gene regulator C (agr C) specific binding peptides (named N1) on the biofilm formation of Staphylococcus epidermidis on the surface of polyvinyl chloride (PVC) materials in vitro.
Methods: Firstly, the two strains (ATCC35984, ATCC12228) were cultured with N1 at concentrations of 100, 200, 400, 800, and 1 600 μg/mL, respectively. The control group was cultured with agrC specific binding unrelated peptides (named N0) at the same concentrations and the absorbance ( A) value was measured after 24 hours to determine the optimal bacteriostatic concentration of N1. The two strains were cultured with N1 and N0 of the optimal concentration, respectively. The A values were measured at 6, 12, 18, 24, 30, and 48 hours to observe the effect of N1 on the biofilm formation ability of Staphylococcus epidermidis. On this basis, the surface structure of the biofilm on the surface of PVC material was observed by scanning electron microscopy after 6, 12, 18, 24, and 30 hours of incubation with PVC material sheet. The thickness of the biofilm was observed by laser confocal microscopy after 6, 12, 18, and 24 hours of incubation with ATCC35984 strain.
Results: The optimal bacteriostatic concentration of N1 was 800 μg/mL. ATCC 12228 strain did not form obvious biofilm after being cultured with N1 and N0. When ATCC35984 strain was cultured with N1 and N0 for 12 hours, the difference in biofilm formation ability between groups N1 and N0 was statistically significant ( P<0.05), but there was no significant difference at 6, 18, 24, 30, and 48 hours ( P>0.05). Scanning electron microscopy examination showed that mature biofilm structure was observed in ATCC35984 strain and was not observed in ATCC12228 strain. Laser confocal microscopy observation showed that the number of bacteria in the group N1 was significantly lower than that in the group N0 at 12 hours, and the most of bacteria were dead bacteria. There was no significant difference in the number of bacteria at 6, 18, and 24 hours, and the most of them were live bacteria. The biofilm thickness of group N1 was significantly lower than that of group N0 at 12 and 18 hours ( P<0.05).
Conclusion: The intensity of N1 inhibiting the formation of Staphylococcus epidermidis biofilm is dose-dependent. During the aggregation period, N1 can inhibit the biofilm formation by hindering the bacterial growth and aggregation. The inhibition effect on mature biofilm is not obvious.
目的: 探讨表皮葡萄球菌附属基因调节子 C（accessory gene regulator C，agr C）特异结合多肽（简称为 N1）对聚氯乙烯（polyvinyl chloride，PVC）材料表面表皮葡萄球菌生物膜形成作用的体外研究。.
方法: 以表皮葡萄球菌 ATCC35984（生物膜表型阳性）和 ATCC12228（生物膜表型阴性）作为研究对象。首先将两菌株分别加入浓度为 100、200、400、800、1 600 μg/mL 的 N1 培养，以相同浓度 agrC 特异结合无关肽（简称为 N0）培养作为对照；24 h 后测定吸光度（ A）值，确定 N1 最佳抑菌浓度。两菌株与最佳抑菌浓度的 N1 及 N0 分别培养，6、12、18、24、30、48 h 测定 A 值，观察 N1 对表皮葡萄球菌生物膜形成能力的影响；在此基础上与 PVC 材料片培养 6、12、18、24、30 h，扫描电镜观察 PVC 材料表面生物膜的表面结构；另取与 ATCC35984 菌株培养 6、12、18、24 h 的 PVC 材料片，激光共聚焦显微镜观察生物膜厚度。.
结果: A 值测定显示，N1 对 ATCC35984 菌株最佳抑菌浓度为 800 μg/mL。ATCC12228 菌株与 N1 及 N0 培养后均未形成明显生物膜；ATCC35984 菌株与 N1 及 N0 培养 12 h 时，生物膜形成能力差异有统计学意义（ P<0.05），6、18、24、30、48 h 时差异无统计学意义（ P>0.05）。扫描电镜观察，ATCC35984 菌株与 N1 及 N0 培养后，随时间延长均见成熟生物膜结构；而 ATCC12228 菌株培养后均未见生物膜形成。激光共聚焦显微镜观察，ATCC35984 菌株与 N1 培养 12 h 时细菌量明显少于与 N0 培养，且以死细菌居多；6、18、24 h 时两种培养条件下细菌数量未见明显差别，均以活细菌居多；同时，N1 培养 12、18 h 时生物膜厚度明显小于 N0 培养（ P<0.05）。.
结论: N1 抑制表皮葡萄球菌生物膜形成的强度有量效关系；其在聚集期阻碍细菌的增殖和聚集，抑制生物膜形成，对成熟生物膜抑制作用不明显。.
Keywords: Staphylococcus epidermidis; accessory gene regulator C; bacterial biofilm; polyvinyl chloride; specific binding peptide.