不同材料硬性透氧性角膜接触镜表面细菌黏附能力的对比研究

Comparison of adherence ability of bacteria on the surface of rigid gas-permeable contact lens made withdifferent materials

背景角膜接触镜的佩戴可能会增加角膜感染的机会，一些研究认为角膜接触镜材料的透氧性与角膜感染的发生有关。目的比较用于制作硬性透氧性角膜接触镜（RGP—CL）的材料，如氟硅丙烯酸酯A（XO）、氟硅丙烯酸酯B（EO）和聚甲基丙烯酸甲酯（PMMA）表面对金黄色葡萄球菌、表皮葡萄球菌和铜绿假单胞杆菌的黏附情况。方法分别将3种RGP—CL镜片材料置于3种细菌悬液中培养24h，采用MTT比色法、旋涡震荡菌落计数法和扫描电子显微镜观察并比较3种材料表面黏附细菌的能力。结果MTT比色法结果显示，XO制镜材料对金黄色葡萄球菌的黏附能力（A值）明显低于EO材料和PMMA材料，差异均有统计学意义（q=7．379、8．207，P〈0．01），但EO材料与PMMA材料对金黄色葡萄球菌黏附能力的比较差异无统计学意义（q=0．828，P〉0．05）；XO材料及EO材料表面表皮葡萄球菌的黏附能力低于PMMA材料，差异均有统计学意义（q=14．000、12．800，P〈0．01），而XO材料与EO材料间表皮葡萄球菌黏附能力的比较差异无统计学意义（q=1．200，P〉0．05）；3种材料对铜绿假单胞杆菌的黏附能力（A值）差异无统计学意义（F=2．155，P=0．138）。旋涡震荡菌落计数法结果显示，XO、EO、PMMA材料表面金黄色葡萄球菌的黏附数量分别为（37．9±1．5）x10^6、（49．9±2．2）x10^6、（67．4±1．6）×10^6个，差异有统计学意义（F=206．240，P=0．000），EO材料、PMMA材料表面金黄色葡萄球菌菌落计数明显高于XO材料，差异均有统计学意义（P〈0．01）。XO、EO、PMMA材料表面表皮葡萄球菌的黏附数量分别为（7．94-1．3）×10。、（10．5±1．5）×10。、（11．2±1．2）×10。个，XO材料表面表皮葡萄球菌的黏附数量明显低于PMMA材料，差异有统计学意义（q=5．060，P〈0．05），XO材料与EO材料、EO材料与PMMA材料之间表皮葡萄球菌黏附数量的差异均无统计学意义（q=3．290、1．770，P〉0．05）。3种材料表面铜绿假单胞杆菌的黏附数量差异无统计学意义（F=0．232，P=0．799）。扫描电子显微镜观察显示，XO材料和EO材料表面金黄色葡萄球菌和表皮葡萄球菌的黏附呈散在性分布，而PMMA材料表面这两种细菌黏附形成“网状”外观，3种镜片材料表面铜绿假单胞杆菌形态无明显差别。结论PMMA材料表面细菌的黏附能力强于XO材料和EO材料，RGP—CL的透氧性对镜片表面细菌黏附的能力无明显影响。

Background Wearing contact lens increases the risk of infection of the cornea. Some studies showed the gas-permeability of materials used for constructing corneal contact lens is one of the contributing factors related to corneal health. Objective This study was to observe the in vitro adherence ability of different bacteria to rigid gas-permeable contact lenses （RGP-CL） made with various materials. Methods Contact lenses made with hexafocon,enflufocon or polymethyl methacrylate （PMMA） were placed into Staphylococcus aureus, Staphylococcus epidermidis,or Pseudomonas aeruginosa bacterial suspensions （0. 5 MCF） for 24 hours. The strength of bacterial adherence was tested and studied by the methyl thiazolyl tetrazolium （MTT） colorimetric method based on absorbance （A value） ,and the vortex method was used to calculate the colony forming units. The bacteria clump formation was examined with a scanning electron microscope （SEM）. Results MTT colorimetric method showed that the adherence ability of Staphylococcus aureus to hexafocon （A value） was significantly lower than that to enf[ufocon and PMMA ,respectively （q =7. 379,8.207 ,P〈0. 01 ） ,but no significant difference was found in the adherence ability of Staphylococcus aureus between enfiufocon and PMMA （ q = 0. 828, P〉0. 05 ）. The adherence ability of Staphylococcus epidermidis to XO and enflufocon was lower than that to PMMA （q = 14. 000,12. 800, P〈0. 01 ）, but no significant difference was found between the adherence of Staphylococcus epidermidis to hexafocon and enfiufocon material （q = 1. 200 ,P〉0.05）. There was no significant difference in the adherence ability of Pseudomonas aerugirtosa to all threematerials （F= 2. 155 ,P= 0. 138 ）. The vortex method presented the colony forming units of Staphylococcus aureus to hexafocon,enflufocon and PMMA with （37.9＋1.5） xl06 , （49.9~2.2） xl06 and （67.4~1.6） xl06 ,respectively ,with a significant difference among them （F= 206. 240 ,P〈0.01 ） , showing the lowest value in hexafocon,the highest value in PMMA and a middle value in enflufocon （ q = 11. 650,28. 640,16. 990, P〈0. 01 ） , Moreover, colony forming unit of Staphylococcus epidermidis to hexafocon, enflufocon and PMMA was （ 7.9 ~ 1.3 ） x 106 , （ 10.5 ~ 1.5 ） x 106, （ 11.2 ~ l. 2 ） ~ 106 , respectively. And that of hexafocon was lower than one of the PMMA material （ q = 5. 060, P〈0. 05 ）. No significant difference was found between hexafocon and enflufocon nor between hexafocon and PMMA （q = 3. 290, 1. 770 ,P〉0.05 ）. In addition, the results that corresponded to the vortex method were seen in the MTT colorimetric assay （F = 0. 232, P = 0.799 ）. SEM examination showed dispersed population of Staphylococcus aureus and Staphylococcus epidermidis on the surfaces of hexafocon and enflufocon;while much more Staphylococcus aureus and Staphylococcus epidermidis adhered on the surface of PMMA, forming a net-like appearance. Conversely, a high number of Pseudomonas aeruginosa was seen on the surface of all three materials,without noticeable differences in the bacterial shape and quantity on each of the material. Conclusions The adherence ability of bacteria to PMMA is stronger than that of hexafocon and enflufocon,and gas-permeable material of RGP-CL does not impact the adherence ability of bacteria.