目的：观察和分析反复使用抗生素患者结膜菌群的变化。此外，确定这种反复暴露对结膜菌群抵抗模式的影响。

方法：研究纳入40例眼科研究所视网膜科患者。所有受试者至少进行了连续4次、每月一次的玻璃体腔注射(IVI)，其中一些患者根据需要延长至6mo或1y。将患者随机分为3组，每组给予氧氟沙星、莫西沙星或头孢他啶任意一种抗生素。使用Kirby-Bauer扩散法对所有细菌进行药敏试验。

结果：研究中，以表皮葡萄球菌(51.2%)为主，其次是金黄色葡萄球菌(14%)，微球菌(12.8%)和其他凝固酶阴性葡萄球菌(CONS)占13%。结果显示，在4次随访中，与随机接受头孢他啶治疗的患者的基线培养相比，接受头孢他啶治疗的患者眼部表皮葡萄球菌的百分比有所增加。相比之下，与基线相比，金黄色葡萄球菌的百分比没有明显增加。在氟喹诺酮治疗眼中观察到表皮葡萄球菌的百分比从基线增加。与头孢他啶治疗组相比，氟喹诺酮治疗组的金黄色葡萄球菌百分比较基线升高。然而，随着新一代和老一代氟喹诺酮类药物的暴露，眼部菌群组成模式发生了变化。我们注意到，从基线开始，莫西沙星治疗组比氧氟沙星治疗组的表皮葡萄球菌增多。暴露于老一代和新一代氟喹诺酮类药物的金黄色葡萄球菌的模式没有差异。

结论：反复使用眼用抗生素不仅会改变正常眼部菌群的组成，还会选择耐药菌株。

METHODS: This study included 40 patients, admitted to the Retina Unit of the Research Institute of Ophthalmology. All chosen patients had a minimum of 4 consecutive, monthly intravitreal injections(IVI), some were extended to 6mo or 1y as required. The patients were randomly divided into 3 groups and each group received one kind of antibiotic which was either ofloxacin, moxifloxacin or ceftazidime. All bacterial isolates were tested for antibiotic susceptibility using Kirby-Bauer disc diffusion technique.

RESULTS: In this study the conjunctival normal flora at baseline culture varied from a predominance of Staphylococcus epidermidis (51.2%), followed by Staphylococcus aureus 14% to Micrococcus species 12.8% and other coagulase negative staphylococci(CONS)13%. Our results showed an increase in the percentage of Staphylococcus epidermidis among ceftazidime treated eyes during the four visits in comparison to baseline cultures of patients randomized to ceftazidime. In contrast, there was no noticeable increase in Staphylococcus aureus percentage from baseline. In fluoroquinolone treated eyes, we also observed an increase in percentage of Staphylococcus epidermidis from base line. In contrast to ceftazidime treated eyes, the Staphylococcus aureus percentage in fluoroquinolone treated eyes showed an increase from baseline. However, the pattern of the ocular flora composition changed with the exposure to the old and newer generation of fluoroquinolones. We noticed an increase of Staphylococcus epidermidis in moxifloxacin treated eyes than that in ofloxacin treated eyes from baseline. There was no observed difference in the pattern of Staphylococcus aureus regarding exposure to older and newer generations of fluoroquinolones.

CONCLUSION: Repeated use of ophthalmic antibiotics not only alters the composition of the normal ocular flora, but also selects for resistant strains.