Staphylococcus epidermidis is the most common pathogen in postoperative endophthalmitis and causes various infectious eye diseases. However, there is very little information on fluoroquinolone antibiotic resistance to S. epidermidis identified in conjunctival microbe and analysis of related genes. Here, the authors investigated the rate of resistance to fluoroquinolones of Staphylococcus epidermidis isolated from normal conjunctival microbes and mutations in the quinolone-resistance determining region (QRDR). 377 eye samples from 187 patients who underwent intravitreal injection and cataract surgery were included. Specimens were taken from the bilateral lower conjunctival sacs using a cotton swab and cultured. The cultures were identified using MALDI-TOP MS and gyrA, gyrB, parC, and parE gene mutations of QRDR were confirmed by DNA extraction from resistant strains of S. epidermidis with a micro-dilution method using ciprofloxacin, levofloxacin, and moxifloxacin. The culture positive rate was 61.8% (231) for 374 eye samples. Of the 303 total strains cultured, S. epidermidis was the most common with 33.7% (102). Ten types of gene mutations were observed in the resistant S. epidermidis of 21 strains. One-point mutation was observed mainly in gyrA and parC, and a small number of mutations were observed in parE in the form of a double point mutations. When there were multiple point mutations in both gyrA and parC, the highest minimum inhibitory concentration was observed. The quinolone resistance rate of S. epidermidis increased in comparison with previous studies, and resistant S. epidermidis showed mostly QRDR mutations, which were mainly found in gyrA and parC, and showed strong resistance when mutated in both genes.

中文翻译：

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健康结膜表皮葡萄球菌对氟喹诺酮类药物的耐药性及喹诺酮类耐药决定区突变分析

表皮葡萄球菌是术后眼内炎最常见的病原体，可引起各种传染性眼病。然而，关于结膜微生物中鉴定的表皮葡萄球菌的氟喹诺酮类抗生素耐药性和相关基因分析的信息很少。在这里，作者研究了从正常结膜微生物中分离的表皮葡萄球菌对氟喹诺酮类药物的耐药率以及喹诺酮耐药性决定区 (QRDR) 的突变。包括来自 187 名接受玻璃体内注射和白内障手术的患者的 377 份眼部样本。使用棉签从双侧下结膜囊中取出标本并进行培养。使用 MALDI-TOP MS 和 gyrA、gyrB、parC、QRDR 和 parE 基因突变通过使用环丙沙星、左氧氟沙星和莫西沙星的微量稀释方法从表皮葡萄球菌的抗性菌株中提取 DNA 来确认。374 个眼部样本的培养阳性率为 61.8% (231)。在培养的 303 个总菌株中，表皮葡萄球菌是最常见的，占 33.7% (102)。在21株耐药表皮葡萄球菌中观察到10种基因突变。单点突变主要在gyrA和parC中观察到，在parE中观察到少量突变以双点突变的形式出现。当gyrA 和parC 均存在多个点突变时，观察到最高的最小抑制浓度。表皮葡萄球菌喹诺酮类药物耐药率较以往研究有所增加，且耐药表皮葡萄球菌主要表现为QRDR突变，