Department of Ophthalmology, Bursa Uludag University, School of Medicine, Bursa, Turkey.
Department of Biology, Eskisehir Technical University, Faculty of Science, Eskisehir, Turkey.
Med Sci Monit. 2023 Apr 19;29:e940266. doi: 10.12659/MSM.940266.
BACKGROUND Coagulase-negative staphylococci (CoNS) are gram-positive, aerobic, commensal bacteria found on the skin and mucus membranes, including the conjunctiva. Usnic acid (UA) is a dibenzofuran derivative isolated from lichens. This study aimed to investigate the effects of usnic acid on inhibition of ocular biofilm formation due to CoNS. MATERIAL AND METHODS Nine Staphylococcus epidermidis isolates, 5 Staphylococcus hominis isolates, 2 Staphylococcus saprophyticus isolates, and 1 Staphylococcus capitis and Staphylococcus lentus isolates were taken as test bacteria. They were inoculated into brain heart infusion broth and incubated for 24 hours at 35°C and activated. Antibiotic susceptibility was investigated by Kirby-Bauer disc diffusion method. Biofilm production was determined using the microtiter plate method and optical densitometry was measured at 570 nm using an automated microplate reader. Anti-biofilm activity of UA was determined by microtitration method and biofilm removal percentage was calculated. RESULTS All tested bacteria were found as high biofilm-producer strains; they were generally resistant to methicillin, but susceptible to vancomycin. UA inhibited the biofilm formation of S. epidermidis isolates, ranging from 5.7% to 81.5%. It inhibited the biofilm formation of S. saprophyticus and S. lentus by 73.3% and 74.3%, respectively. There was no effect of UA on mature biofilms of S. epidermidis 17.7H, S. epidermidis 15.41, S. hominis 9.3, S. hominis 17.2H, S. saprophyticus, and S. lentus. CONCLUSIONS It was determined that UA exerted anti-biofilm activity on some CoNS isolated from the ocular surface. Anti-biofilm activity was found to be higher even in strains that did not show antibacterial activity.
凝固酶阴性葡萄球菌（CoNS）是一种革兰氏阳性、需氧、共生菌，存在于皮肤和黏膜上，包括结膜。乌头酸（UA）是从地衣中分离出来的二苯并呋喃衍生物。本研究旨在探讨乌头酸抑制 CoNS 引起的眼部生物膜形成的作用。
选取 9 株表皮葡萄球菌分离株、5 株人葡萄球菌分离株、2 株腐生葡萄球菌分离株和 1 株头状葡萄球菌和慢生葡萄球菌分离株作为测试细菌。将它们接种到脑心浸液肉汤中，在 35°C 下孵育 24 小时并激活。采用 Kirby-Bauer 纸片扩散法进行抗生素敏感性试验。采用微量滴定板法测定生物膜生成，使用自动微量滴定板读数器在 570nm 处测量光密度。采用微量滴定法测定 UA 的抗生物膜活性，并计算生物膜去除率。
所有测试细菌均被认为是高生物膜产生菌；它们通常对甲氧西林耐药，但对万古霉素敏感。UA 抑制表皮葡萄球菌分离株的生物膜形成，范围为 5.7%至 81.5%。它分别抑制腐生葡萄球菌和慢生葡萄球菌的生物膜形成 73.3%和 74.3%。UA 对表皮葡萄球菌 17.7H、表皮葡萄球菌 15.41、人葡萄球菌 9.3、人葡萄球菌 17.2H、腐生葡萄球菌和慢生葡萄球菌的成熟生物膜没有影响。
确定 UA 对从眼表面分离出的一些 CoNS 具有抗生物膜活性。即使在没有抗菌活性的菌株中，也发现了更高的抗生物膜活性。
