Department of Microbiology, University of Mississippi Medical Center, Jackson, MS 39216, USA.
Cornea. 2009 Oct;28(9):1055-60. doi: 10.1097/ICO.0b013e31819e34cb.
The purpose of this study was to determine the effectiveness of topically applied besifloxacin (0.6%), gatifloxacin (0.3%), and moxifloxacin (0.5%) for the late treatment of experimental methicillin-resistant Staphylococcus aureus (MRSA) keratitis.
One hundred colony-forming units (CFUs) of bacteria were injected intrastromally into rabbit corneas. Sixteen hours after infection, one topical drop of phosphate-buffered saline, besifloxacin, gatifloxacin, or moxifloxacin was applied to each eye every 15 minutes for 5 doses and then every 30 minutes for 14 doses. Eyes were examined before and after treatment by slit lamp biomicroscopy. Corneas were harvested from treated and untreated rabbits for the quantitation of bacteria. Minimal inhibitory concentrations (MICs) were determined in vitro for each fluoroquinolone.
None of the treatments had an effect on clinical severity (P > 0.05). Although there were no differences in clinical severity between any groups after treatment, the mean log10 CFU of MRSA recovered from besifloxacin-treated corneas (5.111 +/- 0.251) was significantly lower than the CFU recovered from corneas treated with phosphate-buffered saline (7.006 +/- 0.144), gatifloxacin (7.108 +/- 0.346), and moxifloxacin (7.473 +/- 0.144; P < 0.001). CFU recovered from gatifloxacin- and moxifloxacin-treated corneas were not significantly different from phosphate-buffered saline-treated corneas (P = 1.000). The MICs against the MRSA strain were 8 microg/mL for both gatifloxacin and moxifloxacin, whereas the MIC for besifloxacin was 1 microg/mL.
Besifloxacin had an 8-fold lower MIC for MRSA than gatifloxacin and moxifloxacin and was significantly more effective than gatifloxacin and moxifloxacin in reducing the number of MRSA in the rabbit cornea 16 hours after infection.
本研究旨在确定局部应用贝西沙星（0.6%）、加替沙星（0.3%）和莫西沙星（0.5%）对实验性耐甲氧西林金黄色葡萄球菌（MRSA）角膜炎的后期治疗效果。
将 100 个细菌集落形成单位（CFUs）注入兔角膜基质内。感染后 16 小时，每只眼每 15 分钟滴一滴磷酸盐缓冲盐水、贝西沙星、加替沙星或莫西沙星，共滴 5 滴，然后每 30 分钟滴 14 滴。治疗前后通过裂隙灯生物显微镜检查眼睛。从治疗和未治疗的兔子中取出角膜，用于定量细菌。体外测定每种氟喹诺酮的最小抑菌浓度（MIC）。
治疗均未影响临床严重程度（P>0.05）。尽管治疗后任何一组之间的临床严重程度均无差异，但贝西沙星治疗的角膜中回收的 MRSA 平均对数 10 CFU（5.111 +/- 0.251）明显低于回收自磷酸盐缓冲盐水（7.006 +/- 0.144）、加替沙星（7.108 +/- 0.346）和莫西沙星（7.473 +/- 0.144）治疗的角膜（P<0.001）。加替沙星和莫西沙星治疗的角膜中回收的 CFU 与磷酸盐缓冲盐水治疗的角膜无显著差异（P=1.000）。MRSA 株对加替沙星和莫西沙星的 MIC 均为 8μg/mL，而贝西沙星的 MIC 为 1μg/mL。
贝西沙星对 MRSA 的 MIC 比加替沙星和莫西沙星低 8 倍，在感染后 16 小时，贝西沙星降低兔角膜中 MRSA 数量的效果明显优于加替沙星和莫西沙星。
