Kowalski R P, Karenchak L M, Gordon Y J
The University of Pittsburgh and Medical Center, Pennsylvania 15213, USA.
Cornea. 1998 May;17(3):282-7.
We compared the in vitro susceptibility of gram-positive bacteria to ciprofloxacin and ofloxacin using human corneal susceptibility levels.
The concentrations of ciprofloxacin and ofloxacin that can be attained in 99% of human corneas (Cornea99) after topical administration were calculated statistically from reported data. The minimal inhibitory concentrations (MICs) were determined for 95 corneal isolates of gram-positive bacteria (51 Staphylococcus aureus, 16 Streptococcus pneumoniae, 16 Streptococcus viridans group, and 12 coagulase-negative staphylococci). Susceptibility was interpreted by comparing the MICs with the respective Cornea99 for each antibiotic. Time-kill studies of representative gram-positive bacteria were tested using the Cornea99 and the maximal corneal concentrations reported for ciprofloxacin and ofloxacin.
The Cornea99 of ciprofloxacin and ofloxacin were calculated to be 3.57 microg/ml (n = 22) and 2.22 microg/ml (n = 20), respectively. The reported mean corneal concentrations of ciprofloxacin (6.90 +/- 6.20 microg/ml) and ofloxacin (5.71 +/- 6.15 microg/ml) were comparable (p = 0.54). All gram-positive bacteria were equally susceptible to ciprofloxacin and ofloxacin (p = 0.54) based on the Cornea99. The time-kill studies determined that 8-24 h were required for both ciprofloxacin and ofloxacin to reach bactericidal levels.
Ciprofloxacin and ofloxacin demonstrated comparable penetration into the cornea and provided equivalent in vitro efficacy against representative gram-positive bacteria. Time-kill studies indicated that 8-24 h of continual corneal concentrations of ciprofloxacin and ofloxacin were necessary in this study to reduce susceptible gram-positive bacteria by 99.9%.
我们使用人角膜药敏水平比较革兰氏阳性菌对环丙沙星和氧氟沙星的体外敏感性。
根据报道的数据，通过统计学方法计算局部给药后99%人角膜（角膜99）中可达到的环丙沙星和氧氟沙星浓度。测定了95株革兰氏阳性菌角膜分离株（51株金黄色葡萄球菌、16株肺炎链球菌、16株草绿色链球菌群和12株凝固酶阴性葡萄球菌）的最低抑菌浓度（MIC）。通过将每种抗生素的MIC与各自的角膜99进行比较来解释药敏情况。使用角膜99以及报道的环丙沙星和氧氟沙星的最大角膜浓度对代表性革兰氏阳性菌进行了时间-杀菌研究。
环丙沙星和氧氟沙星的角膜99分别计算为3.57微克/毫升（n = 22）和2.22微克/毫升（n = 20）。报道的环丙沙星（6.90±6.20微克/毫升）和氧氟沙星（5.71±6.15微克/毫升）的平均角膜浓度具有可比性（p = 0.54）。基于角膜99，所有革兰氏阳性菌对环丙沙星和氧氟沙星的敏感性相同（p = 0.54）。时间-杀菌研究确定，环丙沙星和氧氟沙星均需要8 - 24小时才能达到杀菌水平。
环丙沙星和氧氟沙星在角膜中的穿透性相当，对代表性革兰氏阳性菌具有同等的体外疗效。时间-杀菌研究表明，在本研究中，环丙沙星和氧氟沙星持续8 - 24小时的角膜浓度对于将敏感革兰氏阳性菌减少99.9%是必要的。
