Sun Sheng-tao, Chen Zu-ji, Xu Jun, Tian Xiao-li
Henan Institute of Ophthalmology, Henan Key Laboratory of Keratopathy, Zhengzhou 450003, China.
Zhonghua Yan Ke Za Zhi. 2006 Nov;42(11):989-91.
To examine the mutant prevention concentration (MPC) of the four fluoroquinolones to Staphylococcus epidermidis from ocular in vitro, and to compare the MPCs to the minimal inhibitory concentrations (MICs).
The MICs of the ciprofloxacin, ofloxacin, levofloxacin and gatifloxacin were determined by the standard twofold agar dilution methods of the National Committee for Clinical Laboratory Standards (NCCLS). The single colony of Staphylococcus epidermidis on the blood agar plate was inoculated into Muller Hinton broth. The turbidity of the actively growing broth culture was adjusted to 1 x 10(8) cfu/ml and then the broth was diluted 1:10 and 1 microl of the diluted broth was inoculated on the Muller Hinton agar surface for each drug in different concentrations. The final inoculum was approximately 10(4) cfu. The MPCs were measured by mix-bacterial methods. The concentrations of the drugs used in MPC's determination were determined according to the drug's MIC(50) to the bacteria. 1 ml of drug's broth and 19 ml suspension of the bacteria and Muller Hinton agar were added into one plate with the final 10(10) cfu of inoculum.
The lowest MIC(90) was gatifloxacin at 0.25 mg/L, the medium MIC(90) is levofloxacin at 0.50 mg/L, the highest MIC(90) at 1.00 mg/L was detected in ciprofloxacin and ofloxacin. The MPC(50) and MPC(90) for gatifloxacin were 1.00 mg/L and 2.00 mg/L respectively, which were the lowest concentration among the four drugs tested. The same parameter of the MPC(50) (2.00 mg/L) and MPC(90) (4.00 mg/L) was obtained in levofloxacin and ciprofloxacin, the MPC(50) for ofloxacin was as high as levofloxacin and ciprofloxacin at 2.00 mg/L but its MPC(90) was 8.00 mg/L.
The new fluoroquinolones shows high effect on anti-bacterial Staphylococcus epidermidis. Gatifloxacin and levofloxacin may play a role in prevention Staphylococcus epidermidis from mutation.
检测4种氟喹诺酮类药物对眼部表皮葡萄球菌的突变预防浓度（MPC），并与最低抑菌浓度（MIC）进行比较。
采用美国临床实验室标准化委员会（NCCLS）的标准二倍稀释法测定环丙沙星、氧氟沙星、左氧氟沙星和加替沙星的MIC。将血琼脂平板上的表皮葡萄球菌单菌落接种到Muller Hinton肉汤中。将生长活跃的肉汤培养物的浊度调整至1×10⁸ cfu/ml，然后将肉汤稀释1:10，取1 μl稀释后的肉汤接种到不同浓度的每种药物的Muller Hinton琼脂表面。最终接种量约为10⁴ cfu。采用混合菌法测定MPC。根据药物对细菌的MIC₅₀确定MPC测定中使用的药物浓度。将1 ml药物肉汤、19 ml细菌悬液和Muller Hinton琼脂加入一个平板中，最终接种量为10¹⁰ cfu。
最低的MIC₉₀是加替沙星，为0.25 mg/L，中等的MIC₉₀是左氧氟沙星，为0.50 mg/L，环丙沙星和氧氟沙星的最高MIC₉₀为1.00 mg/L。加替沙星的MPC₅₀和MPC₉₀分别为1.00 mg/L和2.00 mg/L，是所测4种药物中浓度最低的。左氧氟沙星和环丙沙星的MPC₅₀（2.00 mg/L）和MPC₉₀（4.00 mg/L）相同，氧氟沙星的MPC₅₀与左氧氟沙星和环丙沙星一样高，为2.00 mg/L，但其MPC₉₀为8.00 mg/L。
新型氟喹诺酮类药物对表皮葡萄球菌有高效抗菌作用。加替沙星和左氧氟沙星可能在预防表皮葡萄球菌突变方面发挥作用。
