Gattringer Klaus-Bernhard, Suchomel Miranda, Eder Michaela, Lassnigg Andrea M, Graninger Wolfgang, Presterl Elisabeth
Department of Medicine I, Div. Infectious Diseases, Medical University of Vienna, Austria.
Int J Artif Organs. 2010 Sep;33(9):621-6. doi: 10.1177/039139881003300907.
To test the time-dependent effects of rifampicin on established biofilms of Staphylococcus epidermidis isolated from patients with cardiac implant infections and catheter-related bacteremia.
Biofilms were grown in microtiter plates for 24 hours, dyed and stained with crystal violet. The mean optical density (OD) was used for quantification. The OD ratio (ODr = OD of the treated biofilm/OD of the untreated biofilm) was used to measure changes in the thickness of the biofilms over the time. Biofilms were incubated with rifampicin (0.6 mg/mL) for 1, 5, 15, 30 and 60 minutes. Unstained biofilms were sonicated and plated on Columbia agar for time-kill curves.
The incubation of the biofilms with rifampicin led to a significant reduction of the OD of the biofilms within 1 minute (ODr baseline: 1; ODr 1 min: 0.333 ± 0.131) (p<0.001). With regard to bacterial killing, rifampicin reduced the mean log count, but viable bacteria were still grown from biofilms in 13 out of 28 isolates despite MIC values < 0.01 mg/L.
In conclusion, our results confirm that rifampicin at a concentration of 1.2 mg/mL immediately reduces established biofilms formed by S. epidermidis although it is not bactericidal despite very low MICs at planktonic conditions.
测试利福平对从心脏植入物感染和导管相关菌血症患者中分离出的表皮葡萄球菌已形成生物膜的时间依赖性影响。
生物膜在微量滴定板中培养24小时，用结晶紫染色。平均光密度（OD）用于定量。OD比（ODr = 处理后生物膜的OD/未处理生物膜的OD）用于测量生物膜厚度随时间的变化。生物膜与利福平（0.6 mg/mL）孵育1、5、15、30和60分钟。未染色的生物膜经超声处理后接种于哥伦比亚琼脂平板上绘制时间 - 杀菌曲线。
生物膜与利福平孵育1分钟内导致生物膜的OD显著降低（ODr基线：1；ODr 1分钟：0.333±0.131）（p<0.001）。关于细菌杀灭，利福平降低了平均对数计数，但尽管最低抑菌浓度（MIC）值<0.01 mg/L，28株分离株中有13株生物膜中仍有活细菌生长。
总之，我们的结果证实，浓度为1.2 mg/mL的利福平可立即减少表皮葡萄球菌形成的已建立生物膜，尽管在浮游条件下MIC值很低，但它并无杀菌作用。
