采用纸片扩散法对从泰国患者中分离出的耐甲氧西林革兰阴性杆菌进行西他沙星的体外药敏试验。

In vitro susceptibility test of sitafloxacin against resistant gram-negative bacilli isolated from Thai patients by disk diffusion method.

作者信息

Thamlikitkul Visanu, Tiengrim Surapee

出版信息

J Med Assoc Thai. 2014 Mar;97 Suppl 3:S7-12.

Abstract

OBJECTIVE

To determine a correlation of minimum inhibitory concentration (MIC) of sitafloxacin determined by agar dilution method with inhibition zone diameter of sitafloxacin determined by disk diffusion method, and to determine inhibition zone, diameter breakpoints of sitafloxacin against resistant gram-negative bacilli isolated from Thai patients.

MATERIAL AND METHOD

The study bacteria were 332 clinical isolates of gram-negative bacilli including ESBL-producing E. coli, ESBL-producing K. pneumoniae, P. aeruginosa andA. baumannii. Each isolate of the present study bacteria was tested for minimum inhibitory concentration (MIC) of sitafloxacin by agar dilution method and inhibition zone diameter of sitafloxacin by disk diffusion method.

RESULTS

The MICs and inhibition zone diameters of sitafloxacin against gram-negative bacilli were well correlated (correlation coefficient -0.926, p-value < 0.001). The inhibition zone diameter > or = 15 mm had the least total error for determining susceptibility to sitafloxacin based on MIC value of sitafloxacin but the inhibition zone diameter > or = 16 mm had less false susceptibility than that of > or = 15 mm when compared with sitafloxacin MIC < or = 2 mg/l that was considered susceptible. The inhibition zone diameter > or = 19 mm had the least total error for determining susceptibility to sitafloxacin based on MIC value of sitafloxacin but the inhibition zone diameter > or = 18 mm had less false susceptibility than that of > or = 19 mm when compared with sitafloxacin MIC < or = 1 mg/l that was considered susceptible.

CONCLUSION

For the susceptibility test of sitafloxacin against resistant gram-negative bacilli by disk diffusion method, the inhibition zone diameter > or = 16 mm and > or = 18 mm seem to be the appropriate breakpoints for susceptibility for resistant gram-negative bacilli isolated from urine and blood, respectively, since the serum concentration of sitafloxacin is rather low whereas the urinary concentration of sitafloxacin is much higher.

摘要

目的

确定琼脂稀释法测定的西他沙星最低抑菌浓度（MIC）与纸片扩散法测定的西他沙星抑菌圈直径之间的相关性，并确定西他沙星对从泰国患者中分离出的耐药革兰氏阴性杆菌的抑菌圈直径断点。

材料与方法

研究细菌为332株革兰氏阴性杆菌临床分离株，包括产超广谱β-内酰胺酶（ESBL）的大肠埃希菌、产ESBL的肺炎克雷伯菌、铜绿假单胞菌和鲍曼不动杆菌。本研究中的每株细菌均通过琼脂稀释法检测西他沙星的最低抑菌浓度（MIC），并通过纸片扩散法检测西他沙星的抑菌圈直径。

结果

西他沙星对革兰氏阴性杆菌的MIC与抑菌圈直径具有良好的相关性（相关系数-0.926，p值<0.001）。基于西他沙星的MIC值，抑菌圈直径≥15 mm在确定对西他沙星的敏感性时总误差最小，但与被认为敏感的西他沙星MIC≤2 mg/l相比，抑菌圈直径≥16 mm的假敏感性低于≥15 mm。基于西他沙星的MIC值，抑菌圈直径≥19 mm在确定对西他沙星的敏感性时总误差最小，但与被认为敏感的西他沙星MIC≤1 mg/l相比，抑菌圈直径≥18 mm的假敏感性低于≥19 mm。