耐甲氧西林金黄色葡萄球菌对临床常用抗菌药物的药敏性

提要　用琼脂稀释法测定了临床常用9种抗菌药物对76株耐甲氧西林金黄色葡萄球菌(MRSA)的最小抑菌浓度(MIC)，并根据国际推荐的NCCLS的药敏标准判断MRSA的药敏性。验结果MRSA对万古霉素、去甲万古霉素、壁霉素的敏感率均为100%；氧氟沙星、利福平、TMP、SMZ/TMP、庆大霉素和红霉素的耐药率介于14.5～92.1%。

　　关键词　耐甲氧西林金黄色葡萄球菌　抗菌药物　敏感率　耐药率

THE DRUG SENSITIVITY OF SEVENTY-SIX STRAINS OF MRSA TO CONVENTIONAL CLINICALLY USED ANTIBACTERIAL DRUGS

Xu Jing　Pan Peigen　Huang Jun　Guo Xiaojin
(The First Hospital, West China University of Medical Sciences　Chengdu 610041)

　　ABSTRACT　The drug sensitivity of seventy-six strains of MRSA was detected with agar diluting clinically used antibacterials. The result showed that the MIC90 of demethylvancomycin, vancomycin, teicoplanin, ofloxacin, rifampin, TMP, SMZ/TMP, gentamycin and erythromycin were 1mg/L, 1mg/L, 1mg/L, 8mg/L, ≥256mg/L, 256mg/L, ≥256mg/L, 128mg/L and ≥256mg/L, respectively.The sensitivity rates were 100%, 100%, 100%, 80.3%, 52.6%, 17.1%, 15.8%, 13.2% and 1.4%.The resistance rates were 0,0,0,14.5%, 39.5%, 82.9%, 84.2%, 81.6% and 92.1%. We recommend to apply demethylvancomycin, vancomycin, teicoplanin and ofloxacin to the infections with MRSA.

　　Key Words　MRSA,Antibacterial drug,Sensitivity rate,Resistance rate

　　MRSA引起的医院感染率呈上升趋势，且耐药率与日俱增［1，2］，给临床经验用药造成困难。为了选择适宜的抗菌药物用于MRSA感染的治疗，测定了临床常用的9种抗菌药物对MRSA的MIC分布，并根据NCCLS的药敏标准计算出MRSA的敏感率和耐药率。

1　实验部分

1.1　材料
　　76株MRSA(华西医科大学附一院)。庆大霉素、SMZ/TMP、TMP、氧氟沙星、红霉素、利福平、壁霉素、万古霉素、去甲万古霉素(Sigma)。
1.2　方法
　　采用美国国家临床实验室标准化委员会(NCCLS)推荐的琼脂稀释法［3］。试验菌株种于M-H肉汤中，置37℃恒温摇箱培养6h，使菌处于对数生长期。用多点接种仪接种菌液于含抗菌药物浓度梯度的M-H琼脂系列上，每点接种量约为104CFU，37℃培养24h，观察结果和判读MIC，并按照NCCLS的药敏标准判断药敏性。

2　结果

　　76株MRSA对临床常用9种抗菌药物的MIC分布、敏感率和耐药率见表1。

Table 1　The drug sensitivity of seventy-six strains of MRSA to conventional clinically used antibacterial drugs

Antibacterial
drug Range of MIC
(mg/L) MIC50
(mg/L) MIC90
(mg/L) R(No.)
I(No.)
S(No.)
Sensitivity
rate(%) Resistance
rate(%)
Demethylvancomyc

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