长沙地区临床分离金黄色葡萄球菌的耐药监测

目的了解长沙地区临床分离金黄色葡萄球菌（以下简称金葡菌）对常用抗菌药物的耐药现状,探讨金黄色葡萄球菌对甲氧西林的耐药水平。方法收集长沙地区11家医院2009年11月至2010年11月临床分离的非重复金葡菌279株,应用Vitek-2全自动微生物分析系统进行鉴定,K-B法检测金葡菌对24种药物的敏感性,产色头孢菌素试验检测β-内酰胺酶以及D试验检测诱导型克林霉素耐药。应用头孢西丁和苯唑西林纸片扩散法筛查耐甲氧西林的金葡菌（MRSA）,琼脂稀释法检测头孢西丁和苯唑西林的最低抑菌浓度（MIC）。结果在被检测的24种药物中,敏感率〉50%的药物为9种,未发现对万古霉素、替考拉宁和利奈唑胺耐药菌株;耐药率〉50%的抗菌药物有11种,其中以青霉素和氨苄西林的耐药率最高（均为97.1%）。MRSA的分离率达54.5%,且对常用的16种抗菌药物的耐药率均显著高于甲氧西林敏感金黄色葡萄球菌（MSSA）。279株金葡菌中,β-内酰胺酶阳性250株（89.6%）;红霉素耐药而克林霉素敏感或中介的30株中,D试验阳性22株（73.3%）。苯唑西林（OXA）和头孢西丁（FOX）MIC范围分别为0.125～〉256μg/mL和2～〉256μg/mL,苯唑西林的MIC50和MIC90分别为128μg/mL和256μg/mL,头孢西丁的MIC50和MIC90分别为64μg/mL和256μg/mL。结论长沙地区临床分离金葡菌对常用抗菌药物呈多重耐药;MRSA不仅分离率高,而且对甲氧西林呈高水平耐药。

Surveillance of antibiotic resistance in clinical isolates of Staphylococcus aureus from Changsha

Objective To investigate the characteristics of drug resistance and current situation of methicillin-resistance in clinical isolates of Staphylococcus aureus(S.aureus) in Changsha.Method Totally 279 non-duplicate clinical isolates of S.aureus were collected during November 2009 to November 2010 from 11 hospitals in Changsha and then identified by Vitek-2 system.K-B disk method was used to test drug sensitivity to 24 commonly used antibiotics.Chromogenic cephalosporin spot test was applied to detect β-lactamase and D-test were used to check inducible resistance to clindamycin.MRSA was screened by oxacillin and cefoxitin disk diffusion methods.Agar dilution method was used to determine the minimal inhibitory concentrations(MICs) of oxacillin and cefoxitin to isolates of S.aureus.Result Of the 279 S.aureus isolates,the sensitive rates to 9 of the 24 antibiotics tested were higher than 50%.All the isolates were susceptible to tecoplanin,vancomycin and linezolid.The resistance rates to 11 of the 24 antibiotics tested were higher than 50%;resistance rates to penicillin and ampicillin were the highest(both 97.1%).Among the 279 strains,MRSA accounted for 54.5%,which were high sensitive to vancomycin,tecoplanin and linezolid.The resistance rates of MRSA to the other 16 antibiotics were higher than that of MSSA.Of the 279 strains,the positive rate of β-lactamase was 89.6%(250/279).Of the 30 isolates resistant to erythromycin but susceptible or intermediate to clindamycin,22(73.3%) showed a positive result of D-test.The MIC range of oxacillin and cefoxitin on S.aureus was 0.125->256 μg/mL and 2->256 μg/mL respectively.The MIC50 and MIC90 of oxacillin and cefoxitin were 128 μg/mL and 256 μg/mL,64 μg/mL and 256 μg/mL respectively.Conclusion Clinical isolates of S.aureus in Changsha are multiple resistant to commonly used antimicrobial agents.Rate of MRSA and level of resistance to methicillin are very high.