对爱尔兰患者中耐甲氧西林金黄色葡萄球菌分离株对糖肽类药物敏感性降低情况的调查以及对检测异质性糖肽类药物中介金黄色葡萄球菌的琼脂筛选方法的评估。
Investigation of reduced susceptibility to glycopeptides among methicillin-resistant Staphylococcus aureus isolates from patients in Ireland and evaluation of agar screening methods for detection of heterogeneously glycopeptide-intermediate S. aureus.
作者信息
Fitzgibbon Margaret M, Rossney Angela S, O'Connell Brian
机构信息
National MRSA Reference Laboratory, St. James's Hospital, James's St., Dublin 8, Ireland.
出版信息
J Clin Microbiol. 2007 Oct;45(10):3263-9. doi: 10.1128/JCM.00836-07. Epub 2007 Aug 8.
Methicillin-resistant Staphylococcus aureus (MRSA) isolates (n = 3,189) from 2,990 patients were investigated by agar screening and by the Etest macromethod for reduced susceptibility to glycopeptide. No vancomycin-resistant S. aureus or glycopeptide-intermediate S. aureus (GISA) isolates were detected, but 178 isolates were confirmed as hetero-GISA (hGISA) by vancomycin population analysis profile (vPAP)-area under the curve (AUC) ratio determination and/or teicoplanin PAP (tPAP) methods. Of 139 isolates detected using the recommended Etest macromethod cutoff values of > or =8 mg/liter for both vancomycin and teicoplanin or > or =12 mg/liter for teicoplanin alone, 73 were confirmed as hGISA by vPAP-AUC, 95 were confirmed as hGISA by tPAP, and 108 were confirmed as hGISA by both methods. An Etest macromethod cutoff value of 8 mg/liter for teicoplanin alone detected a further 70 hGISA (17 were confirmed by vPAP-AUC and 70 were confirmed by tPAP). Agar screening utilizing brain heart infusion (BHI) agar containing 6 mg of vancomycin/liter (BHIV6) and Mueller-Hinton (MH) agar containing 8 mg of teicoplanin/liter (MHT8) failed to detect hGISA. MH agar containing 5 mg of teicoplanin/liter (MHT5) and BHI containing 5 mg of teicoplanin/liter (BHIT5) were evaluated using 10-microl volumes of three inoculum concentrations (with densities equivalent to 0.5 and 2.0 McFarland turbidity standards and stationary-phase BHI broth subcultures [MHT5(0.5), MHT5(2.0), MHT5(S), BHIT5(0.5), BHIT5(2.0), and BHIT5(S)]). The sensitivity of all methods except MHT5(0.5) and MHT5(2.0) was 100%. The specificity ranged from 4 to 82%. BHIT5(0.5) yielded the best performance, with a specificity of 84% for detecting isolates with teicoplanin Etest macromethod values of > or =8 mg/liter. Screening on BHIT5(0.5) is useful where screen-positive isolates are investigated with the Etest macromethod and confirmed by vPAP-AUC and tPAP. The prevalence of hGISA among patients with blood culture isolates recovered in Irish hospitals between 1999 and 2003 was 2.6%, whereas the prevalence among patients with isolates from all specimen sites collected during a 2-week survey in 1999 was 12%. The prevalence in one hospital decreased from 5.3% in 2003 to 1.5% in 2004.
对来自2990名患者的3189株耐甲氧西林金黄色葡萄球菌（MRSA）分离株进行了琼脂筛选和Etest宏方法检测，以确定其对糖肽类药物的敏感性降低情况。未检测到耐万古霉素金黄色葡萄球菌或万古霉素中介金黄色葡萄球菌（GISA）分离株，但通过万古霉素群体分析图谱（vPAP）-曲线下面积（AUC）比值测定和/或替考拉宁PAP（tPAP）方法，有178株分离株被确认为异质性GISA（hGISA）。在使用推荐的Etest宏方法临界值（万古霉素和替考拉宁均为≥8mg/L或仅替考拉宁为≥12mg/L）检测出的139株分离株中，73株通过vPAP-AUC被确认为hGISA，95株通过tPAP被确认为hGISA，108株通过两种方法均被确认为hGISA。仅替考拉宁的Etest宏方法临界值为8mg/L时，又检测出70株hGISA（17株通过vPAP-AUC被确认，70株通过tPAP被确认）。利用含6mg/L万古霉素的脑心浸液（BHI）琼脂（BHIV6）和含8mg/L替考拉宁的穆勒-欣顿（MH）琼脂（MHT8）进行琼脂筛选未能检测出hGISA。使用10微升三种接种浓度（密度相当于0.5和2.0麦氏浊度标准以及静止期BHI肉汤传代培养物[MHT5(0.5)、MHT5(2.0)、MHT5(S)、BHIT5(0.5)、BHIT5(2.0)和BHIT5(S)]）对含5mg/L替考拉宁的MH琼脂（MHT5）和含5mg/L替考拉宁的BHI（BHIT5）进行了评估。除MHT5(0.5)和MHT5(2.0)外，所有方法的敏感性均为100%。特异性范围为4%至82%。BHIT5(0.5)表现最佳，对于检测替考拉宁Etest宏方法值≥8mg/L的分离株，其特异性为84%。在通过Etest宏方法对筛选阳性分离株进行调查并经vPAP-AUC和tPAP确认的情况下，在BHIT5(0.5)上进行筛选是有用的。1999年至2003年在爱尔兰医院血培养分离株患者中hGISA的患病率为2.6%，而在1999年为期2周的调查中从所有标本部位分离株患者中的患病率为12%。一家医院的患病率从2003年的5.3%降至2004年的1.5%。
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