School of Infection and Host Defence, Duncan Building, University of Liverpool, Daulby Street, Liverpool L69 3GA, UK.
J Antimicrob Chemother. 2010 Apr;65(4):721-4. doi: 10.1093/jac/dkq009. Epub 2010 Feb 2.
To investigate if colonization with heterogeneous glycopeptide-intermediate Staphylococcus aureus (hGISA) is associated with hGISA bacteraemia.
Isolates of methicillin-resistant S. aureus (MRSA) from blood cultures and from swabs to detect MRSA colonization were screened for reduced susceptibility to glycopeptides by an agar incorporation method. Isolates detected by this screen were tested for glycopeptide resistance by MacroEtest, standard MIC Etest methods and population analysis profile-AUC (PAP-AUC) analysis. S. aureus isolates with and without reduced glycopeptide susceptibility were characterized by PFGE and spa typing.
MRSA isolates with reduced susceptibility to glycopeptides, as identified by the MacroEtest method, were detected in the colonization screens of 86 of 2550 MRSA-positive patients. The isolates were confirmed by Etest MIC and PAP-AUC analysis as hGISA. A total of 82/86 of the hGISA colonizing isolates were EMRSA-16 by PFGE; the remainder were EMRSA-15. Bacteraemia with hGISA was identified in five patients during the study period; two isolates were EMRSA-16 and three were EMRSA-15. hGISA colonization could not be linked to hGISA bacteraemia and hGISA bacteraemia could not be linked to hGISA colonization. Four of the five hGISA bacteraemias developed following teicoplanin therapy for a central venous catheter-associated MRSA bacteraemia.
Laboratory strategies to reduce morbidity associated with hGISA should focus on testing for hGISA in bacteraemic (rather than colonizing) MRSA isolates in patients with recurrent S. aureus bacteraemia following glycopeptide exposure.
研究异质性糖肽中介金黄色葡萄球菌（hGISA）定植是否与 hGISA 菌血症相关。
通过琼脂掺入法筛选耐甲氧西林金黄色葡萄球菌（MRSA）血培养和用于检测 MRSA 定植的拭子中对糖肽敏感性降低的分离物。通过该筛选检测到的分离物通过 MacroEtest、标准 MIC Etest 方法和群体分析谱-AUC（PAP-AUC）分析检测糖肽耐药性。对具有和不具有降低糖肽敏感性的金黄色葡萄球菌分离物进行 PFGE 和 spa 分型。
通过 MacroEtest 方法鉴定的对糖肽敏感性降低的 MRSA 分离物在 2550 例 MRSA 阳性患者的定植筛选中被检测到。通过 Etest MIC 和 PAP-AUC 分析进一步确认这些分离物为 hGISA。82/86 株 hGISA 定植分离物通过 PFGE 鉴定为 EMRSA-16；其余为 EMRSA-15。在研究期间，有 5 例患者发生 hGISA 菌血症，其中 2 株分离物为 EMRSA-16，3 株为 EMRSA-15。hGISA 定植与 hGISA 菌血症之间无法关联，hGISA 菌血症也无法与 hGISA 定植相关联。5 例 hGISA 菌血症中有 4 例发生在替考拉宁治疗中心静脉导管相关 MRSA 菌血症后。
减少与 hGISA 相关发病率的实验室策略应侧重于在经历糖肽暴露后复发性金黄色葡萄球菌菌血症患者中，对血培养中发生的（而非定植的）hGISA 耐甲氧西林金黄色葡萄球菌分离物进行 hGISA 检测。
