Semi-selective broth improves screening for methicillin-resistant Staphylococcus aureus
Semi-selective broth improves screening for methicillin-resistant Staphylococcus aureus
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DOI：
10.1093/jac/dkq001
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发表时间：
2010-04-01
影响因子：
5.2
通讯作者：
Friedrich, A. W.
中科院分区：
文献类型：
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作者：
Bocher, S.;Middendorf, B.;Friedrich, A. W.
目的评价两种富集菌液对耐甲氧西林金黄色葡萄球菌（MRSA）的检测效果，并与直接电镀检测结果进行比较。在中心实验室（明斯特）使用六种方法对1224例患者的拭子进行MRSA重新分析。将拭子悬浮于0.5 mL非选择性富集肉汤（NB）中并旋转。将100 μ L等份接种于：(1)ChromID MRSA琼脂；（II）哥伦比亚羊血（5%）琼脂（BA）和铬粒MRSA；（III， IV） NB孵育过夜，然后镀于BA和ChromID MRSA；（V， VI）含头孢西丁和氨曲南的半选择性肉汤（TSB-SSI）孵育过夜，然后镀在BA和ChromID MRSA上。在III-VI阶段，在每个琼脂上镀100 μ L的强化肉汤。合并mrsa阳性率为21.5%。各方法检出的MRSA分离株为：TSB-SSI， n = 223；NB, n = 205；BA和ChromID MRSA， n = 203；单独的MRSA， n = 183。TSB-SSI检测到的喉部阳性样本比比较物更多，并显著降低了甲氧西林敏感金黄色葡萄球菌（MSSA）的生长。获得的最大灵敏度仅为85%，可能是由于研究设计使用预先使用的拭子和拭子材料的稀释。对于997个样品，将明斯特的结果与初始结果进行比较。周边实验室检测到172株MRSA，而明斯特直接镀、NB和TSB-SSI肉汤分别检测到186株、186株和204株MRSA。TSB-SSI在ChromID MRSA和BA上的效果优于NB和直接镀。尽管在研究中重复使用拭子，但我们发现使用半选择性富集肉汤可以显著改善常规诊断筛查。
To evaluate two enrichment broths for methicillin-resistant Staphylococcus aureus (MRSA) detection and compare results with direct plating.Swabs from 1224 patients were re-analysed for MRSA in a central laboratory (Munster) using six methods. Swabs were suspended in 0.5 mL of non-selective enrichment broth (NB) and vortexed. Aliquots of 100 mu L were inoculated on/into: (I) ChromID MRSA agar; (II) Columbia sheep blood (5%) agar (BA) and ChromID MRSA; (III, IV) NB incubated overnight followed by plating on BA and ChromID MRSA; and (V, VI) a semi-selective broth containing cefoxitin and aztreonam (TSB-SSI) incubated overnight followed by plating on BA and ChromID MRSA. In III-VI, 100 mu L of the enriched broth was plated on each agar.The combined MRSA-positive rate was 21.5%. MRSA isolates detected by each method were: TSB-SSI, n = 223; NB, n = 205; BA and ChromID MRSA, n = 203; ChromID MRSA alone, n = 183. TSB-SSI detected more positive throat samples than the comparators and significantly reduced methicillin-susceptible S. aureus (MSSA) growth. The maximum sensitivity obtained was only 85%, possibly due to the study design using pre-used swabs and dilution of swab material. For 997 samples, results from Munster were compared with initial results. Peripheral laboratories identified 172 MRSA compared with Munster where 186, 186 and 204 MRSA were found for direct plating, NB and TSB-SSI broth, respectively.TSB-SSI was superior to both NB and direct plating on ChromID MRSA and BA. Despite re-using swabs for the study, we showed that routine diagnostic screening could be significantly improved, using a semi-selective enrichment broth.