医学检验信息网 检验医学 2007-2-26 16:16:47

目的 ：调查血培养中凝固酶阴性的葡萄球菌(CoNS)血样本的污染率。方法 ：回顾分析1995年到1999年从本院住院病人血中分离到CoNS的病例共70例，判定是菌血症还是血样本污染。结果 ：37/70（52.9%）的病例为菌血症，其中15例（40.5%）原发入侵部位为静脉插管及外来异物，8例（21.6%）为术后伤口感染，4例来自呼吸道，4例来自脐带，1例来自眼，5例来源不明。这37例主要来自重症监护病房、新生儿病房、外科病房和血液病房。48小时内检测出的CoNS中，有24株(39.3%)为污染菌, 49小时以后检出的CoNS，全部为污染菌（9株）；污染菌的检测时间明显长于病原菌的检测时间（P＝0.01）。病原菌与污染菌对青霉素、苯唑西林、庆大霉素、环丙沙星、万古霉素的耐药性无显著差异（P>0.25）。在15例由静脉插管及外来异物引起的菌血症中，10例拔除导管后，菌血症得到控制；5例同时还使用了万古霉素，菌血症才得到控制。结论 ：CoNS菌血症血样本的污染率较高，应当综合临床和实验室的资料判定是否为污染，避免不必要地使用抗微生物药物，特别是万古霉素。 Evaluation of coagulase-negative staphylococci in blood culture. Hui Wang, Zhang Yuexian, Xie Xiuli, Xu Yingchung，Chen Minjun. (Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730) (Abstract) Objective : To investigate the contamination incidence of coagulase-negative staphylococci (CoNS) in blood culture. Methods : Retrospective coagulase-negative staphylococci in blood culture from 70 hospitalized patients at Peking Union Medical College Hospital from 1995 to 1999. We differentiated true bacteremia from contamination by using a criterion reviewed from published papers. Results : 37/70 (52.9%) of cases was bacteremia due to CoNS. 15 strains (40.5%) were related to catheters using and foreign bodies, 8 (21.6%) related to postoperative wounds, 4 related to umbilicus, 1 related to eye infection. The rest 5 strains were unkown. Most of 37 cases of bacteremia were from intensive care units, neonatal ward , surgeon wards and hematology ward. 18 strains from 46 of CoNS (39.3%) isolated from bloodstream within 48 hours and 6 strains from 15 of CoNS (40.0%) isolated from 25 to 48 hours were contaminants; All 9 strains isolated after 49 hours were contaminants. The time to positive for contaminants was significantly longer than that for true pathogens (36.2 h / 21.9 h, P=0.01). The resistance to penicillin, oxacillin, gentamicin ciprofloxacin and vancomycin were no significant difference between contaminants and pathogens (P>0.25). 10 of 15 cases of true bacteremia due to catheters and foreign bodies were cured after only removal of catheters and foreign bodies, and the rest 5 cases were cured by both administering vancomycin and removing catheters. Conclusions : The contamination incidence of CoNS in blood culture was relatively high. We should determine true bacteremia from contamination by reviewing the clinical, epidemiological and laboratory information, which would be helpful to avoid abuse of antimicrobials, especially vancomycin. 凝固酶阴性的葡萄球菌(CoNS) 是从血培养中分离到的最常见的菌种（1, 2）。1993年~1995年从本院的血标本和其他无菌体液标本中分离到的菌种中，CoNS达15.3%, 居第一位（3）。虽然CoNS已被认为是真正的病原菌，可以产生毒力因子而具有严重的致病性，但由于它是人体皮肤的正常菌群，而经常被认为是污染菌。正因如此，已有很多文献提供了如何区别其为菌血症致病菌还是血样本的污染菌的临床及微生物学两方面的原则和方法（4，5）。例如实验室推荐的菌血症致病菌的标准包括血培养 48小时内阳性和多次血培养 为同一种菌；否则，血培养3天以上才报阳性，或血培养出多种皮肤寄居菌， 或虽使用敏感抗生素治疗，血培养仍阳性等预示为污染菌。同时参考临床资料也是至关重要的。我们综合文献推荐的标准，用其分析我院1995年~1999年血培养中分离到CoNS的病例共70例，以了解CoNS血样本的污染率。 材料和方法

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