新生儿室环丙沙星易感EMRSA-15爆发的鉴定和控制

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Identification and control of an outbreak of ciprofloxacin-susceptible EMRSA-15 on a neonatal unit Journal of Hospital Infection
Volume 67, Issue 3, November 2007, Pages 232-239
J.A. Ottera, J.L. Kleinb, T.L. Wattsc, A.M. Kearnsd and G.L. Frencha, ,  
aInfection and Immunology Delivery Unit, St Thomas' Hospital and King's College London, UK
bInfection and Immunology Delivery Unit, St Thomas' Hospital, London, UK
cChildren's Services, St Thomas' Hospital, London, UK
dStaphylococcus Reference Laboratory, Centre for Infections, HPA, London, UK
Received 17 May 2007;  accepted 27 July 2007.  Available online 22 October 2007.



Summary
We report the identification and control of an outbreak of a ciprofloxacin-susceptible strain of UK epidemic meticillin-resistant Staphylococcus aureus (EMRSA)-15 on a neonatal unit (NNU). All babies were screened for MRSA on admission using ciprofloxacin-containing media which did not detect the outbreak strain. The first identified case was a premature baby who developed MRSA bacteraemia with associated tibial osteomyelitis and multiple subcutaneous abscesses. The outbreak strain was subsequently identified in the nasopharyngeal secretions of a second child who was not clinically infected. Screening of all patients on the NNU using non-ciprofloxacin-media identified two other colonised babies. All four patient isolates were EMRSA-15, spa type t022, SCCmec IV, Panton–Valentine leucocidin (PVL) negative, indistinguishable by pulsed-field gel electrophoresis and susceptible to all non-β-lactam antimicrobials tested. The outbreak strain was cultured from four of 48 environmental sites in a communal milk-expressing room. Unsupervised movement of mothers to and from the milk-expressing room may have contributed to the outbreak. Control measures included cohort isolation of affected babies, improved environmental cleaning, increased emphasis on hand hygiene and education of mothers. Ciprofloxacin-containing media should be used with caution for MRSA screening in settings where ciprofloxacin-susceptible strains (including community-associated MRSA) are increasing in prevalence.

Keywords: MRSA; Outbreak; Neonatal; Environmental contamination

胡杨

丙沙星敏感的英国（UK）流行性MRSA-15菌株在新生儿室暴发的鉴别与控制
医院感染杂志（摘要）
    本文报道环丙沙星敏感的英国（UK）流行性MRSA-15菌株在新生儿室暴发事件的鉴别与控制一例。
首例MRSA检出于一名早产儿，其患有胫骨骨髓炎和多发性皮下脓肿。随后在另一个没有临床感染的婴儿鼻咽分泌物中检出MRSA而认定暴发。对新生儿室的所有病人采用无环丙沙星基质（non-ciprofloxacin-media）培养进行筛查，又检出两名婴儿被转染。采用脉冲场凝胶电泳（PFGE）技术和对所有非β -内酰胺类抗菌药物进行敏感性药物试验，结果四名病人的感染菌均为MRSA-15，spa type t022；SCCmec IV；PVL阴性。对48个环境位点采样，培养结果有4点阳性。显示MRSA暴发的疫点为公共牛奶快运间。产妇在公共牛奶快运间的活动未加监管，是造成暴发的直接原因。控制措施包括感染婴儿的同病种分类隔离、改善环境卫生、强调手卫生和产妇的培训教育。含环丙沙星培养的检测方法，越来越流行用于筛查环丙沙星敏感MRSA（包括社区相关MRSA）
关键词：MRSA；暴发；新生儿；环境污染；
备注：
Spa type t022.：（Staphylococcus aureus type t022）金葡菌的分型之一。
SCCmec：（Staphylococcal Cassette Chromosome mec)MRSA菌株帶有的一個可移動的基因片段。共分為四個类型，其中I到III型為院內感染型別，IV型為社區感染型別。
PVL: （Panton–Valentine leucocidin）一种杀白细胞的外毒素。由咝菌体携带后与金葡菌染色体结合，破坏人体白细胞。导致肺部等组织损害。
金葡菌：金黄色葡萄球菌是人类化脓感染中最常见的病原菌，可引起局部化脓感染，也可引起肺炎、伪膜性肠炎、心包炎等，甚至败血症、脓毒症等全身感染。金黄色葡萄球菌的致病力强弱主要取决于其产生的毒素和侵袭性酶：a.溶血毒素：外毒素，分α、β、γ、δ四种，能损伤血小板，破坏溶酶体，引起肌体局部缺血和坏死；b.杀白细胞素：可破坏人的白细胞和巨噬细胞；c.血浆凝固酶：当金黄色葡萄球菌侵入人体时，该酶使血液或血浆中的纤维蛋白沉积于菌体表面或凝固，阻碍吞噬细胞的吞噬作用。葡萄球菌形成的感染易局部化与此酶有关；d.脱氧核糖核酸酶：金黄色葡萄球菌产生的脱氧核糖核酸酶能耐受高温，可用来作为依据鉴定金黄色葡萄球菌；e.肠毒素：金黄色葡萄球菌能产生数种引起急性胃肠炎的蛋白质性肠毒素，分为A、B、C、D、E及F五种血清型。肠毒素可耐受100°C煮沸30分钟而不被破坏。它引起的食物中毒症状是呕吐和腹泻。此外，金黄色葡萄球菌还产生溶表皮素、明胶酶、蛋白酶、脂肪酶、肽酶等。金黄色葡萄球菌按1、血清学分型：（金葡水解，获得两种抗原成分：蛋白抗原和多糖抗原。蛋白抗原是凝集抗原，无特异性。多糖抗原有特异性。绝大多数金葡含有A型抗原，B型抗原主要存在于凝固酶阴性菌株，C型抗原在致病性和非致病性菌株中都存在。）２、噬菌体分型：３、根据肠毒素分型：４、根据血浆凝固酶分型。故其具有多种亚型。SA耐药菌的耐药基因研究，还可以分为多种基因型。

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