Canadian Field Epidemiology Program, Public Health Agency of Canada, Ottawa.
Can J Infect Dis Med Microbiol. 2007 Mar;18(2):128-32. doi: 10.1155/2007/617526.
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has increasingly been isolated from individuals with no predisposing risk factors; however, such strains have rarely been linked to outbreaks in the hospital setting. The present study describes the investigation of an outbreak of CA-MRSA that occurred in the maternal-newborn unit of a large community teaching hospital in Toronto, Ontario.
Screening and clinical specimens collected from mothers and newborns delivered during the outbreak period, as well as from staff on the affected unit, were submitted for microbiological testing. Computerized delivery logs and nursing notes were reviewed, and a case control study was conducted.
Analysis by pulsed-field gel electrophoresis revealed 38 babies and seven mothers with MRSA colonization and/or infection by the same unique strain (Canadian MRSA-10-related) from September to December 2004. Isolates were characterized as having the staphylococcal chromosome cassette mec type IVa and were positive for the Panton-Valentine leukocidin gene. No one health care worker was associated with all cases; however, mothers and newborns exposed to one particular nurse (Nurse A) were almost 23 times (odds ratio 22.7, 95% CI 3.3 to 195.9) more likely to acquire MRSA than those with no such contact. MRSA was successfully isolated from Nurse A and from an environmental swab of a telephone recently used by Nurse A; both isolates matched the pulsed-field gel electrophoresis pattern of the outbreak strain.
The first nosocomial outbreak of CA-MRSA among healthy newborns and postpartum mothers in Canada is described. Effective control of sustained MRSA transmission within an institution may require prompt identification, treatment and monitoring of colonized and/or infected staff.
社区获得性耐甲氧西林金黄色葡萄球菌（CA-MRSA）越来越多地从没有易感危险因素的个体中分离出来；然而，此类菌株很少与医院环境中的暴发有关。本研究描述了在安大略省多伦多市一家大型社区教学医院的母婴病房中发生的 CA-MRSA 暴发的调查情况。
对暴发期间分娩的母亲和新生儿以及受影响病房的工作人员的筛查和临床标本进行了微生物学检测。对计算机化的分娩记录和护理记录进行了审查，并进行了病例对照研究。
脉冲场凝胶电泳分析显示，2004 年 9 月至 12 月期间，有 38 名婴儿和 7 名母亲通过同一独特的菌株（加拿大 MRSA-10 相关）发生了 MRSA 定植和/或感染。分离株的特征为具有葡萄球菌染色体盒 mec 类型 IVa，并且对 Panton-Valentine 白细胞毒素基因呈阳性。没有一个医护人员与所有病例有关；然而，与一名特定护士（护士 A）接触的母亲和新生儿感染 MRSA 的可能性几乎是没有这种接触的母亲和新生儿的 23 倍（比值比 22.7，95%CI 3.3 至 195.9）。MRSA 成功地从护士 A 和护士 A 最近使用过的电话的环境拭子中分离出来；这两个分离株与暴发菌株的脉冲场凝胶电泳模式相匹配。
描述了加拿大首例健康新生儿和产后母亲的社区获得性耐甲氧西林金黄色葡萄球菌（CA-MRSA）医院内暴发。在一个机构内有效控制持续的 MRSA 传播可能需要迅速识别、治疗和监测定植和/或感染的工作人员。
