北台灣某教學醫院外科加護病房萬古黴素抗藥性腸球菌疑似群突發調查

Laboratory Investigation of an Outbreak of Infection Caused by Vancomycin-Resistant Enterococcus Faecium in a Surgical ICU at a Teaching Hospital in Northern Taiwan

葛茂成(Mao-Cheng Ge) ； 蘇玲慧(Lin-Hui Su) ； 劉翠萍(Tsui-Ping Liu) ； 郭安靜(An-Jing Kuo) ； 陳美蓮(Mei-Lien Cheng) ； 林均穗(Chun-Sui Lin) ； 張璧月(Pi-Yueh Chang) ； 甯孝真(Hsia-Chen Ning) ； 吳竹蘭(Tsu-Lan Wu)

《Journal of Biomedical & Laboratory Sciences》 24卷2期 (2012/06) Pp. 39-45

https://doi.org/10.30046/JBLS.201206.0002

摘要

根據疾病管制局院內感染監視系統顯示，醫院加護病房中萬古黴素（vancomycin）抗藥性腸球菌造成的醫療照護相關感染（healthcare-associated infection，HAI）個案，在近年有明顯增加。2007年9月，北台灣某教學醫院外科加護病房被發現有vancomycin-resistant Enterococcus faecium（VREf）感染個案異常增加的情形。為了瞭解是否爆發了群突發事件，我們回溯收集了該病房自2007年2月至2008年3月之間，由11位病人培養出的VREf共40株進行分析。此外，我們亦在2007年9月進行該單位環境及工作人員手部的採檢，培養結果共獲得18株VREf，其中16株來自於環境檢體，2株來自於人員檢體，陽性率分別為14.7%（環境）及16.7%（人員）。另外，6株流行病學上不相關的VREf也被收集作為對照組分析用。檢測萬古黴素van抗藥基因型的結果顯示，全部64株VREf皆為vanA型。為了釐清這些菌株彼此的相關性，我們使用基因分型方法進行分析，包括脈衝式電泳分析法（pulsed-field gel electrophoresis；PFGE）、多位點序列分型法（multilocus sequence typing；MLST）及多位點可變數目串聯重複序列分析法（multilocus variable number tandem repeat analysis；ML-VNTR）。此64株VREf共可分成13種PFGE型（A-M）與3種ML-VNTR型（1，7，159）。進一步根據PFGE型別選擇了16株進行MLST分析，得到5種MLST型，包括ST-17，18，78，280，661。在6株對照組菌株中，共可分成6個PFGE型，顯示PFGE對VREf的分型能力是足夠的。11位病人的40株VREf中，PFGE分成9型，其中10株（5位病人）屬於A型。環境及手部培養18株VREf中，有17株也是A型。此結果顯示，VREf感染個案的增加，可能與環境被此A型VREf污染，並經由醫護人員的手在病人之間互相傳遞有關。我們希望這些分析調查可以提供感控人員在擬定感控措施時作為參考。

關鍵字

萬古黴素抗藥性 ； 腸球菌 ； 醫療相關感染 ； 基因分型

並列摘要

Objective: According to the nosocomial surveillance system hosted by the Center for Disease Control in Taiwan, healthcare-associated infection (HAI) caused by vancomycin-resistant enterococci increased significantly in hospital intensive care units (ICUs) during the past few years. In September 2007, an abnormal increase in the number of vancomycin-resistant Enterococcus faecium (VREf) infection cases was noted in a surgical ICU at a teaching hospital in northern Taiwan. In order to clarify whether an outbreak was encountered, 40 VREf were retrospectively collected for study. They were isolated from 11 patients during February 2007 and March 2008 from this surgical ICU. Furthermore, environmental surveillance culture was also performed in the surgical ICU in September 2007. A total of 18 VREf isolates were collected from the environment specimens (16 isolates, positive rate=14.7%) and the hand cultures of staff members (2 isolates, positive rate=16.7%). Another 6 isolates of epidemiologically-nonrelated VREf were included as a control. The presence of vancomycin resistance gene, van, was examined. All the 64 VREf isolates were of vanA type. In order to elucidate the genetic relatedness among the VREf isolates, genotyping methods, such as pulsed-filed gel electrophoresis (PFGE), multilocus sequence typing (MLST), and multiple-locus variable-number tandem repeats analysis (ML-VNTR), were performed. A total of 13 PFGE types (A-M) and 3 ML-VNTR types (1, 7, and 159) were derived among the 64 VREf isolates studied. Analysis of 16 representative VREf isolates from the 13 PFGE types revealed 5 MLST types (ST-17, ST-18, ST-78, ST-280, ST-661). As 6 PFGE types were derived from the 6 epidemiologically- nonrelated isolates, the discrimination power of PFGE appears to be sufficient in differentiating VREf isolates. A predominant PFGE type A was identified from 10 VREf isolates derived from 5 patients. The type-A pattern also was found in 17 of the 18 VREf isolates yielded from the environmental surveillance cultures. The increase of VREf infection cases was apparently related to the vast contamination of the environment by the type-A VREf isolates and the further mutual transmission among patients via the hands of staff members working in the surgical ICU. We hope this investigation could be of some help for infection control personnel in defining or updating infection control measures.

並列關鍵字

vancomycin-resistant ； Enterococcus ； healthcare-associated infection ； genotyping