McGill University Health Centre, Montreal;
Can J Infect Dis Med Microbiol. 2012 Fall;23(3):117-20. doi: 10.1155/2012/725151.
Organisms expressing Klebsiella pneumoniae carbapenemase (KPC) are found in several regions worldwide but are rarely detected in Canada. The first outbreak of KPC-expressing strains of Enterobacteriaceae clinical isolates in a university-affiliated hospital intensive care unit (ICU) in Canada is described.
Enterobacteriaceae isolates that were flagged by the Vitek 2 (bioMérieux, France) system as possible carbapenemase producers were subjected to the modified Hodge test. Modified Hodge test-positive organisms were analyzed by pulsed-field gel electrophoresis, tested for KPC and other beta-lactamase genes by polymerase chain reaction analysis and underwent subsequent nucleic acid sequencing. Antimicrobial susceptibility profiles were determined by Vitek 2 and Etest (bioMérieux, France). A chart review was conducted to establish epidemiological links.
During the study period, 10 unique Enterobacteriaceae isolates expressing KPC were detected from nine ICU patients. Five patients had infections (three pneumonias, one surgical site infection, one urinary tract infection). Isolates included Escherichia coli (5), Klebsiella oxytoca (2), Serratia marcescens (2) and Citrobacter freundii (1). Polymerase chain reaction analysis and sequencing confirmed the presence of KPC-3 in all isolates; four also carried TEM, two CTX-M and one CMY-2. The imipenem minimum inhibitory concentrations as determined by Etest ranged from 0.75 μg/mL to ≥32 μg/mL. Pulsed field gel electrophoresis clonal patterns and patient location in the ICU revealed presumptive horizontal transmission events.
In the present study, Enterobacteriaceae isolates with KPC are emerging and can result in serious infections. The KPC gene can spread via plasmids to different genera of the Enterobacteriaceae family. The dissemination of KPC in Enterobacteriaceae and the consequences for treatment and infection control measures warrant a high degree of vigilance among clinicians and microbiologists.
在世界多个地区都发现了表达肺炎克雷伯菌碳青霉烯酶（KPC）的生物体，但在加拿大却很少检测到。本文描述了加拿大一家大学附属医院重症监护病房（ICU）中首次爆发的产 KPC 型肠杆菌科临床分离株。
采用 Vitek 2 系统（法国生物梅里埃公司）对可能产生碳青霉烯酶的肠杆菌科分离株进行 flagged 检测，对改良 Hodge 试验阳性的菌株进行脉冲场凝胶电泳分析，采用聚合酶链反应分析检测 KPC 和其他β-内酰胺酶基因，并进行后续核酸测序。采用 Vitek 2 和 Etest（法国生物梅里埃公司）进行药敏试验。进行病例回顾以建立流行病学联系。
在研究期间，从 9 名 ICU 患者中检测到 10 株独特的表达 KPC 的肠杆菌科分离株。其中 5 名患者发生感染（3 例肺炎、1 例手术部位感染、1 例尿路感染）。分离株包括大肠埃希菌（5 株）、产酸克雷伯菌（2 株）、粘质沙雷菌（2 株）和弗氏柠檬酸杆菌（1 株）。聚合酶链反应分析和测序证实所有分离株均存在 KPC-3；其中 4 株还携带 TEM、2 株 CTX-M 和 1 株 CMY-2。Etest 测定的亚胺培南最小抑菌浓度范围为 0.75μg/ml 至≥32μg/ml。脉冲场凝胶电泳克隆模式和 ICU 中患者的位置显示了推定的水平传播事件。
在本研究中，出现了具有 KPC 的肠杆菌科分离株，并可能导致严重感染。KPC 基因可通过质粒传播到肠杆菌科的不同属。肠杆菌科中 KPC 的传播及其对治疗和感染控制措施的影响，需要临床医生和微生物学家高度警惕。
