Unidad Clínica de Enfermedades Infecciosas y Microbiología, Hospital Universitario Virgen Macarena, Sevilla, Spain.
PLoS One. 2012;7(9):e44238. doi: 10.1371/journal.pone.0044238. Epub 2012 Sep 7.
There is scarce data about the importance of phylogroups and virulence factors (VF) in bloodstream infections (BSI) caused by extended-spectrum β-lactamase-producing Escherichia coli (ESBLEC). A prospective multicenter Spanish cohort including 191 cases of BSI due to ESBLEC was studied. Phylogroups and 25 VF genes were investigated by PCR. ESBLEC were classified into clusters according to their virulence profiles. The association of phylogropus, VF, and clusters with epidemiological features were studied using multivariate analysis. Overall, 57.6%, 26.7%, and 15.7% of isolates belonged to A/B1, D and B2 phylogroups, respectively. By multivariate analysis (adjusted OR [95% CI]), virulence cluster C2 was independently associated with urinary tract source (5.05 [0.96-25.48]); cluster C4 with sources other than urinary of biliary tract (2.89 [1.05-7.93]), and cluster C5 with BSI in non-predisposed patients (2.80 [0.99-7.93]). Isolates producing CTX-M-9 group ESBLs and from phylogroup D predominated among cluster C2 and C5, while CTX-M-1 group of ESBL and phylogroup B2 predominantes among C4 isolates. These results suggest that host factors and previous antimicrobial use were more important than phylogroup or specific VF in the occurrence of BSI due to ESBLEC. However, some associations between virulence clusters and some specific epidemiological features were found.
关于产超广谱β-内酰胺酶大肠杆菌（ESBLEC）引起的血流感染（BSI）中菌系和毒力因子（VF）的重要性的数据很少。本研究纳入了一项前瞻性、多中心的西班牙队列研究，共纳入了 191 例 ESBLEC 引起的 BSI 患者。通过 PCR 检测了菌系和 25 个 VF 基因。根据毒力谱对 ESBLEC 进行聚类分析。使用多变量分析研究了菌系、VF 和聚类与流行病学特征的关系。总的来说，57.6%、26.7%和 15.7%的分离株分别属于 A/B1、D 和 B2 菌系。多变量分析（调整 OR [95%CI]）显示，毒力簇 C2 与尿路感染（5.05 [0.96-25.48]）独立相关；簇 C4 与除尿路感染和胆道感染以外的其他来源相关（2.89 [1.05-7.93]），簇 C5 与无基础疾病患者的 BSI 相关（2.80 [0.99-7.93]）。产 CTX-M-9 组 ESBL 且来自 D 菌系的分离株主要存在于 C2 和 C5 簇中，而产 CTX-M-1 组 ESBL 且来自 B2 菌系的分离株主要存在于 C4 簇中。这些结果表明，宿主因素和既往抗菌药物使用比菌系或特定 VF 更重要，与 ESBLEC 引起的 BSI 发生有关。然而，发现了一些毒力簇与某些特定流行病学特征之间的关联。
