来自人和禽类的肠外致病性大肠杆菌O1:K1:H7/NM：具有不同宿主分布的B2克隆群ST95和D克隆群ST59的检测
Extraintestinal pathogenic Escherichia coli O1:K1:H7/NM from human and avian origin: detection of clonal groups B2 ST95 and D ST59 with different host distribution.
作者信息
Mora Azucena, López Cecilia, Dabhi Ghizlane, Blanco Miguel, Blanco Jesús E, Alonso María Pilar, Herrera Alexandra, Mamani Rosalía, Bonacorsi Stéphane, Moulin-Schouleur Maryvonne, Blanco Jorge
机构信息
Laboratorio de Referencia de E, coli, Departamento de Microbiología y Parasitología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain.
出版信息
BMC Microbiol. 2009 Jul 7;9:132. doi: 10.1186/1471-2180-9-132.
BACKGROUND
Extraintestinal pathogenic Escherichia coli (ExPEC) strains of serotype O1:K1:H7/NM are frequently implicated in neonatal meningitis, urinary tract infections and septicemia in humans. They are also commonly isolated from colibacillosis in poultry. Studies to determine the similarities of ExPEC from different origins have indicated that avian strains potentially have zoonotic properties.
RESULTS
A total of 59 ExPEC O1:K1:H7/NM isolates (21 from avian colibacillosis, 15 from human meningitis, and 23 from human urinary tract infection and septicemia) originated from four countries were characterized by phylogenetic PCR grouping, Multilocus Sequence Typing (MLST), Pulsed Field Gel Electrophoresis (PFGE) and genotyping based on several genes known for their association with ExPEC or avian pathogenic Escherichia coli (APEC) virulence.APEC and human ExPEC isolates differed significantly in their assignments to phylogenetic groups, being phylogroup B2 more prevalent among APEC than among human ExPEC (95% vs. 53%, P = 0.001), whereas phylogroup D was almost exclusively associated with human ExPEC (47% vs. 5%, P = 0.0000). Seven virulence genes showed significant differences, being fimAvMT78 and sat genes linked to human isolates, while papGII, tsh, iron, cvaC and iss were significantly associated to APEC. By MLST, 39 of 40 ExPEC belonging to phylogroup B2, and 17 of 19 belonging to phylogroup D exhibited the Sequence Types (STs) ST95 and ST59, respectively. Additionally, two novel STs (ST1013 and ST1006) were established. Considering strains sharing the same ST, phylogenetic group, virulence genotype and PFGE cluster to belong to the same subclone, five subclones were detected; one of those grouped six strains of human and animal origin from two countries.
CONCLUSION
Present results reveal that the clonal group B2 O1:K1:H7/NM ST95, detected in strains of animal and human origin, recovered from different dates and geographic sources, provides evidence that some APEC isolates may act as potential pathogens for humans and, consequently, poultry as a foodborne source, suggesting no host specificity for this type of isolates. A novel and important finding has been the detection of the clonal group D O1:K1:H7/NM ST59 almost exclusively in humans, carrying pathogenic genes linked to the phylogenetic group D. This finding would suggest D O1:K1:H7/NM ST59 as a host specific pathotype for humans.
背景
血清型为O1:K1:H7/NM的肠外致病性大肠杆菌（ExPEC）菌株常与人类新生儿脑膜炎、尿路感染和败血症有关。它们也常见于家禽大肠杆菌病中。确定不同来源的ExPEC之间相似性的研究表明，禽类菌株可能具有人畜共患病属性。
结果
对来自四个国家的总共59株ExPEC O1:K1:H7/NM分离株（21株来自禽大肠杆菌病，15株来自人类脑膜炎，23株来自人类尿路感染和败血症）进行了系统发育PCR分组、多位点序列分型（MLST）、脉冲场凝胶电泳（PFGE）以及基于几个已知与ExPEC或禽致病性大肠杆菌（APEC）毒力相关基因的基因分型。APEC和人类ExPEC分离株在系统发育组的分类上有显著差异，B2系统发育组在APEC中比在人类ExPEC中更普遍（95%对53%，P = 0.001），而D系统发育组几乎只与人类ExPEC相关（47%对5%，P = 0.0000）。七个毒力基因显示出显著差异，fimAvMT78和sat基因与人类分离株相关，而papGII、tsh、铁、cvaC和iss与APEC显著相关。通过MLST，属于B2系统发育组的40株ExPEC中的39株，以及属于D系统发育组的19株中的17株分别表现出序列型（STs）ST95和ST59。此外，还确定了两个新的STs（ST1013和ST1006）。考虑到共享相同ST、系统发育组、毒力基因型和PFGE簇的菌株属于同一亚克隆，检测到了五个亚克隆；其中一个亚克隆包含来自两个国家的六株人和动物来源的菌株。
结论
目前的结果表明，在不同日期和地理来源分离得到的动物和人类来源菌株中检测到的克隆群B2 O1:K1:H7/NM ST95，证明了一些APEC分离株可能是人类的潜在病原体，因此，家禽作为食源，表明这类分离株没有宿主特异性。一个新的重要发现是几乎只在人类中检测到克隆群D O1:K1:H7/NM ST59，其携带与D系统发育组相关的致病基因。这一发现表明D O1:K1:H7/NM ST59是人类宿主特异性致病型。
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