Identification of an aggregative adhesion fimbria (AAF) type III-encoding operon in enteroaggregative Escherichia coli as a sensitive probe for detecting the AAF-Encoding operon family
Identification of an aggregative adhesion fimbria (AAF) type III-encoding operon in enteroaggregative Escherichia coli as a sensitive probe for detecting the AAF-Encoding operon family
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DOI：
10.1128/iai.70.8.4302-4311.2002
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发表时间：
2002-08-01
影响因子：
3.1
通讯作者：
Le Bouguénec, C
中科院分区：
文献类型：
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作者：
Bernier, C;Gounon, P;Le Bouguénec, C
肠聚集性大肠杆菌（EAEC）被认为是全球儿童和成人腹泻的新原因，最近的研究表明，EAEC与人类免疫缺陷病毒（HIV）感染患者的持续性腹泻有关。本研究在典型EAFC菌株55989分离株中鉴定出聚集黏附菌III型（AAF-III）。对编码aaf - iii的质粒携带的agg-3基因簇的序列分析表明，该簇与扩散粘附致病性E. coh携带的agg和aaf操纵子以及afa操纵子密切相关。我们研究了从呈现持续性腹泻的hiv感染患者中分离的25株EAEC菌株的粘附特性。我们发现少数菌株（36%）携带与agg和aaf操作子相似的序列，分别编码aaf - i和aaf - ii。我们开发了针对agg-3操纵子的特异性PCR检测方法。在我们的收集中，AAF-III株的频率与AAF-I株（16%）相似（12%），但高于AAF-II株（0%）。EAEC菌株在毒力因素方面存在差异，使得现有DNA探针难以检测这些菌株。在比较agg、aaf和agg-3操纵子的基础上，我们定义了粘附基因簇内部的aaf探针，并证明该探针对EAEC菌株的鉴定是有效的。32株EAEC分离株，经典CVD432探针（检测pAA毒力质粒）检出率仅为34.4%，而AAF探针检出率为65.6%。
Enteroaggregative Escherichia coli (EAEC) is recognized as an emerging cause of diarrhea in children and adults worldwide, and recent studies have implicated EAEC in persistent diarrhea in patients infected with human immunodeficiency virus (HIV). In this study, we identified aggregative adhesion fimbria type III (AAF-III) in isolate 55989, a typical EAFC strain. Analysis of the sequence of the plasmid-borne agg-3 gene cluster encoding AAF-III showed this cluster to be closely related to the agg and aaf operons and to the afa operons carried by diffusely adherent pathogenic E. coh. We investigated the adhesion properties of a collection of 25 EAEC strains isolated from HIV-infected patients presenting with persistent diarrhea. We found that a minority of strains (36%) carried sequences similar to those of the agg and aaf operons, which encode AAF-I and AAF-II, respectively. We developed PCR assays specific for the agg-3 operon. In our collection, the frequency of AAF-III strains was similar (12%) to that of AAF-I strains (16%) but higher than that of AAF-II isolates (0%). Differences between EAEC strains in terms of the virulence factors present render detection of these strains difficult with the available DNA probes. Based on comparison of the agg, aaf, and agg-3 operons, we defined an AAF probe internal to the adhesion gene clusters and demonstrated that it was efficient for the identification of EAEC strains. We investigated 32 EAEC isolates, of which only 34.4% were detected with the classical CVD432 probe (detecting pAA virulence plasmids) whereas 65.6% were detected with the AAF probe.