Pereira Ana Claudia M, Britto-Filho Jonas D, José de Carvalho Jorge, de Luna Maria das Graças, Rosa Ana Cláudia P
Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Vila Isabel, RJ, Brazil.
Microb Pathog. 2008 Nov-Dec;45(5-6):310-4. doi: 10.1016/j.micpath.2008.07.001. Epub 2008 Jul 12.
Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen associated to cases of acute or persistent diarrhea in children and adults from developed and developing countries. These microorganisms also have been isolated from human immunodeficiency virus-infected patients. EAEC exhibits aggregative adherence (AA) in HEp-2 cells. This pattern is characterized by the production of bacteria aggregates adhered to monolayer cultured cells with a "stacked brick" phenotype. The AA pattern is related to the presence of a 60MDa plasmid (pAA). In the present study, we evaluated the adherence, invasion and persistent survival of five EAEC strains with Caco-2 and T84 cells, by a bacteria invasion assay and transmission electron microscopy. EAEC isolated from cases of acute infantile diarrhea can be internalized by intestinal epithelial cells cultivated in vitro, suggesting that these strains may employ a mechanism of host cell invasion to colonize the intestinal mucosa. Results showed that EAEC strains could survive intracellularly up to 72h. Our data support evidence that EAEC is able to invade, persist and replicate within intestinal cells for extended time. This strategy may be advantageous to EAEC in colonization and survival, favoring the exploitation of an intracellular niche where these strains are protected against host clearance mechanisms, immune system and antibiotic treatment. Intracellular persistence of EAEC may be associated with development of persistent diarrhea associated to these microorganisms. To our knowledge, this is the first report of EAEC intracellular survival in cultured intestinal epithelial cells.
肠集聚性大肠杆菌（EAEC）是一种新出现的病原体，与发达国家和发展中国家儿童及成人的急性或持续性腹泻病例相关。这些微生物也已从感染人类免疫缺陷病毒的患者中分离出来。EAEC在人喉表皮癌细胞（HEp-2细胞）中表现出集聚性黏附（AA）。这种模式的特征是产生黏附于单层培养细胞的细菌聚集体，呈“堆叠砖”表型。AA模式与一个60MDa质粒（pAA）的存在有关。在本研究中，我们通过细菌侵袭试验和透射电子显微镜，评估了5株EAEC菌株对人结肠腺癌细胞（Caco-2细胞）和人小肠上皮细胞（T84细胞）的黏附、侵袭及持续存活情况。从急性婴儿腹泻病例中分离出的EAEC可被体外培养的肠道上皮细胞内化，这表明这些菌株可能采用宿主细胞侵袭机制来定殖于肠道黏膜。结果显示，EAEC菌株可在细胞内存活长达72小时。我们的数据支持了EAEC能够在肠道细胞内侵袭、持续存在并长时间复制的证据。这种策略可能对EAEC的定殖和存活有利，有利于利用细胞内生态位，在其中这些菌株可免受宿主清除机制、免疫系统和抗生素治疗的影响。EAEC在细胞内的持续存在可能与这些微生物相关的持续性腹泻的发生有关。据我们所知，这是关于EAEC在培养的肠道上皮细胞内存活的首次报道。
