Luiz Bruna M, Cergole-Novella Maria C, Dantas Stéfani T A, de Lira Daiany R P, de Souza Guilherme F R, Fernandes Iranildo do A, Orsi Henrique, Solveira Guilherme, Rall Vera L M, Dos Santos Luís F, Hernandes Rodrigo T
Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, SP, Brasil.
Laboratório Regional de Santo André, Instituto Adolfo Lutz, Santo André, SP, Brasil.
Braz J Microbiol. 2024 Dec;55(4):3551-3561. doi: 10.1007/s42770-024-01471-2. Epub 2024 Jul 31.
Enteroaggregative E. coli (EAEC) is one of the most frequent pathogens isolated from diarrheal patients as well as from healthy individuals in Brazil and has recently also been implicated as an extraintestinal pathogenic E. coli (ExPEC) associated with bloodstream and urinary tract infections. In this study, 37 EAEC isolates, obtained from fecal samples of non-diarrheic children, were molecularly and phenotypically characterized to access the pathogenic features of these isolates. The EAEC isolates were assigned into the phylogroups A (54.1%), D (29.7%), B1 (13.5%) and B2 (2.7%); and harbored genes responsible for encoding the major pilin subunit of the aggregative adherence fimbriae (AAFs) or aggregate-forming pili (AFP) adhesins as follows: aggA (24.3%), agg3A (5.4%), agg4A (27.0%), agg5A (32.4%) and afpA (10.8%). The most frequent O:H serotypes were O15:H2 (8.1%), O38:H25 (5.4%) and O86:H2 (5.4%). Twenty-one isolates (56.8%) produce the aggregative adherence (AA) pattern on HeLa cells, and biofilm formation was more efficient among EAEC isolates harboring the aggA and agg5A genes. PFGE analysis showed that 31 (83.8%) of the isolates were classified into 10 distinct clusters, which reinforces the high diversity found among the isolates studied. Of note, 40.5% (15/37) of the EAEC isolates have a genetic profile compatible with E. coli isolates with intrinsic potential to cause extraintestinal infections in healthy individuals, and therefore, classified as EAEC/ExPEC hybrids. In conclusion, we showed the presence of EAEC/ExPEC hybrids in the intestinal microbiota of non-diarrheic children, possibly representing the source of some endogenous extraintestinal infections.
肠聚集性大肠杆菌（EAEC）是巴西腹泻患者以及健康个体中最常分离出的病原体之一，最近也被认为是一种与血流和尿路感染相关的肠外致病性大肠杆菌（ExPEC）。在本研究中，从非腹泻儿童粪便样本中获得37株EAEC分离株，对其进行分子和表型特征分析，以了解这些分离株的致病特征。EAEC分离株被分为A（54.1%）、D（29.7%）、B1（13.5%）和B2（2.7%）系统发育群；并携带负责编码聚集性黏附菌毛（AAFs）或聚集形成菌毛（AFP）黏附素主要菌毛亚基的基因，如下所示：aggA（24.3%）、agg3A（5.4%）、agg4A（27.0%）、agg5A（32.4%）和afpA（10.8%）。最常见的O:H血清型为O15:H2（8.1%）、O38:H25（5.4%）和O86:H2（5.4%）。21株分离株（56.8%）在HeLa细胞上产生聚集性黏附（AA）模式，并且在携带aggA和agg5A基因的EAEC分离株中生物膜形成更有效。脉冲场凝胶电泳（PFGE）分析表明，31株（83.8%）分离株被分为10个不同的簇，这加强了在所研究分离株中发现的高度多样性。值得注意的是，40.5%（15/37）的EAEC分离株具有与在健康个体中具有引起肠外感染内在潜力的大肠杆菌分离株相容的基因谱，因此被归类为EAEC/ExPEC杂交株。总之，我们证明了非腹泻儿童肠道微生物群中存在EAEC/ExPEC杂交株，可能代表了一些内源性肠外感染的来源。
