Analysis of the Virulence Profile and Phenotypic Features of Typical and Atypical Enteroaggregative Escherichia coli (EAEC) Isolated From Diarrheal Patients in Brazil

Abstract

Enteroaggregative Escherichia coli (EAEC) is an important agent of acute and persistent diarrhea in children and adults worldwide. Here we report a characterization of 220 EAEC isolates, 88.2% (194/220) of which were typical and 11.8% (26/220) were atypical, obtained from diarrheal patients during seven years (2010)(2011)(2012)(2013)(2014)(2015)(2016) of epidemiological surveillance in Brazil. The majority of the isolates were assigned to phylogroups A (44.1%, 97/220) or B1 (21.4%, 47/220). The aggregative adherence (AA) pattern was detected in 92.7% (204/220) of the isolates, with six of them exhibiting AA concomitantly with a chain-like adherence pattern; and agg5A and agg4A were the most common adhesin-encoding genes, which were equally detected in 14.5% (32/220) of the isolates. Each of 12 virulence factor-encoding genes (agg4A, agg5A, pic, aap, aaiA, aaiC, aaiG, orf3, aar, air, capU, and shf) were statistically associated with typical EAEC (P < 0.05). The genes encoding the newly described aggregate-forming pili (AFP) searched (afpB, afpD, afpP, and afpA2), and/or its regulator (afpR), were exclusively detected in atypical EAEC (57.7%, 15/26), and showed a significant association with this subgroup of EAEC (P < 0.001). In conclusion, we presented an extensive characterization of the EAEC circulating in the Brazilian settings and identified the afp genes as putative markers for increasing the efficiency of atypical EAEC diagnosis.

Surface Protein Dispersin of Enteroaggregative Escherichia coli Binds Plasminogen That Is Converted Into Active Plasmin

“…As AafA and dispersin are exposed on the bacterial surface, our data suggest that laminin binding could be a combined feature of both proteins, at least in strains expressing AAF/II and dispersin. However, AAF/II is found in low frequencies in EAEC collections, while dispersin is highly frequent (Czeczulin et al, 1999;Elias et al, 2002;Jenkins et al, 2007;Boisen et al, 2012;Havt et al, 2017;Hebbelstrup Jensen et al, 2017;Dias et al, 2020). Therefore, our data further demonstrate that dispersin could also contribute to EAEC binding to laminin, which is the major component of the basement membrane (BM) that separates epithelial cells from the underlying stromal cells (Durbeej, 2010).…”

“…Considering that dispersin could be involved in the capacity of E. coli strains to disseminate in tissues and bloodstream, we searched for the presence of aap in a collection of E. coli strains isolated from patients with bacteremia, detecting 8 (2.9%) aap-positive strains. Although found in low frequency in our strains isolated from the bloodstream, dispersin-positive strains isolated from feces are very frequent (Boisen et al, 2012;Durand et al, 2016;Havt et al, 2017;Hebbelstrup Jensen et al, 2017;Dias et al, 2020). Therefore, the attributes of binding to laminin and degrading ECM may represent a more significant role for dispersin as virulence factor in localized rather than systemic infections.…”

“…The dispersin encoding gene is highly prevalent in EAEC collections of different studies, yet not present in all strains (Czeczulin et al, 1999;Elias et al, 2002;Jenkins et al, 2007;Boisen et al, 2012;Durand et al, 2016;Havt et al, 2017;Hebbelstrup Jensen et al, 2017;Dias et al, 2020;Guerrieri et al, 2020). The presence of aap was also detected in EAEC strains capable to cause urinary tract infection (Olesen et al, 2012;Boll et al, 2013;Herzog et al, 2014) and in Shiga toxin-producing EAEC of serotypes O104:H4 and 0111:H21 (Scheutz et al, 2011;Dallman et al, 2012).…”

Virulence factors of Enteric Pathogenic Escherichia coli: A Review

“…Therefore, EAEC strains are divided into typical, carrying AggR and AggR-regulated virulence factors and atypical EAEC, lacking the AggR regulon. The first stage of EAEC pathogenesis is attachment and adherence to the intestinal mucosal cells [97]. Aggregative adherence of EAEC is associated with aggregative adhesion fimbria (AAF), which is encoded by AAF genes [97].…”

Prevalence of Enteropathogens and Virulence Traits in Brazilian Children With and Without Diarrhea

“…It is important to note that DEC pathotypes have been largely disregarded because of the lack of laboratory capabilities (Piazza et al, 2010;Miliwebsky et al, 2016). Moreover, in several case-control studies, it shows almost equal distribution, especially in EPEC and EAEC pathotypes (Bueris et al, 2007;Hernandes et al, 2009;Gomes et al, 2016;Imdad et al, 2018;Dias et al, 2020).…”