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

Enteroaggregative (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 (2010-2016) 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 and 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 (, and ) were statistically associated with typical EAEC ( < 0.05). The genes encoding the newly described aggregate-forming pili (AFP) searched (, and ), and/or its regulator (), were exclusively detected in atypical EAEC (57.7%, 15/26), and showed a significant association with this subgroup of EAEC ( < 0.001). In conclusion, we presented an extensive characterization of the EAEC circulating in the Brazilian settings and identified the genes as putative markers for increasing the efficiency of atypical EAEC diagnosis.