AUTHOR=Guerrieri Caroline Gastaldi , Pereira Monalessa Fábia , Galdino Anna Clara Milesi , Santos André Luis Souza dos , Elias Waldir Pereira , Schuenck Ricardo Pinto , Spano Liliana Cruz 

TITLE=Typical and Atypical Enteroaggregative Escherichia coli Are Both Virulent in the Galleria mellonella Model

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01791

DOI=10.3389/fmicb.2019.01791

ISSN=1664-302X

ABSTRACT=<p>Enteroaggregative <italic>Escherichia coli</italic> (EAEC) is an emerging pathotype responsible for acute and persistent diarrhea. It can be classified as typical and atypical strains, respectively, based on the presence or absence of the AggR regulon, suggesting a higher virulence for typical EAEC. This study aims to evaluate in the <italic>Galleria mellonella</italic> model if there are differences in the virulence profiles among clinical strains of typical and atypical EAEC, prototype strains EAEC C1096, 042 and its <italic>aggR</italic> mutant. The clinical EAEC strains (<italic>n</italic> = 20) were analyzed for the presence of 22 putative virulence factors of EAEC or extraintestinal <italic>E. coli</italic> by PCR, as well as phenotypic characteristics of virulence (enzymes, siderophore, and biofilm). The survival of the larvae was analyzed after inoculation of 10<sup>4</sup>–10<sup>7</sup> CFU/larva; the monitoring of bacterial growth <italic>in vivo</italic> and hemocyte quantification was determined after inoculation of the prototype strains (10<sup>5</sup> CFU/larva) at different periods after infection. The strains of typical and atypical EAEC presented the same virulence profile for the larva, regardless of the amount or type of genes and phenotypic aspects of virulence analyzed. In addition, the EAEC 042 <italic>aggR</italic> mutant strain showed a significant reduction in the mortality of the inoculated larvae compared to the wild-type strain. In conclusion, the results obtained herein demonstrate that the virulence of EAEC seems to be related to the AggR regulon, but not exclusively, and atypical EAEC strains may be as virulent as typical ones <italic>in vivo</italic> in the <italic>G. mellonella</italic> model.</p>