Congresso Brasileiro de Microbiologia 2023

Congresso Brasileiro de Microbiologia 2023

Resumo: 829-1

829-1

Presence of extraintestinal Escherichia coli virulence markers in enteroaggregative E.coli isolates obtained from asymptomatic children

Autores:

Bruna Mendes Luiz (UNESP - Universidade Estadual Paulista) ; Maria Cecilia Cergole-novella (CLR IAL VIII - CLR VIII Santo André - Instituto Adolfo Lutz) ; Luis Fernando dos Santos (IAL - Centro de Bacteriologia - Instituto Adolfo Lutz ) ; Stéfani Thais Alves Dantas (FMVZ - USP - Faculdade de Medicina Veterinária e Zootecnia - USP ) ; Vera Lucia Mores Rall (UNESP - Universidade Estadual Paulista) ; Daiany Ribeiro Paz de Lira (UNESP - Universidade Estadual Paulista) ; Guilherme Frizzarin Ramalhães de Souza (UNESP - Universidade Estadual Paulista) ; Iranildo do Amarante Fernandes (UNESP - Universidade Estadual Paulista) ; Guilherme Solveira (UNESP - Universidade Estadual Paulista) ; Rodrigo Hernandes (UNESP - Universidade Estadual Paulista)

Resumo:

Escherichia coli is one of the main etiological agents associated with diarrheal disease worldwide. Among the E. coli pathotypes, enteroaggregative E. coli (EAEC) is one of the most frequent pathotype isolated from cases of diarrhea in Brazil. Recent studies have been reporting the occurrence of EAEC isolates carrying virulence genes (VGs) associated with extraintestinal pathogenic Escherichia coli (ExPEC). The aim of this study was to search for typical ExPEC virulence factors in EAEC isolates obtained from asymptomatic children, in order to investigate if the gastrointestinal tract could be a source of EAEC with potential to cause extraintestinal infections. A collection of 37 EAEC isolates, obtained from fecal samples of asymptomatic children, was examined regarding the presence of several VGs. Additionally, the isolates were also assigned into the distinct E. coli phylogroups, serotyped in terms of somatic (O) and flagellar (H) antigens, and phenotypically evaluated for their ability to form biofilm and adhere to HeLa cells. Furthermore, the Pulsed-field gel electrophoresis (PFGE) analysis was used to assess the similarities between the EAEC isolates studied. The EAEC isolates were assigned into the phylogroups A (54.1%), D (29.7%), B1 (13.5%) and B2 (2.7%), and most of them carry genes responsible for encoding the aggregative adherence fimbriae (AAF) of type V (32.4%), followed by types IV (27%), I (24.3%) and III (5.4%). In addition, 4 isolates (10.8 %) harbor genes of the afp (aggregate-forming pili) operon. The most frequent O:H serotypes were O15:H2 (8.1%), O38:H25 (5.4%) and O86:H2 (5.4%). The EAEC isolates studied presented an expressive number of genes responsible for encoding virulence factors from ExPEC, with fimH (97.3%), picU (83.8%), fyuA (78.4%), iutA (59.5%) and traT (56.8%) the most frequently detected. Twenty-one isolates (56.8%) produce the aggregative adherence (AA) pattern on HeLa cells, and biofilm formation was more efficient in isolates that harbored the AAF/I and AAF/V adhesins. PFGE analysis showed that 31 (83.8%) of the isolates were classified into 10 distinct clusters, which reinforces the high diversity found among the EAEC isolates studied. Of note, 40.5% (15/37) of the EAEC isolates carry at least two of the five genes (papA/papC, afa/dra, sfa/foc, kpsMTII, and iutA) that distinguishes E. coli isolates with intrinsic potential to cause extraintestinal infections in healthy individuals, and therefore, were classified as hybrid EAEC/ExPEC. In conclusion, we observed that many of the EAEC isolates obtained from healthy subjects may have a genetic background commonly found in ExPEC isolates, and most likely represent the source of some endogenous extraintestinal infections.

Palavras-chave:

EAEC, Escherichia coli, ExPEC, hybrid, virulence

Agência de fomento:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), (88887.884039/2023-00)