Infecção entérica por Escherichia coli enteroagregativa em crianças no semiárido brasileiro: caracterização do diagnóstico, perfil dos genes de virulência e coinfecção

Abstract

Enteroaggregative Escherichia coli (EAEC) is one of the most prevalent enteric E. coli pathotype associated with diarrhea and asymptomatic infections in children less than five years of age living in developing countries. In the present study, we investigated the socioeconomic determinants related to the development of diarrhea or asymptomatic infection in the childhood population colonized by the EAEC, as well as the influence of virulence-related genes (GRVs) and coinfections during clinical manifestations. In order to better understand the versatility of this infection and to identified DNA markers for potential intervention or used to measure the infection severity. A cross-section study of diarrhea etiology in children aging 2-36 months old from Brazilian semiarid was conducted during 2009 to 2011. Data on health and socio-economic status and health-related behaviors and habits, collected via questionnaires, anthropometric measurements and stool sample have collected from all participants. The extracted DNA and RNA were used for the diagnosis of the enteropathogenic panels (bacteria, viruses and protozoa) by the Luminex platform. EAEC was detected in 54.6% (650/1191) of the children. Only 232 samples identified with the two genetic targets of EAEC diagnoses were selected to the evaluation of 27 GRVs investigated by polymerase chain reactions. Our results showed that children aged 0-6 months, mothers aged 14-25 years and non-exclusive breastfeeding were associated with the development of diarrhea; while the asymptomatic infection was correlated with the third year of infant life, non-exclusive breastfeeding, untreated water sources, and reduction of weight-for-height z scores when compared to the diarrheic group. In the evaluation of GRVs, the plasmid-borne gene encoding a hexosyltransferase homolog (capU) was the most frequently detected (89.7%). The gene encoding enterotoxin EspC (espC) was correlated with diarrhea infantile and its severe condition. While the presence of the hypothetical plasmid-encoded hemolysin (aar) was associated with a reduction of the number of diarrhea days and episodes by day. In addition, only AAF/IV fimbrial subunit (agg4A) was associated significantly with the control group. Regarding coinfections analysis, the most detected co-pathogen was atypical enteropathogenic Escherichia coli (aEPEC) (43,5%), followed by Giardia lamblia (23.5%), enterotoxigenic Escherichia coli (20.7%). The combination of EAEC and Giardia lamblia in the absence of aEPEC was associated specifically with the control group. Our data indicate that different VRGs and coinfection profile could influence diarrhea outcomes. The espC gene is proposed as an indicator of disease severity increase, whereas the aar would indicate the opposite effect.