Prevalence of Escherichia coli and analysis of virulence factors in endocervical cultures from pregnant women.

PEREYRA ADRIANA; SACERDOTI FLAVIA; SCALISE MARÍA LUJÁN; CASALE ROBERTO; IBARRA CRISTINA; LEONINO PATRICIA; FERREIROS JOSÉ A

Mar del Plata, Buenos Aires

Congreso; LXIV Reunión Anual de la Sociedad Argentina de Investigación Clínica (SAIC); 2019

Presence of E.coli in the endocervical microbiome has been associated to pregnancy complications. We have previously reported that Shiga toxin (Stx) producing E. coli (STEC) infections during pregnancy may cause maternal or fetal damage mediated by Stx2 in rats in early stage of gestation. Moreover, Stx2 inhibits migration, invasion and cell viability in extravillous trophoblast human cells of first trimester. Therefore, we propose to study the presence of STEC in female genital tract in the pregnant women since might be risk factor during gestation. Our objective was to identify different virulence factors of STEC cultures of endocervix of pregnant women. Endocervical swabs from 103 asymptomatic pregnant women with gestational age of 14 to 30 weeks from the National Hospital Posadas were enrolled. Samples were enriched in Tryptic Soy Broth and sub-cultivated on sorbitol-MacConkey (SMAC) agar in order to detect no sorbitol fermenting colonies, characteristic of STEC. Genomic DNA was purified from colonies and the presence of the uidA gene, exclusive for E. coli was analyzed by polymerase chain reaction (PCR). Positive colonies for uidA were checked for rfbO157, lpfAO113, hcp, eae, stx1, stx2 genes. STEC strains positive for stx2 genes were also cultured in the presence of mitomycin C (2µg/ml) to evaluate expression of Stx2 by viability assays on Vero cells. The PCR results showed that 16/103 samples were positive for SMAC agar and 15/103 were positive for the uidA gene. Furthermore, 6/15 E. coli expressed lpfAO113 and hcp, and 9/15. All of them were negative for rfbO157, eae. stx1 genes. One STEC strain positive for stx2 gene showed cytotoxic effects even in absence of mitomycin C. These results suggest that STEC strains could colonize the endocervix of pregnant women.