Presence of Shiga toxin producing Escherichia coli in endocervix of asymptomatic pregnant women from Argentina.

SCALISE M.LUJÁN; GARIMANO NICOLÁS; PORPORATO MELINA, ; LEONINO PATRICIA; PEREYRA ADRIANA; CASALE ROBERTO; FERREIROS JOSÉ; AMARAL MMARTA; IBARRA CRISTINA; SACERDOTI FLAVIA

virtual meeting

Congreso; International Federation of Placenta Associations (IFPA); 2021

International Federation of Placenta Associations

Objective: The aim of this study was to detect virulence factor genes from Shiga toxin producing E. coli (STEC) in the endocervix from ASYMPTOMATIC PREGNANT WOMEN and to shed light on the possible role of STEC as a pathogen responsible for adverse pregnancy outcomes. Methods: Endocervical swabs were collected from 103 pregnant women (12 to 30 weeks of pregnancy) from Hospital Posadas, Buenos Aires, Argentina, during their antenatal examination. Swab samples were enriched in Tryptic Soy Broth (TSB) overnight at 37°C and then streaked into Sorbitol MacConkey agar. E. coli colonies were confirmed by identification of the uidA gene by PCR. Then, E. coli positive samples were analyzed for STEC virulence factors genes: stx1, stx2, eae, rfbO157, lpfAO113 and hcpA. E. coli samples that were positive for stx2 gene detection were grown in Luria-Bertani Broth (LB) by Shiga toxin type 2 (Stx2) cytotoxicity evaluation. For that, bacterial supernatants were filter-sterilized and cytotoxicity was evaluated on Vero, Swan 71 and HeLa cell lines. Results: Our results showed that 14.5% of the samples were positive for E. coli (uidA positive gene). Furthermore, 9/15 (60 %) of the E. coli-positive samples carried the stx2 gene and 6/15 (40 %) carried the lpfAO113 and hcpA genes. Bacterial supernatant from an E. coli-positive endocervical sample carrying stx2 gene exhibited high cytotoxic activity on Vero, Swan 71 and HeLa cells. Stx2 identity was confirmed by cytotoxicity neutralization with an anti-Stx2 monoclonal antibody. Conclusions: The main finding of this work was to identify STEC in the endocervical microbiota of asymptomatic pregnant women. Additionally, we demonstrated that STEC can secrete Stx2 with a high cytotoxic activity on human extravillous trophoblast (Swan 71) cells and endocervical (HeLa) cells. These results open a new perspective with respect to the possible role of STEC in the reproductive health of women.