AUTHOR=Scalise María Luján , Garimano Nicolás , Sanz Marcelo , Padola Nora Lia , Leonino Patricia , Pereyra Adriana , Casale Roberto , Amaral María Marta , Sacerdoti Flavia , Ibarra Cristina 

TITLE=Detection of Shiga Toxin-Producing Escherichia coli (STEC) in the Endocervix of Asymptomatic Pregnant Women. Can STEC Be a Risk Factor for Adverse Pregnancy Outcomes?

JOURNAL=Frontiers in Endocrinology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2022.945736

DOI=10.3389/fendo.2022.945736

ISSN=1664-2392

ABSTRACT=<p>The presence of <italic>Escherichia coli</italic> in the vaginal microbiome has been associated with pregnancy complications. In previous works, we demonstrated that Shiga toxin-producing <italic>Escherichia coli</italic> (STEC) can produce abortion and premature delivery in rats and that Shiga toxin type 2 (Stx2) can impair human trophoblast cell lines. The hypothesis of this work was that STEC may colonize the lower female reproductive tract and be responsible for adverse pregnancy outcomes. Thus, the aim of this work was to evaluate the presence and prevalence of virulence factor genes from STEC in the endocervix of asymptomatic pregnant women. For that purpose, endocervical swabs were collected from pregnant women during their prenatal examination. Swab samples were enriched in a differential medium to select <italic>Enterobacteria</italic>. Then, positive samples were analyzed by PCR to detect genes characteristic of <italic>Escherichia</italic> sp. (such as <italic>uidA</italic> and <italic>yaiO</italic>), genes specific for portions of the <italic>rfb</italic> (O-antigen-encoding) regions of STEC O157 (<italic>rfb</italic><sub>O157</sub>), and STEC virulence factor genes (such as <italic>stx1</italic>, <italic>stx2</italic>, <italic>eae</italic>, <italic>lpfA</italic><sub>O113</sub>, <italic>hcpA</italic>, <italic>iha</italic>, <italic>sab, subAB</italic>). The cytotoxic effects of stx2-positive supernatants from <italic>E. coli</italic> recovered from the endocervix were evaluated in Vero cells. Our results showed that 11.7% of the endocervical samples were positive for <italic>E. coli</italic>. Additionally, we found samples positive for <italic>stx2</italic> and other virulence factors for STEC. The bacterial supernatant from an isolate identified as <italic>E. coli</italic> O113:NT, carrying the <italic>stx2</italic> gene, exhibited cytotoxic activity in Vero, Swan 71 and Hela cells. Our results open a new perspective regarding the presence of STEC during pregnancy.</p>