542: Influence of vaginal microbiota on the pathophysiology of intra-amniotic infection and sterile-inflammation in preterm labor

Abstract

Intra-amniotic infection and intra-amniotic inflammation (IAI) are leading responsible of spontaneous preterm delivery at early gestational ages being the ascending pathway the most common dissemination way. The influence of intra-amniotic infection and IAI on the vaginal diversity and Lactobacillus spp. abundance is poorly unknown. Our aim was to evaluate, in women with preterm labor (PTL), whether vaginal microbiota differs among different infectious/inflammatory phenotypes. Women admitted with PTL <34.0 weeks with an amniocentesis to rule out infection or IAI were included. Vaginal fluid was collected within 24 h after amniocentesis. Intra-amniotic infection was diagnosed based on amniotic fluid (AF) cultures or a positive AF PCR of 16S rDNA. IAI was defined based on AF IL-6 levels (≥13.4 ng/mL). Sequencing of 16S rRNA gene was performed using MiSeq platform. Data processing was performed using QIIME. Statistical analyses were performed using R and SPSS program (v24.0). Sixty-nine women were included being 26% women with intra-amniotic infection and 10% women with sterile IAI (negative culture but high levels of IL6). Only one woman with intra-amniotic infection had low levels of IL-6. Most common microorganisms isolated in the amniotic fluid were Ureaplasma spp. 37%. No differences were observed regarding progesterone administration or cerclage among groups. We found differences on ethnicity so sequencing data was adjusted for this variable. Higher diversity (Shannon index), (p = 0.02) and lower Lactobacillus spp. abundance (p = 0.01) were observed in women with intra-amniotic infection compared with the non-infection/non-IAI group. Using LEfSE test, we observed at genera level that Ureaplasma was enriched in women with infection, Haemophilus in women with sterile IAI and Lactobacillus in women with non-infection/non-IAI group. Vaginal diversity (OR = 2.8, CI 95% (1.1 – 7.1)) and Lactobacillus spp. abundance (OR = 0.98, CI 95% (0.97 – 0.99)) were found to be independent factors of preterm delivery < 34 weeks being Ureaplasma spp. an independent risk factor for preterm delivery < 32 weeks (OR = 1.7, CI 95% (1.0 – 2.7)). A higher vaginal diversity and lower Lactobacillus spp. abundance was observed in women with intra-amniotic infection being Lactobacillus spp. the microorganism dominated in women without infection or IAI.View Large Image Figure ViewerDownload Hi-res image Download (PPT)