Barcoded sequencing reveals diverse intrauterine microbiomes in patients suffering with endometrial polyps.

Results of this study showed that the bacterial composition in vagina (V) greatly differed from intrauterine microbiome (I). Microbiomes were present in all intrauterine samples of healthy women (Group H (I)) and patients with endometrial polyps (EP) (including Group EP (I) and Group EP/chronic endometritis (CE) (I)). Indeed, the intrauterine bacteria population in Group EP/CE (I) were more diverse than those in Groups EP (I) and H (I). The result also confirmed the bacterial composition differences between vagina and uterus as well as the intrauterine microbiome alteration in the patients, compared to the healthy. Although bacteria of Proteobacteria, Firmicutes and Actinobacteria, dominated the intrauterine microbiome in all samples, however, proportions of Firmicutes from Group EP/CE (I) and Group EP (I) were much higher than that from Group H (I), in contrast, the proportions of Proteobacteria were far lower than the healthy. At the genus level, compared to Group H (I), it is found that proportions of Lactobacillus, Gardnerella, Bifidobacterium, Streptococcus, and Alteromonas were significantly higher, and that of Pseudomonas were significantly lower in Group EP/CE (I) or Group EP (I). In addition, lower proportions of Enterobacter and Sphingomonas and a higher proportion of Prevotella were also observed in Group EP/CE (I). In conclusion, uterine microbiomes between patients with EP and the healthy are significantly different and all the potentially important variation of uterine microbes may cause EP, but not definitively related to CE. Further experiments should be performed to test these relationships to endometritis occurrence.