Contribution of Lactobacillus iners to Vaginal Health and Diseases: A Systematic Review

Abstract

Lactobacillus iners, first described in 1999, is a prevalent bacterial species of the vaginal microbiome. As L. iners does not easily grow on de Man-Rogosa-Sharpe agar, but can grow anaerobically on blood agar, it has been initially overlooked by traditional culture methods. It was not until the wide application of molecular biology techniques that the function of L. iners in the vaginal microbiome was carefully explored. L. iners has the smallest genome among known Lactobacilli and it has many probiotic characteristics, but is partly different from other major vaginal Lactobacillus species, such as L. crispatus, in contributing to the maintenance of a healthy vaginal microbiome. It is not only commonly present in the healthy vagina but quite often recovered in high numbers in bacterial vaginosis (BV). Increasing evidence suggests that L. iners is a transitional species that colonizes after the vaginal environment is disturbed and offers overall less protection against vaginal dysbiosis and, subsequently, leads to BV, sexually transmitted infections, and adverse pregnancy outcomes. Accordingly, under certain conditions, L. iners is a genuine vaginal symbiont, but it also seems to be an opportunistic pathogen. Further studies are necessary to identify the exact role of this intriguing species in vaginal health and diseases.

Shikonin, Gallic Acid, and Hydroxysafflor Yellow A Decrease the Pathogenesis and Normalize the Microbiota of Cervical Erosion

“…After treatment with the gel, although the disease symptoms were ameliorated, the vaginal microbial structure was still suboptimal, and the reproductive tract pH value was higher than healthy women, which may be unsuitable for the survival and function of L. crispatus in the vaginal microenvironment. Therefore, the relative abundance of L. crispatus did not signi cantly increase, while L. iners exhibited strong environmental adaptability [44]. The increase in the abundance of L. iners contributed to the restoration of the normal reproductive tract microbial environment, which was consistent with other research results [43].…”

Changes of the vaginal microbiota in HPV infection and cervical intraepithelial neoplasia: a cross-sectional analysis

“…Secondly, our study only focused on the distribution of different microbiota, ignoring the identification of Lactobacillus species. Recent researches suggest that Lactobacillus iners is a transitional species that colonize after the vaginal environment is disturbed and leads to BV, sexually transmitted infections, and adverse pregnancy outcomes 33 . Further studies are necessary to identify the exact role of different Lactobacillus species in larger samples.…”

Clue Cells and Pseudo Clue Cells in Different Morphotypes of Bacterial Vaginosis

“…A situation could be basic and rooted in the natural history of polymicrobial communities of which some were specialized to grow attached to firm surfaces and form biofilms like stromatolites or vaginal biofilms ( Swidsinski et al., 2014 ) and others were swimming free in fluids forming activated sludge ( Mesquita et al., 2013 ). It is therefore and also imaginable that BeV could be further subdivided into etiologically relevant subgroups according to organisms leading the sludge-like microbial proliferation, of which cohesive L. iners could be of special interest not only for its high frequency in vaginal dysbiosis but also for the increasingly reported clinical significance ( Zheng et al., 2021 ). A possible name for such could be L. iners excess vaginosis.…”