Lactobacillus-dominated Microbiota Research Articles

The role of lactic acid production by probiotic Lactobacillus species in vaginal health

Vaginal eubiosis is characterised by beneficial lactobacillus-dominated microbiota. In contrast, vaginal dysbiosis (e.g. bacterial vaginosis, BV), characterised by an overgrowth of multiple anaerobes, is associated with an increased risk of adverse urogenital and reproductive health outcomes. A major distinguishing feature between the vaginal environment in states of eubiosis and dysbiosis is a high concentration of lactic acid, produced by lactobacilli, that acidifies the vagina in eubiosis versus a sharp drop in lactic acid and an increase in pH in dysbiosis. Here we review the antimicrobial, antiviral and immunomodulatory properties of lactic acid and the use of lactic acid and lactobacilli probiotics in preventing or treating BV.

Evidence that the endometrial microbiota has an effect on implantation success or failure

Bacterial cells in the human body account for 1-3% of total body weight and are at least equal in number to human cells. Recent research has focused on understanding how the different bacterial communities in the body (eg, gut, respiratory, skin, and vaginal microbiomes) predispose to health and disease. The microbiota of the reproductive tract has been inferred from the vaginal bacterial communities, and the uterus has been classically considered a sterile cavity. However, while the vaginal microbiota has been investigated in depth, there is a paucity of consistent data regarding the existence of an endometrial microbiota and its possible impact in reproductive function. This study sought to test the existence of an endometrial microbiota that differs from that in the vagina, assess its hormonal regulation, and analyze the impact of the endometrial microbial community on reproductive outcome in infertile patients undergoing invitro fertilization. To identify the existence of an endometrial microbiota, paired samples of endometrial fluid and vaginal aspirates were obtained simultaneously from 13 fertile women in prereceptive and receptive phases within the same menstrual cycle (total samples analyzed n= 52). To investigate the hormonal regulation of the endometrial microbiota during the acquisition of endometrial receptivity, endometrial fluid was collected at prereceptive and receptive phases within the same cycle from 22 fertile women (n= 44). Finally, the reproductive impact of an altered endometrial microbiota in endometrial fluid was assessed by implantation, ongoing pregnancy, and live birth rates in 35 infertile patients undergoing invitro fertilization (total samples n= 41) with a receptive endometrium diagnosed using the endometrial receptivity array. Genomic DNA was obtained either from endometrial fluid or vaginal aspirate and sequenced by 454 pyrosequencing of the V3-V5 region of the 16S ribosomal RNA (rRNA) gene; the resulting sequences were taxonomically assigned using QIIME. Data analysis was performed using R packages. The χ2 test, Student t test, and analysis of variance were used for statistical analyses. When bacterial communities from paired endometrial fluid and vaginal aspirate samples within the same subjects were interrogated, different bacterial communities were detected between the uterine cavity and the vagina of some subjects. Based on its composition, the microbiota in the endometrial fluid, comprising up to 191 operational taxonomic units, was defined as a Lactobacillus-dominated microbiota (>90% Lactobacillus spp.) or a non-Lactobacillus-dominated microbiota (<90% Lactobacillus spp. with >10% of other bacteria). Although the endometrial microbiota was not hormonally regulated during the acquisition of endometrial receptivity, the presence of a non-Lactobacillus-dominated microbiota in a receptive endometrium was associated with significant decreases in implantation [60.7% vs 23.1% (P= .02)], pregnancy [70.6% vs 33.3% (P= .03)], ongoing pregnancy [58.8% vs 13.3% (P= .02)], and live birth [58.8% vs 6.7% (P= .002)] rates. Our results demonstrate the existence of an endometrial microbiota that is highly stable during the acquisition of endometrial receptivity. However, pathological modification of its profile is associated with poor reproductive outcomes for invitro fertilization patients. This finding adds a novel microbiological dimension to the reproductive process.

Domestication and cereal feeding developed domestic pig-type intestinal microbiota in animals of suidae.

Intestinal microbiota are characterized by host-specific microorganisms, which have been selected through host-microbe interactions under phylogenetic evolution and transition of feeding behavior by the host. Although many studies have focused on disease-related intestinal microbiota, the origin and evolution of host-specific intestinal microbiota have not been well elucidated. Pig is the ideal mammal model to reveal the origin and evolution of host-specific intestinal microbiota because their direct wild ancestor and close phylogenetic neighbors are available for comparison. The pig has been recognized as a Lactobacillus-type animal. We analyzed the intestinal microbiota of various animals in Suidae: domestic pigs, wild boars and Red river hogs to survey the origin and evolution of Lactobacillus-dominated intestinal microbiota by metagenomic approach and following quantitative PCR confirmation. The metagenomic datasets were separated in two clusters; the wild animal cluster being characterized by a high abundance of Bifidobacterium, whereas the domesticated (or captured) animal cluster by Lactobacillus. In addition, Enterobacteriaceae were harbored as the major family only in domestic Sus scrofa. We conclude that domestication may have induced a larger Enterobacteriaceae population in pigs, and the introduction of modern feeding system further caused the development of Lactobacillus-dominated intestinal microbiota, with genetic and geographical factors possibly having a minor impact.

Lactobacillus species as biomarkers and agents that can promote various aspects of vaginal health.

The human body is colonized by a vast number of microorganisms collectively referred to as the human microbiota. One of the main microbiota body sites is the female genital tract, commonly dominated by Lactobacillus spp., in approximately 70% of women. Each individual species can constitute approximately 99% of the ribotypes observed in any individual woman. The most frequently isolated species are Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus jensenii and Lactobacillus iners. Residing at the port of entry of bacterial and viral pathogens, the vaginal Lactobacillus species can create a barrier against pathogen invasion since mainly products of their metabolism secreted in the cervicovaginal fluid can play an important role in the inhibition of bacterial and viral infections. Therefore, a Lactobacillus-dominated microbiota appears to be a good biomarker for a healthy vaginal ecosystem. This balance can be rapidly altered during processes such as menstruation, sexual activity, pregnancy and various infections. An abnormal vaginal microbiota is characterized by an increased diversity of microbial species, leading to a condition known as bacterial vaginosis. Information on the vaginal microbiota can be gathered from the analysis of cervicovaginal fluid, by using the Nugent scoring or the Amsel's criteria, or at the molecular level by investigating the number and type of Lactobacillus species. However, when translating this to the clinical setting, it should be noted that the absence of a Lactobacillus-dominated microbiota does not appear to directly imply a diseased condition or dysbiosis. Nevertheless, the widely documented beneficial role of vaginal Lactobacillus species demonstrates the potential of data on the composition and activity of lactobacilli as biomarkers for vaginal health. The substantiation and further validation of such biomarkers will allow the design of better targeted probiotic strategies.

Vaginal microbiota and sexually transmitted infections that may influence transmission of cell-associated HIV.

Vaginal microbiota and sexually transmitted infections (STIs) are likely to influence the transmission of cell-associated human immunodeficiency virus (HIV). Lactic acid produced by Lactobacillus-dominated microbiota (Nugent score 0-3) will likely inhibit transmission, especially female-to-male transmission. In contrast, polymicrobial microbiota (Nugent score 4-10), community state types IV-A and IV-B, and STIs will likely increase transmission of cell-associated HIV.

P1.030 A Molecular Study of Vaginal Bacterial Communities and Candida Albicans Detection

BackgroundVulvovaginal candidosis (VVC) is commonly diagnosed in STD clinic populations and has been found in longitudinal studies to be associated with increased risk for HIV infection. Many women with recurrent...

Composition of the vaginal microbiota in women of reproductive age--sensitive and specific molecular diagnosis of bacterial vaginosis is possible?

Background and ObjectiveBacterial vaginosis (BV) is the most common vaginal disorder, characterized by depletion of the normal lactobacillus-dominant microbiota and overgrowth of commensal anaerobic bacteria. This study aimed to investigate the composition of the vaginal microbiota in women of reproductive age (healthy women and women with BV), with the view of developing molecular criteria for BV diagnosis.Materials and MethodsVaginal samples from 163 women (79 control, 73 BV and 11 intermediate (Lactobacillary grade II flora) cases) were analyzed using 454 pyrosequencing of the hypervariable regions V3–V4 of the 16S rRNA gene and 16 quantitative bacterial species/genus-specific real-time PCR assays. Sensitivities and specificities of potential BV markers were computed using the Amsel criteria as reference standard for BV. The use of quantitative thresholds for prediction of BV, determined for both relative abundance measured with 454 pyrosequencing and bacterial load measured with qPCR, was evaluated.ResultsRelative to the healthy women, the BV patients had in their vaginal microbiota significantly higher prevalence, loads and relative abundances of the majority of BV associated bacteria. However, only Gardnerella vaginalis, Atopobium vaginae, Eggerthella, Prevotella, BVAB2 and Megasphaera type 1 detected at or above optimal thresholds were highly predictable for BV, with the best diagnostic accuracy shown for A. vaginae. The depletion of Lactobacillus species combined with the presence of either G. vaginalis or A. vaginae at diagnostic levels was a highly accurate BV predictor.ConclusionsQuantitative determination of the presence of G. vaginalis, A. vaginae, Eggerthella, Prevotella, BVAB2 and Megasphaera type 1 as well as the depletion of Lactobacillus was highly accurate for BV diagnosis. Measurements of abundance of normal and BV microbiota relative to total bacteria in vaginal fluid may provide more accurate BV diagnosis, and be used for test-of-cure, rather than qualitative detection or absolute counts of BV related microorganisms.

16S rRNA pyrosequencing-based investigation of the bacterial community in nukadoko, a pickling bed of fermented rice bran

Nukadoko is a naturally fermented rice bran mash traditionally used for pickling vegetables in Japan; its refreshment and fermentation cycles sometimes continue for many years. Here, we investigated the structure and dynamics of the bacterial community in nukadoko by conducting pyrosequencing and quantitative polymerase chain reaction (PCR) analyses of 16S ribosomal RNA genes (rDNA). Of the 16 different samples studied, 13 showed Lactobacillus-dominated microbiota, suggesting that aged nukadoko samples tend to realize a niche, favorable Lactobacillus species. The lactic acid bacterial community of each of the 16 samples was classified into 3 types according to the presence or absence of 2 predominant species, Lactobacillus namurensis and Lactobacillus acetotolerans. The dynamics of the bacterial community during fermentation and the subsequent ripening process were examined using a laboratory model of nukadoko inoculated with an aged nukadoko sample (inoculated model). Lb. namurensis grew rapidly in the first 2days, accompanied with a rapid decrease in pH and an increase in lactate levels, while Lb. acetotolerans grew with a longer doubling time and slow acidification during the 20days after inoculation. On the other hand, spontaneous fermentation of the nukadoko model prepared from fresh rice bran without the nukadoko inoculation (inoculant-free model), showed the growth of some non-Lactobacillus species such as staphylococci and bacilli within the first 10days; thereafter, Lb. namurensis was dominant, while Lb. acetotolerans was not detected during the 20-day experimental period. These results suggest that the naturally established Lactobacillus community in aged nukadoko is effectively involved in the biocontrol of the microbial community of nukadoko during the refreshment and fermentation cycles.