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The Uterine Microbiota
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Jonah Bardos, Carlos Simón, Inmaculada Moreno
Recently, a study by Moreno et al. looked at the endometrial microbiota in early pregnancy. The study looked at one patient who had had a prior miscarriage of a euploid embryo at eight weeks. In a subsequent pregnancy, the researchers compared the microbiome composition between the ongoing pregnancy and the miscarriage. They found that the microbial profile prior to the miscarriage had greater bacterial diversity and lower Lactobacillus abundance than the endometrial fluid from the healthy pregnancy. They then did functional metagenomics which detected different Lactobacillus species between the two samples. In this case, an unstable functional pattern, characterized by transposases and insertion elements, were seen prior to the miscarriage, with only a small proportion of the functional genes observed in the sample belonging to L. crispatus. Lactobacillus iners was the most prevalent microbe found in the endometrium during early pregnancy after a dilation and curettage, suggesting, in this small study, that the presence of this species could protect against growth of other dysbiotic pathogens.14
Diagnosis of Vulvovaginal Disease
Published in William J. Ledger, Steven S. Witkin, Vulvovaginal Infections, 2017
William J. Ledger, Steven S. Witkin
There are major problems in interpreting these Gram stain testing results. This microscopic scoring system justifiably equates the presence of Lactobacilli with vaginal health. The problem is that the absence of Lactobacilli does not indicate disease if other bacteria are present that produce lactic acid. One example is Atopobium vaginae, a very short rod that is indistinguishable from Gardnerella on Gram stain, but it helps maintain vaginal health, because it produces lactic acid.5 In addition, Lactobacillus iners, the most frequently recovered Lactobacillus from the vaginae of healthy women using nonculture technology and associated with health, is a short rod and can be construed on Gram stain viewing to be the short rod associated with BV.6 These are the reasons that more women will be diagnosed with BV when Nugent scoring is used rather than the Amsel criteria7 and accounts for a new patient category, the women with asymptomatic BV.
Host–Biofilm Interactions at Mucosal Surfaces and Implications in Human Health
Published in Chaminda Jayampath Seneviratne, Microbial Biofilms, 2017
Nityasri Venkiteswaran, Kassapa Ellepola, Chaminda Jayampath Seneviratne, Yuan Kun Lee, Kia Joo Puan, Siew Cheng Wong
Lactobacillus is the most common genus colonising the vagina of healthy women during their child-bearing age. The different species of lactobacilli seen are Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus jensenii and Lactobacillus iners. These originate primarily in the intestine and exhibit vaginotropism or pronounced affinity to attach to the vaginal mucosa. Other genera identified through DNA sequencing include Atopobium, Prevotella, and Propionibacterium [71,72]. Non-beneficial bacteria from genera such as Streptococcus, Staphylococcus, Gardnerella and Enterococcus may also be present in low concentrations in a healthy vagina but in insufficient numbers to cause disease [73,74]. The potentially pathogenic organisms that inhabit the vaginal mucosa are Neisseria, certain species of streptococci such as S. pyogenes, S. pneumoniae, Haemophilus and Listeria [75]. Figure 9.3 shows common bacteria associated with the vaginal mucosa.
Low genitourinary tract risks in women living with the human immunodeficiency virus
Published in Climacteric, 2023
F. R. Pérez-López, A. M. Fernández-Alonso, E. Mezones-Holguín, P. Vieira-Baptista
The vaginal microbiota, particularly if dominated by Lactobacillus spp., may be beneficial to the female genital tract by producing hydrogen peroxide and lactic acid that have antimicrobial properties [17]. The most protective community state types are likely I, II and V, dominated by Lactobacillus crispatus, Lactobacillus gasseri and Lactobacillus jensenii, respectively. On the contrary, the higher HIV risk is associated with community state type IV (the diversity group, encompassing bacterial vaginosis and aerobic vaginitis/desquamative inflammatory vaginitis). The role of community state type III (Lactobacillus iners) is more controversial but seems to be a less favorable profile [18–20]. The protective effect against HIV is partially mediated by extracellular vesicles released by the symbiotic bacteria [21]. However, their abundance declines during menopause, with a more or less pronounced decrease in lactobacilli and an increase in diversity [22,23]. The lactobacillus-depleted genital microbiome may increase the risk of HIV infection in women [24]. Menopause hormone treatment can promote the presence of lactobacilli [22]. Compliance with ART reduces the genital shedding risk of HIV [25].
Lactic acid bacteria: prominent player in the fight against human pathogens
Published in Expert Review of Anti-infective Therapy, 2022
Ujjayni B. Saha, Sunil D. Saroj
Lactobacilli, which dominate the healthy vaginal microbiota, are considered guardians of this environment, keeping it healthy and preventing pathogen proliferation [54]. Lactobacilli can help prevent UTIs by preventing pathogenic or potentially pathogenic microorganisms from adhering to the vaginal epithelial surface, forming biofilm, co-aggregating with pathogens, producing antimicrobial substances like organic acids, hydrogen peroxide (H2O2), and bacteriocins, competing for nutrients, and stimulating the local immune response [55]. Recent research on the vaginal microbiome in healthy reproductive-aged women using 16S rRNA gene sequencing revealed at least five community state types (CSTs), four of which were dominated by Lactobacillus crispatus (CST-I), Lactobacillus gasseri (CST-II), Lactobacillus iners (CST-III), Lactobacillus jensenii (CST-V), and one by the microbial community (CST-IV) composed of polymicrobial species, demonstrating that the Lactobacillus spp. population has a significant protective role against possible UTI pathogens [56,57]. Lactobacillus is one of the most common species in the endocervical microbial populations, with 107 to 108 CFU/mL of vaginal fluid in healthy postmenopausal and premenopausal women [58].
The effect of different contraceptive methods on the vaginal microbiome
Published in Expert Review of Clinical Pharmacology, 2021
Carlo Bastianelli, Manuela Farris, Paola Bianchi, Giuseppe Benagiano
Turning the attention to vaginal microbiome (VM), in 2011, Ravel et al [14] evaluated vaginal bacterial communities of four asymptomatic North American ethnic groups (white, black, Hispanic, and Asian) and found that they were clustered into five groups. Four were dominated by Lactobacillus iners, L. crispatus, L. gasseri, or L. jensenii, whereas the fifth had lower proportions of lactic acid-producing bacteria and higher proportions of strictly anaerobic organisms. Ravel et al concluded that the production of lactic acid seems conserved in all bacterial communities of healthy women, irrespective of ethnic background, although the proportions varied in a significant way (P < 0.0001) among ethnic groups [14]. This means that there is a need to define in a more refined way the inherent differences in bacterial communities normally found in healthy women, as well as a need to appreciate individual differences between healthy individuals. Recently, additional information has become available, confirming that the prevalence of certain bacterial community structures varies between populations, an important consideration in evaluating microbiome associations with disease [15].