Quantitative determination by real-time PCR of four vaginal Lactobacillus species, Gardnerella vaginalis and Atopobium vaginae indicates an inverse relationship between L. gasseri and L. iners
Ellen De BackerRita VerhelstHans VerstraelenMohammed A. A. AlqumberJeremy P. BurtonJohn TaggMarleen TemmermanMario Vaneechoutte
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Most studies of the vaginal microflora have been based on culture or on qualitative molecular techniques. Here we applied existing real-time PCR formats for Lactobacillus crispatus, L. gasseri and Gardnerella vaginalis and developed new formats for Atopobium vaginae, L. iners and L. jensenii to obtain a quantitative non culture-based determination of these species in 71 vaginal samples from 32 pregnant and 28 non-pregnant women aged between 18 and 45 years.The 71 vaginal microflora samples of these women were categorized, using the Ison and Hay criteria, as refined by Verhelst et al. (2005), as follows: grade Ia: 8 samples, grade Iab: 10, grade Ib: 13, grade I-like: 10, grade II: 11, grade III: 12 and grade IV: 7.L. crispatus was found in all but 5 samples and was the most frequent Lactobacillus species detected. A significantly lower concentration of L. crispatus was found in grades II (p < 0.0001) and III (p = 0.002) compared to grade I. L. jensenii was found in all grades but showed higher concentration in grade Iab than in grade Ia (p = 0.024). A. vaginae and G. vaginalis were present in high concentrations in grade III, with log10 median concentrations (log10 MC), respectively of 9.0 and 9.2 cells/ml. Twenty (38.5%) of the 52 G. vaginalis positive samples were also positive for A. vaginae. In grade II we found almost no L. iners (log10 MC: 0/ml) but a high concentration of L. gasseri (log10 MC: 8.7/ml). By contrast, in grade III we found a high concentration of L. iners (log10 MC: 8.3/ml) and a low concentration of L. gasseri (log10 MC: 0/ml). These results show a negative association between L. gasseri and L. iners (r = -0.397, p = 0.001) and between L. gasseri and A. vaginae (r = -0.408, p < 0.0001).In our study we found a clear negative association between L. iners and L. gasseri and between A. vaginae and L. gasseri. Our results do not provide support for the generally held proposition that grade II is an intermediate stage between grades I and III, because L. gasseri, abundant in grade II is not predominant in grade III, whereas L. iners, abundant in grade III is present only in low numbers in grade II samples.Keywords:
Gardnerella vaginalis
Lactobacillus crispatus
The vaginal microbiota can impact the susceptibility of women to bacterial vaginosis (BV) and sexually transmitted infections (STIs). BV is characterized by depletion of Lactobacillus spp., an overgrowth of anaerobes (often dominated by Gardnerella vaginalis) and a pH > 4.5. BV is associated with an increased risk of acquiring STIs such as chlamydia and gonorrhea. While these associations have been identified, the molecular mechanism(s) driving the risk of infections are unknown. An ex vivo porcine vaginal mucosal model (PVM) was developed to explore the mechanistic role of Lactobacillus spp. in affecting colonization by G. vaginalis and Neisseria gonorrhoeae.The data presented here demonstrate that all organisms tested can colonize and grow on PVM to clinically relevant densities. Additionally, G. vaginalis and N. gonorrhoeae form biofilms on PVM. It was observed that lactic acid, acetic acid, and hydrochloric acid inhibit the growth of G. vaginalis on PVM in a pH-dependent manner. N. gonorrhoeae grows best in the presence of lactic acid at pH 5.5, but did not grow well at this pH in the presence of acetic acid. Finally, a clinical Lactobacillus crispatus isolate (24-9-7) produces lactic acid and inhibits growth of both G. vaginalis and N. gonorrhoeae on PVM.These data reveal differences in the effects of pH, various acids and L. crispatus on the growth of G. vaginalis and N. gonorrhoeae on a live vaginal mucosal surface. The PVM is a useful model for studying the interactions of commensal vaginal microbes with pathogens and the mechanisms of biofilm formation on the vaginal mucosa.
Gardnerella vaginalis
Lactobacillus crispatus
Neisseria gonorrhoeae
Parasitology
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Our objective was to determine the morphotype of the adherent bacteria in liquid-based cytology (LBC) in smears with healthy and disturbed vaginal flora. And to use PCR technology on the same fixed cell sample to establish DNA patterns of the 16S RNA genes of the bacteria in the sample. Thirty samples were randomly selected from a large group of cervical cell samples suspended in a commercial coagulant fixative "(BoonFix)." PCR was used to amplify DNA of five bacterial species: Lactobacillus acidophilus, Lactobacillus crispatus, Lactobacillus jensenii, Gardnerella vaginalis, and Mycoplasma hominis. The LBC slides were then analyzed by light microscopy to estimate bacterial adhesion. DNA of lactobacilli was detected in all cell samples. Seventeen smears showed colonization with Gardnerella vaginalis (range 2.6 x 10(2)-3.0 x 10(5) bacteria/mul BoonFix sample). Two cases were identified as dysbacteriotic with high DNA values for Gardnerella vaginalis and low values for Lactobacillus crispatus. The sample with the highest concentration for Gardnerella vaginalis showed an unequivocal Gardnerella infection. This study indicates that the adherence pattern of a disturbed flora in liquid-based cervical samples can be identified unequivocally, and that these samples are suitable for quantitative PCR analysis. This cultivation independent method reveals a strong inverse relationship between Gardnerella vaginalis and Lactobacillus crispatus in dysbacteriosis and unequivocal Gardnerella infection.
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This pilot study aimed to evaluate whether different microbial compositions cause symptoms in patients with Lactobacillus overgrowth and to investigate the variation in Lactobacillus microbiome in cytolytic vaginosis (CV).Lactobacillus species were identified from the vaginal fluid of 70 healthy women and 79 patients with CV using molecular analysis of the 16S rRNA gene. χ and Fisher exact tests were used to compare the isolated rates of Lactobacillus species between the 2 groups. The capabilities of dominant Lactobacillus strain to produce acid in the 2 groups were analyzed by repeated measures analysis of variance.The isolation of 2 or more Lactobacillus species per vaginal sampling was significantly less common in the CV group (1.3%) compared with the healthy control (HC) group 12.2% (p = .013). Significant differences in Lactobacillus species were observed between the 2 groups (p < .001). Lactobacillus crispatus was more often found in the CV group (88.7%) than in the HC group (56.4%, p < .001). Compared with that in the HC group, the dominant L. crispatus strain in the CV group tended to produce more acid.The CV group carried a less diverse Lactobacillus species, vaginally. Lactobacillus crispatus was common to both CV and HC groups but demonstrated enhanced acid-producing capability in the CV group. The pathogenesis of CV may be based, in part, on an overgrowth of L. crispatus with enhanced acid-producing capability.
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The purpose of this study was to investigate how human vaginal isolates of Lactobacillus acidophilus, Lactobacillus jensenii, Lactobacillus gasseri and Lactobacillus crispatus inhibit the vaginosis-associated pathogens Gardnerella vaginalis and Prevotella bivia. Results show that all the strains in coculture condition reduced the viability of G. vaginalis and P. bivia, but with differing degrees of efficacy. The treatment of G. vaginalis- and P. bivia-infected cultured human cervix epithelial HeLa cells with L. gasseri strain KS120.1 culture or cell-free culture supernatant (CFCS) results in the killing of the pathogens that are adhering to the cells. The mechanism of the killing activity is not attributable to low pH and the presence of lactic acid alone, but rather to the presence of hydrogen peroxide and proteolytic enzyme-resistant compound(s) present in the CFCSs. In addition, coculture of G. vaginalis or P. bivia with L. gasseri KS120.1 culture or KS120.1 bacteria results in inhibition of the adhesion of the pathogens onto HeLa cells.
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Lactobacillus gasseri
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Introduction
The vaginal microbiota affects susceptibility to bacterial vaginosis (BV) and sexually transmitted infections (STIs). BV is characterised by depletion of Lactobacillus spp., an overgrowth of anaerobes (usually dominated by Gardnerella vaginalis) and a pH > 4.5. BV is associated with an increased risk of acquiring STIs such as chlamydia and gonorrhoea. An ex vivo porcine vaginal mucosal model (PVM) was developed to explore the mechanistic role of Lactobacillus in affecting vaginal colonisation by G. vaginalis and Neisseria gonorrhoeae.Methods
Explants (5 mm) of freshly collected PVM were placed in transwells over various media, including Lactobacillus culture supernatant, inoculated with bacteria and incubated under aerobic or anaerobic conditions. Colonised explants were processed for CFU enumeration and presence of biofilm (via confocal microscopy) at indicated times. Lactic acid produced by a clinical isolate of L. crispatus growing on PVM was also quantified.Results
All isolates tested could colonise and grow on PVM. G. vaginalis and N. gonorrhoeae form biofilms on PVM. L. crispatus produces lactic acid on PVM and inhibits the growth of N. gonorrhoeae and G. vaginalis in a pH-dependent manner. Finally, L. crispatus produces a secreted factor that kills N. gonorrhoeae on PVM at an otherwise permissible pH.Conclusion
These data demonstrate that PVM is a useful model for studying the interactions of commensal vaginal microbes with pathogens on the vaginal mucosa. The data confirm a role for lactic acid in inhibiting growth of G. vaginalis and N. gonorrhoeae. The discovery of an L. crispatus secreted factor that kills N. gonorrhoeae is intriguing and future work will identify this compound and explore its mechanism of action.Disclosure of interest statement
Funding provided by the Office of the Vice President for Research, University of Minnesota and NIH grant U19AI084044. No pharmaceutical grants were received in the development of this study.Lactobacillus crispatus
Gardnerella vaginalis
Neisseria gonorrhoeae
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To assess antagonistic properties of Lactobacillus strains isolated from the vaginas of healthy women as compared to the most common bacterial agents related to vaginosis.Antagonistic activity of different Lactobacillus strains isolated from the vaginas of healthy women not treated for infections with an antibiotic for the previous three months was screened using an agar slab method. The activity was tested against test organisms associated with bacterial vaginosis and/or urinary tract infections: Staphylococcus aureus, Enterococcus faecalis, Streptococcus agalactiae, Escherichia coli, Gardnerella vaginalis, Peptostreptococcus anaerobius and Prevotella bivia.Many of the 146 Lactobacillus strains tested exerted apparent antagonistic activities against gram-positive aerobic cocci and gram-negative rods, such as S aureus and E coli, and a marked number of Lactobacillus strains inhibited facultative bacteria, such as Gardnerella vaginalis and the anaerobes P anaerobius and P bivia. Only a few lactobacilli were able to inhibit growth of E faecalis and S agalactiae. Indicator bacteria growth inhibition probably relies upon several different complementary mechanisms. The specific indicator bacteria species determines which mechanism predominates.Lactobacillus strains taken from normal vaginal flora demonstrated antagonistic activity against a variety of bacteria related to vaginal and urinary tract infections. The specific occurrence rates of active Lactobacillus strains are different, and this difference is dependent on the indicator bacteria species.
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Peptostreptococcus
Lactobacillus crispatus
Bacteroides fragilis
Enterococcus faecalis
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Abstract Background Bacterial vaginosis (BV) is a common vaginal infection occurring in women of reproductive age. It is widely accepted that the microbial switch from normal microflora to BV is characterized by a decrease in vaginal colonization by Lactobacillus species together with an increase of Gardnerella vaginalis and other anaerobes. Our goal was to develop and optimize a novel Peptide Nucleic Acid (PNA) Fluorescence in situ Hybridization assay (PNA FISH) for the detection of Lactobacillus spp. and G. vaginalis in mixed samples. Results Therefore, we evaluated and validated two specific PNA probes by using 36 representative Lactobacillus strains, 22 representative G. vaginalis strains and 27 other taxonomically related or pathogenic bacterial strains commonly found in vaginal samples. The probes were also tested at different concentrations of G. vaginalis and Lactobacillus species in vitro, in the presence of a HeLa cell line. Specificity and sensitivity of the PNA probes were found to be 98.0% (95% confidence interval (CI), from 87.8 to 99.9%) and 100% (95% CI, from 88.0 to 100.0%), for Lactobacillus spp.; and 100% (95% CI, from 92.8 to 100%) and 100% (95% CI, from 81.5 to 100.0%) for G. vaginalis . Moreover, the probes were evaluated in mixed samples mimicking women with BV or normal vaginal microflora, demonstrating efficiency and applicability of our PNA FISH. Conclusions This quick method accurately detects Lactobacillus spp. and G. vaginalis species in mixed samples, thus enabling efficient evaluation of the two bacterial groups, most frequently encountered in the vagina.
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Peptide nucleic acid
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The objectives of the present study were to evaluate in vitro the production of antagonistic compounds against Gardnerella vaginalis by Lactobacillus strains isolated from women with or without bacterial vaginosis (BV), and to select one of the better Lactobacillus producers of such a substance to be tested in vivo using a gnotobiotic animal model challenged with one of the more sensitive G. vaginalis isolates. A total of 24 isolates from women with and without BV were identified as G. vaginalis. A higher frequency (P<0.05) of this bacterium was observed in women with BV (56.7%) when compared to healthy women (17.6%). A total of 86 strains of Lactobacillus were obtained from healthy women and women with BV. Lactobacillus strains were more frequently present (P<0.05) in healthy women (97.5%) than in women with BV (76.7%). Lactobacillus crispatus was the predominating strain in both healthy women and women with BV. Lactobacillus jensenii, Lactobacillus johnsonii, Lactobacillus gasseri and Lactobacillus vaginalis were isolated with an intermediate frequency in the two groups. In vitro antagonism assays were performed using as indicators 17 reference strains and the G. vaginalis strains isolated from women with BV and from healthy women. Lactobacillus isolated from healthy women showed the higher antagonistic activity against all the indicator strains when compared with isolates from women with BV. Concerning the indicator strains, G. vaginalis found in women with BV was more resistant to the antagonism, particularly when Lactobacillus isolates from women with BV were used as producer strains. A high vaginal population level of G. vaginalis was obtained by intravaginal inoculation of germ-free mice, and this colonization was accompanied by vaginal histopathological lesions. A tenfold decrease in vaginal population level of G. vaginalis and a reduction of histological lesions were observed when the pathogenic challenge was performed in mice previously monoassociated with an L. johnsonii strain. Concluding, results of the present study suggest that progression of G. vaginalis-associated BV depends in part on a simultaneous presence of Lactobacillus populations with a low antagonistic capacity and of a G. vaginalis strain with a high resistance to this antagonism. The results could also explain why G. vaginalis is frequently found in the vaginal ecosystem of healthy women.
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Lactobacillus crispatus
Gardnerella vaginalis
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Two strains of Lactobacillus crispatus (15L08 and 21L07) and one strain of Lactobacillus jensenii (5L08) were selected from amongst 100 isolates from the vaginas of healthy premenopausal women for properties relevant to mucosal colonization and the production of H2O2 and/or bacteriocin-like compound. All three strains self-aggregated and adhered to vaginal epithelial cells, displacing well-known vaginal pathogens, such as Gardnerella vaginalis and Candida albicans. Lactobacillus crispatus 15L08 was characterized as a potential H2O2 producer. A high level of bacteriocin-like compound was synthesized by L. jensenii 5L08, with a bactericidal mode of action for G. vaginalis, C. albicans and Escherichia coli. However, H2O2-dependent activity alone was not sufficient to inhibit the growth of C. albicans. Simultaneous actions of H2O2 and bacteriocin-like compound produced by lactobacilli may be important for antagonizing pathogenic bacteria. These strains of lactobacilli may be excellent candidates for eventual use as probiotics to restore the normal microbial communities in the vaginal ecosystem.
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Gardnerella vaginalis
Vaginal flora
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