Salient features of Haemophilus vaginalis

Emended description of Gardnerella vaginalis and description of Gardnerella leopoldii sp. nov., Gardnerella piotii sp. nov. and Gardnerella swidsinskii sp. nov., with delineation of 13 genomic species within the genus Gardnerella

Whole genome sequence analysis (digital DNA-DNA hybridization and average nucleotide identity) was carried out for 81 sequenced full genomes of the genus Gardnerella, including ten determined in this study, and indicated the existence of 13 genomic species, of which five consist of only one strain and of which only five contain more than four sequenced genomes. Furthermore, a collection of ten Gardnerella strains, representing the emended species G. vaginalis and the newly described species Gardnerella leopoldii, Gardnerella piotii and Gardnerella swidsinskii, was studied. Matrix-assisted laser desorption ionization time-of-flight MS analysis of the protein signatures identified specific peaks that can be used to differentiate these four species. Only strains of G. vaginalis produce β-galactosidase. We emend the description of G. vaginalis (type strain ATCC 14018^T=LMG 7832^T=CCUG 3717^T) and describe the novel species Gardnerella leopoldii sp. nov. (UGent 06.41^T=LMG 30814^T=CCUG 72425^T), Gardnerella piotii sp. nov. (UGent 18.01^T=LMG 30818^T=CCUG 72427^T) and Gardnerella swidsinskii sp. nov. (GS 9838-1^T=LMG 30812^T=CCUG 72429^T).

Polycladomyces subterraneus sp. nov., isolated from soil in Thailand

A thermophilic poly(L-lactide)-degrading Gram-stain-positive filamentous bacterial strain that develops single spores on the aerial mycelium was isolated from forest soil at Srinagarind Dam, Kanchanaburi Province, Thailand. The results of a polyphasic taxonomic study showed that our isolate had characteristics typical of members of the genus Polycladomyces. The isolate grew aerobically at an optimum temperature of 50-55 °C and optimal pH 6-7. Meso-diaminopimelic acid was present as the diagnostic diamino acid in the peptidoglycan but no characteristic sugars are detected. The predominant menaquinone was MK-7. The diagnostic phospholipids were phosphatidylethanolamine, phosphatidylmethylethanolamine diphosphatidylglycerol, phosphatidylglycerol and phosphatidylserine. The predominant cellular fatty acid was iso-C15 : 0. The DNA G+C content of strain KSR 13T was 53.4 mol%. The 16S rRNA gene sequence analysis also indicated that strain KSR 13T belonged to the genus Polycladomyces, being most closely related to Polycladomyces abyssicola JIR-001T (99.2 %). The DNA-DNA relatedness values that distinguished KSR 13T from P. abyssicola JIR-001T were 17.8-32.1 %, which were significantly below the 70 % cutoff value recommended for species delineation. Following an evaluation of phenotypic, chemotaxonomic and genotypic studies, the new isolate is proposed as a novel species and named Polycladomyces subterraneus sp. nov. The type strain is KSR 13T (=BCC 50740T=NBRC 109332T).

Etiology of bacterial vaginosis and polymicrobial biofilm formation

Microorganisms in nature rarely exist in a planktonic form, but in the form of biofilms. Biofilms have been identified as the cause of many chronic and persistent infections and have been implicated in the etiology of bacterial vaginosis (BV). Bacterial vaginosis is the most common form of vaginal infection in women of reproductive age. Similar to other biofilm infections, BV biofilms protect the BV-related bacteria against antibiotics and cause recurrent BV. In this review, an overview of BV-related bacteria, conceptual models and the stages involved in the polymicrobial BV biofilm formation will be discussed.

Planomonospora corallina sp. nov., isolated from soil

A novel actinomycete strain, A-T 11038T, was isolated from bamboo rhizospheric soil collected in Thailand. Based on a polyphasic approach, the novel strain was characterized as a member of the genus Planomonospora, which developed cylindrical to clavate sporangia containing a single motile spore on aerial mycelium. The 16S rRNA gene sequence and phylogenetic analysis indicated that strain A-T 11038T was closely related to Planomonospora sphaerica JCM 9374T (98.82 %), P.lanomonospora parontospora subsp. parontospora NBRC 13880T and P.parontospora subsp. antibiotica JCM 3094T (98.54 %), Planomonospora alba JCM 9373T (98.41 %) and Planomonospora venezuelensis JCM 3167T (97.51 %). The DNA-DNA relatedness values that distinguished strain A-T 11038T from the most closely related species were below 45 %. The novel strain contained meso-diaminopimelic acid in cell-wall hydrolysates, and rhamnose, ribose, madurose and glucose in whole-cell hydrolysates. The predominant menaquinone was MK-9(H2). The diagnostic phospholipids were diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol mannosides, phosphatidylinositol and aminophosphoglycolipids. The predominant cellular fatty acids were unsaturated fatty acids C17 : 1 and C16 : 1 and saturated fatty acid C16 : 0. The G+C content of the genomic DNA was 73.5 mol%. Following the evidence obtained using a polyphasic approach, the novel strain is proposed as a representative of a novel species to be named Planomonospora corallina sp. nov. The type strain is A-T 11038T (=BCC 67829T=TBRC 4489T=NBRC 110609T).

Bacterial vaginosis: a synthesis of the literature on etiology, prevalence, risk factors, and relationship with chlamydia and gonorrhea infections

Bacterial vaginosis (BV) is a common vaginal disorder in women of reproductive age. Since the initial work of Leopoldo in 1953 and Gardner and Dukes in 1955, researchers have not been able to identify the causative etiologic agent of BV. There is increasing evidence, however, that BV occurs when Lactobacillus spp., the predominant species in healthy vaginal flora, are replaced by anaerobic bacteria, such as Gardenella vaginalis, Mobiluncus curtisii, M. mulieris, other anaerobic bacteria and/or Mycoplasma hominis. Worldwide, it estimated that 20-30 % of women of reproductive age attending sexually transmitted infection (STI) clinics suffer from BV, and that its prevalence can be as high as 50-60 % in high-risk populations (e.g., those who practice commercial sex work (CSW). Epidemiological data show that women are more likely to report BV if they: 1) have had a higher number of lifetime sexual partners; 2) are unmarried; 3) have engaged in their first intercourse at a younger age; 4) have engaged in CSW, and 5) practice regular douching. In the past decade, several studies have provided evidence on the contribution of sexual activity to BV. However, it is difficult to state that BV is a STI without being able to identify the etiologic agent. BV has also emerged as a public health problem due to its association with other STIs, including: human immunodeficiency virus (HIV), herpes simplex virus type 2 (HSV-2), Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG). The most recent evidence on the association between BV and CT/NG infection comes from two secondary analyses of cohort data conducted among women attending STI clinics. Based on these studies, women with BV had a 1.8 and 1.9-fold increased risk for NG and CT infection, respectively. Taken together, BV is likely a risk factor or at least an important contributor to subsequent NG or CT infection in high-risk women. Additional research is required to determine whether this association is also present in other low-risk sexually active populations, such as among women in the US military. It is essential to conduct large scale cross-sectional or population-based case-control studies to investigate the role of BV as a risk factor for CT/NG infections. These studies could lead to the development of interventions aimed at reducing the burden associated with bacterial STIs worldwide.

Optimization of culture conditions for Gardnerella vaginalis biofilm formation

Bacterial vaginosis is the leading vaginal disorder in women in reproductive age. Although bacterial vaginosis is related with presence of a biofilm composed predominantly by Gardnerella vaginalis, there has not been a detailed information addressing the environmental conditions that influence the biofilm formation of this bacterial species. Here, we evaluated the influence of some common culture conditions on G. vaginalis biofilm formation, namely inoculum concentration, incubation period, feeding conditions and culture medium composition. Our results showed that culture conditions strongly influenced G. vaginalis biofilm formation and that biofilm formation was enhanced when starting the culture with a higher inoculum, using a fed-batch system and supplementing the growth medium with maltose.

Actinoplanes luteus sp. nov., isolated from soil

A novel filamentous bacterial strain, A-T 5190T, which developed irregular sporangia at the end of sporangiophores on substrate mycelia, was isolated from dry evergreen forest soil collected in Thailand. The 16S rRNA gene sequence and phylogenetic analysis indicated that strain A-T 5190T belonged to the genus Actinoplanes and was related most closely to Actinoplanes palleronii NBRC 14916T (98.88 % similarity) and Actinoplanes rectilineatus NBRC 13941T (98.54 %). DNA-DNA relatedness values between strain A-T 5190T and its closest relatives were below 70 %. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained rhamnose, ribose, galactose and xylose. The predominant menaquinone was MK-9(H4). The diagnostic phospholipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. The predominant cellular fatty acids were unsaturated fatty acid C17 : 1 and branched fatty acids iso-C16 : 0, iso-C15 : 0 and anteiso-C17 : 0. The G+C content of the genomic DNA was 71.9 mol%. Evidence from phenotypic, chemotaxonomic and genotypic studies indicate that strain A-T 5190T represents a novel species of the genus Actinoplanes, for which the name Actinoplanes luteus sp. nov. is proposed. The type strain is A-T 5190T ( = BCC 41582T = NBRC 109644T).

Sinosporangium fuscum sp. nov., isolated from soil

A novel actinomycete, A-T 8343T was isolated from a moist evergreen forest soil sample collected in the Trat Province, Thailand. Based on 16S rRNA gene sequence analysis, strain A-T 8343T belonged to the genus Sinosporangium and was closely related to Sinosporangium siamense A-T 1946T (98.81 %) and Sinosporangium album 6014T (98.54 %). The DNA-DNA relatedness values were 21.8-27 % with S. siamense A-T 1946T and 31.1-31.9 % with S. album 6014T, which were significantly below 70 %. The result differentiated A-T 8343T from the closest species. The organism developed spherical sporangia containing non-motile spores on aerial mycelia. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained rhamnose, ribose, madurose and glucose. The predominant menaquinones were MK-9(H2) and MK-9(H4). The diagnostic phospholipids were phosphatidylmethylethanolamine, phosphatidylethanolamine, hydroxyl-phosphatidylethanolamine, diphosphatidylglycerol, lyso-phosphatidylethanolamine, N-acetylglucosamine-containing phospholipids, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol-mannosides, aminophosphoglycolipid and one unknown phospholipid. The major cellular fatty acids were saturated C16 : 0, iso C16 : 0, unsaturated C16 : 1 and C18 : 1. Following an evaluation of phenotypic, chemotaxonomic and genotypic characteristics, the new isolate is proposed as a representative novel species of the genus Sinosporangium to be named Sinosporangiumfuscum sp. nov. The type strain is A-T 8343T ( = BCC 52770T = NBRC 109516T).

Role of Gardnerella vaginalis as an etiological agent of bacterial vaginosis

BACKGROUND AND OBJECTIVES

Bacterial vaginosis is a risk factor for obstetric infections, various adverse outcomes of pregnancy and pelvic inflammatory disease. The objectives of this study were to assess the prevalence of bacterial vaginosis in women attending Gynaecology Outpatient Department (O.P.D) and sexually transmitted disease (S.T.D.) clinic and to assess the role of Gardnerella vaginalis as an etiological agent of bacterial vaginosis.

MATERIALS AND METHODS

Two hundred women attending Gynaecology O.P.D and S.T.D. clinic with symptoms suggesting lower genital tract infection were included in the study. pH of the vaginal discharge was measured and three high vaginal swabs were collected. Bacterial vaginosis was diagnosed using Amsel's criteria and Nugent's method. Gardnerella vaginalis was isolated and identified by standard methods.

RESULTS

Prevalence of bacterial vaginosis using Amsel's criteria and Gram stain scoring method was found to be 51.5% and 49% respectively. Gardnerella vaginalis was isolated in only 8.7% cases of bacterial vaginosis.

CONCLUSION

Our study showed a relatively high prevalence of bacterial vaginosis in the population under study. Women attending various healthcare facilities should be screened and treated properly to prevent recurrence. Low isolation rate of Gardnerella vaginalis may be attributed to factors like poor viability and fastidiousness of the organism to grow in various media.

Sinosporangium siamense sp. nov., isolated from soil and emended description of the genus Sinosporangium

An actinomycetes strain A-T 1946(T) that developed spherical sporangia containing non-motile spores on aerial mycelia was isolated from dry deciduous forest soil in Thailand. 16S rRNA gene sequence analysis indicated that strain A-T 1946(T) belongs to the genus Sinosporangium, being closely related to Sinosporangium album 6014(T) (98.8% sequence similarity). The DNA-DNA relatedness values were 43.7-50.9%, which were significantly below 70% and differentiated strain A-T 1946(T) from the closest species. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained rhamnose, ribose, madurose and glucose. The predominant menaquinone was MK-9(H2). The diagnostic phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, lysophosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol-mannoside, N-acetylglucosamine-containing phospholipids, two unknown phosphoglycolipids and two unknown phospholipids. The predominant cellular fatty acids were unsaturated C(16 : 1) and C(17 : 1), and saturated C(16 : 0) and 10-methyl-C(17 : 0). Following an evaluation of phenotypic, chemotaxonomic and genotypic characteristics, the isolate is proposed to represent a novel species of genus Sinosporangium to be named Sinosporangium siamense sp. nov. The type strain is A-T 1946(T) ( = BCC 29081(T) = NBRC 109515(T)). An emended description of the genus Sinosporangium is also provided.

Planobispora takensis sp. nov., isolated from soil

A novel Gram-stain-positive, filamentous bacterial strain (A-T 7458(T)) was isolated from soil collected from hill evergreen forest in Thailand. The strain developed cylindrical sporangia containing a longitudinal pair of motile spores, on short ramifications of aerial mycelia. From a taxonomic study using a polyphasic approach, strain A-T 7458(T) had typical characteristics of members of the genus Planobispora. 16S rRNA gene sequence analysis indicated that the isolate was closely related to Planobispora siamensis A-T 4600(T) (98.5 %), Planobispora rosea JCM 3166(T) (97.6 %) and Planobispora longispora NBRC 13918(T) (97.6 %). The DNA-DNA relatedness values, which differentiated the novel strain from the closest species, were significantly below 70 %. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, madurose, mannose and glucose. The predominant menaquinone was MK-9(H2). The diagnostic phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylinositol, phosphatidylinositol-mannoside and aminophosphoglycolipid. The predominant cellular fatty acids were unsaturated C17 : 1 and C18 : 1, and saturated C16 : 0 and C17 : 0. Following an evaluation of phenotypic, chemotaxonomic and genotypic characteristics, the novel isolate is proposed to represent a novel species of the genus Planobispora, to be named Planobispora takensis sp. nov. The type strain is A-T 7458(T) ( = BCC 48396(T) = NBRC 109077(T)).

Actinoplanes siamensis sp. nov., isolated from soil

A Gram-positive filamentous bacterial strain that developed large campanulate sporangia at the ends of sporangiophores on substrate mycelium was isolated from bamboo forest soil in Thailand. According to the results of a polyphasic taxonomic study, our isolate had typical characteristics of members of the genus Actinoplanes . The 16S rRNA gene sequence analysis also indicated that strain A-T 6646T belonged to the genus Actinoplanes , being most closely related to Actinoplanes liguriensis DSM 43865T (97.61 %) and Actinoplanes octamycinicus NBRC 14524T (97.52 %). The DNA–DNA relatedness values, which differentiate the new strain from the most closely related species, were significantly below 70 %. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained xylose and arabinose. The predominant menaquinone was MK-9(H4). The diagnostic phospholipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. The predominant cellular fatty acids were iso-C16 : 0, anteiso-C17 : 0, iso-C15 : 0 and anteiso-C15 : 0. Following an evaluation of phenotypic, chemotaxonomic and genotypic studies, the isolate is proposed to represent a novel species to be named Actinoplanes siamensis sp. nov. The type strain is A-T 6646T ( = BCC 46194T = NBRC 109076T).

Planobispora siamensis sp. nov., isolated from soil

A novel actinomycete strain, A-T 4600(T), which developed cylindrical sporangia containing a longitudinal pair of motile spores forming singly or in bundles on short ramifications of the aerial mycelium, was isolated from soil collected from an evergreen forest in Thailand. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, madurose, mannose and glucose. The predominant menaquinones were MK-9(H2). Mycolic acids were not detected. The diagnostic phospholipids were phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylinositol, phosphatidylglycerol, phosphatidylinositol mannoside, diphosphatidylglycerol and aminophosphoglycolipid. The predominant cellular fatty acids were unsaturated C17 : 1, C18 : 1, saturated C16 : 0, and C17 : 0. The G+C content of the DNA was 70.8 mol%. Phenotypic and chemotaxonomic analyses showed that the isolate had the typical characteristics of members of the genus Planobispora. Furthermore, 16S rRNA gene sequence analysis also indicated that this strain belonged to the genus Planobispora but as a putative novel species. DNA-DNA relatedness values that differentiate the isolate from previously described members of the genus Planobispora were significantly below 70 %. Following an evaluation of phenotypic, chemotaxonomic and genotypic studies, it is proposed that the isolate represents a novel species, Planobispora siamensis sp. nov.; the type strain is A-T 4600(T) ( = BCC 39469(T) = NBRC 107568(T)).

Sphaerisporangium krabiense sp. nov., isolated from soil

A Gram-staining-positive, filamentous bacterial strain, designated A-T 0308(T), was isolated from soil of a tropical mangrove forest in Thailand. Strain A-T 0308(T) developed spherical sporangia containing non-motile spores on aerial mycelium. The novel strain contained meso-diaminopimelic acid, N-acetyl-type peptidoglycan and madurose, mannose, ribose, galactose and glucose as whole-cell sugars. The predominant menaquinones were MK-9(H(4)) and MK-9(H(6)); a small amount of MK-9(H(2)) and MK-9 was also detected. Mycolic acids were not detected. The diagnostic phospholipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and phosphoglycolipid. The predominant cellular fatty acids were iso-C(16:0) and 10-methylated C(17:0). The G+C content of the DNA was 72 mol%. Phenotypic and chemotaxonomic analyses showed that the novel isolate had characteristics typical of members of the genus Sphaerisporangium. 16S rRNA gene sequence analysis also indicated that the strain belongs to the genus Sphaerisporangium and that it represents a clade distinct from other members of the genus with sequence similarities ranging from 96.3 to 97.8% between the novel strain and its closest relatives. Based on the results of phenotypic, chemotaxonomic and phylogenetic studies, strain A-T 0308(T) (=BCC 21702(T) =NBRC 107571(T)) represents a novel species of the genus Sphaerisporangium, for which the name Sphaerisporangium krabiense sp. nov. is proposed.

Drawing the line between commensal and pathogenic Gardnerella vaginalis through genome analysis and virulence studies

Background

Worldwide, bacterial vaginosis (BV) is the most common vaginal disorder. It is associated with risk for preterm birth and HIV infection. The etiology of the condition has been debated for nearly half a century and the lack of knowledge about its cause and progression has stymied efforts to improve therapy and prevention. Gardnerella vaginalis was originally identified as the causative agent, but subsequent findings that it is commonly isolated from seemingly healthy women cast doubt on this claim. Recent studies shedding light on the virulence properties of G. vaginalis, however, have drawn the species back into the spotlight.

Results

In this study, we sequenced the genomes of a strain of G. vaginalis from a healthy woman, and one from a woman with bacterial vaginosis. Comparative analysis of the genomes revealed significant divergence and in vitro studies indicated disparities in the virulence potential of the two strains. The commensal isolate exhibited reduced cytotoxicity and yet the cytolysin proteins encoded by the two strains were nearly identical, differing at a single amino acid, and were transcribed at similar levels. The BV-associated strain encoded a different variant of a biofilm associated protein gene and demonstrated greater adherence, aggregation, and biofilm formation. Using filters with different pore sizes, we found that direct contact between the bacteria and epithelial cells is required for cytotoxicity.

Conclusions

The results indicated that contact is required for cytotoxicity and suggested that reduced cytotoxicity in the commensal isolate could be due to impaired adherence. This study outlines two distinct genotypic variants of G. vaginalis, one apparently commensal and one pathogenic, and presents evidence for disparate virulence potentials.

Vaginal microbial flora and outcome of pregnancy

BACKGROUND

The vaginal microflora of a healthy asymptomatic woman consists of a wide variety of anaerobic and aerobic bacterial genera and species dominated by the facultative, microaerophilic, anaerobic genus Lactobacillus. The activity of Lactobacillus is essential to protect women from genital infections and to maintain the natural healthy balance of the vaginal flora. Increasing evidence associates abnormalities in vaginal flora during pregnancy with preterm labor and delivery with potential neonatal sequelae due to prematurity and poor perinatal outcome. Although this phenomenon is relatively common, even in populations of women at low risk for adverse events, the pathogenetic mechanism that leads to complications in pregnancy is still poorly understood.

OBJECTIVE

This review summarizes the current knowledge and uncertainties in defining alterations of vaginal flora in non-pregnant adult women and during pregnancy, and, in particular, investigates the issue of bacterial vaginosis and aerobic vaginitis. This could help specialists to identify women amenable to treatment during pregnancy leading to the possibility to reduce the preterm birth rate, preterm premature rupture of membranes, chorioamnionitis, neonatal, puerperal and maternal-fetal infectious diseases.

CONCLUSIONS

Vaginal ecosystem study with the detection of pathogens is a key instrument in the prevention of preterm delivery, pPROM, chorioamnionitis, neonatal, puerperal and maternal-fetal infections.

Prevotella bivia as a source of lipopolysaccharide in the vagina

OBJECTIVES

To compare vaginal lipopolysaccharides (LPS) concentrations between patients with and without bacterial vaginosis (BV), to evaluate the correlation between Prevotella bivia colonization density and LPS concentration, and to determine the impact of LPS on loss of dopamine neurons (DA).

METHODS

Vaginal washes obtained from patients with (n=43) and without (n=59) BV were tested for quantity of P. bivia cells using quantitative PCR and for concentrations of LPS using the Limulus Amebocyte Lysate gel clot method. Prevotella bivia, Gardnerella vaginalis and Escherichia coli sonicated cell extracts were also tested for LPS production. DA neuron cells obtained from embryonic day (E) 14.5 pregnant rats were exposed to fluid from eight vaginal washes; tyrosine hydrolase immunoreactive staining was applied for visualization and cell counts.

RESULTS

The median LPS concentrations were dramatically higher among patients who had symptoms of BV compared to those who did not have symptoms (3235.0 vs 46.4 EU/ml, respectively, P<0.001); patients who had BV also had much higher colonization densities of P. bivia (0.06+/-0.36 vs 5.4+/-2.2 log(10) CFU/ml, respectively, P<0.001). Prevotella bivia cell lysates resulted in a higher LPS concentration (10,713.0+/-306.6 EU/ml) than either E. coli (4679.0+/-585.3 EU/ml) or G. vaginalis (0.07+/-0.01 EU/ml of LPS). The loss of DA neuron was 20-27% in cultures treated with vaginal washes from BV-negative patients and 58-97% in cultures treated with vaginal washes from patients with BV.

CONCLUSION

P. bivia produces high LPS concentration, which may create a toxic vaginal environment that damages DA neurons.

Functional and phylogenetic characterization of Vaginolysin, the human-specific cytolysin from Gardnerella vaginalis

Pore-forming toxins are essential to the virulence of a wide variety of pathogenic bacteria. Gardnerella vaginalis is a bacterial species associated with bacterial vaginosis (BV) and its significant adverse sequelae, including preterm birth and acquisition of human immunodeficiency virus. G. vaginalis makes a protein toxin that generates host immune responses and has been hypothesized to be involved in the pathogenesis of BV. We demonstrate that G. vaginalis produces a toxin (vaginolysin [VLY]) that is a member of the cholesterol-dependent cytolysin (CDC) family, most closely related to intermedilysin from Streptococcus intermedius. Consistent with this predicted relationship, VLY lyses target cells in a species-specific manner, dependent upon the complement regulatory molecule CD59. In addition to causing erythrocyte lysis, VLY activates the conserved epithelial p38 mitogen-activated protein kinase pathway and induces interleukin-8 production by human epithelial cells. Transfection of human CD59 into nonsusceptible cells renders them sensitive to VLY-mediated lysis. In addition, a single amino acid substitution in the VLY undecapeptide [VLY(P480W)] generates a toxoid that does not form pores, and introduction of the analogous proline residue into another CDC, pneumolysin, significantly decreases its cytolytic activity. Further investigation of the mechanism of action of VLY may improve understanding of the functions of the CDC family as well as diagnosis and therapy for BV.

Pore-forming and haemolytic properties of the Gardnerella vaginalis cytolysin

The pleomorphic bacterium Gardnerella vaginalis releases in the culture broth a haemolytic exotoxin (Gvh) which is probably a virulence determinant of this unique bacterium, implicated in gynaecological and urological disorders. This 59 kDa cytolysin was purified to homogeneity in just one chromatographic step directly from the culture supernatant, a final specific activity up to 1.9 x 10(6) HU mg-1 being obtained. The toxin-induced lesion on human erythrocytes results from the formation of a pore whose radius is approximately 2.4 nm. The damage is inhibited by osmotic protectants and shows a sigmoidal dose-response profile suggesting an aggregation process of haemolysin molecules on the target membrane to create the functional lesion. The extent and the kinetics of haemolysis are strongly dependent on temperature and an activation energy of 64.0 kJ mol-1 has been derived. Lipid membranes can be very efficient inhibitors of Gvh-haemolysis, being able to bind the toxin quite avidly. The inhibitory effect requires the presence of cholesterol and it is stronger when cholesterol is mixed with negatively charged phospholipids rather than with zwitterionic phospholipids, suggesting that a negative surface potential increases the affinity of the toxin for the lipid bilayer. The functional properties of Gvh have been compared with those of Clostridium perfringens thetatoxin (PFO) and Escherichia coli haemolysin (HlyA), which are representative of widespread haemolysins produced by Gram-positive and Gram-negative bacteria, respectively. The toxin shares several features with the family of the so-called 'sulphydryl-activated' cytolysins produced by Gram-positive bacteria, although Gvh does not truly belong to this family, being deactivated by beta-mercaptoethanol and being antigenically distinct from them. We report here for the first time the detection in the vaginal fluid of infected women of a specific IgA response against the toxin.

Physical characterization of the pore forming cytolysine from Gardnerella vaginalis

The cytolytic toxin (CTox) produced by Gardnerella vaginalis is able to form voltage-dependent cationic channels when incorporated in lipid membranes (Moran et al. (1991) FEBS Lett. 283, 317-320). Osmotic protection experiments show that toxin incorporated in human erythrocytes forms pores between 18 A and 28 A in diameter. A hypothesis of pore formation as a primary event to produce cytolysis is proposed. The CTox activity increases when cells are depolarized by increasing the extracellular K+ concentration, probably reflecting the voltage dependent character of CTox formed channels. The cytolytic effect of the toxin was prevented by low temperatures and was a function of the extracellular Ca2+ concentration, suggesting a Ca2+ influx as part of the lytic mechanism. Binding of CTox to erythrocytes was dependent on external Ca2+ and was less temperature-dependent. Dose-response analysis suggests cooperativity of the toxin for the lytic activity, although no direct evidence of oligomerization has been found.

Gardnerella vaginalis: characteristics, clinical considerations, and controversies

The clinical significance, Gram stain reaction, and genus affiliation of Gardnerella vaginalis have been controversial since Gardner and Dukes described the organism as the cause of "nonspecific vaginitis," a common disease of women which is now called bacterial vaginosis. The organism was named G. vaginalis when taxonomic studies showed that it was unrelated to bacteria in various genera including Haemophilus and Corynebacterium. Electron microscopy and chemical analyses have elucidated the organism's gram-variable reaction. Controversy over the etiology of bacterial vaginosis was largely resolved by (i) studies using improved media and methods for the isolation and identification of bacteria in vaginal fluids and (ii) standardization of criteria for clinical and laboratory diagnosis. Besides G. vaginalis, Mobiluncus spp., Mycoplasma hominis, and certain obligate anaerobes are now acknowledged as participants in bacterial vaginosis. The finding that G. vaginalis, Mobiluncus spp., and M. hominis inhabit the rectum indicates a potential source of autoinfection in addition to sexual transmission. Extravaginal infections with G. vaginalis are increasingly recognized, especially when the toxic anticoagulant polyanetholesulfonate is omitted from blood cultures and when urine cultures are incubated anaerobically for 48 h. The finding that mares harbor G. vaginalis suggests that an equine model can be developed for studies of Gardnerella pathogenesis.

Bacterial vaginosis

Bacterial vaginosis (BV) is the most common of the vaginitides affecting women of reproductive age. It appears to be due to an alteration in the vaginal ecology by which Lactobacillus spp., the predominant organisms in the healthy vagina, are replaced by a mixed flora including Prevotella bivia, Prevotella disiens, Porphyromonas spp., Mobiluncus spp., and Peptostreptococcus spp. All of these organisms except Mobiluncus spp. are also members of the endogenous vaginal flora. While evidence from treatment trials does not support the notion that BV is sexually transmitted, recent studies have shown an increased risk associated with multiple sexual partners. It has also been suggested that the pathogenesis of BV may be similar to that of urinary tract infections, with the rectum serving as a reservoir for some BV-associated flora. The organisms associated with BV have also been recognized as agents of female upper genital tract infection, including pelvic inflammatory disease, and the syndrome BV has been associated with adverse outcome of pregnancy, including premature rupture of membranes, chorioamnionitis, and fetal loss; postpartum endometritis; cuff cellulitis; and urinary tract infections. The mechanisms by which the BV-associated flora causes the signs of BV are not well understood, but a role for H2O2-producing Lactobacillus spp. in protecting against colonization by catalase-negative anaerobic bacteria has been recognized. These and other aspects of BV are reviewed.

Characterization of Gardnerella vaginalis and G. vaginalis-like organisms from the reproductive tract of the mare

Gardnerella vaginalis has been isolated from women with bacterial vaginosis, from the genital tracts of asymptomatic women, and from several other infected body sites in humans. However, until recently, it has not been isolated from any other animal species. Between June 1988 and October 1989, 31 isolates identified as G. vaginalis and 70 isolates identified as G. vaginalis-like organisms have been recovered from the genital tracts of 93 mares from Michigan and Ohio. Identification was based on biochemical reactions, hemolysis on media containing blood from various animal sources, and susceptibility to select antimicrobial agents. This report details the characterization of G. vaginalis and G. vaginalis-like organism isolates obtained from the reproductive tracts of these mares and compares the equine isolates with human isolates.

Identification and partial characterization of a cytolytic toxin produced by Gardnerella vaginalis

Generation and release into the culture medium of a cytolytic toxin by Gardnerella vaginalis has been demonstrated. Addition of starch and of the nonionic detergent Tween 80 to the culture medium was essential to recover cytolytic activity. A protein with an apparent molecular mass of 61 to 63 kDa was purified from the culture supernatants showing lytic activity towards erythrocytes and nucleated cells, such as human endothelial cells and human neutrophils. The protein had marked selectivity for human erythrocytes, while erythrocytes from other species were not lysed or were lysed at much higher concentrations of the protein than those needed for human erythrocytes. The cytolytic activity was remarkably unstable in polar media, but was stabilized by nonionic detergents, by binding, or by insertion into the target cell membrane, suggesting its amphiphilic nature.

Isolation of Gardnerella vaginalis from the reproductive tract of four mares

A gram-variable pleomorphic bacillus was isolated from the reproductive tracts of 4 mares during routine prebreeding soundness examinations. Using a commercial bacterial identification system, these organisms were identified as Streptococcus acidominimus. However, colonial and Gram-staining characteristics did not support this identification. Subsequent testing indicated the organism was similar to Gardnerella vaginalis. Additional growth and biochemical analysis performed in our laboratory and at the Michigan Department of Public Health and by the Center for Disease Control, Atlanta, Georgia, confirmed the identification of G. vaginalis.

Prevalence of non-specific vaginitis and correlation with isolation of Gardnerella vaginalis in Italian outpatients

Among all subjects attending a Center for prevention of female genital tract cancer Gardnerella vaginalis was isolated from 57 out of 171 women affected by non-specific vaginitis (NSV), from 15 of 703 non-NSV vaginitis patients and from 10 of 338 healthy adults. Postmenopausal women showed an increased rate of asymptomatic carriage of G. vaginalis. The data suggest a relatively weak association between clinical diagnosis of NSV and isolation of G. vaginalis.

Evaluation of the enhanced rapid identification method for Gardnerella vaginalis

The enhanced rapid identification method (RIM; Austin Biological Laboratories), a micromethod for the identification of Gardnerella vaginalis, is based on starch and raffinose fermentation and hippurate hydrolysis. We tested 105 clinical isolates of G. vaginalis with both the RIM and standard biochemical tests. The RIM agreed with the standard biochemical methods for 96 (91.4%) of the strains; nine isolates which were hippurate hydrolysis positive by standard biochemical tests were hippurate hydrolysis negative in the RIM. RIM may serve as a useful adjunct to Gram stain and colony morphology for the identification of G. vaginalis.

A 24 hour plastic envelope method for isolating and identifying Gardnerella vaginalis (PEM-GVA)

A new plastic envelope culture test that is selective for Gardnerella vaginalis was compared with a conventional method. Vaginal specimens from 92 women were cultured. Results from both methods were compared with the results of pelvic examinations and clinic screening tests used to diagnose bacterial vaginosis (BV). G vaginalis was isolated more often in the envelope than by the conventional method from patients with BV and those without, though the difference was not significant. Isolation and identification of G vaginalis was completed in 18-24 hours by the envelope method; the conventional method took a mean of 72 hours (range two to six days). Polymorphonuclear leucocytes (PMNLs) occurred significantly more in specimens from the patients without BV than from those with BV. Both clue cells and a positive amine test reaction were found significantly more in specimens from patients with BV than from those without BV. Clue cells and G vaginalis isolation correlated best with BV (in 47 women), followed by clue cells and positive amine test results (in 39). Adherence of G vaginalis in the envelope also correlated more with BV, clue cells, and positive amine test results (32) than with patients without BV (14). When there were no clue cells and amine test results were negative the results correlated totally with a prediction of no BV. The use of the rapid envelope culture test would have confirmed BV in 20% of the cases where clue cell and amine test results were discordant.

Detection of Gardnerella vaginalis in vaginal specimens by direct immunofluorescence

The preparation of a fluorescein-labeled Gardnerella vaginalis polyclonal antibody is described, and its usefulness is assessed for the detection of this microorganism in vaginal samples obtained from 263 women attending the gynecological department of a general hospital, 66 of whom harbored an intrauterine device. The direct immunofluorescence technique was positive for G. vaginalis in 21% of the specimens, whereas only 12.5% of the total bacteriological cultures were positive. The frequency was higher in patients harboring intrauterine devices since 34.8% exhibited positive immunofluorescence and 30.3% exhibited positive cultures.

Predictive value of the "clue cells" investigation and the amine volatilization test in vaginal infections caused by Gardnerella vaginalis

Although still controversial, an etiologic role of Gardnerella vaginalis is imputed in vaginitis. Besides isolation of the organism by culture, two alternative diagnostic procedures have been claimed to be useful: the investigation of "clue cells" in clinical specimens and the amine volatilization test or fishy odor perception in genital secretions. Herein we report on the findings of the simultaneous use of G. vaginalis isolation, the clue cell test and amine volatilization perception in specimens from 1,263 consecutive female patients referred to our clinic. Our results show that the simultaneous use of both alternative tests is very useful as a screening procedure. A negative result of both tests predicts a negative culture result in 99% of the cases. However, a positive result of either or both should be considered as an indication to proceed to culture and not as diagnostic of infection.

Identification of Gardnerella vaginalis with the API 20 Strep system

A total of 137 strains of Gardnerella vaginalis were examined by the API 20 Strep system. The system was shown to be reliable when the tests were compared with standard identification methods, and very little confusion occurred with streptococcal profiles; consequently, G. vaginalis has been included in the API 20 Strep data base.

Use of a sodium polyanetholesulfonate disk for the identification of Gardnerella vaginalis

Several methods have been previously suggested for the presumptive identification of Gardnerella vaginalis in clinical laboratories, but none is entirely satisfactory. We previously found that sodium polyanetholesulfonate (SPS) inhibits G. vaginalis in blood culture media. We compared susceptibility to an SPS-containing paper disk with beta-hemolysis on human blood agar, hippurate hydrolysis, and inhibition by alpha-hemolytic streptococci for identification of 62 previously confirmed G. vaginalis strains. All strains were positive by SPS disk and alpha-hemolytic streptococcus inhibition, 78% were positive by beta-hemolysis, and 81% were positive by hippurate hydrolysis. Although positive reactions occurred with SPS disk and alpha-hemolytic streptococcus tests for 5 and 9 of 84 other bacteria tested, respectively, none of these bacteria were positive for both tests. We conclude that a combination of SPS disk susceptibility and alpha-hemolytic streptococcus inhibition provides excellent identification of G. vaginalis when performed by the methods suggested.

Fatty acid, polar lipid and wall amino acid composition of Gardnerella vaginalis

Representative strains of Gardnerella vaginalis were degraded using both an alkaline and an acid methanolysis and the fatty acid methyl esters released examined by thin-layer and gas chromatography. The profiles obtained were both qualitatively and quantitatively similar and were comprised of straight chain saturated and unsaturated non-hydroxylated fatty acids with hexadecanoic acid (16:0) and octadecenoic acid (18:1) the major components. All of the strains contained very characteristic polar lipid patterns consisting of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, five partially identified glycolipids and an uncharacterised phospholipid. Analyses of wall amino acid preparations using gas chromatography showed that Gardnerella vaginalis strains contain major amounts of alanine, glycine, glutamic acid and lysine. The chemical data support the integrity of the genus Gardnerella.

Semiquantitative culture of Gardnerella vaginalis in laboratory determination of nonspecific vaginitis

To evaluate the usefulness of quantitative cultures of Gardnerella vaginalis in the laboratory determination of nonspecific vaginitis, the actual and relative numbers of G. vaginalis in genital cultures of a general patient population were assessed semiquantitatively, and the laboratory results were then correlated with the clinical findings. Of the 1,585 women studied, 417 (26.3%) yielded G. vaginalis in culture. Of these, only 113 (27.1%) were found to have symptoms and signs consistent with nonspecific vaginitis. G. vaginalis was obtained in pure or predominant growth from 87 of 100 consecutive cases with nonspecific vaginitis and 32 of 100 consecutive cases without the symptoms or signs of vaginitis (P less than 0.001). Hence, the positive predictive value of isolation of G. vaginalis in pure and predominant growths was determined to be 73% (87 of 119). Conversely, G. vaginalis was isolated in mixed or light growth significantly more often from asymptomatic women than from symptomatic patients, i.e., 68 versus 13 cases. Therefore, the negative predictive value of isolation of G. vaginalis in mixed and light growths was found to be 84% (68 of 81). Quantitation of the relative amount of G. vaginalis growth had higher predictive values as compared with the assessment of G. vaginalis growth alone. We conclude that quantitative culture of G. vaginalis is essential to obtain maximum reliability of culture results in the laboratory determination of nonspecific vaginitis. Although quantitated cultures of G. vaginalis have high predictive values, laboratory results must be interpreted in conjunction with the clinical findings.

Minimal criteria for the identification of Gardnerella vaginalis isolated from the vagina

Vaginal swabs were examined for the presence of Gardnerella vaginalis. Of 294 isolates with appropriate colonial and cellular morphology subjected to an identification procedure, 203 (69%) were identified as G vaginalis. The 91 isolates not identified as G vaginalis were differentiated by their inability to ferment starch, cause diffuse beta haemolysis on human blood agar or hydrolyse hippurate. Other tests, often used in the identification of G vaginalis, were found to be insufficiently specific. Failure to ferment starch coexisted with failure to cause beta haemolysis and/or hydrolyse hippurate. The starch fermentation test may therefore be omitted. The tests for beta haemolysis and hippurate hydrolysis, being relatively simple to perform and interpret, are considered indispensable for the accurate identification of G vaginalis in the service laboratory.

Gardnerella vaginalis and anaerobic bacteria in genital disease

In a study of Gardnerella vaginalis and anaerobic bacteria in non-specific vaginitis (NSV) and other genital disease 89 patients attending a genital medicine clinic had vaginal samples examined for conventional pathogens and for quantitative analysis of G vaginalis and aerobic and anaerobic bacterial flora. The overall incidence of G vaginalis was 20%; G vaginalis (mean concentration 7.0 log10/g of secretion) occurred predominantly in patients with NSV (57%) but also in sexual contacts of non-specific urethritis (NSU) (37.5%) and in patients with other conditions (11.8%). G vaginalis is therefore a relatively common isolate in patients with vaginal discharge. The concentration of aerobic and anaerobic bacteria ranged from 4.9-11.0 log10/g of secretion with an anaerobe-to-aerobe ratio of 10:1. Anaerobic bacteria, particularly anaerobic Gram-positive cocci (mean concentrations 7.7 log10/g), were present in patients with NSV and in association with G vaginalis, but they also occurred in other clinical groups and with other pathogens, particularly Trichomonas vaginalis. Anaerobic bacteria may therefore play an important role in the pathogenesis of vaginal infections.

Isolation and rapid identification of Haemophilus ducreyi

During a 2-month period, 62 strains of Haemophilus ducreyi were isolated from 168 genital lesions and 2 lymph node aspirates. Of these strains, 22 were found on both chocolate agar and fetal bovine serum agar supplemented with vancomycin, 29 were found only on chocolate agar, and 9 were found only on fetal bovine serum agar. Two additional strains were isolated on sheep blood agar. All of these isolates were correctly identified with the RapID NH system (Innovative Diagnostic Systems, Inc., Decatur, Ga.) a new identification kit that has a database for Haemophilus, Neisseria, and other genera that include fastidious gram-negative bacilli.

Rapid microbiochemical method for identification of Gardnerella (Haemophilus) vaginalis

A rapid biochemical method for the identification of Gardnerella vaginalis has been developed. The method is based on the fermentation of starch and raffinose and on the hydrolysis of hippurate. With this new procedure, identification was confirmed for 390 of 396 G. vaginalis isolates within 1 h after their inoculation into the three substrates.

Comparison of culture and microscopy in the diagnosis of Gardnerella vaginalis infection

A comparison was made between human blood agar containing amphotericin B, nalidixic acid and either gentamicin or colistin for the isolation of Gardnerella vaginalis from cases of non-specific vaginitis seen in a clinic for sexually transmitted diseases. The medium containing gentamicin was more inhibitory for non-Gardnerella species, but not sufficiently inhibitory to allow direct plating in the clinic without spreading for single colonies. The diffuse beta haemolysis produced by G vaginalis on human, but not on horse blood agar, proved very useful in differentiating it from other vaginal organisms and was not affected by the antibiotics used. This characteristic, together with Gram stain morphology, oxidase and catalase, provides a simple, reliable methods of identifying G vaginalis. Sixty women with symptoms of vaginitis, in whom no other pathogen was isolated, were examined by culture and microscopy. Gardnerella vaginalis was grown from 45 whereas only 31 had positive microscopy (clue cells or Gram-variable bacilli). There was no significant difference between the rate of isolation of G vaginalis in the group with positive microscopy (25/31) and that with negative microscopy (20/31).

Method for isolation of gardnerella vaginalis (Haemophilus vaginalis). Characterization of isolates by gas chromatography

A method for the isolation of Gardnerella vaginalis (Haemophilus vaginalis) is presented. Bacteria isolated from 48-hour cultures grown on human blood agar were identified by means of beta-hemolysis, colony morphology, sensitivity to antimicrobial agents, oxydase and catalase reactions. Thirty-eight clinical isolates and one test strain were examined for fatty acid composition. Hexadecanoic (16:0), octadecenoic (18:1) and octadecanoic (18:0) were the major fatty acids. Also present, but in minor quantities, were myristic (14:0), hexadecenoic (16:1) and octadecadienoic (18:2) acids. Only insignificant differences between isolates could be detected. No hydroxy fatty acids commonly found in gram-negative bacteria were encountered. Gas chromatographic analysis of G. vaginalis revealed a characteristic and relatively simple pattern. The results support the use of the isolation method, which provides conditions highly selective for G. vaginalis.

Selective differential human blood bilayer media for isolation of Gardnerella (Haemophilus) vaginalis

New selective and differential human blood bilayer agar media with Tween 80 (HBT medium) or without Tween 80 (HB medium), developed for the isolation of Gardnerella (Haemophilus) vaginalis, permitted significantly higher G. vaginalis isolation rates than have been obtained for other media used for this purpose. HB medium consists of a basal layer of Columbia agar base containing colistin and naladixic acid with added amphotericin B and an overlayer of the same composition plus 5% human blood. HBT agar also contains Proteose Peptone No. 3 (Difco Laboratories) and Tween 80 in the basal layer and the overlayer. Both Tween 80 and the bilayer composition enhanced G. vaginalis production of human blood hemolysis, permitting detection of this organism even in the presence of heavy growth of other vaginal flora. The use of HB or HBT medium thus permitted the demonstration that G. vaginalis was present in vaginal fluid from a large percentage (up to 68%) of normal women. However, the concentration of G. vaginalis was found by semiquantitative analysis to be significantly higher in vaginal fluid from women with nonspecific vaginitis than in fluid from normal women.

Identification of Gardnerella (Haemophilus) vaginalis

Different tests for the identification of Gardnerella (Haemophilus) vaginalis and for its differentiation from catalase-negative unclassified coryneforms from the vagina were evaluated on over 200 bacterial strains, with special emphasis on optimal test conditions. A presumptive identification of G. vaginalis in the clinical laboratory can be made on the basis of colonial morphology, clear beta-hemolysis with diffuse edges on human blood bilayer-Tween agar, a negative catalase test, and typical cell morphology in the Gram stain. This procedure will correctly identify 90 to 98% of suspect colonies of G. vaginalis with human blood bilayer-Tween agar as primary isolation medium. Useful additional reactions for the confirmation of G. vaginalis include positive hippurate and starch hydrolysis, positive alpha-glucosidase but negative beta-glucosidase tests, the production of acid from glucose and maltose but not from mannitol, and susceptibility to disks containing metronidazole, nitrofurantoin, sulfonamides, and bile.

Rapid identification of Corynebacterium vaginale in non-purulent vaginitis

A simple set of tests is proposed to give excellent probability for the identification of Corynebacterium vaginale from clinical material. Using these tests, 380 C vaginale were isolated from genital tract specimens from 1402 patients. Of these isolates 70 were from symptomatic patients. These 70 isolates were subjected to a further set of tests to confirm their identity. The advantage of these primary tests is that they can be completed on the day of isolation of the organism. Of these 70 isolates 66 were confirmed as C vaginale thus giving the primary set of tests a 94% rate of accurate identification. However this rate may be increased beyond 97% by the promotion of one of the key secondary tests to the primary set.