Gardnerella vaginalis purulent meningitis in an adolescent male: a case report

Background

We report a rare case of Gardnerella vaginalis found in the cerebrospinal fluid of a young boy.

Case presentation

A 14-year-old boy was admitted to hospital with headache, vomiting, fever, drowsiness and positive meningeal irritation signs on examination. Cerebrospinal fluid (CSF) shows white blood cell and protein were elevated, and glucose was low. Traditional aerobic and anaerobic culture of CSF did not grow any organisms. However, metagenomic next-generation sequencing (mNGS) reveals G. vaginalis in his CSF. The patient was diagnosed with purulent meningitis, and treated with intravenous meropenem and linezolid for a week, followed by oral administration of amoxicillin for two weeks. He recovered without sequelae.

Conclusions

Purulent meningitis caused by Gardnerella vaginalis is extremely rare. Metagenomic next-generation sequencing of CSF should be highlighted for early diagnosis. With effective antibiotic treatment, the prognosis was excellent.

Prosthetic Joint Infection Caused by Gardnerella vaginalis: Case Report and Review of the Literature

Prosthetic joint infection is not uncommon, but Gardnerella vaginalis has been reported rarely as a causative agent. A 45-year-old patient with no remarkable history was admitted to the hospital ten months after total hip replacement because of loosening of the prosthesis. Initial culture grew S. anginosus. Repeated culture of the debridement material grew G. vaginalis. After adequate and effective treatment, he was discharged in good health. This is the first case of a male patient with prosthetic joint infection caused by G. vaginalis. This pathogen should be considered in the presence of slow-growing, gram-variable rods in culture.

Metagenomic Next-Generation Sequencing Assists in the Diagnosis of Gardnerella vaginalis in Males with Pleural Effusion and Lung Infection: A Case Report and Literature Review

Gardnerella vaginalis is a pathogen responsible for bacterial vaginosis, which is commonly found in female vaginas and rarely causes infections outside the female genitalia. Here, we report the use of metagenomic next-generation sequencing (mNGS) to detect and confirm pulmonary infection and pleural effusion caused by G. vaginalis in a 47-year-old man. The patient’s symptoms and imaging improved after 2 weeks of oral ornidazole, and he was cured after 3 months. Overall, the findings of this case demonstrate that mNGS is a useful tool for diagnosis of unexplained lung infections and pleural effusions. Its effectiveness in rapid and accurate etiological diagnosis and monitoring of diseases can allow detection of the etiology of difficult cases that return negative results after traditional cultures.

Gardnerella vaginalis in urinary tract infections, are men spared?

Gardnerella vaginalis in association with anaerobes has been linked to bacterial vaginosis in women, while urinary tract infections (UTIs) in men have rarely been reported. The aim of the review was to reveal the significance of G. vaginalis UTIs in men. Prevalence of G. vaginalis UTIs in men varied from 0.5 to >27% according to patients' groups. Most patients had comorbidity such as urolithiasis or stents, transplants, tumors and diabetes, however, infections can also affect immunocompetent patients. We observed G. vaginalis-associated bacteriuria and leukocyturia in a kidney transplant man. Complications of the UTIs such as bacteremia (in 9/11 cases), hydronephrosis (4/11) and abscesses or septic emboli have been reported. Bacterial vaginosis in female partners has been a risk factor for UTIs in males. In women, biofilm Gardnerella phenotype, stabilized by Atopobium vaginae and Prevotella bivia was linked to ≥6-fold higher antibiotic resistance rates compared with the planktonic phenotype. Non-susceptibility to metronidazole and levofloxacin was found also in males. Therefore, if aerobic urine cultures are negative, urine and blood samples from male patients with predisposing factors and clinical signs of UTIs and bacteremia, can be taken. Plates should be incubated for 2-4 days in capnophilic/microaerophilic conditions, however only anaerobic incubation can help with detecting G. vaginalis strains which grow only anaerobically. Susceptibility testing of the isolates is highly important. Briefly, adherent G. vaginalis phenotype can be sexually transmissible. Despite the infrequency of G. vaginalis UTIs in men, the infections should be considered since they are often linked to severe complications.

Gardnerella vaginalis Is a Rare Cause of Ventilator-Associated Pneumonia: A Case Report and Literature Review

Gardnerella vaginalis (G. vaginalis) is a commensal bacterium of the vaginal flora, facultative anerobic with Gram-variable, frequently implicated in cases of vaginosis or even infections of the genitourinary tract, rarely responsible for systemic infections and very exceptionally isolated in bronchopulmonary damage. We report here a case of G. vaginalis pneumonia in a 45-year-old man admitted to the intensive care unit for cardiorespiratory arrest (CRA) by hanging, whose course was unfavorable following severe post-anoxic encephalopathy. During his hospitalization, the patient presented ventilator-associated pneumonia (VAP) with identification of G. vaginalis at a significant threshold on the protected distal bronchial sampling (PDBS). Antibiotic therapy with cefotaxime and metronidazole had a good response to this infection. In this observation, we discuss the pathogenic role and identification of G. vaginalis at the pulmonary level.

A case report of septic gardnerellosis

Gardnerella vaginalis is a bacterium that is found as the most common cause of bacterial vaginitis in women. In this paper, we describe a case report of a 22-years old woman infected with G. vaginalis, who was initially suspected to have Dengue fever. The similarity of clinical symptoms developed by this disease with the symptoms of some other tropical infectious diseases, as well as a travel history, complicated identification of the disease cause for this particular patient. Here, we present a detailed epidemiological and clinical description of this case, leading to a final diagnosis of a septic form of gardnerellosis.

Gardnerella and vaginal health: the truth is out there

The human vagina is a dynamic ecosystem in which homeostasis depends on mutually beneficial interactions between the host and their microorganisms. However, the vaginal ecosystem can be thrown off balance by a wide variety of factors. Bacterial vaginosis (BV) is the most common vaginal infection in women of childbearing age but its etiology is not yet fully understood, with different controversial theories being raised over the years. What is generally accepted is that BV is often characterized by a shift in the composition of the normal vaginal microbiota, from a Lactobacillus species dominated microbiota to a mixture of anaerobic and facultative anaerobic bacteria. During BV, a polymicrobial biofilm develops in the vaginal microenvironment, being mainly composed of Gardnerella species. The interactions between vaginal microorganisms are thought to play a pivotal role in the shift from health to disease and might also increase the risk of sexually transmitted infections acquisition. Here, we review the current knowledge regarding the specific interactions that occur in the vaginal niche and discuss mechanisms by which these interactions might be mediated. Furthermore, we discuss the importance of novel strategies to fight chronic vaginal infections.

Bacterial infection of the male reproductive system causing infertility

Bacterial infections play a disruptive and hidden role in male reproductive failure. Different kinds of bacteria are often able to interfere with reproductive function in both sexes and lead to infertility. In this study, to further evaluate the role of bacterial infections in male reproduction we provided an extensive overview of so far researches investigating the effects of bacterial infections on male fertility. We searched Medline, PubMed, Scopus and Google scholar databases to identify the potentially relevant studies on bacterial infections and their implications in male infertility. All the bacteria included in this article have negative effects on the male reproductive function; however, there is ample evidence to blame bacteria such as Escherichia coli, Chlamydia trachomatis, Ureaplasma, Mycoplasma and Staphylococcus aureus for reduced fertility and deterioration of sperm parameters. More studies are needed to clarify the molecular mechanisms by which different bacteria exert their detrimental effects on male reproductive system. Getting more insight into probable mechanisms, would significantly facilitate the production of new, advanced, and effective remedies in the future. In view of all evidence, we strongly suggest increasing awareness among people and considering screening programs for patients seeking fertility both to avoid transmission and to improve fertility outcomes among them.

A Rare Cause of a Scrotal Abscess due to the Symbiotic Infection of Gardnerella vaginalis and Prevotella bivia in an Adult Male

Gardnerella vaginalis (G. vaginalis) is the major bacteria detected in women with bacterial vaginosis (BV). Prevotella bivia (P. bivia) has been demonstrated to show a symbiotic relationship with G. vaginalis. Some men have been shown to be colonized with G. vaginalis in their urogenital or anorectal tracts, however genitourinary infections in males, including balanitis and urethritis, due to this organism appear to be much less common. In this report, we summarize previous cases of men with G. vaginalis infection, and we present a rare and unusual case of a unilateral scrotal abscess caused by G. vaginalis in co-infection with P. bivia.

Not Your Garden-Variety Bacteremia: Gardnerella in an Immunocompromised Man

Systemic Gardnerella infections are rare and usually associated with surgical instrumentation of the genitourinary tract. We present a case of symptomatic and transient Gardnerella bacteremia in a man with AIDS after a traumatic urinary catheter insertion.

Prevalence of vaginolysin, sialidase and phospholipase genes in Gardnerella vaginalis isolates between bacterial vaginosis and healthy individuals

Background: Gardnerella vaginalis is considered as the predominant microorganism found in bacterial vaginosis (BV). The aim of this study was to evaluate the prevalence of virulence factors in G. vaginalis associated with BV or non-BV cases and their correlations with this disorder. Methods: A total of 102 vaginal specimens were collected from patients during their visit to Akbar Abadi hospital in Tehran, Iran. Bacterial vaginosis was determined by Nugent score and Amsel's criteria. Polymerase chain reaction (PCR) was used for the detection of G. vaginalis 16S rRNA, vaginolysin, sialidase and phospholipase genes. To evaluate the association between the presence of vly, pho, and sld genes and BV. Pearson Chi-square test was applied using SPSS software. P-value ≤0.05 was considered as significant. Results: Totally, 27.4% of the patients were suffering from BV. Gardnerella vaginalis was found in 100% women with BV and in 56.7% women with normal vaginal discharge. The prevalence of vly, sld and pho genes in BV-associated G. vaginalis was 10 (35.7%) (95% CI [0.18, 0.53]), 19 (67.8%) (95% CI [0.51, 0.85]) and 6 (21.4%) (95% CI [0.06, 0.37]), respectively. The prevalence of the aforementioned genes in non-BV associated G. vaginalis was 20 (47.6%) (95% CI [0.33, 0.63]), 28 (66.6%) (95% CI [0.52, 0.81]), and 5 (11.9%) (95% CI [0.02, 0.22]), respectively. Our results showed no statistically significant association between the presence of the virulence genes and BV associatedness of this microorganism. Conclusion: Our results showed the presence of G. vaginalis in all BV patients and relatively high prevalence in healthy individuals. The prevalence rates of the three virulence genes were different in BV and non-BV associated G. vaginalis; however, the differences were not statistically significant.

Gram-Positive Uropathogens, Polymicrobial Urinary Tract Infection, and the Emerging Microbiota of the Urinary Tract

Gram-positive bacteria are a common cause of urinary-tract infection (UTI), particularly among individuals who are elderly, pregnant, or who have other risk factors for UTI. Here we review the epidemiology, virulence mechanisms, and host response to the most frequently isolated Gram-positive uropathogens: Staphylococcus saprophyticus, Enterococcus faecalis, and Streptococcus agalactiae. We also review several emerging, rare, misclassified, and otherwise underreported Gram-positive pathogens of the urinary tract including Aerococcus, Corynebacterium, Actinobaculum, and Gardnerella. The literature strongly suggests that urologic diseases involving Gram-positive bacteria may be easily overlooked due to limited culture-based assays typically utilized for urine in hospital microbiology laboratories. Some UTIs are polymicrobial in nature, often involving one or more Gram-positive bacteria. We herein review the risk factors and recent evidence for mechanisms of bacterial synergy in experimental models of polymicrobial UTI. Recent experimental data has demonstrated that, despite being cleared quickly from the bladder, some Gram-positive bacteria can impact pathogenic outcomes of co-infecting organisms. When taken together, the available evidence argues that Gram-positive bacteria are important uropathogens in their own right, but that some can be easily overlooked because they are missed by routine diagnostic methods. Finally, a growing body of evidence demonstrates that a surprising variety of fastidious Gram-positive bacteria may either reside in or be regularly exposed to the urinary tract and further suggests that their presence is widespread among women, as well as men. Experimental studies in this area are needed; however, there is a growing appreciation that the composition of bacteria found in the bladder could be a potentially important determinant in urologic disease, including susceptibility to UTI.

Transient microbiota exposures activate dormant Escherichia coli infection in the bladder and drive severe outcomes of recurrent disease

Pathogens often inhabit the body asymptomatically, emerging to cause disease in response to unknown triggers. In the bladder, latent intracellular Escherichia coli reservoirs are regarded as likely origins of recurrent urinary tract infection (rUTI), a problem affecting millions of women worldwide. However, clinically plausible triggers that activate these reservoirs are unknown. Clinical studies suggest that the composition of a woman’s vaginal microbiota influences her susceptibility to rUTI, but the mechanisms behind these associations are unclear. Several lines of evidence suggest that the urinary tract is routinely exposed to vaginal bacteria, including Gardnerella vaginalis, a dominant member of the vaginal microbiota in some women. Using a mouse model, we show that bladder exposure to G. vaginalis triggers E. coli egress from latent bladder reservoirs and enhances the potential for life-threatening outcomes of the resulting E. coli rUTI. Transient G. vaginalis exposures were sufficient to cause bladder epithelial apoptosis and exfoliation and interleukin-1-receptor-mediated kidney injury, which persisted after G. vaginalis clearance from the urinary tract. These results support a broader view of UTI pathogenesis in which disease can be driven by short-lived but powerful urinary tract exposures to vaginal bacteria that are themselves not “uropathogenic” in the classic sense. This “covert pathogenesis” paradigm may apply to other latent infections, (e.g., tuberculosis), or for diseases currently defined as noninfectious because routine culture fails to detect microbes of recognized significance.

Millions of women suffer from recurrent urinary tract infections (rUTI) and the only treatment option is prophylactic antibiotics, which contributes to antibiotic resistance. In experimental models, Escherichia coli, the dominant UTI pathogen, establishes reservoirs inside the bladder lining; it is believed that some cases of rUTI in women may be due to these reservoirs awakening in response to triggers that are still unknown. Here we present a new mouse model that demonstrates the first clinically plausible trigger of rUTI arising from these reservoirs. Specifically, we show that bladder exposure to Gardnerella vaginalis, a common member of the vaginal microbial community, can drive the emergence of E. coli from bladder reservoirs. Furthermore, upon its exposure to the urinary tract, this vaginal organism caused severe kidney damage and other complications, suggesting that carriage of particular vaginal bacteria could also impact a woman’s risk for kidney infection. Bladder exposure to G. vaginalis is likely to occur during sexual activity in many women. Taken together, these data provide the first explanation for why certain characteristics of the vaginal microbiota have been linked with rUTI. Finally, our findings suggest that targeting specific members of the vaginal community may be an effective strategy for treating rUTI.

Alloscardovia macacae sp. nov., isolated from the milk of a macaque (Macaca mulatta), emended description of the genus Alloscardovia and proposal of Alloscardovia criceti comb. nov

A novel bacterial strain, designated M8T, was isolated from milk of a female macaque bred in captivity. The strain was Gram-stain-positive, anaerobic, irregular coccoid–rod-shaped without catalase activity. Analysis of 16S rRNA gene sequence similarity revealed that the isolate was most closely related to Alloscardovia omnicolens CCUG 31649T (96.4 %) and Metascardovia criceti OMB105T (96.6 %). Sequences of hsp60, fusA, and xfp genes also confirmed that the strain was most closely related to the type strains of A. omnicolens and M. criceti . The isolate produced fructose-6-phosphate phosphoketolase which is in agreement with classification within the family Bifidobacteriaceae . The major fatty acids were C18 : 1ω9c (35.8 %), C16 : 1 (6.2 %) and C14 : 0 (5.7 %). Polar lipid analysis revealed five different glycolipids, two unidentified phospholipids and diphosphatidylglycerol. The peptidoglycan was of the type A4α l-Lys–d-Asp with the presence of d(l)-alanine, d-glutamine, d-asparagine and l-lysine. The DNA G+C content of strain M8T was 50.1 mol%. On the basis of genetic, phylogenetic and phenotypic data, strain M8T represents a novel species of the genus Alloscardovia for which the name Alloscardovia macacae sp. nov. is proposed. The type strain is M8T ( = DSM 24762T = CCM 7944T). In addition, our results also revealed that Alloscardovia omnicolens DSM 21503T and Metascardovia criceti DSM 17774T do not belong to different genera within the family Bifidobacteriaceae . We therefore propose to reclassify Metascardovia criceti as Alloscardovia criceti comb. nov. An emended description of the genus Alloscardovia is also provided.

Identification, quantification and subtyping of Gardnerella vaginalis in noncultured clinical vaginal samples by quantitative PCR

Gardnerella vaginalis is an important component of the human vaginal microflora. It is proposed to play a key role in the pathogenesis of bacterial vaginosis (BV), the most common vaginal condition. Here we describe the development, validation and comparative analysis of a novel molecular approach capable of G. vaginalis identification, quantification and subtyping in noncultured vaginal specimens. Using two quantitative PCR (qPCR) assays, we analysed G. vaginalis bacterial loads and clade distribution in 60 clinical vaginal-swab samples. A very high pathogen prevalence was revealed by species-specific qPCR not only among BV patients (100 %), but also in healthy women (97 %), although the G. vaginalis concentration was significantly lower in non-BV samples. G. vaginalis clades identified in vaginal specimens by subtyping multiplex qPCR, which targets four clade-specific genetic markers, had frequencies of 53 % for clade 1, 25 % for clade 2, 32 % for clade 3 and 83 % for clade 4. Multiple clades were found in 70 % of samples. Single G. vaginalis clades were represented by clade 1 and clade 4 in 28 % of specimens. A positive association with BV was shown for clade 1 and clade 3, while clade 2 was positively associated with intermediate vaginal microflora, but not with BV. Clade 4 demonstrated no correlation with the disorder. The presence of multiple clades had a high positive association with BV, whereas G. vaginalis identified as a single clade was negatively linked with the condition. Polyclonal G. vaginalis infection may be a risk factor for BV.

Bacterial vaginosis diagnosed by analysis of first-void-urine specimens

Bacterial vaginosis (BV) is traditionally diagnosed using vaginal samples. The aim of this study was to investigate whether BV can be diagnosed from first-void urine (FVU). Self-collected vaginal smears, vaginal swabs, and FVU were obtained from 176 women. BV was diagnosed by Nugent's criteria. The FVU and vaginal swabs were analyzed by quantitative PCRs (qPCRs) for selected vaginal bacteria (Atopobium vaginae, Prevotella spp., Gardnerella vaginalis, bacterial vaginosis-associated bacterium 2, Eggerthella-like bacterium, "Leptotrichia amnionii," Megasphaera type 1), and all had an area under the receiver operating characteristic (ROC) curve of >85%, suggesting good prediction of BV according to the Nugent score. All seven bacteria in FVU were significantly associated with BV in univariate analysis. An accurate diagnosis of BV from urine was obtained in this population by a combination of qPCRs for Megasphaera type 1 and Prevotella spp. The same two bacteria remained significantly associated with BV in a multivariate model after adjusting for the other five species. There was no statistically significant difference between the sensitivities and specificities of BV diagnosis by molecular methods performed on swabs and FVU samples. A linear regression analysis showed good agreement between bacterial loads from swabs and FVU, but Prevotella spp. could be detected in high numbers in a few FVU samples without being present in swabs. This method will allow diagnosis of BV in studies where only urine has been collected and where detection of BV is considered relevant.

Genetic and biochemical diversity of Gardnerella vaginalis strains isolated from women with bacterial vaginosis

Gardnerella vaginalis is considered a substantial player in the progression of bacterial vaginosis (BV). We analysed 17 G. vaginalis strains isolated from the genital tract of women diagnosed with BV to establish a potential link between genotypes/biotypes and the expression of virulence factors, vaginolysin (VLY) and sialidase, which are assumed to play a substantial role in the pathogenesis of BV. Amplified ribosomal DNA restriction analysis revealed two G. vaginalis genotypes. Gardnerella vaginalis isolates of genotype 2 appeared more complex than genotype 1 and were subdivided into three subtypes. Biochemical typing allowed us to distinguish four different biotypes. A great diversity of the level of VLY production among the isolates of G. vaginalis may be related to a different cytotoxicity level of the strains. We did not find any correlation between VLY production level and G. vaginalis genotype/biotype. In contrast, a link between G. vaginalis genotype and sialidase production was established. Our findings on the diversity of VLY expression level in different clinical isolates and linking sialidase activity with the genotype of G. vaginalis could help to evaluate the pathogenic potential of different G. vaginalis strains.

Generation of recombinant single-chain antibodies neutralizing the cytolytic activity of vaginolysin, the main virulence factor of Gardnerella vaginalis

Background

Gardnerella vaginalis is identified as the predominant colonist of the vaginal tract in women with bacterial vaginosis. Vaginolysin (VLY) is a protein toxin released by G. vaginalis. VLY possesses cytolytic activity and is considered as a main virulence factor of G. vaginalis. Inhibition of VLY-mediated cell lysis by antibodies may have important physiological relevance.

Results

Single-chain variable fragments of immunoglobulins (scFvs) were cloned from two hybridoma cell lines producing neutralizing antibodies against VLY and expressed as active proteins in E. coli. For each hybridoma, two variants of anti-VLY scFv consisting of either VL-VH or VH-VL linked with a 20 aa-long linker sequence (G₄S)₄ were constructed. Recovery of scFvs from inclusion bodies with subsequent purification by metal-chelate chromatography resulted in VLY-binding proteins that were predominantly monomeric. The antigen-binding activity of purified scFvs was verified by an indirect ELISA. The neutralizing activity was investigated by in vitro hemolytic assay and cytolytic assay using HeLa cell line. Calculated apparent K_d values and neutralizing potency of scFvs were in agreement with those of parental full-length antibodies. VH-VL and VL-VH variants of scFvs showed similar affinity and neutralizing potency. The anti-VLY scFvs derived from hybridoma clone 9B4 exhibited high VLY-neutralizing activity both on human erythrocytes and cervical epithelial HeLa cells.

Conclusions

Hybridoma-derived scFvs with VLY-binding activity were expressed in E. coli. Recombinant anti-VLY scFvs inhibited VLY-mediated cell lysis. The monovalent scFvs showed reduced affinity and neutralizing potency as compared to the respective full-length antibodies. The loss of avidity could be restored by generating scFv constructs with multivalent binding properties. Generated scFvs is the first example of recombinant single-chain antibodies with VLY-neutralizing activity produced in prokaryote expression system. G. vaginalis caused infections continue to be a world-wide problem, therefore neutralizing recombinant antibodies may provide novel therapeutic agents useful in the treatment of bacterial vaginosis and other diseases caused by G. vaginalis.