Association of Bacterial Vaginosis With Chlamydia and Gonorrhea Among Women in the U.S. Army

Deciphering Intermediate Nugent scores: Utility of Real-time PCR for Bacterial Vaginosis diagnosis

PURPOSE

To optimize real-time PCR assays for diagnosis of Bacterial Vaginosis (BV) and determine cut-off loads by ROC analysis for Gardnerella vaginalis, Atopobium vaginae and Lactobacillus spp. as compared to Nugent scoring (Gold standard) in clinical samples.

RESULTS

Out of 125 women, 34 were positive, 26 intermediate and 65 negative for BV by Nugent scoring. All three real-time PCR assays were found to be highly sensitive & specific and AUC suggested excellent diagnostic accuracy. An optimal cut-off was >9.45 × 103 copies/ ml, >3.34 × 103 copies/ ml & ≤ 18.63 × 103 copies/ ml for G. vaginalis, A. vaginae and Lactobacillus spp. respectively, in BV positives. Gram staining and qPCR were discordant only in patients with intermediate scores (n = 26) where qPCR identified 15 (57.69%) as positive and 11 (42.3%) as negative.

CONCLUSION

PCR-based molecular BV diagnosis is more accurate and can be used for deciphering intermediate Nugent scores.

Association of Chlamydia trachomatis burden with the vaginal microbiota, bacterial vaginosis, and metronidazole treatment

Bacterial vaginosis (BV), a dysbiosis of the vaginal microbiota, is a common coinfection with Chlamydia trachomatis (Ct), and BV-associated bacteria (BVAB) and their products have been implicated in aiding Ct evade natural immunity. Here, we determined if a non-optimal vaginal microbiota was associated with a higher genital Ct burden and if metronidazole, a standard treatment for BV, would reduce Ct burden or aid in natural clearance of Ct infection. Cervicovaginal samples were collected from women at enrollment and, if testing positive for Ct infection, at a follow-up visit approximately one week later. Cervical Ct burden was assessed by inclusion forming units (IFU) and Ct genome copy number (GCN), and 16S rRNA gene sequencing was used to determine the composition of the vaginal microbiota. We observed a six-log spectrum of IFU and an eight-log spectrum of GCN in our study participants at their enrollment visit, but BV, as indicated by Amsel's criteria, Nugent scoring, or VALENCIA community state typing, did not predict infectious and total Ct burden, although IFU : GCN increased with Amsel and Nugent scores and in BV-like community state types. Ct burden was, however, associated with the abundance of bacterial species in the vaginal microbiota, negatively with Lactobacillus crispatus and positively with Prevotella bivia. Women diagnosed with BV were treated with metronidazole, and Ct burden was significantly reduced in those who resolved BV with treatment. A subset of women naturally cleared Ct infection in the interim, typified by low Ct burden at enrollment and resolution of BV. Abundance of many BVAB decreased, and Lactobacillus increased, in response to metronidazole treatment, but no changes in abundances of specific vaginal bacteria were unique to women who spontaneously cleared Ct infection.

Resident microbes shape the vaginal epithelial glycan landscape

Epithelial cells are covered in carbohydrates (glycans). This glycan coat or "glycocalyx" interfaces directly with microbes, providing a protective barrier against potential pathogens. Bacterial vaginosis (BV) is a condition associated with adverse health outcomes in which bacteria reside in direct proximity to the vaginal epithelium. Some of these bacteria, including Gardnerella, produce glycosyl hydrolase enzymes. However, glycans of the human vaginal epithelial surface have not been studied in detail. Here, we elucidate key characteristics of the "normal" vaginal epithelial glycan landscape and analyze the impact of resident microbes on the surface glycocalyx. In human BV, glycocalyx staining was visibly diminished in electron micrographs compared to controls. Biochemical and mass spectrometric analysis showed that, compared to normal vaginal epithelial cells, BV cells were depleted of sialylated N- and O-glycans, with underlying galactose residues exposed on the surface. Treatment of primary epithelial cells from BV-negative women with recombinant Gardnerella sialidases generated BV-like glycan phenotypes. Exposure of cultured VK2 vaginal epithelial cells to recombinant Gardnerella sialidase led to desialylation of glycans and induction of pathways regulating cell death, differentiation, and inflammatory responses. These data provide evidence that vaginal epithelial cells exhibit an altered glycan landscape in BV and suggest that BV-associated glycosidic enzymes may lead to changes in epithelial gene transcription that promote cell turnover and regulate responses toward the resident microbiome.

Natural Clearance of Chlamydia trachomatis Infection Is Associated With Distinct Differences in Cervicovaginal Metabolites

BACKGROUND

Natural clearance of Chlamydia trachomatis in women occurs in the interval between screening and treatment. In vitro, interferon-γ (IFN-γ)-mediated tryptophan depletion results in C. trachomatis clearance, but whether this mechanism occurs in vivo remains unclear. We previously found that women who naturally cleared C. trachomatis had lower cervicovaginal levels of tryptophan and IFN-γ compared to women with persisting infection, suggesting IFN-γ-independent pathways may promote C. trachomatis clearance.

METHODS

Cervicovaginal lavages from 34 women who did (n = 17) or did not (n = 17) naturally clear C. trachomatis were subjected to untargeted high-performance liquid chromatography mass-spectrometry to identify metabolites and metabolic pathways associated with natural clearance.

RESULTS

In total, 375 positively charged metabolites and 149 negatively charged metabolites were annotated. Compared to women with persisting infection, C. trachomatis natural clearance was associated with increased levels of oligosaccharides trehalose, sucrose, melezitose, and maltotriose, and lower levels of indoline and various amino acids. Metabolites were associated with valine, leucine, and isoleucine biosynthesis pathways.

CONCLUSIONS

The cervicovaginal metabolome in women who did or did not naturally clear C. trachomatis is distinct. In women who cleared C. trachomatis, depletion of various amino acids, especially valine, leucine, and isoleucine, suggests that amino acids other than tryptophan impact C. trachomatis survival in vivo.

Prevalence of and risk factors for chlamydia in female outpatients with genital tract infections: a nationwide multi-center, cross-sectional study in China

Introduction

Chlamydia trachomatis is the etiological agent of the commonest sexually transmitted bacterial infection. This study aimed to examine the prevalence of genital chlamydia and associated risk factors in Chinese female outpatients with genital tract infections.

Methods

A prospective, multicenter epidemiological study of genital chlamydia prevalence in 3008 patients with genital tract infections in 13 hospitals in 12 provinces of China was performed between May 2017 and November 2018. Vaginal secretion specimens were collected for the clinical diagnosis of vaginitis, whereas cervical secretion specimens were tested for Chlamydia trachomatis and Neisseria gonorrhoeae. All patients participated in a one-on-one cross-sectional questionnaire interview.

Results

Totally 2,908 participants were included. The prevalence rates of chlamydia and gonococcal infections in women with genital tract infections were 6.33% (184/2908) and 0.01% (20/2908), respectively. Multivariate analysis showed high risk factors for chlamydia were premarital sex behavior, first sexual intercourse before the age of 20 and bacterial vaginosis.

Discussion

Given that most chlamydia cases are asymptomatic and no vaccine is currently available, chlamydia prevention strategies should include behavioral interventions as well as early screening programs to identify and treat individuals with genital tract infections, especially those with the above identified risk factors.

Effect of a combination of pea protein, grape seed extract and lactic acid in an in vivo model of bacterial vaginosis

Bacterial vaginosis (BV) is a common vaginal dysbiosis characterized by a malodorous discharge and irritation. The imbalance of the vaginal microbiota plays a key role in the development of BV. It has been demonstrated that Gardnerella vaginalis (GV), a facultative anaerobic bacillus, is involved in BV. Due to the rising number of antimicrobial-resistant species, recurrence of BV is becoming more frequent in women; thus, alternative treatments to antibiotics are needed. Natural substances have recently shown a great efficacy for the treatment of vaginal dysbiosis. Thus, this study aimed to investigate the beneficial effect of a product containing pea protein (PP), grape seed extract (GS) and lactic acid (LA) in an in vivo model of Gardnerella vaginalis-induced vaginosis by intravaginal administration of GV suspension (1 × 10⁶ CFU/20 µL saline). Our results demonstrated that the product containing PP, GS and LA significantly reduced GV proliferation. More specifically, it significantly preserved tissue architecture and reduced neutrophil infiltration, inflammatory markers and sialidase activity when used both as a pre- or a post-treatment. Moreover, the product displayed strong bioadhesive properties. Therefore, our data suggested that the product containing PP, GS and LA could be used as alternative preventive or curative treatment for the management of BV.

Neisseria gonorrhoeae Infection in Women Increases With Rising Gonococcal Burdens in Partners: Chlamydia Coinfection in Women Increases Gonococcal Burden

BACKGROUND

Likelihood of Neisseria gonorrhoeae infection in women exposed to male sex partners with increasing N. gonorrhoeae burdens and enhancement by Chlamydia trachomatis is not defined.

METHODS

We identified men with urethritis and their regular female sex partners. Exposure to N. gonorrhoeae burdens in men was compared in N. gonorrhoeae-infected versus -uninfected partners. Association of N. gonorrhoeae infection in women with burdens in male partners was estimated using logistic regression. Association of C. trachomatis coinfection and N. gonorrhoeae burdens in women adjusted for burdens in male partners was estimated by linear regression.

RESULTS

In total, 1816 men were enrolled; 202 had ≥2 partners, 91 who confirmed monogamy and were enrolled; 77% were married. Seventy were partners of N. gonorrhoeae-infected men; 58 (83%) were N. gonorrhoeae infected, 26 (45%) C. trachomatis coinfected. Infected women had partners with 9.3-fold higher N. gonorrhoeae burdens than partners of uninfected women (P = .0041). Association of N. gonorrhoeae infection in women with upper quartiles of N. gonorrhoeae burdens in partners increased (odds ratios ≥ 2.97)compared to the first quartile (P = .032). N. gonorrhoeae burdens in C. trachomatis-coinfected women were 2.82-fold higher than in C. trachomatis-uninfected women (P = .036).

CONCLUSIONS

N. gonorrhoeae infections increased in women whose partners were infected with higher N. gonorrhoeae burdens. C. trachomatis coinfection was associated with increased N. gonorrhoeae burdens in women.

Bacterial Vaginosis and Associated Factors Among Pregnant Women Attending Antenatal Care in Harar City, Eastern Ethiopia

Background

Bacterial vaginosis is one of the most common causes of abnormal vaginal discharge in women of reproductive age, especially pregnant women. It is characterized by the decrement of lactobacilli and increasing proliferation of diverse anaerobic bacteria. The prevalence of bacterial vaginosis and contributing factors vary between countries, within the same country, and among different populations.

Objective

The purpose of this study was to determine the prevalence of bacterial vaginosis and associated factors among pregnant women attending antenatal care from May 5-July 15, 2021 in health-care facilities found in Harar town, eastern Ethiopia.

Methods and Materials

An institutional-based cross-sectional study was conducted among 248 pregnant women attending antenatal care through systematic random sampling. Data were collected using a structured questionnaire and two vaginal swabs were collected using sterile swabs and transported to the microbiology laboratory. Samples were analyzed using Amsel's criteria or using Nugent scoring criteria and culture. Data were entered into EpiData version 3.1 and transferred to SPSS version 25 for analysis. Binary logistic regression was used to identify variables associated with bacterial vaginosis. P-value <0.05 was considered statistically significant.

Results

Altogether 248 pregnant women were included in the study. Overall, 21.4% (95% CI: 16, 27) of study participants had bacterial vaginosis. History of sexually transmitted infection (AOR = 6.0, 95% CI: 1.94, 19.07; P = 0.002), history of spontaneous abortion (AOR = 5.8, 95% CI: 1.55, 22.02; P = 0.009), multiple sex partners (AOR = 8.6, 95% CI: 2.93, 25.79; P = 0.000) and having vaginal discharge (AOR = 5.5, 95% CI: 2.48, 12.41; P = 0.000) were significantly associated with bacterial vaginosis.

Conclusion

The prevalence of bacterial vaginosis is higher among symptomatic pregnant women and associated with a history of sexually transmitted infection, vaginal discharge, multiple sexual partners and spontaneous abortion.

Research Progress on the Correlation Between Gardnerella Typing and Bacterial Vaginosis

Bacterial vaginosis (BV) is the most common infectious disease of the reproductive tract in women of childbearing age. It often manifests as an imbalance in the vaginal microbiome, including a decrease in Lactobacillus and an increase in anaerobic bacteria. While Gardnerella spp. are considered a major cause of BV, they are also detected in the vaginal microbiome of healthy women. G. vaginalis was the only recognized species of Gardnerella until a recent study characterized three new species, G. leopoldii, G. piotii, and G. swidsinskii. This review describes the different types and genetic diversity of Gardnerella, as well as new findings on the correlation between different Gardnerella spp. and BV.

Astodrimer sodium and bacterial vaginosis: a mini review

Bacterial vaginosis (BV) is the most common vaginal infection affecting women of childbearing age, and is associated with a substantial burden on women’s physical, emotional, sexual and social lives, as well as being linked to a number of gynaecological and obstetrical complications and adverse pregnancy outcomes. Antibiotics, such as metronidazole or clindamycin, are recommended as first-line treatment for BV, but may be associated with antibiotic resistance, high rates of recurrence and poor patient treatment satisfaction. Astodrimer sodium gel is a novel, non-antibiotic treatment for BV that is not systemically absorbed. It prevents pathogenic bacteria from adhering to the vaginal wall, and disrupts and inhibits the formation of pathogenic bacterial biofilms. Clinical cure rates of 50–57% were observed in patients with BV treated with astodrimer sodium compared with 17–21% treated with placebo (p < 0.001) in Phase 3 trials. In a separate Phase 3 trial, recurrence of BV occurred in 44% of patients treated with astodrimer sodium compared with 54% of patients who received placebo (p = 0.015). Astodrimer sodium is well tolerated, with vulvovaginal candidosis being the only treatment-related adverse event reported to occur more often than with placebo. The availability of astodrimer sodium, a well-tolerated, convenient, non-antibiotic treatment for BV, represents significant progress in the treatment of this burdensome condition.

Cervicovaginal Microbiota Predicts Neisseria gonorrhoeae Clinical Presentation

Neisseria gonorrhoeae infection of the female lower genital tract can present with a spectrum of phenotypes ranging from asymptomatic carriage to symptomatic cervical inflammation, or cervicitis. The factors that contribute to the development of asymptomatic or symptomatic infections are largely uncharacterized. We conducted a pilot study to assess differences in the cervicovaginal microbial community of patients presenting with symptomatic vs. asymptomatic N. gonorrhoeae infections to a sexually transmitted infections (STI) clinic. DNA was isolated from cervicovaginal swab specimens from women who tested positive for N. gonorrhoeae infection using a clinical diagnostic nucleic acid amplification test. We performed deep sequencing of 16S ribosomal RNA gene amplicons, followed by microbiome analyses with QIIME, and species-specific real-time PCR to assess the composition of microbial communities cohabitating the lower genital tract with the infecting N. gonorrhoeae. Specimens collected from asymptomatic individuals with N. gonorrhoeae infection and no co-infection with Chlamydia trachomatis and/or Trichomonas vaginalis carried Lactobacillus-dominant microbial communities more frequently than symptomatic patients without co-infection. When compared to asymptomatic individuals, symptomatic women had microbial communities characterized by more diverse and heterogenous bacterial taxa, typically associated with bacterial vaginosis (BV) [Prevotella, Sneathia, Mycoplasma hominis, and Bacterial Vaginosis-Associated Bacterium-1 (BVAB1)/"Candidatus Lachnocurva vaginae"]. Both symptomatic and asymptomatic N. gonorrhoeae patients with additional STI co-infection displayed a BV-like microbial community. These findings suggest that Lactobacillus-dominant vaginal microbial community may protect individuals from developing symptoms during lower genital tract infection with N. gonorrhoeae.

The Microbiome as a Key Regulator of Female Genital Tract Barrier Function

The microbiome, the collection of microbial species at a site or compartment, has been an underappreciated realm of human health up until the last decade. Mounting evidence suggests the microbiome has a critical role in regulating the female genital tract (FGT) mucosa's function as a barrier against sexually transmitted infections (STIs) and pathogens. In this review, we provide the most recent experimental systems and studies for analyzing the interplay between the microbiome and host cells and soluble factors with an influence on barrier function. Key components, such as microbial diversity, soluble factors secreted by host and microbe, as well as host immune system, all contribute to both the physical and immunologic aspects of the FGT mucosal barrier. Current gaps in what is known about the effects of the microbiome on FGT mucosal barrier function are compared and contrasted with the literature of the gut and respiratory mucosa. This review article presents evidence supporting that the vaginal microbiome, directly and indirectly, contributes to how well the FGT protects against infection.

Hookworm Infections and Sociodemographic Factors Associated With Female Reproductive Tract Infections in Rural Areas of the Central Region of Togo

Female reproductive tract infections (FRTIs) have a huge impact on women’s health including their reproductive health in rural areas. Immunomodulation by helminth infections could influence the occurrence of FRTIs. This study aimed to investigate the association between FRTIs, hookworm infections, and sociodemographic factors in six rural areas of the central region of Togo. A semi-structured questionnaire was used to collect sociodemographical information, and parasitological assessments were used to diagnose helminth infections. Moreover, cytobacteriological examination of vaginal swabs was performed for the diagnosis of candidiasis and bacterial vaginosis (BV), and real-time PCR method was used to determine sexually transmitted infections (STIs). Finally, a logistic regression analysis was performed to assess the relationship and association of these factors to FRTIs. The prevalence of FRTIs was 82.3% including STIs (74.38%), BV (31.79%), and vulvovaginal candidiasis (9.85%). In detail, FRTIs were caused by bacteria such as Ureaplasma parvum (50%), Ureaplasma urealyticum (26.5%), and Mycoplasma hominis (17.5%) and viruses such us cytomegalovirus (5%) and human papilloma virus (HPV) (20%). No cases of Haemophilus ducreyi, Treponema pallidum, or varicella-zoster virus (VZV) were observed. Interestingly, women who had hookworm infections were at high risk of HPV. The use of condoms was a protective factor [adjusted odds ratio (aOR) = 0.23; 95% CI [0.11–0.51)], while the use of contraceptive methods was a risk factor [aOR = 2.49; 95% CI (1.19–5.19)] for STIs. The risk of BV was lower among participants who had more than four pregnancies [aOR = 0.27; 95% CI (0.11–0.65)]. Furthermore, women who had ever been paid for sexual intercourse were at high probability risk of vulvovaginal candidiasis [aOR = 16.92; 95% CI (1.46–196.48)]. This study highlighted risk factors associated with FRTIs, the control of which would help to reduce the incidence of these diseases. Health-care professionals could develop education and sensitization strategies based on these risk factors, and anti-hookworm treatment concepts may be taken into consideration to minimize the risk of HPV infections.

Vaginal Microbiota of the Sexually Transmitted Infections Caused by Chlamydia trachomatis and Trichomonas vaginalis in Women with Vaginitis in Taiwan

The three most common sexually transmitted infections (STIs) are Chlamydia trachomatis (CT), Neisseria gonorrhoeae (GC) and Trichomonas vaginalis (TV). The prevalence of these STIs in Taiwan remains largely unknown and the risk of STI acquisition affected by the vaginal microbiota is also elusive. In this study, a total of 327 vaginal swabs collected from women with vaginitis were analyzed to determine the presence of STIs and the associated microorganisms by using the BD Max CT/GC/TV molecular assay, microbial cultures, and 16S rRNA sequencing. The prevalence of CT, TV, and GC was 10.8%, 2.2% and 0.6%, respectively. A culture-dependent method identified that Escherichia coli and Streptococcus agalactiae (GBS) were more likely to be associated with CT and TV infections. In CT-positive patients, the vaginal microbiota was dominated by L. iners, and the relative abundance of Gardnerella vaginalis (12.46%) was also higher than that in TV-positive patients and the non-STIs group. However, Lactobacillus spp. was significantly lower in TV-positive patients, while GBS (10.11%), Prevotella bivia (6.19%), Sneathia sanguinegens (12.75%), and Gemella asaccharolytica (5.31%) were significantly enriched. Using an in vitro co-culture assay, we demonstrated that the growth of L. iners was suppressed in the initial interaction with TV, but it may adapt and survive after longer exposure to TV. Additionally, it is noteworthy that TV was able to promote GBS growth. Our study highlights the vaginal microbiota composition associated with the common STIs and the crosstalk between TV and the associated bacteria, paving the way for future development of health interventions targeting the specific vaginal bacterial taxa to reduce the risk of common STIs.

Sexually Transmitted Infections in U.S. Military Women: A Scoping Review 2000-2018

PURPOSE

High rates of sexually transmitted infections (STIs) have been documented among U.S. military servicemembers. The purpose of this scoping review is to evaluate the literature to determine what is known about the risk factors, preventive measures, and health outcomes regarding STIs among active duty servicewomen.

METHODS

A search of six bibliographic databases and the grey literature identified articles published from January 1, 2000, to December 31, 2018. A two-level review process was used to evaluate the inclusion of articles.

RESULTS

Fifty-six articles were included. The majority of studies (n = 47) were descriptive (95%). The primary STIs of focus were chlamydia (66%) and gonorrhea (38%), with a lesser focus on herpes simplex virus 1 and 2 (17%) and syphilis (11%). There were no studies on chancroid or pubic lice. Chlamydia and gonorrhea were highly prevalent. Age, race, and gender were nonmodifiable risk factors, whereas behaviors, beliefs, socioeconomic level, marital status, and concomitant or repeat infections were modifiable risk factors. Educational programs and studies evaluating efficacious STI prevention methods were lacking. STI diagnoses occurred in servicewomen at their home stations as well as in deployed settings.

CONCLUSION

STIs remain an ongoing public health challenge with insufficient research to guide military and health care leaders. Future research should focus on prospective designs that leverage identified risk factors and at-risk populations where the most impact can be made to promote reproductive health.

Female warfighters' perceptions of urogenital health in operational settings

BACKGROUND

An increased incidence in hygiene-related urogenital infections (bacterial vaginitis, vulvovaginal candidiasis, and urinary tract) has been reported in female warfighters serving in austere environments with decreased availability of water and sanitation resources, and when personal safety outweighs concerns for hygiene. Knowledge and access to an innovative kit designed for the female warfighter to self-test, self-identify, and self-treat common urogenital symptoms is critical to force health.

PURPOSE

The purpose of this descriptive, cross-sectional, exploratory qualitative study was to explore female warfighters': 1) confidence in seeking sex-specific health care in field and deployment environments and 2) acceptance and willingness to self-test, self-identify, and self-treat urogenital symptoms and infections.

METHODOLOGICAL ORIENTATION

Qualitative data for this thematic analysis were collected during administration of the Military Women's Readiness Urogenital Health Questionnaire. Participants provided open-ended comments associated with three survey questions. Braun and Clarke's inductive thematic analysis method guided the narrative analysis.

SAMPLE

Our sample included a diverse group of US Army women (USAW; n = 152) from a large, military installation.

RESULTS

Narratives and themes demonstrate USAW's desire and need for the availability of a self-test and self-treatment kit. Access, time, mission, and prevention of self-harm by quicker resolve of symptoms are cited as key reasons in support of such a kit.

CONCLUSIONS AND PRACTICE IMPLICATIONS

Nurse practitioners (NPs) are ideally positioned to provide sex-specific educational interventions and anticipatory guidance that supports physical health, to include urogenital conditions. As urogenital self-testing becomes available for female warfighters, NPs are the model healthcare provider for educating women on their use.

The Complex Link between the Female Genital Microbiota, Genital Infections, and Inflammation

The female genital tract microbiota is part of a complex ecosystem influenced by several physiological, genetic, and behavioral factors. It is uniquely linked to a woman's mucosal immunity and plays a critical role in the regulation of genital inflammation. A vaginal microbiota characterized by a high abundance of lactobacilli and low overall bacterial diversity is associated with lower inflammation. On the other hand, a more diverse microbiota is linked to high mucosal inflammation levels, a compromised genital epithelial barrier, and an increased risk of sexually transmitted infections and other conditions. Several bacterial taxa such as Gardnerella spp., Prevotella spp., Sneathia spp., and Atopobium spp. are well known to have adverse effects; however, the definitive cause of this microbial dysbiosis is yet to be fully elucidated. The aim of this review is to discuss the multiple ways in which the microbiota influences the overall genital inflammatory milieu and to explore the causes and consequences of this inflammatory response. While there is abundant evidence linking a diverse genital microbiota to elevated inflammation, understanding the risk factors and mechanisms through which it affects genital health is essential. A robust appreciation of these factors is important for identifying effective prevention and treatment strategies.

Bacterial Vaginosis and Sexually Transmitted Infections in an HIV-Positive Cohort

The World Health Organization (WHO) and the Joint United Nations Programme on HIV and AIDS (UNAIDS) suggest that sexually transmitted infection (STI) surveillance should include other genital infections and not only human immunodeficiency virus (HIV). To monitor the concomitance of bacterial vaginosis (BV) and STIs in HIV-seropositive (HIV+) and HIV-seronegative (HIV–) patients, a prospective study was conducted in a cohort of 349 volunteers at a clinic specializing in treating STIs in Mexico City. Microbiological and molecular methods were used to detect STIs and dysbiosis in HIV+ and HIV– individuals. The prevalence of infection was higher in HIV+ (69.28%) than in HIV– (54.87%) individuals. BV was the most frequent infection in HIV+ individuals, and polymicrobial infections were 3 times more common in HIV+ individuals than in HIV– individuals (31.48 vs. 10.98%). Behaviors documented in a self-administered questionnaire included low condom use frequency in HIV+ individuals co-infected with BV or a STI. This finding highlights the importance of surveillance using routine microbiological evaluations for the correct management of genital infections in HIV+ patients because in the presence of HIV, the clinical presentations, courses, and therapeutic responses of some STIs can differ from those in patients without HIV infection.

The Female Vaginal Microbiome in Health and Bacterial Vaginosis

The vaginal microbiome is an intricate and dynamic microecosystem that constantly undergoes fluctuations during the female menstrual cycle and the woman’s entire life. A healthy vaginal microbiome is dominated by Lactobacillus which produce various antimicrobial compounds. Bacterial vaginosis (BV) is characterized by the loss or sharp decline in the total number of Lactobacillus and a corresponding marked increase in the concentration of anaerobic microbes. BV is a highly prevalent disorder of the vaginal microbiota among women of reproductive age globally. BV is confirmed to be associated with adverse gynecologic and obstetric outcomes, such as sexually transmitted infections, pelvic inflammatory disease, and preterm birth. Gardnerella vaginalis is the most common microorganism identified from BV. It is the predominant microbe in polymicrobial biofilms that could shelter G. vaginalis and other BV-associated microbes from adverse host environments. Many efforts have been made to increase our understanding of the vaginal microbiome in health and BV. Thus, improved novel and accurate diagnosis and therapeutic strategies for BV have been developed. This review covers the features of vaginal microbiome, BV, BV-associated diseases, and various strategies of diagnosis and treatment of BV, with an emphasis on recent research progresses.

Current and emerging pharmacotherapy for recurrent bacterial vaginosis

INTRODUCTION

Given the frequency of recurrent bacterial vaginosis (RBV), enhancing treatment and preventing recurrence have become the central target of pharmacotherapy today. Antimicrobial failure is occurring at a time when knowledge of pathogenesis of bacterial vaginosis (BV) and RBV is incomplete, limiting rational treatment modification.

AREAS COVERED

The current manuscript reviews pathogenesis of RBV and the performance of available antimicrobials as well as attempts employed to enhance activity and pharmacologic strategies to reduce BV recurrence and refractory vaginal disease. The authors also provide their expert perspectives on the subject area, including their outlook for the future.

EXPERT OPINION

In the face of an empty pipeline of new antibiotics, strategies have emerged to enhance existing antibiotic efficacy, which include modifying drug dose, treatment duration, long-term prophylactic regimens, and use of biofilm disrupting agents. It is likely that future effective therapy will include several simultaneous and consecutive treatment components, including combinations of antibiotics, antibiofilm agents, and probiotics. Measures to prevent sexual transmission and reinfection are also essential.

Bacterial vaginosis and its association with infertility, endometritis, and pelvic inflammatory disease

Bacterial vaginosis, pelvic inflammatory disease, and endometritis are infections of the genital tract that can lead to many adverse health outcomes, including infertility. Bacterial vaginosis is characterized by a lower prevalence of lactobacilli and a higher prevalence of anaerobic bacteria, including Gardnerella vaginalis, Megasphaera spp., and Atopobium vaginae. Endometritis and pelvic inflammatory disease are caused by the ascension of pathogenic bacteria to the uterus, although the mechanisms by which they do so are unclear. Bacterial vaginosis, chronic endometritis, and pelvic inflammatory disease have been linked to infertility in retrospective and prospective trials. Similarly, the causes of bacterial vaginosis and endometritis-related infertility are likely multifactorial and stem from inflammation, immune targeting of sperm antigens, the presence of bacterial toxins, and increased risk of sexually transmitted infections. Diagnosis and treatment of bacterial vaginosis, chronic endometritis, and pelvic inflammatory disease before attempting conception may be important components of preconceptional care for symptomatic women to improve outcomes of natural and assisted reproduction.

[Sexually transmissible infections in African-descendant women in maroon communities in Brazil: prevalence and associated factors]

The study aimed to estimate the prevalence of sexually transmissible infections (STIs) and associated factors in women in quilombola (maroon) communities in Brazil. This was a population-based cross-sectional study of quilombola women from March 2017 to January 2019. A questionnaire was used with sociodemographic, behavioral, and clinical information. A gynecological examination was performed for the collection of uterine cervical cells for oncotic cytology and the detection of Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and human papillomavirus (HPV) via polymerase chain reaction. Rapid tests for HIV and syphilis were performed. The main outcome was defined as infection with one or more sexually transmissible pathogens. The analysis used chi-square test and hierarchical logistic regression. From a total of 380 women, 352 (92.6%) were included in the study. Prevalence of at least one STI was 18.5% (95%CI: 14.76-22.85). The highest prevalence was for HPV, with 11.1%, followed by 6.3% for T. vaginalis and 4.3% for C. trachomatis. There were no cases of N. gonorrhoeae. Prevalence was 0.3% for HIV and 4.3% for syphilis. Cervical-vaginal cytology was altered in 7.7% of the women. Detection of one or more STIs was significantly associated with age 25 to 44 years (OR = 2.33; 95%CI: 1.05-5.18), alcohol consumption (OR = 1.96; 95%CI: 1.06-3.64), altered cervical cytology (OR = 3.96; 95%CI: 1.65-9.48), and bacterial vaginosis (OR = 3.61; 95%CI: 2.01-6.47). Quilombola women showed high prevalence of one or more STIs, emphasizing the importance of organizing prevention strategies targeted to these women.

Nanophotonic Sialidase Immunoassay for Bacterial Vaginosis Diagnosis

Bacterial vaginosis (BV) affects reproductive-age women and can lead to pelvic inflammatory disease, postpartum endometritis, and preterm labor/delivery and predisposes the infection of sexually transmitted diseases. Typically, BV diagnosis involves the analysis of vaginal swab samples via microscopy operated by highly skilled personnel. Hence, novel approaches for BV diagnosis are an existing need. In response, the first immunosensing platform targeting sialidase, a BV biomarker, is reported. The nanophotonic operational principle of this biosensing platform allows for a cheaper, faster, and simpler analysis when compared with an indirect enzyme-linked immunosorbent assay (ELISA). The clinical evaluation of such a nanotechnology is highlighted, where 162 vaginal swab samples were analyzed with high sensitivity and specificity (96.29%, respectively). The resulting nanoimmunosensing platform offers a resourceful approach to perform a timely BV diagnosis.

Factors associated with sexually transmitted infection diagnosis in women who have sex with women, women who have sex with men and women who have sex with both

INTRODUCTION

Many US women report same sex behaviour, yet data on risk factors and STIs in women who have sex with women (WSW), women who have sex with both men and women (WSB) and how these compare to women who have sex with men only (WSM) remain limited. Here we compared self-identified WSW, WSB and WSM attending two STI clinics in Baltimore, Maryland.

METHODS

This was a retrospective analysis using a database of first clinic visits 2005-2016. WSW and WSB were compared with an age-matched random sample of WSM. Proportions were compared using the χ² test. Acute STI (aSTI) was defined as gonorrhoea (Neisseria gonorrhoeae, GC), chlamydia (Chlamydia trachomatis, CT), trichomonas (Trichomonas vaginalis, TV) or early syphilis. Logistic regression was used to assess aSTI predictors. CT testing was not uniformly done, so a sensitivity analysis removing CT from the aSTI definition was conducted.

RESULTS

Visits from 1095 WSW, 1678 WSB and 2773 WSM were analysed. WSB had equal or higher test positivity for all STIs except urogenital chlamydia, had more sexual partners, were more likely to engage in transactional sex and were more likely to report drug use and binge drinking than WSM (p≤0.01). WSW had lower test positivity for urogenital GC and CT than WSM or WSB, but comparable test positivity for TV, higher reported binge drinking and comparable reported substance use as WSM. Younger age and cocaine use predicted STI diagnosis only in WSM.

CONCLUSIONS

WSB in these clinics bear an equal or higher burden of most STIs, have more partners and report more substance use than WSM. WSW carry a lower, but still substantial burden of STIs, and many report substance use. Factors predicting STI diagnosis differ between WSW, WSB and WSM suggesting that tailored STI prevention and testing approaches are needed in these groups.

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 Vaginosis: Current Diagnostic Avenues and Future Opportunities

A healthy female genital tract harbors a microbiome dominated by lactic acid and hydrogen peroxide producing bacteria, which provide protection against infections by maintaining a low pH. Changes in the bacterial compositions of the vaginal microbiome can lead to bacterial vaginosis (BV), which is often associated with vaginal inflammation. Bacterial vaginosis increases the risk of acquiring sexually transmitted infections (STIs) like human immunodeficiency virus (HIV) and affects women's reproductive health negatively. In pregnant women, BV can lead to chorioamnionitis and adverse pregnancy outcomes, including preterm premature rupture of the membranes and preterm birth. In order to manage BV effectively, good diagnostic procedures are required. Traditionally clinical and microscopic methods have been used to diagnose BV; however, these methods require skilled staff and time and suffer from reduced sensitivity and specificity. New diagnostics, including highly sensitive and specific point-of-care (POC) tests, treatment modalities and vaccines can be developed based on the identification of biomarkers from the growing pool of vaginal microbiome and vaginal metabolome data. In this review the current and future diagnostic avenues will be discussed.

Antimicrobial Susceptibility Testing of Metronidazole and Clindamycin against Gardnerella vaginalis in Planktonic and Biofilm Formation

Background

Bacterial vaginosis (BV), one of the most common vaginal ecosystem-related microbiologic syndromes, is the most common disorder in women of reproductive age. Gardnerella (G.) vaginalis is the predominant species causing this infection. Our aim was to compare the antimicrobial susceptibilities of metronidazole and clindamycin against G. vaginalis at planktonic and biofilm levels.

Methods

From September 2019 to October 2019, we recruited a total of 10 patients with BV who underwent gynecological examinations at Beijing Obstetrics and Gynecology Hospital. G. vaginalis isolates were obtained from the vagina and identified using their characteristic colony morphology. Sequence data of clinical G. vaginalis isolates were confirmed by comparing 16S rDNA sequences. Subsequently, clinical isolates were evaluated for antimicrobial susceptibilities in vitro to metronidazole and clindamycin at planktonic and biofilm levels. The minimum inhibitory concentration (MIC) for metronidazole and clindamycin was evaluated by antimicrobial susceptibility testing. The minimum biofilm eradication concentration (MBEC) was evaluated by the biofilm inhibition assay.

Results

Planktonic clinical isolates showed a significantly higher susceptibility rate (76.67%) and lower resistance rate (23.33%) to clindamycin than to metronidazole (susceptibility rate: 38.24%; resistance rate: 58.82%; P < 0.05 for both). Furthermore, in comparison to planktonic isolates, the minimum inhibitory concentration (MIC) of metronidazole was significantly higher for biofilm-forming isolates (7.3 ± 2.6 μg/mL vs. 72.4 ± 18.3 μg/mL; P=0.005); the resistance rate was 27.3%, and the minimum biofilm eradication concentration (MBEC) was >128 μg/mL. Moreover, the MIC of clindamycin was higher too for biofilm-forming isolates (0.099 ± 0.041 μg/mL vs. 23.7 ± 9.49 μg/mL; P=0.034); the resistance rate was 27.3%, and the MBEC of clindamycin was 28.4 ± 6.50 μg/mL.

Conclusion

Our results indicate that in comparison to metronidazole, clindamycin seems to be a better choice to tackle G. vaginalis as it exhibits a relatively higher susceptibility rate and lower resistance rate.

Molecular-based Testing for Sexually Transmitted Infections Using Samples Previously Collected for Vaginitis Diagnosis

Background

Vaginal symptoms are a leading cause of primary care visits for women. Individuals exhibiting symptoms often receive laboratory testing based on clinic-specific standards of care. Thus, women seen at a family practice clinic might only receive a vaginitis workup, whereas those seen at a sexually transmitted diseases clinic could be more likely to receive only sexually transmitted infection (STI) testing.

Methods

The likelihood of STIs was assessed in women from whom samples were tested for vaginitis using a molecular diagnostic assay. Positivity rates for Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis DNA, detected using the BD MAX CT/GC/TV assay, were calculated. Concordance between the BD MAX Vaginal Panel and the BD MAX CT/GC/TV assay for detection of T. vaginalis was determined.

Results

Women with bacterial vaginosis alone or with concurrent Candida spp infections had high rates of coinfection with sexually transmitted infections (24.4%–25.7%); samples from women who were negative for vaginitis had significantly lower positivity rates (7.9%; P < .001). Trichomonas vaginalis results were concordant between the BD MAX Vaginal Panel and the BD MAX CT/GC/TV assay in 559 of 560 samples tested.

Conclusions

These data suggest, as have other studies, that women with vaginitis symptoms may be at risk for an STI. Molecular testing could provide broad diagnostic coverage for symptomatic women and improve patient management, regardless of the type of clinic in which patients are treated.

Bacterial vaginosis and surgical site infections

Bacterial vaginosis is the most common cause of abnormal vaginal discharge or malodor, affecting up to one third of US women. Most women with bacterial vaginosis are unaware of the infection, making it difficult to diagnose in the absence of a microscopic examination of vaginal discharge or using point-of-care testing. Untreated bacterial vaginosis elevates the risk of postoperative surgical infections in women undergoing obstetric and gynecological procedures. Treatment with antimicrobial agents that target bacterial vaginosis has been shown to reduce the rate of postoperative infections following hysterectomy and surgical abortions. Furthermore, in a cost-comparison model, screening for and treatment of bacterial vaginosis prior to hysterectomy was shown to be superior to no screening in terms of infection rates and cost. The bacterial vaginosis diagnostic criteria are simple and screening tests are inexpensive; bacterial vaginosis screening is a relatively fast process in patients who present for preoperative appointments. Treatment options approved by the Food and Drug Administration include metronidazole, clindamycin, tinidazole, and secnidazole. Given the prevalence of bacterial vaginosis and the risks associated with operating on a woman with untreated bacterial vaginosis, women undergoing hysterectomy, surgical abortion, and potentially cesarean delivery should be screened for bacterial vaginosis, and those who screen positive should be treated with an appropriate antimicrobial agent.

Bacterial vaginosis-A brief synopsis of the literature

Bacterial vaginosis (BV) affects women of reproductive age and can either be symptomatic or asymptomatic. Approximately 50 % of women are symptomatic and experience vaginal malodor, discharge, itching and increased vaginal pH. BV can increase the risk of contracting many sexually transmitted infections (STIs) such as human immunodeficiency virus (HIV), Neisseria gonorrhea (NG), Chlamydia trachomatis (CT), Trichomonas vaginalis (TV) and herpes simplex virus-2 (HSV-2). Though effective treatment options do exist, metronidazole or clindamycin, these methods have proven not to be effective long term. The purpose of this review is to summarize current literature on the epidemiology of BV and highlight areas of deficiency in current clinical practice with respect to BV. BV recurrence rates are high, approximately 80 % three months after effective treatment. Furthermore, in some instances treatment is ineffective and BV persists. Literature also documents the relationship between BV and human papillomavirus (HPV). HPV is the most common sexually transmitted infection among young adult women while BV is the most common cause of vaginal symptoms among women of reproductive age. BV is associated with high levels of anaerobic organisms which can damage the vaginal epithelium and increase the risk of HPV infection. Recent research also highlights the role of the vaginal microbiome in BV. The results of this review warrant further exploration into the etiology of BV as well as exploration of more long-term effective treatment and the investigation of prognostic indicators. Additionally, the need for a standard definition of recurrent and persistent BV is recognized.

Comparative analysis of the vaginal microbiome of pregnant women with either Trichomonas vaginalis or Chlamydia trachomatis

Background

Although the significance of the human vaginal microbiome for health and disease is increasingly acknowledged, there is paucity of data on the differences in the composition of the vaginal microbiome upon infection with different sexually transmitted pathogens.

Method

The composition of the vaginal bacterial community of women with Trichomonas vaginalis (TV, N = 18) was compared to that of women with Chlamydia trachomatis (CT, N = 14), and to that of controls (N = 21) (women negative for TV, CT and bacterial vaginosis). The vaginal bacterial composition was determined using high throughput sequencing with the Ion 16S metagenomics kit of the variable regions 2, 4 and 8 of the bacterial 16S ribosomal RNA gene from the vaginal swab DNA extract of the women. QIIME and R package “Phyloseq” were used to assess the α- and β-diversity and absolute abundance of the 16S rRNA gene per sample in the three groups. Differences in taxa at various levels were determined using the independent T-test.

Results

A total of 545 operational taxonomic units (OTUs) were identified in all the three groups of which 488 occurred in all three groups (core OTUs). Bacterial α-diversity, by both Simpson’s and Shannon’s indices, was significantly higher, (p = 0.056) and (p = 0.001) respectively, among women with either TV or CT than among controls (mean α-diversity TV-infected > CT-infected > Controls). At the genus level, women infected with TV had a significantly (p < 0.01) higher abundance of Parvimonas and Prevotella species compared to both controls and CT-infected women, whereas women infected with CT had a significantly (p < 0.05) higher abundance of Anaerococcus, Collinsella, Corynebacterium and Dialister.

Conclusion

The vaginal microbiomes of TV and CT-infected women were markedly different from each other and from women without TV and CT. Future studies should determine whether the altered microbiomes are merely markers of disease, or whether they actively contribute to the pathology of the two genital infections.

Diversity of endocervical microbiota associated with genital Chlamydia trachomatis infection and infertility among women visiting obstetrics and gynecology clinics in Malaysia

The cervical microbiota constitutes an important protective barrier against the invasion of pathogenic microorganisms. A disruption of microbiota within the cervical milieu has been suggested to be a driving factor of sexually transmitted infections. These include Chlamydia trachomatis which frequently causes serious reproductive sequelae such as infertility in women. In this study, we profiled the cervical microbial composition of a population of 70 reproductive-age Malaysian women; among which 40 (57.1%) were diagnosed with genital C. trachomatis infection, and 30 (42.8%) without C. trachomatis infection. Our findings showed a distinct compositional difference between the cervical microbiota of C. trachomatis-infected subjects and subjects without C. trachomatis infection. Specifically, significant elevations of mostly strict and facultative anaerobes such as Streptococcus, Megasphaera, Prevotella, and Veillonella in the cervical microbiota of C. trachomatis-positive women were detected. The results from the current study highlights an interaction of C. trachomatis with the environmental microbiome in the endocervical region.

Molecular epidemiology of bacterial vaginosis and its association with genital micro-organisms in asymptomatic women

Introduction. Bacterial vaginosis (BV) is dysbiosis associated with an increased risk of several sexually transmitted infections. It is primarily diagnosed via Gram staining, although molecular analyses have presented higher diagnostic accuracy.Aim. This study aimed to evaluate the molecular epidemiology of BV in asymptomatic women to determine its association with several commensal and pathogenic micro-organisms of the genitalia.Methodology. The prevalence of BV was investigated through semiquantitative assessment of 201 women recruited during their routine gynaecological inspection at an outpatient clinic in Tabasco, Mexico.Results. Women with BV showed an increased prevalence of Chlamydia trachomatis (P=0.021) and Mycoplasma hominis (P=0.001). Of the BV-associated micro-organisms, Gardnerella vaginalis was significantly associated with C. trachomatis (P=0.005) and/or Ureaplasma parvum (P=0.003), whereas Atopobium vaginae and Megasphaera type 1 correlated significantly with Mycoplasma hominis (P=0.001). No significant association was observed between human papillomavirus (HPV) infection and BV, although there was increased prevalence of HPV59, HPV73, HPV52 and HPV58 in women displaying cervical cytological abnormalities.Conclusion. Identification of BV-associated micro-organisms via molecular analysis may help to distinguish recurrent cases from new infections and identify micro-organisms potentially associated with pharmacological resistance.

Longitudinal association of gonorrhea and bacterial vaginosis with repeat chlamydia diagnoses among U.S. Army women: a retrospective cohort analysis

BACKGROUND

Historically, sexually transmitted infections have affected the health of the U.S. military. To determine whether gonorrhea, bacterial vaginosis, genital herpes, and trichomoniasis are predictors of repeat chlamydia diagnoses among U.S. Army women, medical data reported into the Defense Medical Surveillance System during the 2006-2012 period were analyzed.

METHODS

For all inpatient and outpatient medical records, the first and second International Classification of Diseases, version 9 (ICD-9) diagnostic positions were reviewed for each chlamydia case to determine the occurrence of repeat diagnoses. The Andersen-Gill regression model, an extension of the Cox model for multiple failure-time data, was used to study associations between predictors and repeat chlamydia diagnoses.

RESULTS

Among 28,201 women with a first chlamydia diagnosis, 5145 (18.2%), 1163 (4.1%), 267 (0.9%), and 88 (0.3%) had one, two, three, and four or more repeat diagnoses, respectively. Overall, the incidence of repeat chlamydia was 8.31 cases per 100 person-years, with a median follow-up time of 3.39 years. Gonorrhea (hazard ratio (HR) = 1.58, 95% CI: 1.44-1.73) and bacterial vaginosis (HR = 1.40, 95% CI: 1.09-1.79) were significant predictors for repeat chlamydia. These estimated hazard ratios were attenuated, but remained significant, after controlling for age, race/ethnicity, marital status, and military rank. No significant association was found for genital herpes (HR = 1.13, 95% CI: 0.55-2.29) and trichomoniasis (HR = 1.43, 95% CI: 0.43-4.68).

CONCLUSIONS

This large cohort study suggests that gonorrhea and bacterial vaginosis were associated with repeat chlamydia diagnoses among U.S. Army women. These findings can be used in formulating new interventions to prevent repeat chlamydia diagnoses.

In vitro activity of Spirulina platensis water extract against different Candida species isolated from vulvo-vaginal candidiasis cases

The high incidence of vulvo-vaginal candidiasis, combined with the growing problems about azole resistance and toxicity of antifungal drugs, highlights the need for the development of new effective strategies for the treatment of this condition. In this context, natural compounds represent promising alternatives. The cyanobacterium Spirulina platensis, a blue-green alga, exhibits antimicrobial activities against several microorganisms. Nevertheless, only few data about the antifungal properties of Spirulina platensis are available and its potential toxic effects have not been largely investigated. The aim of this study was to evaluate the in vitro activity of a fully-characterized water extract of Spirulina platensis against 22 strains of Candida spp. Prior to considering its potential topical use, we both investigated whether the extract exerted target activities on guinea pig uterine smooth muscle, and the impact of Spirulina platensis on the dominant microorganisms of the vaginal microbiota (i.e., lactobacilli), in order to exclude possible adverse events. By means of a broth microdilution assay, we found that the microalga extract possesses good antifungal properties (MIC: 0.125-0.5 mg/ml), against all the Candida species with a fungicidal activity. At the concentrations active against candida, Spirulina platensis did not modify the spontaneous basic waves pattern of uterine myometrium as underlined by the absence of aberrant contractions, and did not affect the main health-promoting bacteria of the vaginal ecosystem. Finally, we evaluated the selectivity index of our extract by testing its cytotoxicity on three different cell lines and it showed values ranging between 2 and 16. Further in vivo studies are needed, in particular to evaluate the use of control-release formulations in order to maintain Spirulina platensis concentrations at anti-Candida active doses but below the toxic levels found in the present work.