In vitro activities of Garenoxacin (BMS 284756) against 108 clinical isolates of Gardnerella vaginalis

Gardnerella vaginalis population dynamics in bacterial vaginosis

Bacterial vaginosis (BV) is the leading cause of vaginal discharge and is associated with the facultative Gram-variable bacterium Gardnerella vaginalis, whose population structure consists of four clades. Our goal was to determine if these clades differ with regard to abundance during BV. We performed a short-term longitudinal study of BV. Patients were evaluated according to the Amsel criteria and Nugent scoring at initial diagnosis, immediately after treatment and at a 40- to 45-day follow-up visit. G. vaginalis clade abundance was determined by quantitative real-time polymerase chain reactions (qPCRs). Among all specimens, the abundance of clades 1 and 4 were higher than that of clades 2 and 3 (P < 0.001). In general, the abundance of each clade increased with the degree of vaginal dysbiosis, as determined by the Nugent score and was greater in women with Amsel 4 compared with those with Amsel 0. Only clade 1 abundance was greater when Amsel 0 or 1 specimens were compared with Amsel 2 or 3 specimens (P < 0.01). Following antimicrobial treatment, abundance of clades 1 (P < 0.001) and 4 (P < 0.05) decreased regardless of the clinical and microbiological outcome, whereas clade 2 only decreased in women who had a sustained treatment response for 40-45 days (P < 0.01). Recurrent BV was characterized by post-treatment increases of clade 1 and 2 (P < 0.01). Clades 1 and 4 predominate in vaginal specimens. Clade abundance differs with regard to the Nugent score, the Amsel criteria, and response to therapy and BV recurrence.

Utilization of molecular methods to identify prognostic markers for recurrent bacterial vaginosis

BACKGROUND

Recurrent bacterial vaginosis (BV) after antimicrobial therapy is a major problem, affecting >50% of patients within 1 year. The objective of this study was to determine if prospective identification of patients at risk for recurrence using molecular methods is feasible.

METHODS

Women were evaluated for BV by Amsel criteria and Nugent score. Vaginal specimens were analyzed using a panel of quantitative real-time polymerase chain reactions (qPCRs) at three times: pre-treatment, 7-10days post-treatment and 40-45days post-treatment. The PCRs quantified DNA of the following organisms: Gardnerella vaginalis; Atopobium vaginae; Bacterial Vaginosis-Associated Bacteria-1 (BVAB1), -2 (BVAB2) and -3 (BVAB3); Leptotrichia/Sneathia; Megasphaera Phylotypes 1 and 2; and Lactobacillus spp. (L. crispatus, L. gasseri, L. iners and L. jensenii).

RESULTS

Out of 84 women diagnosed with BV (Amsel ≥3 and Nugent ≥4), 77 (91.7%) were successfully treated after 7-10days (asymptomatic and Amsel of either 0 or 1 with elevated vaginal pH and Nugent ≤6). Of these 77 women, 46 (59.7%) remained cured after 40-45days and 31 (40.3%) developed recurrent BV. In univariate analysis, we found that women who would have recurrent BV during the study had greater concentrations of Megasphaera Phylotype 2 (P=0.001) and BVAB2 (P=0.015) at initial diagnosis and greater vaginal pH (P=0.030), higher Nugent score (P=0.043) and a greater concentration of G. vaginalis (P=0.012) post-treatment, when compared to women who were cured during the study. These differences largely remained when cure was defined as Nugent ≤3 or when only women treated with intravaginal metronidazole were evaluated.

CONCLUSION

Molecular analysis of BV is a useful adjunct to clinical and microscopic analysis to prospectively identify patients at high risk for recurrent BV.

Advances in the Prevention of Infection-Related Preterm Birth

Infection-related preterm birth (PTB) is more common at early gestational ages and is associated with major neonatal mortality and morbidity. Abnormal genital tract microflora in early pregnancy predicts late miscarriage and early PTB. Accordingly, it is logical to consider antibiotics as an intervention. Unfortunately, the conclusions of systematic reviews and meta-analyses (SR&MAs) carried out in an attempt to explain the confusion over the heterogeneity of individual studies are flawed by the fact that undue reliance was placed on studies which: (a) had a suboptimal choice of antibiotic (mainly metronidazole) or used antibiotics not recommended for the treatment of bacterial vaginosis (BV) or BV-related organisms; (b) used antibiotics too late in pregnancy to influence outcome (23–27 weeks); and (c) included women whose risk of PTB was not due to abnormal genital tract colonization and hence unlikely to respond to antibiotics. These risks included: (a) previous PTB of indeterminate etiology; (b) low weight/body mass index; or (c) detection of fetal fibronectin, ureaplasmas, Group B streptococcus or Trichomonas vaginalis). While individual studies have found benefit of antibiotic intervention for the prevention of PTB, in meta-analyses these effects have been negated by large methodologically flawed studies with negative results. As a result, many clinicians think that any antibiotic given at any time in pregnancy to any woman at risk of PTB will cause more harm than good. Recently, a more focused SR&MA has demonstrated that antibiotics active against BV-related organisms, used in women whose risk of PTB is due to abnormal microflora, and used early in pregnancy before irreversible inflammatory damage has occurred, can reduce the rate of PTB. This review presents those data, the background and attempts to explain the confusion using new information from culture-independent molecular-based techniques. It also gives guidance on the structure of putative future antibiotic intervention studies.

Draft Genome Sequence of a Metronidazole-Resistant Derivative of Gardnerella vaginalis Strain ATCC 14019

We report the genome sequence of a metronidazole-resistant derivative of Gardnerella vaginalis ATCC 14019. This strain was obtained after serial selection to increase the MIC from 4 to ≥500 µg/ml. Two coding changes, in genes encoding a response regulator and an NAD(+) synthetase, arose during selection.

Use of locally delivered dequalinium chloride in the treatment of vaginal infections: a review

Background

Vaginal infections are responsible for a large proportion of gynaecological outpatient visits. Those are bacterial vaginosis (BV), vulvovaginal candidosis (VVC), aerobic vaginitis (AV) associated with aerobic bacteria, and mixed infections. Usual treatments show similar acceptable short-term efficacy, but frequent recurrences and increasing microbial resistance are unsolved issues. Furthermore, vaginal infections are associated with a variety of serious adverse outcomes in pregnancy and generally have a major impact on quality of life. Identifying the correct therapy can be challenging for the clinician, particularly in mixed infections.

Findings

Dequalinium chloride (DQC) is an anti-microbial antiseptic agent with a broad bactericidal and fungicidal activity. Systemic absorption after vaginal application of DQC is very low and systemic effects negligible. Vaginal DQC (Fluomizin^®vaginal tablets) has been shown to have equal clinical efficacy as clindamycin in the treatment of BV. Its broad antimicrobial activity makes it appropriate for the treatment of mixed vaginal infections and in case of uncertain diagnosis. Moreover, resistance of pathogens is unlikely due to its multiple mode of action, and vaginal DQC provides also a reduced risk for post-treatment vaginal infections.

Conclusions

Vaginal DQC (10 mg) as 6-day therapy offers a safe and effective option for empiric therapy of different vaginal infections in daily practice. This review summarizes the available and relevant pharmacological and clinical data for the therapy of vaginal infections with vaginal DQC and provides the rationale for its use in daily gynaecologic practice.

Identification of intrinsically metronidazole-resistant clades of Gardnerella vaginalis

Gardnerella vaginalis is associated with bacterial vaginosis (BV), the most common cause of vaginal discharge. Metronidazole is a front-line therapy for BV, and treatment failure and recurrent disease are common problems. Whole-genome sequencing studies have revealed that G. vaginalis has a population structure that consists of 4 clades: clades 1 and 3 are associated with BV, whereas clades 2 and 4 are not. To determine if metronidazole susceptibility is associated with population structure, we analyzed 87 clinical isolates and found that metronidazole resistance (MIC ≥32 μg/mL) was highly associated with clade (P<0.0001), as 14/14 clade 3 isolates (100%) and 22/22 clade 4 isolates (100%) exhibited resistance, compared to only 16/37 clade 1 isolates (35%) and 1/14 clade 2 isolates (7.1%). The identification of intrinsically metronidazole-resistant G. vaginalis clades will facilitate future studies on the relationship between metronidazole resistance and BV treatment failure.

Draft Genome Sequence of a Metronidazole-Resistant Gardnerella vaginalis Isolate

We report the draft genome sequence of a Gardnerella vaginalis strain (3549624) isolated from a vaginal specimen. G. vaginalis is associated with bacterial vaginosis, the most common cause of vaginal discharge, which is often treated with metronidazole. This isolate is highly resistant to metronidazole (MIC, 500 µg/ml) and may be useful for comparative genomic studies to determine the molecular basis of metronidazole resistance in this species.

Bacterial vaginosis, Atopobium vaginae and nifuratel

As bacterial vaginosis (BV) is a potential cause of obstetric complications and gynecological disorders, there is substantial interest in establishing the most effective treatment. Standard treatment - metronidazole or clindamycin, by either vaginal or oral route � is followed by relapses in about 30% of cases, within a month from treatment completion. This inability to prevent recurrences reflects our lack of knowledge on the origins of BV. Atopobium vaginae has been recently reported to be associated with BV in around 80% of the cases and might be involved in the therapeutic failures. This review looks at the potential benefits of nifuratel against A. vaginae compared to the standard treatments with metronidazole and clindamycin. In vitro, nifuratel is able to inhibit the growth of A. vaginae, with a MIC range of 0.125-1 μg/mL; it is active against G. vaginalis and does not affect lactobacilli. Metronidazole is active against A. vaginae only at very high concentrations (8-256 μg/mL); it is partially active against G. vaginalis and also has no effect on lactobacilli. Clindamycin acts against A. vaginae with an MIC lower than 0.125 μg/mL and is active on G. vaginalis but it also affects lactobacilli, altering the vaginal environment. These observations suggest that nifuratel is probably the most valid therapeutic agent for BV treatment.

Treatment of abnormal vaginal flora in early pregnancy with clindamycin for the prevention of spontaneous preterm birth: a systematic review and metaanalysis

The purpose of this study was to determine whether the administration of clindamycin to women with abnormal vaginal flora at <22 weeks of gestation reduces the risk of preterm birth and late miscarriage. We conducted a systematic review and metaanalysis of randomized controlled trials of the early administration of clindamycin to women with abnormal vaginal flora at <22 weeks of gestation. Five trials that comprised 2346 women were included. Clindamycin that was administered at <22 weeks of gestation was associated with a significantly reduced risk of preterm birth at <37 weeks of gestation and late miscarriage. There were no overall differences in the risk of preterm birth at <33 weeks of gestation, low birthweight, very low birthweight, admission to neonatal intensive care unit, stillbirth, peripartum infection, and adverse effects. Clindamycin in early pregnancy in women with abnormal vaginal flora reduces the risk of spontaneous preterm birth at <37 weeks of gestation and late miscarriage. There is evidence to justify further randomized controlled trials of clindamycin for the prevention of preterm birth. However, a deeper understanding of the vaginal microbiome, mucosal immunity, and the biology of BV will be needed to inform the design of such trials.

In vitro activity of nifuratel on vaginal bacteria: could it be a good candidate for the treatment of bacterial vaginosis?

Bacterial vaginosis is characterized by a shift of the physiological flora to a diverse spectrum of bacteria, where Gardnerella vaginalis and Atopobium vaginae are the most important markers. In this study, the antimicrobial activity of nifuratel against G. vaginalis, A. vaginae, and lactobacilli was compared with that of the two currently used antibiotics metronidazole and clindamycin. Results suggest that nifuratel has a better spectrum of activity, being highly active against G. vaginalis and A. vaginae without affecting lactobacilli.

Periodontal disease and bacterial vaginosis as genetic and environmental markers for the risk of spontaneous preterm labor and preterm birth

OBJECTIVE

The aim of this study was to review the evidence associating periodontal disease, and bacterial vaginosis with preterm birth, and the link with gene polymorphism, as well as the preventions and interventions which might reduce the risk of spontaneous preterm labor and preterm births in women with periodontal disease and/or bacterial vaginosis.

BACKGROUND

Preterm birth accounts for 70% of perinatal mortality, nearly 50% of long term neurological morbidity, and a significant impact on health care costs. There is evidence that spontaneous preterm labor and preterm birth are associated with intrauterine infection due to abnormal genital and/or oral colonization. Periodontal disease and bacterial vaginosis share microbiological similarities, and both conditions are associated with spontaneous preterm labor and preterm birth. In addition, periodontal disease and bacterial vaginosis have been linked through gene polymorphism.

METHODS

A review of the literature using widely accepted scientific search engines in English language.

RESULTS

Studies evaluating antibiotic administration to eradicate periodontal disease and/or bacterial vaginosis responsible organisms, and minimize the risk of preterm births have yielded conflicting results. With respect to bacterial vaginosis, the timing and the choice of antibiotic administration might partly explain the conflicting results. The use of scaling and/or root planning for women with periodontal disease appears to reduce the risk of preterm birth, but routine administration of antibiotics has not demonstrated any impact on preterm birth.

CONCLUSION

Prospective studies evaluating the association of gene polymorphism with preterm birth, and the contribution of periodontal disease and bacterial vaginosis are needed.

[Bacterial vaginosis]

Bacterial vaginosis is a widely spread health problem with multiple connotations. It has been the subject of many studies and work during decades and it still remains a polemic entity, with contradictory finding. The polymicrobian etiology, unsolved epidemiology, obstetrico-gynecological complications and high recurrence rate following treatment, make this infection a target for researchers. It is not an inflammatory process -yet an immune response exists. In this disorder, vaginal discharge increases, and it is associated with a high risk of developing sexually transmitted diseases.

Antimicrobial resistance and the management of anaerobic infections

Management of anaerobic infections encompasses surgical procedures, antibacterial therapy and adjuncts. At present, metronidazole, penems, beta-lactam/beta-lactamase inhibitor combinations and chloramphenicol have the highest activity against obligate anaerobes. Tigecycline is a promising new agent. Other antibacterials (e.g., nitazoxanide, moxifloxacin, garenoxacin and ramoplanin) and nonantibiotic agents show potential but need further investigation. The patient's characteristics, mixed anaerobic/aerobic infections, infection sites, bacterial resistance patterns, bactericidal activity of agents and their pharmacokinetics, toxicity and influence on the normal flora should be considered. Susceptibility patterns of anaerobes have become less predictable owing to increasing antibacterial resistance. Emergence of highly virulent or multidrug-resistant strains is challenging the current therapy. To counteract these trends, regular resistance surveillance in anaerobes, rational antibiotic use and evaluation of new treatment alternatives are important.

Antibiotic susceptibility of Atopobium vaginae

Background

Previous studies have indicated that a recently described anaerobic bacterium, Atopobium vaginae is associated with bacterial vaginosis (BV). Thus far the four isolates of this fastidious micro-organism were found to be highly resistant to metronidazole and susceptible for clindamycin, two antibiotics preferred for the treatment of BV.

Methods

Nine strains of Atopobium vaginae, four strains of Gardnerella vaginalis, two strains of Lactobacillus iners and one strain each of Bifidobacterium breve, B. longum, L. crispatus, L. gasseri and L. jensenii were tested against 15 antimicrobial agents using the Etest.

Results

All nine strains of A. vaginae were highly resistant to nalidixic acid and colistin while being inhibited by low concentrations of clindamycin (range: < 0.016 μg/ml), rifampicin (< 0.002 μg/ml), azithromycin (< 0.016 – 0.32 μg/ml), penicillin (0.008 – 0.25 μg/ml), ampicillin (< 0.016 – 0.94 μg/ml), ciprofloxacin (0.023 – 0.25 μg/ml) and linezolid (0.016 – 0.125 μg/ml). We found a variable susceptibility for metronidazole, ranging from 2 to more than 256 μg/ml. The four G. vaginalis strains were also susceptible for clindamycin (< 0.016 – 0.047 μg/ml) and three strains were susceptible to less than 1 μg/ml of metronidazole. All lactobacilli were resistant to metronidazole (> 256 μg/ml) but susceptible to clindamycin (0.023 – 0.125 μg/ml).

Conclusion

Clindamycin has higher activity against G. vaginalis and A. vaginae than metronidazole, but not all A. vaginae isolates are metronidazole resistant, as seemed to be a straightforward conclusion from previous studies on a more limited number of strains.

INTRAVITREAL TOXICITY OF GARENOXACIN

PURPOSE

To assess the retinal toxicity of varying concentrations of intravitreally injected garenoxacin.

METHODS

Twenty eyes of 20 New Zealand albino rabbits were used for this study. The animals were anesthetized with ketamine (35-50 mg/kg) and xylazine (3-5 mg/kg). Garenoxacin was titrated using distilled water to the following concentrations: 4,000, 2,000, 1,000, 400, 200, and 100 microg/0.1 mL. Each concentration was injected intravitreally (0.1 mL) into three rabbit eyes. Three control eyes were injected with 0.1 mL of balanced saline solution. All animals were examined before and after injection by indirect ophthalmoscopy and slit-lamp biomicroscopy. Electroretinography was performed on all animals before intravitreal injection and 14 days after injection. The animals were examined by indirect ophthalmoscopy and slit-lamp biomicroscopy before they were killed; the eyes were enucleated and examined with light microscopy.

RESULTS

No electroretinographic changes or signs of retinal toxicity by slit-lamp examination, indirect ophthalmoscopy, or light microscopy were seen in any eyes 14 days after intravitreal injection of garenoxacin (< or =4,000 microg/0.1 mL).

CONCLUSIONS

Garenoxacin injected intravitreally appeared safe at concentrations of < or =4,000 microg/0.1 mL.

A preliminary survey of Atopobium vaginae in women attending the Dunedin gynaecology out-patients clinic: is the contribution of the hard-to-culture microbiota overlooked in gynaecological disorders?

Preliminary studies have indicated that the recently described bacterium Atopobium vaginae may have an association with bacterial vaginosis (BV). Fifty-five women attending the gynaecology out-patient's clinic were tested for the presence of this micro-organism, Gardnerella vaginalis, Mobiluncus and Bacteroides species by polymerase chain reaction (PCR)-based assays. The frequency of detection was 40%. PCR detection of Gardnerella vaginalis with A. vaginae, occurred in 50% of A. vaginae-positive cases. Due to the high detection rate of A. vaginae we believe that it is important to determine whether this and other hard-to-culture microorganisms have a role in gynaecological disorders.

Klinische Bedeutung der Antibiotikaresistenz in Gynäkologie und Geburtshilfe

Antibiotic resistance of microorganisms that cause infections of the urogenital tract is a clinically relevant problem in obstetrics and gynecology. Due to methodological difficulties, resistance testing is rarely used for the management of these infections. Therefore, solid epidemiological data on resistance rates of most involved pathogens are scarce. Antibiotic resistance of several microorganisms appears to be increasing in various areas of the world, mainly Trichomonas vaginalis and Gardnerella vaginalis (metronidazole),Streptococcus agalactiae (macrolides, clindamycin), Mycoplasma hominis (tetracyclines, intrinsically macrolide resistant). In addition,isolated cases of clinical infections caused by multi-resistant Chlamydia trachomatis have been reported. The presence of antibiotic resistance should therefore be considered in patients with an unfavorable course despite adequate antibiotic therapy. In light of the growing problem of antibiotic resistance and the large gaps in our knowledge in this particular area, research efforts in the field of anti-biotic resistance in gynecological infections should be markedly intensified.