Bacterial vaginosis-associated microflora and effects of topical intravaginal clindamycin

Organism diversity between women with and without bacterial vaginosis as determined by polymerase chain reaction denaturing gradient gel electrophoresis and 16S rRNA gene sequence

AIMS

The aim of this study was to characterize the different structures of microbial communities between 20 healthy women and 17 bacterial vaginosis (BV)-positive women of reproductive age using denaturing gradient gel electrophoresis (DGGE).

MATERIAL AND METHODS

Vaginal samples from 17 BV-positive and 20 BV-negative women were subjected to DNA extraction, and amplified with eubacterial 16S rRNA gene-specific primers via polymerase chain reaction. The polymerase chain reaction products were separated using DGGE. Bands were excised, re-amplified, purified and sequenced. DNA sequences were compared with GenBank database. Phylip software packages were used to calculate sequencing data and form a phylogenetic tree to identify the genetic relations for microbiota inhabited in vaginal ecosystems of BV-positive women.

RESULTS

In total, 28 kinds of organisms were detected that comprised BV(+) vagina microbial community, varying from three to nine kinds with an average of 5.71 kinds per woman. Only seven species were detected in BV(-) women, ranging between one and five species with an average of 2.40 species per woman, which was significantly lower than that detected in BV(+) women (t = 7.39, P < 0.001). A strain of Uncultured Lactobacillus sp. clone EHFS1_S05c (29/37; 78.38%) was most commonly presented in both BV-negative and BV-positive women, but the mean proportion of this Lactobacillus sp. strain to the whole microbial population colonized in the vaginal tract of BV(-) women was sharply higher than that calculated from BV(+) women (t = 2.92, P < 0.01).

CONCLUSIONS

The findings indicate further diversity in the category of vaginal microorganisms associated with BV. The presence of Gardnerella vaginalis is not necessary as a sign for gynecologists to determine whether or not a woman is affected by BV.

Treatment options for bacterial vaginosis in patients at high risk of preterm labor and premature rupture of membranes

AIM

To estimate the efficacy of different therapeutic modalities on proven cases of bacterial vaginosis (BV) in patients at high risk of preterm labor and premature rupture of membranes.

METHODS

This was a longitudinal prospective comparative study set in the antenatal outpatient clinic of the department of Obstetrics and Gynecology, Faculty of Medicine, Assiut University, Assiut, Egypt. Four hundred and sixty-eight patients with a clinical picture of threatened preterm labor or at high risk of premature rupture of membranes in the third trimester were screened for BV. Positive BV was diagnosed in 156 patients. They were randomly classified into four equal groups according to the line of medical treatment. The treatments were: (i) oral metronidazole, (ii) clindamycin vaginal cream, (iii) oral clindamycin, or (iv) metronidazole vaginal suppositories. The effects of medical treatment on Amsel's criteria as well as maternal and fetal outcomes were measured.

RESULTS

Based on Amsel's criteria, 156 patients (33.3%) were diagnosed with BV. There was a significant disappearance of vaginal discharge, with decreased percentages of pH > 4.5, positive amine test, and clue cells after treatment of BV in the four groups without any statistically significant difference between them. There were variable effects of the different treatments on increasing birthweight values, admission to neonatal intensive care units, and prolongation of the gestational age. Some maternal adverse effects have been recorded. There were significant improvements of the outcomes for oral metronidazole and clindamycin compared with outcomes for intravaginal metronidazole and clindamycin.

CONCLUSIONS

Metronidazole and clindamycin achieve nearly equivalent cure rates when administered orally or vaginally in patients at high risk of preterm labor and premature rupture of membranes. Oral metronidazole is considered the drug of choice in treating BV due its high cure rate, better outcomes, and low cost.

Transurethral ultrasonography-guided injection of adult autologous stem cells versus transurethral endoscopic injection of collagen in treatment of urinary incontinence

In the last years preclinical studies have paved the way for the use of adult muscle derived stem cells for reconstruction of the lower urinary tract. Between September 2002 and October 2004, 42 women and 21 men suffering from urinary stress incontinence (age 36-84 years) were recruited and subsequently treated with transurethral ultrasonography-guided injections of autologous myoblasts and fibroblasts obtained from skeletal muscle biopsies. The fibroblasts were injected into the urethral submucosa, while the myoblasts were implanted into the rhabdosphincter. In parallel, 7 men and 21 women (age 39-83 years) also diagnosed with urinary stress incontinence were treated with standard transurethral endoscopic injections of collagen. Patients were randomly assigned to both groups. After a follow-up of 12 months incontinence was cured in 39 women and 11 men after injection of autologous myoblasts and fibroblasts. Mean quality of life score (51.38 preoperatively, 104.06 postoperatively), thickness of urethra and rhabdosphincter (2.103 mm preoperatively, 3.303 mm postoperatively) as well as contractility of the rhabdosphincter (0.56 mm preoperatively, 1.462 mm postoperatively) were improved postoperatively. Only in two patients treated with injections of collagen incontinence was cured. The present clinical results demonstrate that, in contrast to injections of collagen, urinary incontinence can be treated effectively with ultrasonography-guided injections of autologous myo- and fibroblasts.

Role of antibiotic therapy for bacterial vaginosis and intermediate flora in pregnancy

Bacterial vaginosis and intermediate flora are associated with late miscarriage and preterm delivery. The mechanisms involved are not yet fully understood. Clinical trials of antibiotic therapy to reduce these complications have yielded conflicting results. These trials, however, were conducted in mixed populations of pregnant women with variable risk profiles for preterm delivery. Furthermore, investigators used different criteria for diagnosis, treated with different antibiotics at different doses and via different routes, and initiated treatment at different gestational ages. Over 80% of pregnant women with abnormal vaginal flora have a good outcome, and in some populations the presence of bacterial vaginosis is not associated with preterm delivery, suggesting that other host factors may modify the risk. Recent studies have examined the roles of genetic regulation of host immune response, bacterial pathogenic factors, and enzymes in the vagina, and how these factors interact to drive a given outcome. These markers have the potential to better define the women at maximal risk and therefore guide future interventions. This chapter aims to appraise the current state of treatment of abnormal vaginal flora in pregnancy and suggest appropriate management based on the available evidence.

Molecular identification of bacteria associated with bacterial vaginosis

BACKGROUND

Bacterial vaginosis affects millions of women and is associated with several serious health conditions. The cause of bacterial vaginosis remains poorly understood despite numerous studies based on cultures. Bacteria in microbial communities can be identified without cultivation by characterizing their ribosomal DNA (rDNA) sequences.

METHODS

We identified bacteria in samples of vaginal fluid with a combination of broad-range polymerase-chain-reaction (PCR) amplification of 16S rDNA with clone analysis, bacterium-specific PCR assay of 16S rDNA, and fluorescence in situ hybridization (FISH) performed directly on vaginal fluid from 27 subjects with bacterial vaginosis and 46 without the condition. Twenty-one subjects were studied with the use of broad-range PCR of 16S rDNA, and 73 subjects were studied with the use of bacterium-specific PCR.

RESULTS

Women without bacterial vaginosis had 1 to 6 vaginal bacterial species (phylotypes) in each sample (mean, 3.3), as detected by broad-range PCR of 16S rDNA, and lactobacillus species were the predominant bacteria noted (83 to 100 percent of clones). Women with bacterial vaginosis had greater bacterial diversity (P<0.001), with 9 to 17 phylotypes (mean, 12.6) detected per sample and newly recognized species present in 32 to 89 percent of clones per sample library (mean, 58 percent). Thirty-five unique bacterial species were detected in the women with bacterial vaginosis, including several species with no close cultivated relatives. Bacterium-specific PCR assays showed that several bacteria that had not been previously described were highly prevalent in subjects with bacterial vaginosis but rare in healthy controls. FISH confirmed that newly recognized bacteria detected by PCR corresponded to specific bacterial morphotypes visible in vaginal fluid.

CONCLUSIONS

Women with bacterial vaginosis have complex vaginal infections with many newly recognized species, including three bacteria in the Clostridiales order that were highly specific for bacterial vaginosis.

Inhibition of vaginal lactobacilli by a bacteriocin-like inhibitor produced by Enterococcus faecium 62-6: potential significance for bacterial vaginosis

Objective: Bacterial vaginosis (BV) is characterized by a shift in vaginal tract ecology, which includes a decrease in the concentration and/or prevalence of facultative lactobacilli. Currently, mechanisms which could account for the disappearance of lactobacilli are not well understood. The objective of this study was to determine whether vaginal streptococci/enterococci can produce bacteriocin-like inhibitors antagonistic to vaginal lactobacilli.

Methods: Seventy strains of vaginal streptococci or enterococci were tested for antagonistic activities against vaginal lactobacilli using the deferred antagonism technique.

Results: One strain, Enterococcus faecium 62-6, which strongly inhibited growth of lactobacilli was selected for further characterization. The spectrum of inhibitory activity of strain 62-6 included Gram-positive organisms from the vaginal environment, although native lactobacilli from the same host were resistant to inhibitor action. Following growth inMRSbroth the strain 62-6 inhibitor was shown to be heat- (100℃, 30 minutes), cold- (4℃, less than 114 days) and pH- (4–7) stable. The sensitivity of inhibitor-containing supernatants to pepsin and α-chymotrypsin suggested an essential proteinaceous component. The inhibitor was sensitive to lipase but resistant to lysozyme. Dialysis of inhibitor-containing culture supernatants suggested a molecular mass greater than 12 000 Da. All physicochemical properties were consistent with its classification as a bacteriocin-like inhibitor. Kinetic assays demonstrated a sharp onset of inhibitor production coinciding with a concentration of 62-6 of 10⁷ cfu/ml, suggesting that production may be regulated by quorum sensing.

Conclusions: These results may have clinical significance as a novel mechanism to account for the decline of vaginal Lactobacillus populations and contribute to both the establishment and recurrence of BV.

Microbiology and management of polymicrobial female genital tract infections in adolescents

This review describes the microbiology and management of female genital tract infections in adolescents. These infections include vulvovaginitis, vulvovaginal pyogenic infections (abscesses of Bartholin's and Skene's glands, infected labial inclusion cysts, labial abscesses, furunculosis, and hidradenitis), endometritis, pyometritis, salpingitis, pelvic inflammatory disease, and tubo-ovarian and pelvic abscess. Anaerobes can be cultured in 50% to 90% of females with a variety of genital infections and are the exclusive isolates in 20% to 50%. Obligate anaerobes are particularly common in closed-space infections, such as tubo-ovarian and vulvovaginal abscesses. The most common anaerobes found in these infections are gram-negative bacilli (especially P. bivia and P. disiens) and anaerobic cocci. Anaerobes generally are not the only pathogens found, but are usually mixed with aerobes. The most common aerobic pathogens are members of the Enterobacteriaceae family, especially E. coli, and aerobic or microaerophilic streptococci. Sexually acquired infections include Neisseria gonorrhoeae, Gardnerella vaginalis, Trichomonas vaginalis, Chlamydia trachomatis, herpes simplex, and Condyloma accuminata. Treatment regimens must provide antimicrobial coverage for N gonorrhoeae, C trachomatis, anaerobes, streptococci, and gram-negative facultative bacteria.

Changes in the vaginal flora after two percent clindamycin vaginal cream in women at high risk of spontaneous preterm birth

OBJECTIVE

To analyse alterationS in the vaginal flora after 2% clindamycin vaginal cream or placebo administered for the prevention of preterm delivery in high risk women.

DESIGN

Observational study during a randomised multicentre double-blind placebo controlled trial.

SETTING

Twelve city hospitals in The Netherlands.

PARTICIPANTS

One hundred and sixty-eight women were enrolled. Alterations in the vaginal flora could be analysed in one hundred and twenty-four women by comparing the Nugent score on entry to the trial and at 31 weeks' gestation. The Nugent score was classified into normal, intermediate and bacterial vaginosis.

INTERVENTIONS

Two percent clindamycin vaginal cream or placebo cream administered daily for seven days at week 26 of pregnancy.

MAIN OUTCOME

Changes in the vaginal flora at week 31 of pregnancy.

RESULTS

The placebo group consisted of 64 women and the clindamycin group of 60 women. At week 31 the vaginal flora was similar to week 26 with placebo cream but changed from normal vaginal flora to intermediate or bacterial vaginosis with 2% clindamycin vaginal cream.

CONCLUSION

Obstetricians should not prescribe 2% clindamycin vaginal cream to pregnant women with normal vaginal flora in order to reduce the incidence of preterm birth. because it has no beneficial effects and is actually harmful. 2% Clindamycin vaginal cream encourages the presence of bacterial vaginosis which is epidemiologically associated with preterm birth.

The inhibitory effect of clindamycin on Lactobacillus in vitro

OBJECTIVE

To evaluate the in vitro effect of varying concentrations of clindamycin on Lactobocillus spp.

METHODS

Concentrations of clindamycin ranging from 1.95-20,000 microg/ml were studied for their effect on the growth of six strains of Lactobacillus.

RESULTS

Clindamycin concentrations between 1.95-31.25 microg/ml had no statistically significant effect on growth of lactobacilli (p > 0.05). Concentrations 125 and 250 microg/ml had a bacteriostatic effect. The mean minimum inhibitory concentration (MIC) for studied Lactobacillus strains was determined as 1,000 microg/ml.

CONCLUSION

High concentrations of clindamycin achieved in the vagina by intravaginal application might be inhibitory for Lactobacillus.

Effect of intravaginal clindamycin cream on pregnancy outcome and on abnormal vaginal microbial flora of pregnant women

OBJECTIVES

To determine whether intravaginal clindamycin cream reduces the incidence of abnormal pregnancy outcome in women with abnormal vaginal microbial flora graded as intermediate or BV and to investigate the effect of the antibiotic on vaginal microbial flora.

METHODS

A prospective cohort study of pregnant women in an antenatal clinic of a district general hospital. The subjects were 268 women who had abnormal vaginal microbial flora at first clinic visit by examination of a Gram-stained vaginal smear and 34 women with a normal vaginal flora. Two hundred and thirty-seven women were evaluable. Women with abnormal Gram-stained smears (graded as II or III) on clinic recall were randomised to receive treatment (intravaginal clindamycin cream) or placebo and followed to assess outcome of pregnancy, vaginal flora, and detection of Mycoplasma hominis and Ureaplasma urealyticum after treatment.

RESULTS

Abnormal outcomes of pregnancy were not significantly different in treated and placebo groups by Chi square (P = 0.2). However, women with grade III flora responded better to clindamycin than women with grade II flora by numbers of abnormal outcomes (P = 0.03) and return to normal vaginal flora (P = 0.01) (logistic regression analysis model). This may be due to differences in vaginal bacterial species in these grades. Women whose abnormal vaginal flora had spontaneously returned to normal on follow-up and were therefore not treated (revertants) had as many abnormal outcomes as placebos suggesting that damage by abnormal bacterial species occurred early in pregnancy.

CONCLUSIONS

Gram-stain screening distinguishing grade II from grade III flora may be helpful in prescribing treatment other than clindamycin for women with grade II flora. Earlier diagnosis and treatment may be more effective in preventing an abnormal outcome, possibly as soon as pregnancy is diagnosed or even offered as a pre-conception screen.

Isolation of Mobiluncus species from the human vagina

We report the results of a study concerning the characteristics of 52 strains of Mobiluncus spp. isolated from 982 vaginal secretions from patients with suspected bacterial vaginosis. 158 of these women presented the features of this bacterial infection. Of the strains isolated, 39 belonged to the species Mobiluncus curtisii, (25 of these which to M. curtisii subsp. curtisii and 14, to M. curtisii subsp. holmesii), and 13, to Mobiluncus mulieris. The vaginal isolates of Mobiluncus spp. were identified by comparing their biochemical profiles with those of the type strains M. curtisii subsp. holmesii (ATCC 35,242), M. curtisii subsp. curtisii (ATCC 35,241) and M. mulieris (ATCC 35,243). All strains of M. mulieris proved to be sensitive to the antimicrobial agents assayed, while strains of M. curtisii were seen to be resistant only to metronidazole.

Prophylactic administration of clindamycin 2% vaginal cream to reduce the incidence of spontaneous preterm birth in women with an increased recurrence risk: a randomised placebo-controlled double-blind trial

OBJECTIVE

To test the hypothesis that prophylactic administration of clindamycin 2% vaginal cream can reduce the incidence of preterm birth in a high risk population.

DESIGN

A multi-centre, randomised, double-blind, placebo-controlled trial.

SETTING

Twelve city hospitals in The Netherlands.

PARTICIPANTS

One hundred and sixty-eight women with a singleton pregnancy and a history of a spontaneous preterm delivery in the preceding pregnancy.

INTERVENTIONS

Clindamycin 2% vaginal cream, or placebo cream, administered daily for seven days at 26 and 32 weeks of gestation.

MAIN OUTCOME MEASURES

Spontaneous preterm birth at < 37 weeks, admission for threatened preterm labour, neonatal infectious morbidity.

RESULTS

In the intention-to-treat analysis no difference was found in overall preterm birth between clindamycin and placebo (23% vs 18%, respectively). In the subgroup who completed the trial and administered all medication, more women delivered before 34 weeks in the clindamycin group (1.4% in the placebo vs 9.0% in the clindamycin group; P < 0.05). The length of admissions for threatened preterm labour did not differ. More infectious neonatal morbidity was seen in the clindamycin group (5/83 vs 0/85; P < 0.05).

CONCLUSION

Clindamycin 2% vaginal cream given prophylactically to women with a spontaneous preterm birth in the preceding pregnancy did not prevent preterm delivery or reduce the number of admissions for threatened preterm labour. The neonatal infectious morbidity in the group treated with clindamycin was significantly higher and a major concern.

Preterm birth: associations with genital and possibly oral microflora

Opportunistic pathogenic microbes are indigenous to the female lower genital tract and etiologic in many types of pelvic infections and, apparently, a portion of preterm birth (PTB) cases. Bacterial vaginosis (BV) is a clinical syndrome based on an altered genital microflora in which Gardnerella vaginalis; anaerobic species primarily among Prevotella, Porphyromonas, Bacteroides, Peptostreptococcus, and Mobiluncus; Mycoplasma hominis; and Ureaplasma urealyticum become predominant in vaginal secretions. This BV complex of microbes, compared to a normal vaginal microflora dominated by facultative lactobacilli, is associated with significantly increased risks for preterm labor, preterm premature rupture of membranes, PTB, and other perinatal infectious complications. Pathogenetic mechanisms include an ascending route of infection and/or inflammatory process due to microbial products and maternal and/or fetal response(s) with production of prostaglandins and cytokines. In the presence of periodontal disease, oral opportunistic pathogens and/or their inflammatory products also may have a role in prematurity via a hematogenous route. Fusobacterium nucleatum, a common oral species, is the most frequently isolated species from amniotic fluid cultures among women with preterm labor and intact membranes. Also, the species and subspecies of fusobacteria identified from amniotic fluid most closely match those reported from healthy and diseased subgingival sites, namely F. nucleatum subspecies vincentii and F. nucleatum subspecies nucleatum, compared to strains identified from the lower genital tract. Although these fusobacteria also could be acquired through cunnilingus from a partner, new data associating maternal periodontal disease with preterm low birth weight taken with the isolation of F. nucleatum, Capnocytophaga, and other oral species from amniotic fluid support further study of a possible additional route, oral-hematogenous, to PTB.

Evaluation and management of vaginitis

OBJECTIVE

To evaluate recent advances in our understanding of the clinical relevance, diagnosis, and treatment of vaginal infections, and to determine an efficient and effective method of evaluating this clinical problem in the outpatient setting.

DATA SOURCES

Relevant papers on vaginitis limited to the English language obtained through a MEDLINE search for the years 1985 to 1997 were reviewed.

DATA SYNTHESIS

Techniques that enable the identification of the various strains of candida have helped lead to a better understanding of the mechanisms of recurrent candida infection. From this information a rationale for the treatment of recurrent disease can be developed. Bacterial vaginosis has been associated with complications, including upper genital tract infection, preterm delivery, and wound infection. Women undergoing pelvic surgery, procedures in pregnancy, or pregnant women at risk of preterm delivery should be evaluated for bacterial vaginosis to decrease the rate of complications associated with this condition. New, more standardized criteria for the diagnosis of bacterial vaginosis may improve diagnostic consistency among clinicians and comparability of study results. Use of topical therapies in the treatment of bacterial vaginosis are effective and associated with fewer side effects than systemic medication. Trichomonas vaginalis, although decreasing in incidence, has been associated with upper genital tract infection. Therapy of T. vaginalis infection has been complicated by an increasing incidence of resistance to metronidazole.

CONCLUSIONS

Vaginitis is a common medical problem in women that is associated with significant morbidity and previously unrecognized complications. Research in recent years has improved diagnostic tools as well as treatment modalities for all forms of vaginitis.

Gram-positive anaerobic cocci

Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms defined by their morphological appearance and their inability to grow in the presence of oxygen; most clinical isolates are identified to species in the genus Peptostreptococcus. GPAC are part of the normal flora of all mucocutaneous surfaces and are often isolated from infections such as deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections. They have been little studied for several reasons, which include an inadequate classification, difficulties with laboratory identification, and the mixed nature of the infections from which they are usually isolated. Nucleic acid studies indicate that the classification is in need of radical revision at the genus level. Several species of Peptostreptococcus have recently been described, but others still await formal recognition. Identification has been based on carbohydrate fermentation tests, but most GPAC are asaccharolytic and use the products of protein degradation for their metabolism; the introduction of commercially available preformed enzyme kits affords a physiologically more appropriate method of identification, which is simple and relatively rapid and can be used in routine diagnostic laboratories. Recent reports have documented the isolation in pure culture of several species, notably Peptostreptococcus magnus, from serious infections. Studies of P. magnus have elucidated several virulence factors which correlate with the site of infection, and reveal some similarities to Staphylococcus aureus. P. micros is a strongly proteolytic species; it is increasingly recognized as an important pathogen in intraoral infections, particularly periodontitis, and mixed anaerobic deep-organ abscesses. Comparison of antibiotic susceptibility patterns reveals major differences between species. Penicillins are the antibiotics of choice, although some strains of P. anaerobius show broad-spectrum beta-lactam resistance.

Intravaginal clindamycin treatment for bacterial vaginosis: effects on preterm delivery and low birth weight

OBJECTIVE

Our goal was to evaluate whether treatment of bacterial vaginosis during pregnancy with 2% clindamycin vaginal cream reduces the incidence of either preterm delivery or low birth weight or of both.

STUDY DESIGN

A multicenter, double-blind, randomized, placebo-controlled trial in Indonesia compared a 2% clindamycin vaginal cream with a placebo cream. Women seeking prenatal care at 14 to 26 weeks of gestational age who had bacterial vaginosis (Gram stain score > 6 and pH of vaginal fluid > 4.5) were invited to participate. Of the 745 women enrolled, 681 (91.4%) women were followed up through delivery.

RESULTS

Clindamycin vaginal cream was an effective treatment for bacterial vaginosis. Two weeks after completion of the treatment, 85.5% of the women were cured. The rate of preterm delivery (< 37 weeks) was 15.0% for clindamycin patients and 13.5% for placebo patients (odds ratio 1.1, 95% confidence interval 0.7 to 1.7). The rate of low birth weight was 9.0% for clindamycin patients and 6.8% for placebo patients (odds ratio 1.3, 95% confidence interval 0.8 to 2.4).

CONCLUSIONS

Treatment of bacterial vaginosis with clindamycin vaginal cream did not reduce preterm delivery or low birth weight. Although clindamycin vaginal cream is an effective treatment for bacterial vaginosis, intravaginal treatment would not be effective against bacterial vaginosis-associated microorganisms harbored in the upper genital tract. Systemic treatment may be required to eradicate upper tract infection to reduce preterm delivery.