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Predictors of Bacterial Vaginosis in Adolescent Women Who Douche

Schwebke, Jane R. MD*; Desmond, Renee A. PhD*; Oh, M Kim MD

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Sexually Transmitted Diseases: July 2004 - Volume 31 - Issue 7 - p 433-436
doi: 10.1097/01.OLQ.0000129948.91055.9F
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BACTERIAL VAGINOSIS (BV) is the most prevalent form of vaginitis, yet the etiology is unknown.1,2 Microbiologic changes consistent with BV include a decrease in the lactobacillus population, particularly those that produce hydrogen peroxide, and an increase in anaerobic and facultative anaerobic bacteria such as Gardnerella vaginalis, mycoplasma, Mobiluncus spp., and black-pigmented anaerobic rods.3–5 The most common diagnostic methods for BV include the clinical criteria of Amsel et al. and the Gram stain criteria of Nugent et al.1,6 Both sexual behavior and vaginal douching have been shown to be associated with BV. For the latter, however, the cause-and-effect relationship is unknown. The purpose of this study was to determine correlates of BV among adolescent women who douche to help determine the relative significance of douching in the development of BV.

Materials and Methods

The baseline data of the first 250 participants in an ongoing randomized, controlled trial of a douching behavioral intervention was analyzed. Women were eligible for enrollment if they were 14 to 23 years of age, had douched at least once in the preceding 35 days, and had been douching for at least 6 months. Participants were enrolled at a general adolescent clinic and recruited from primary care clinics and local university campuses. The Institutional Review Board of the University of Alabama at Birmingham approved the study. Women were interviewed about their sexual practices, douching behavior, and sexually transmitted disease (STD) history. Women were screened for STDs, including gonorrhea, chlamydia, trichomonas, BV, and herpes simplex virus type 2 (HSV-2), at their initial visit.

Laboratory Methods

Urine specimens were tested for Neisseria gonorrhoeae and Chlamydia trachomatis using the ligase chain reaction (Abbott Laboratories, Abbott Park, IL). The presence of Trichomonas vaginalis was detected using the InPouch TV culture technique (BioMed Diagnostics, Inc., San Jose, CA). BV was detected using the Nugent method to interpret Gram-stained vaginal fluid specimens.6 Scores of 0 to 3 were considered normal, 4 to 6 as evidence of intermediate flora, and 7 to 10 as BV. Vaginal swab specimens were also cultured for lactobacilli. Specimens were transported in anaerobic holding media and inoculated onto MRS agar.7 Plates were incubated anaerobically for 48 to 72 hours and lactobacilli were identified as Gram-positive catalase-negative rods, which produced predominantly lactic acid as detected by gas chromatography.8 Type-specific serology for HSV was performed using a type-specific enzyme-linked immunosorbent assay using recombinant gG2 for herpes simplex type 2 (HerpeSelect, Focus Technologies, Herndon, VA).

Statistical Methods

Baseline descriptive continuous variables were compared using the t test and categorical variables were compared across vaginosis categories by chi-squared test or Fisher exact test. Factors that were significant in the univariate analysis at a P value of ≤0.10 were examined as risk factors in the multivariate analysis. Logistic regression was performed with backward and forward selection procedures to determine the significant predictors of vaginosis. Model fit was compared by using Akaike’s Information Criteria and the model with the smallest AIC was selected as the best model. For all final analyses, a P value of <0.05 was deemed statistically significant.


Demographic Characteristics

The analyses presented are based on the first 250 women enrolled into the study. The mean age of participants was 18.7 years, whereas the mean age of sexual debut was 15 years. Ninety percent of the participants were black. BV was present in 44.8% (112 of 250) of women, whereas 32.8% (82 of 250) had a lactobacillus-predominant vaginal flora. The remaining 22.4% (56 of 250) had intermediate vaginal flora.

Table 1 shows the comparisons of demographic, sexual history, behavioral and clinical variables for women stratified by the presence or absence of BV. Women with more than 1 sexual partner in the prior 3 months were significantly more likely to have BV than women without BV (29.3% vs. 17.8%, respectively, P = 0.04). Sexual activity within the week before study visit was also associated with BV but not significantly (P = 0.08). Otherwise, there were no significant differences in terms of STD/BV history or sexual behavior, including condom use between the groups.

Demographic, Behavioral and Clinical Variables for Adolescents With and Without Bacterial Vaginosis (BV) (n = 250)

Behavioral Characteristics

The mean age at which douching was initiated was 16 years. Approximately 50% of women douched more than once per month with nearly all using a commercial product. Douching after menses was significantly associated with BV (P = 0.001). Furthermore, last douching within the previous week before the study visit was positively associated with BV (P = 0.04). Frequency of douching, duration of douching in terms of years, and douching for symptoms were not associated with BV.

Prevalence of Sexually Transmitted Diseases

On entry to the study, the prevalence of chlamydia, gonorrhea, and trichomoniasis in this group of teenagers was 16.4% (41 of 250), 4% (10 of 250), and 8% (20 of 250), respectively. Gonorrhea was significantly less frequent among women without BV. Although not statistically significant, more women in the BV group had trichomoniasis, chlamydia, and HSV-2 than did women without BV. Lactobacilli were isolated significantly more often from women without evidence of BV than from women with BV (61.5% vs. 27.2%, P <0.001). Prevalence of STD was not associated with frequency of or last episode of douching (data not shown)

Multivariate Analyses

Data from the multivariate analysis are presented in Table 2. At baseline, women who reported douching after menses were over 5 times more likely to have BV compared with those without BV (odds ratio [OR], 5.11; 95% confidence interval [CI], 1.99–13.15). Women who douched within the last week were significantly more likely to have BV (OR, 1.84; 95% CI, 1.07–3.18) controlling for sexual activity within the last 7 days.

Multivariate Risk Factors for Bacterial Vaginosis


Bacterial vaginosis is an extremely common vaginal infection characterized by prominent changes in the type and quantity of vaginal bacteria.9 The etiology remains unknown, hampering adequate treatment and prevention efforts. Several behaviors have been associated with BV, most notably sexual behavior and douching.1,10–18 Although douching has been frequently associated with BV, the cause-and-effect relationships are less clear. It is possible that douching has a direct effect on the vaginal flora leading to a decrease in lactobacilli and an increase in BV-associated bacteria. It is also possible that women could douche as a result of experiencing vaginal symptoms associated with BV. Data on the relationship between douching and BV are limited to cross-sectional studies with prospective data lacking and differing results have been reported. In a study of women attending clinics in Michigan, vaginal douching in the past 2 months was significantly associated with BV (OR, 2.9; 95% CI, 1.5–5.6). Unprotected sexual activity as well as greater than 15 lifetime male partners was also associated with BV but did not reach statistical significance. Use of hormonal contraception within the past 6 months appeared protective (OR, 0.4; 95% CI, 0.3–0.7).18 In a study of female sex workers in Nairobi, Kenya, douching was significantly associated with BV (P = 0.05) after controlling for the association of BV and STDs; however, sexual activity was not associated with BV in this cohort of highly sexually active women.16

Ness et al. reported on the results of a large multicenter study of the health consequences of douching and found that douching once or more per month was associated with abnormal vaginal flora (BV or intermediate flora) after controlling for other variables (OR, 1.4; 95% CI, 1.1–1.9). Douching within 0 to 7 days of the study visit was also associated with abnormal vaginal flora (OR, 2.1; 95% CI, 1.3–3.1). However, the majority of women reported douching because of vaginal symptoms.19 A longitudinal study of women attending an STD clinic in Seattle found acquisition of BV to be associated with both douching for hygiene (hazard ratio [HR], 2.1; P = 0.05) and with a new sexual partner (HR, 2.5; P = 0.004).20 Finally, in a study of women who have sex with women, Marrazzo et al. failed to find an association between BV and douching but did find an association with greater number of lifetime female partners, oral-anal sex, and failure to clean insertive sex toys.21 Our results are consistent with findings from previous studies in that both sexual activity and the timing of douching are associated with abnormal vaginal flora. In our study, multiple partners in the past 3 months, sexual intercourse within 1 week before the study visit, infection with gonorrhea, douching after menses, and douching within 1 week of the study visit were all associated with BV or intermediate vaginal flora. However, BV was not associated with frequency of douching, types of solutions used, or reasons for douching.

The strong association, which was noted in this study between douching after menses and BV, further strengthens the data linking douching to BV but does not resolve the question of cause and effect. Menses could exacerbate vaginal symptoms of discharge and/or odor either through a direct effect of blood in the vault or as a result of the instability of vaginal flora that has been shown to occur in many women around the time of menses.22,23 Thus, women could douche in an attempt to ameliorate these transient symptoms. It is also possible, however, that douching at a time of vaginal flora instability and vulnerability leads to BV.

Although the data associating BV with douching is compelling, it is still not possible to analyze douching and sexual activity as separate risk factors because the 2, as evidenced by this study, are interrelated activities. Although cross-sectional, our results for the prevalence of STDs at the initial study visit is of interest and compatible with previously published findings.24–26 Gonorrhea was significantly associated with BV as were chlamydia, trichomonas, and HSV-2, although these associations were not statistically significant.

In summary, douching after menses was strongly associated with BV; however, the findings from our study reconfirm the inherent difficulties in studying the independent effects of sexual activity and douching on the vaginal flora. Prospective studies are needed to determine if douching itself directly influences the composition of the vaginal flora.


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