包括乳酸在内的细菌性阴道病替代治疗策略： 抗生素耐药性问题的潜在解决方案

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BACKGROUND

Bacterial vaginosis (BV) is a clinical and laboratory non-inflammatory condition of the vagina in which the dominant lactobacilli lose their predominant position in the microbiome. In women of reproductive age, the prevalence of BV ranges from 23% to 29%, exhibiting variations based on ethnicity and geographical location. For instance, in North America, 33% of non-Hispanic black women and 31% of Hispanic women are affected by BV, whereas the rates for Asian and Caucasian women are 11% and 23%, respectively [1].

BV contributes to an increased likelihood of contracting sexually transmitted infections (STIs) such as human immunodeficiency virus, herpes simplex virus, chlamydia, gonorrhea, trichomoniasis, and mycoplasma infection and increases the risk of pelvic inflammatory disease [2]. In addition, this condition is associated with adverse pregnancy and fetal outcomes, including intrauterine infections, premature rupture of the fetal membranes, late spontaneous miscarriage, preterm labor, and postpartum and postabortion purulent-septic complications [3, 4]. Currently, the first-line treatment of BV is antibacterial medications. These include oral metronidazole 500 mg twice daily for seven days, intravaginal metronidazole 5 g once daily for five days, and intravaginal clindamycin 5 g once daily for seven days [5]. However, BV recurrence after standard antibiotic therapy occurs in 43% of women within 3 months and in 58% within 12 months. This may be due to resistance to antimicrobial therapy, biofilm formation, subsequent persistence of microorganisms, and reinfection [6]. The most promising alternative method for the treatment and prevention of BV is the use of the antiseptic dequalinium chloride and lactic acid, an agent that lowers the vaginal pH.

Aim

The study aimed to evaluate the efficacy and tolerability of a comprehensive two-step treatment regimen for BV, including clindamycin or dequalinium chloride and lactic acid, in women of reproductive age.

METHODS

An open-label, randomized, clinical trial was conducted involving 93 women aged 18–45 years with BV diagnosed according to the Amsel criteria. The study was conducted as part of A.D. Minakova’s dissertation research and approved by the Local Ethics Committee of the Sechenov First Moscow State Medical University (Protocol No. 01-22 dated January 20, 2022). After obtaining voluntary informed consent to participate in the study, the women were randomly divided into three groups. Group 1 (n = 31) was treated vaginally with 100 mg of lactic acid for ten days. Group 2 (n = 31) received 100 mg of vaginal clindamycin for three days, followed by 100 mg of lactic acid for ten days. Group 3 (n = 31) received 10 mg of vaginal dequalinium chloride for six days, followed by 100 mg of lactic acid for ten days.

Inclusion criteria: complaints of malodorous genital discharge and patient age between 18 and 45 years. Exclusion criteria: pregnant and lactating women; acute or chronic active pelvic inflammatory disease; STIs (infections caused by N. gonorrhoeae, C. trachomatis, T. vaginalis, and M. genitalium), vulvovaginal candidiasis, aerobic vaginitis; and menopause before the age of 45 years.

Upon enrollment, patients underwent a gynecological examination. Vaginal pH was measured using Kolpo-Test pH indicator strips (Russia), and vaginal secretions were collected from the upper third of the lateral vaginal vault for Gram-staining microscopy. STI screening by polymerase chain reaction was performed if indicated (less than 25 years of age, new sexual partner in the past 12 weeks, two or more sexual partners, sexual contacts without barrier contraception, history of STIs in the woman or her partner, and procedures that interrupted the cervical barrier in the past six weeks).

The patients were followed up for three months. Two weeks after the end of treatment, complaints were assessed; a gynecological examination was performed; the pH of the vaginal contents was measured, and vaginal fluid was collected from the upper third of the lateral vaginal vault for Gram-staining microscopy. Three months after the end of treatment, the women who complained of genital discharge and/or odor underwent were re-examined; vaginal pH was measured, and Gram microscopy was performed. The evaluation of treatment efficacy was based on the following parameters: the absence of a homogeneous, malodorous, white-gray discharge; a pH of the vaginal fluid below 4.5, and the absence of clue cells on microscopy.

The analysis of the study’s results was conducted by employing Python statistical libraries, namely Numpy and Pandas.

RESULTS

The mean age of the women was 29.70 ± 2.70 years in group 1, 31.40 ± 2.71 years in group 2, and 33.50 ± 2.53 years in group 3. Group 1 did not include any smokers, whereas 3.2% (n = 1) of the women in group 2 used tobacco. This number increased significantly to 32.3% (n = 10) in group 3.

The results showed that no infections were detected in any of the examined women: 38.7% (12/31) in group 1, 29.0% (9/31) in group 2, and 38.7% (12/31) in group 3.

There were no significant differences between the groups in the presence of somatic diseases. The analysis of the history of urinary tract infections in women in each group showed that chronic cystitis was diagnosed in 19.4% (n = 6) of the women in group 1, 9.7% (n = 3) of those in group 2, and 3.2% (n = 1) of those in group 3. Postcoital cystitis was identified in 3.2% (n = 1) of the participants in group 2. In group 3, chronic pyelonephritis was diagnosed in 12.9% of the patients (n = 4). These findings are consistent with prior reports of statistically significant associations between urinary tract infections and BV.

Most women chose barrier methods of contraception, including 28 (90.3%) participants in group 1, 22 (71.0%) in group 2, and 23 (74.2%) in group 3. Combined oral contraceptives were used by one (3.2%) woman in group 2 and the copper intrauterine device by one (3.2%) woman in group 3. Interrupted coitus as a contraceptive method was used in all groups, including three (9.7%) women in group 1, eight (25.8%) in group 2, and six (19.4%) in group 3. In addition, one (3.2%) woman in group 3 did not use any contraception because she was planning a pregnancy.

A preliminary examination with a Cusco speculum revealed that patients in all three groups exhibited substantial amounts of grayish-white vaginal discharge accompanied by an amine malodor.

The mean pH of the vaginal discharge before treatment was 5.3 ± 0.1 in group 1, 5.6 ± 0.2 in group 2 and 5.5 ± 0.2 in group 3.

In all three groups, clue cells were found in 32.3% (n = 10), 54.8% (n = 17) and 48.4% (n = 15) of the women, respectively.

Two weeks after the end of treatment, all participants in group 3 had mucus discharge without a characteristic odor. Three patients (9.7%) in group 1 and one patient (3.2%) in group 2 continued to have odorous vaginal discharge, although in smaller amounts.

The mean pH of vaginal discharge 14 days after therapy in patients of all three groups was 4.4 ± 0.1, 4.4 ± 0.1 and 4.5 ± 0.1, respectively.

Two weeks after treatment, clue cells were detected in only 3.2% (n = 1) of the women in group 1, whereas none were detected in other participants.

As a result of clinical and laboratory examination using Amsel criteria, three patients in group 1 and one patient in group 2 were rediagnosed with BV, indicating the lack of treatment efficacy, and the patients were therefore excluded from further follow-up.

When lactic acid was used as a second step of treatment, one patient in group 2 and one in group 3 experienced adverse effects in the form of vaginal burning. One woman in group 3 stopped taking the product after the fifth suppository and withdrew from the study. After discontinuing the lactic acid, this discomfort resolved. The participant in group 2 continued to use the product despite the burning sensation, which ceased after the end of therapy. The group that received lactic acid alone did not exhibit any adverse effects.

Three months after therapy, one (3.6%) woman in group 1, two (6.7%) in group 2, and two (6.7%) in group 3 complained of genital discharge.

The mean pH of the vaginal discharge was 4.3 ± 0.1, 4.5 ± 0.1, and 4.5 ± 0.1 in all three groups, respectively.

Gram microscopy was performed to detect clue cells three months after treatment in cases where patients complained of discharge and/or odor from the genital tract. Clue cells were detected in 3.3% (n = 1) of the participants in group 2 and in an equal proportion (n = 1) in group 3. Conversely, no such cells were identified in group 1.

Three months after the end of treatment, recurrence of BV (3 or 4 positive Amsel criteria) was diagnosed. One case (3.6%) was recorded in group 1, one case (3.3%) in group 2, and two cases (6.7%) in group 3. In addition, one case of vulvovaginal candidiasis (3.3%) was recorded in group 2 after three months.

The efficacy of lactic acid treatment after 14 days was 90.3% (28/31). After three months, this figure increased to 96.4% (27/28), thereby indicating the durability of achieved results. A two-step treatment regimen, including clindamycin and lactic acid, demonstrated 96.8% (30/31) efficacy after two weeks and 96.7% (29/30) efficacy after three months. Treatment with dequalinium chloride and lactic acid showed 100.0% (30/30) efficacy after 14 days and 93.3% (28/30) efficacy after three months.

DISCUSSION

The problems associated with the use of standard antibiotic therapy in the treatment of BV, such as low long-term efficacy and high recurrence rates, as well as adverse side effects of antibiotics, emphasize the need to find alternative therapies. Lactic acid produced by lactobacilli has been shown to help maintain an acidic pH in the vagina, creating favorable conditions for lactobacilli growth and reproduction while preventing the development of anaerobic microorganisms [7]. A study by O’Hanlon et al. [8] demonstrated that physiological concentrations of lactic acid under anaerobic conditions inactivated BV-associated bacteria without affecting lactobacilli.

A study by Kira et al. [9] included 116 women diagnosed with BV according to the Amsel criteria. The aim of the study was to evaluate the efficacy and safety of vaginal suppositories containing lactic acid on days 2–3 and 32 after the end of therapy. The participants were divided into two groups: 64 women received lactic acid and 52 received placebo. The results showed a significant decrease in the incidence of pathological discharge (from 100.00% to 4.69% and 10.94%), pH (from 6.84 to 4.28 and 4.34), and the number of clue cells (from 100.00% to 7.81% and 10.94%) in the group receiving lactic acid. The absence of adverse effects suggests the safety of this method.

Another study by Ross et al. [10] found that metronidazole was more effective than lactic acid-based gel in women with recurrent BV (70% vs. 47% at day 14). After six months, however, recurrence rates were similar (71% vs. 70%), raising concerns about the long-term benefits of metronidazole. Nevertheless, many patients preferred the lactic acid gel, probably because of fewer adverse effects.

A study conducted by Paavonen et al. [11] found that oral administration of metronidazole showed similar efficacy to intravaginal clindamycin, but with lower tolerability among patients.

Thus, the results of this study are consistent with the data presented by Kira et al. [9] and confirm the efficacy and good tolerability of lactic acid monotherapy in BV. The study by Ross et al. [10] suggests a lower efficacy of lactic acid gel in BV recurrences compared with metronidazole. However, the long-term recurrence rate was comparable, suggesting that lactic acid monotherapy may not be effective enough in such cases, but may remain effective in sporadic manifestations of the disease. In the present study, a two-step treatment consisting of dequalinium chloride and lactic acid or clindamycin and lactic acid showed better short-term efficacy than treatment with lactic acid alone. However, the recurrence rate at three months was similar to that reported in the study by Ross et al.

When considering alternative antiseptic treatments for BV, special attention should be paid to dequalinium chloride.

Dequalinium chloride, a quaternary ammonium salt, exhibits both anti-inflammatory and antibacterial properties. The anti-inflammatory effect is attributed to the inhibition of protein kinase C, whereas the antibacterial activity is the result of multiple mechanisms, including adsorption on the surface of microorganisms, interaction with the cytoplasmic membrane, changes in cell wall permeability, denaturation of proteins, inhibition of glucose metabolism and adenosine triphosphate synthesis in bacterial mitochondria, disruption of ribosomal protein synthesis and its precipitation, and precipitation of nucleic acids. These are the factors that explain the lack of resistance to dequalinium chloride. Furthermore, dequalinium chloride exhibits minimal systemic absorption, resulting in negligible systemic effects [12].

An in vitro study by Gaspar et al. [13] showed that dequalinium chloride effectively destroys biofilms dominated by Gardnerella spp. by affecting their biomass and metabolic activity.

A retrospective, multicenter, observational study by Vives et al. [14] demonstrated the efficacy of treatment of BV with 10 mg of dequalinium chloride vaginally for six days in 573 women. Four to six weeks after the end of therapy, 84.8% of participants reported complete resolution of symptoms. A multicenter, blinded, randomized trial by Weissenbacher et al. [15] compared the efficacy of clindamycin with that of dequalinium chloride in women with BV. The clinical cure rate seven days after therapy was 81.5% in the dequalinium chloride group and 78.4% in the clindamycin group. Twenty-five days after therapy, clinical cure rates remained high at 79.5% and 77.6% in the dequalinium chloride and clindamycin groups, respectively.

According to our study, combination therapy with clindamycin and lactic acid showed higher clinical efficacy than clindamycin monotherapy, as reviewed in the study by Weissenbacher et al. [15]. Nevertheless, both the combination therapy during the 3-month follow-up and the clindamycin monotherapy during the 1-month follow-up in the previous study showed high efficacy. In addition, both studies showed good tolerability.

Raba et al. [16] conducted a multicenter, triple-blind, randomized clinical trial to evaluate the efficacy of 10 mg of intravaginal dequalinium chloride used once daily for six days versus 500 mg of oral metronidazole used twice daily for seven days. The clinical cure rate was achieved within 7–11 days after the start of therapy in 92.8% (n = 64/69) of the women receiving dequalinium chloride and 93.2% (n = 69/74) of those receiving metronidazole. However, 20–40 days after treatment, the clinical cure rate decreased in both groups to 79.7% in the dequalinium chloride group and 87.3% in the metronidazole group. Tolerability was rated as very good by 60.0% of patients in the dequalinium chloride group and 38.9% in the metronidazole group. The difference in tolerability between the groups was statistically significant.

The present study, utilizing a two-step treatment with dequalinium chloride and lactic acid, exhibited higher clinical efficacy compared with the studies conducted by Weissenbacher et al. [15] and Raba et al. [16], which evaluated dequalinium chloride monotherapy. In contrast to patients receiving dequalinium chloride monotherapy, patients in our study demonstrated sustained efficacy over a period of three months, a finding that surpasses the outcomes observed in previous studies of dequalinium chloride monotherapy. Furthermore, the tolerability of dequalinium chloride in the two-step therapy in our study was superior to that of monotherapy in previous studies.

The short-term efficacy of two-step therapy, comprising clindamycin and lactic acid, as well as dequalinium chloride and lactic acid, is consistent with the efficacy of clindamycin and dequalinium chloride monotherapy observed in previous studies. Nonetheless, the long-term results of the two-step treatment in this study demonstrated greater efficacy compared with the use of monotherapy in previous studies.

Due to the low sensitivity of this diagnostic criterion, the microscopic examination of the Gram-stained vaginal smear revealed clue cells in a few patients. However, the presence of the other three Amsel criteria (homogeneous grayish-white discharge, specific amine odor, and pH of vaginal discharge >4.5) in the absence of clue cells in the smear allows for the diagnosis of BV [17].

CONCLUSION

The present study demonstrated the high efficacy of a two-step regimen that included both clindamycin and lactic acid and dequalinium chloride and lactic acid. The efficacy of both treatment regimens was demonstrated by their positive impact on both short-term and long-term outcomes. In contrast, lactic acid monotherapy exhibited less pronounced results on day 14 (90.3% vs. 96.8% and 100.0% for the two-step regimens), yet the rates were more comparable after three months (96.4% vs. 96.7% and 93.3%). Importantly, two-step therapy with dequalinium chloride and lactic acid showed high efficacy comparable to two-step therapy with clindamycin and lactic acid. Taking into account the increasing antibiotic resistance, this strategy is particularly relevant in clinical practice.

The study was conducted as part of A.D. Minakova’s dissertation research and was approved by the Local Ethics Committee of First Moscow State Medical University (Protocol No. 01-22, dated January 20, 2022).

ADDITIONAL INFORMATION

Authors’ contribution. A.D. Minakova: concept and design of the study, collection and processing of material, statistical data processing, writing the text; T.A. Dzhibladze writing the text; V.M. Zuev, I.D. Khokhlova editing the article. All authors confirm that their authorship meets the international ICMJE criteria (all authors made a substantial contribution to the conception of the work, acquisition, analysis, interpretation of data for the work, drafting and revising the work, final approval of the version to be published and agree to be accountable for all aspects of the work).

Ethics approval. The study was conducted as part of A.D. Minakova’s dissertation research and was approved by the Local Ethics Committee of First Moscow State Medical University (Protocol No. 1-22, dated January 20, 2022).

Funding source. This study was not supported by any external sources of funding.

Disclosure of interest. The authors declares that there are no obvious and potential conflicts of interest associated with the publication of this article.

作者简介

Alena D. Minakova

I.M. Sechenov First Moscow State Medical University

编辑信件的主要联系方式.
Email: alenami1205@yandex.ru
ORCID iD: 0000-0002-5157-1888
SPIN 代码: 6649-7776

Postgraduate Student

俄罗斯联邦, 8 Trubetskaya st, bldg 2, Moscow, 119048

Tea A. Dzhibladze

I.M. Sechenov First Moscow State Medical University

Email: djiba@bk.ru
ORCID iD: 0000-0003-1540-5628
SPIN 代码: 5688-1084

MD, Dr. Sci. (Medicine), Professor

俄罗斯联邦, 8 Trubetskaya st, bldg 2, Moscow, 119048

Vladimir M. Zuev

I.M. Sechenov First Moscow State Medical University

Email: vlzuev@bk.ru
ORCID iD: 0000-0001-8715-2020
SPIN 代码: 2857-0309

MD, Dr. Sci. (Medicine), Professor

俄罗斯联邦, 8 Trubetskaya st, bldg 2, Moscow, 119048

Irina D. Khokhlova

I.M. Sechenov First Moscow State Medical University

Email: irhohlova5@gmail.com
ORCID iD: 0000-0001-8547-6750
SPIN 代码: 6858-5235

MD, Cand. Sci. (Medicine), Assistant Professor

俄罗斯联邦, 8 Trubetskaya st, bldg 2, Moscow, 119048

参考

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