This journal article summarizes a study that analyzed the vaginal microbiota (VMB) of 68 women in Rwanda before and after treatment for bacterial vaginosis (BV) with oral metronidazole. The study found that after treatment, 54.5% of women were cured based on Nugent scoring, with treatment failure associated with higher levels of certain bacteria like Gardnerella vaginalis pretreatment. While most women saw increased lactobacilli and decreased BV-associated bacteria after treatment, the reductions were more modest than expected. The implications are that alternative treatments targeting vaginal biofilms or specific bacteria may be needed to improve cure rates.

1. Journal Reading
Presenter: FM R2盧敬文
Supervisor: VS 何宗錦
2020.02.14

2. • vaginal microbiota (VMB)
• vaginal dysbiosis
• bacterial vaginosis (BV)
characterized by a reduction of lactobacilli and an increase of other anaerobes
• bacterial pathobionts
(Proteobacteria, streptococci, staphylococci, and enterococci)
• Candida albicans
• Trichomonas vaginalis

3. • Vaginal dysbiosis  pelvic inflammatory disease, HIV acquisition, and
adverse pregnancy outcomes.
• BV is diagnosed by:
Nugent scoring of vaginal Gram stains
or by the Amsel criteria.
• BV is treated with antibiotics
• recurrence rates are high
https://en.wikipedia.org/wiki/Nugent_score

4. • Metronidazole is a nitroimidazole class drug.
• Culture studies have shown that lactobacilli are not sensitive to
metronidazole.
High recurrence rate?
• Hypothesized:
due to vaginal mucosal biofilm formation
by G. vaginalis and other BV-associated anaerobes

5. Materials and Methods
• Rinda Ubuzima research clinic in Kigali, Rwanda, in 2015
• women at high risk of BV/T. vaginalis
• in the last 12 months
• more than 1 sex partner
• having been treated for BV and/or a sexually transmitted infection
• BV-positive and/or T. vaginalis -positive
• treated with 7 days of 500 mg generic oral metronidazole, BID
• Posttreatment visit within 3 days after treatment completion

6. Diagnostic procedures
• BV was diagnosed by
• Gram stain Nugent scoring
a score of 0-3 was considered optimal,
4-6 intermediate microbiota,
and 7-10 BV
• modified Amsel criteria
defined as the presence of 2/3 criteria:
• vaginal pH >4.5
• positive whiff test
• and/or > 20% clue cells
黃珮茹、林益卿。常見陰道炎診斷與治療。家庭醫學與基層醫療。第三十一卷，第五期。

7. Molecular VMB testing
• DNA was extracted from 1 swab per woman per visit
• The V3-V4 region of 16S rRNA genes were amplified and sequenced
• The panbacterial 16S rRNA gene copy concentration per sample was
determined
http://www.yourgene.com.tw/content/messagess/contents/655643254701452640/
16S 核糖體 RNA (16S rRNA) 在演化過程中，改變的程度相當
的低，大多數 16S rRNA 其中有 V1~V9 共 9 個高度變異區域
(High Variable Regions，HVRs)
透過選擇其中高變區的序列，進行 PCR 專一性增幅放大，
經過定序，將序列作為分類與鑑定環境或生物體內微生物
之種類與群落

8. Statistical analyses
• VMB characteristics pre- and posttreatment were compared
• all women (N=68),
• women stratified by treatment success/failure(n=55)
• Pretreatment C. trachomatis/N. gonorrhoeae status(N=67)
• Received another antibiotic in addition to metronidazole at the pretreatment
visit or not (N=68)
• having reported unusual vaginal discharge pretreatment or not(N=68)

9. Ethical statement
• Written informed consent provided
• approved by the National Ethics Committee of Rwanda
• and the University of Liverpool Research Ethics Subcommittee for
Physical Interventions.

10. Results

12. Results

13. 82.4%: BV alone
2.9%: T. vaginalis alone
14.7%: both BV and T. vaginalis
38.2%: Ongoing C. trachomatis
and/or N. Gonorrhoeae infection

14. mean bacterial group relative abundances

15. Pre- and posttreatment
16S microbiota data
shift toward
increased relative
abundance of
lactobacilli
 decreased relative
abundances of several
BV anaerobes

16. Total bacterial concentration Total lactobacilli
Total BV-anaerobes Total pathobionts
But interindividual variability was high
Most
variability

17. • Participants with treatment failure as defined by Nugent scoring
• posttreatment
Lower mean lactobacilli relative abundance,
smaller decreases in mean total bacteria and BV-anaerobes concentrations,
less often a lactobacilli-dominated VMB type,
• pretreatment
Greater mean pathobionts concentration

18. • Successfully treated participants:
significant decreases in the mean concentrations of all 8 common BV
anaerobes
• unsuccessfully treated participants:
not decreases in G. vaginalis and BVAB1
• not identify any statistically significant sociodemographic or biological
correlates of treatment failure
• except for pathobionts concentration pretreatment

19. Discussion
• cure rate of 7-day oral metronidazole treatment by Nugent scoring
only 54.5%.
• Treatment failure associated with:
• greater levels of pretreatment Gardnerella vaginalis or pathobionts
• not with sociodemographic factors.

20. • unknown which concentrations of which pathobionts in the vagina
should be treated to prevent complications
• metronidazole treatment
 not change the pathobionts concentration
 increase the relative abundance
• Greater pretreatment pathobionts concentration
 increased likelihood of treatment failure

21. Results of the study in context of what is known
• The extent of BV-anaerobes reduction was more modest than
expected
• lactobacilli are not sensitive to Metronidazole
• Women with a pretreatment VMB type containing a relative
abundance of >50% G. vaginalis, compared with <50%
more likely to continue to have a dysbiotic VMB type posttreatment
• CRISPR-genes may protect the bacteria against metronidazole.

22. Research and clinical implications
• vaginal biofilm disrupting treatment?
• adjuvant therapy with lactobacilli-based live biotherapeutics?
• treatment with drugs that specifically target all G. vaginalis clades?
• diagnostic tests to determine
the presence of a biofilm
or concentrations of G. vaginalis
 are not yet available

23. Strengths and limitations of the study
• limited generalizability of the results
to lower risk and non-African populations
• lack of vaginal biofilm detection
• Strength: used multiple laboratory and analytic methods

24. 黃珮茹、林益卿。常見陰道炎診斷與治療。家庭醫學與基層醫療。第三十一卷，第五期。

25. Thank you
for
your attention.
https://www.flickr.com/photos/lksriv/9413310222/