Epidemiologic studies performed in the Melbourne Sexual Health Center
over several years have explored and emphasized the role of sexual
transmission in the pathogenesis of sporadic bacterial vaginosis (BV) as
well as recurrent BV (Fethers KA., et al. Infect. Dis. 2008; 47:
1426-1435). Some of the most definitive studies documenting details of
heterosexual sexual transmission followed. There can be little doubt as
to the causal role of sexual transmission in BV particularly with regard
to the initial episode (Cherpes, TL., et al. Sex. Transm. Dis 2008; 35:
78-83). The present study adds solid molecular data to their previous
epidemiologic data that recurrent BV is more likely to occur in a
heterosexual woman with a single regular male partner (Ratten L., et al
BJOG 2020 xxxx): Moreover, the risk is mitigated by use of an oral
contraceptive and barrier contraceptives. Specifically, Ratten et al
conclude that sex is associated with persistence of non-optimal,
BV-associated vaginal dysbiosis following appropriate antimicrobial
treatment for BV in a cohort followed prospectively, likely the result
of sexual transmission from a regular partner. The key term used in the
title of the study is persistence, which implies that the non-optimal
vaginal microbiota fails to resolve, as opposed to future reintroduction
from the same guilty partner. Persistence in this context,
unfortunately, also indirectly suggests that inadequate antimicrobial
treatment is currently prescribed to women, perhaps sufficient to
relieve symptoms and meet diagnostic criteria of satisfactory response,
but insufficient to eradicate BV pathogens. The author emphasizes needed
improvement in the, so far, futile male partner therapy to prevent
female reinfection, a goal that has repeatedly eluded experts to date.
The unanswered question facing patients and clinicians alike is the role
of sexual reinfection as opposed to vaginal relapse in the causation and
likelihood of BV recurrence. The tone of the article would indicate that
reinfection is the more likely causal mechanism of BV recurrence, by
emphasizing “persistence” and outweighing the role of unexplained
relapse. In dealing with a symptomatic patient suffering from an episode
of recurrent BV, it is currently not possible to differentiate relapse
from reinfection unless the patient declares herself to be celibate,
ergo relapse is the cause of recurrence. The clinical picture is
identical as are Amsel or Nugent criteria. Unfortunately, molecular
microbiome studies have not revealed significant differences between
sequential episodes regardless of causation. We lack a “unique
fingerprint” to differentiate cause or nature of the recurrent episode.
Even with reinfection, sexual or otherwise, details of pathogenesis are
still lacking. We know too that coitus can elicit symptoms of BV (post
coital malodor) even with use of a condom. The role of receptive
oral-vulvovaginal sex is also undetermined, as is the role of penile –
anorectal penetration although the latter was found to be minimal in the
latest study by Ratten L., et al. (BJOG 2020 xxxx): Moreover, not all
longitudinal studies have revealed that heterosexual sex is a major
factor in recurrence (Sobel J.D., et al. Infect. Drug Resist. 2019: 12;
2297-2307).
The role of sex and reinfection in causation of RBV will depend
significantly upon the population studied, including biologic and
behavioral differences. Determination of causation of BV recurrence in
different patient populations should be personalized and acknowledged as
we admit our current limitations. Will more effective male treatment
help reduce BV recurrence? Hopefully but still unknown. Determining all
the causes of vaginal microbiota persistence, including the role of
biofilm, remains a challenge.
No disclosures: A completed disclosure of interest form is
available to view online as supporting information.