Transcript Bacterial Vaginosis - MICROBIOLOGY MATTERS

Bacterial Vaginosis
Michael Addidle
What is Bacterial Vaginosis (BV) ?
• Polymicrobial vaginal infection involving a
reduction in the amount of Lactobacilli
bacteria and an overgrowth of anaerobic
bacteria.
Some key facts
• Condition first described by Gardner and
Dukes in 1955.
• Initially thought to be due to which
organism?
• Most common infective cause of vaginal
discharge in women of childbearing age.
• Prevalence is approximately 20-30%
• Approximately 50% symptomatic
• The absence of inflammation is the basis
of the term vaginosis as opposed to
vaginitis
Risk Factors for BV
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Multiple or new sexual partners
Oro-genital sex
Smoking
Genetic predisposition
Normal vaginal flora ?
What else is normal vaginal flora?
What part does age play in the make-up of normal vaginal flora?
Pathogenesis
• Normal vaginal flora in women of reproductive age is
predominately lactobacilli. (Bit unusual)
• At puberty eostrogen levels increase, stimulates
glycogen uptake by vaginal epithelial cells. Glycogen
one of main food sources of lactobacilli.
• Lactobacilli produce both lactic acid and hydrogen
peroxide.
• Vaginal epithelial cells also produce lactic acid as a byproduct of glycogenolysis.
• This makes the vaginal pH acidic
• The hydrogen peroxide is also toxic against other
bacterial species.
• Lactobacilli per se are very low virulence bacteria. (Probiotic yoghurts etc), therefore its predominance is
thought to have a protective effect against vaginal/pelvic
infections.
• At menopause, eostrogen levels decrease so lactobacilli
often become non-dominant. Makes BV more difficult to
diagnose
Names to remember in BV
• Amsel
• Nugent
• Hay
Presentation of BV
Amsel’s Criteria (introduced 1984)
(3 out of 4 criteria below required to establish the diagnosis)
• Vaginal discharge, thin white/grey
• Fish like odour. (accentuated by addition
of Potassium Hydroxide KOH)
• Vaginal PH >4.5 (Litmus paper is a
bedside test)
• Presence of clue cells on laboratory
examination.
What are the problems with Amsel’s criteria?
Introduced
1991
Hay’s Criteria (2002)
Problems with Hay’s criteria?
Other methods
• DNA probes
• DNA probes + pH
Bacterial Vaginosis:
Quality Assurance of results
• Condition of degrees
• Clear cut at either end of the spectrum.
• Those in the middle (including AVF) are
less clear cut.
• Degree of subjectivity
• External QC/Internal QC?
The consequences of Bacterial Vaginosis
• Causal relationship between BV and
endometrial bacterial colonisation,
endometritis, premature labour, postpartum fever, post-hysterectomy vaginal
cuff cellulitis and post-abortal infection.
• BV is a risk factor for HIV transmission
(&other STDs). May be due to the lack of
hydrogen peroxide producing lactobacilli in
the vaginal flora of women with BV
Bacterial vaginosis :
Treatment
• Metronidazole 400mg orally bd for 7 days.
• Clindamycin 300mg orally bd for 7 days.
• Metronidazole and Clindamycin gels can also be
used.
• Avoid gels during pregnancy. No evidence that
they reduce the risks to the baby.
• No evidence to suggest that woman’s response
to therapy and risk of relapse are influenced by
treatment of her male sex partner.
Screening and treatment of
asymptomatic infection
• Generally asymptomatic infection not
treated as patients often spontaneously
improve and therapy often complicated by
symptomatic vaginal yeast infection.
• Treatment indicated for asymptomatic
women who are about to undergo gynae
procedures(in particular termination of
pregnancy) and in “high risk pregnancies.”
• No evidence that treating sexual partners
of women with BV is beneficial.
Bacterial Vaginosis (BV)
in pregnancy (15-30%)
• Why is BV a particular problem in pregnancy
– More common than in non-pregnant pop.
– Associated with premature labour &
delivery
– Controversial association with miscarriage
– Post-partum endometriosis
However treatment of BV may not return these
risks to baseline levels. Benefit greatest in
those higher risk pregnancies.
When to look for and treat BV in
pregnancy
• Asymptomatic High Risk Pregnant women
(previous pre-term delivery). Can
consider screening these women for BV
even if asymptomatic.
• There is no evidence for routine screening
for BV in pregnancy in all expectant
mothers.
Bacterial Vaginosis:Relapse
• 30% recurrence in 3 months
• 50% recurrence in 12 months
• Long term suppressive antibiotics may be
indicated when three or more episodes
within a 12 month period.