This infection is caused by an overgrowth of Gardnarella vaginalis, Mycoplasma hominis or Mobiluncus, amongst other predominantly anaerobic causative organisms, in the vagina. In replacing naturally occurring lactobacilli, they increase the pH of the vagina from 4.5 to around 7. Bacterial vaginosis is not a sexually transmitted infection, and presented with a grey discharge that is accompanied by an unpleasant 'fishy' smelling odour. Often itching is also a presenting complaint. Approximately 50% of cases are asymptomatic.
The Amsel criteria states that at least three of the four criteria must be present for diagnosis to be confirmed:
- Thin, white, homogeneous discharge
- Clue cells on microscopy of wet mount
- pH of vaginal fluid >4.5
- Release of a fishy odour on adding alkali (10% KOH). This is otherwise known as a whiff test.
The isolation of G. vaginalis as a diagnostic criterion cannot be used, as it is present in the normal flora of the majority of women.
Medical treatment is considered for the following categories:
- Symptomatic women who are not pregnant.
- Women undergoing gynaecological operations.
- Symptomatic pregnant women,
- Pregnant women with a history of preterm delivery without an obvious cause, or second trimester miscarriage (even if they are asymptomatic).
There is evidence for the benefit of screening for and treating bacterial vaginosis (BV) prior to termination of pregnancy in order to reduce risk of endometritis and pelvic inflammatory disease.
Antibiotic treatment with 2g Metronidazole or intravaginal Clindamycin cream can be recommended.
Complications of bacterial vaginosis can include preterm labour, intra-amniotic infection, increased susceptibility to HIV or post-termination sepsis.
Trichomoniasis is a sexually transmitted parasitic infection caused by flagellated anaerobes named T. vaginalis. This protozoa infects over 160 million people worldwide annually. It presents with an offensive 'fishy', green-yellow discharge, which often appears 'frothy'. In men, the infection can mimic symptoms of urethritis. 10% of women will present with a 'strawberry haemorrhage' on examination of the cervix.
When 'triple swab' of the vagina/cervix is undertaken, diagnosis is via overnight culture, with a sensitivity range of 75-95%. Newer methods of diagnosis include PCR analysis, but these are not currently in widespread use. A vaginal pH > 4.5 may also be indicative of infection.
As with B. vaginalis, treatment is curative, with metronidazole or tinidazole. Sexual partners may also be offered treatment, as they may be asymptomatic carriers of the infection.
Complications of T. vaginalis can include preterm labour, low birth weight and a predisposition to HIV, AIDS or cervical cancer. Recent research also suggests a link between T. vaginalis infection in males and subsequent aggressive prostate cancer.
Vaginal candidiasis is a yeast infection of the female genital tract, most commonly taking the form of Candida albicans. Whilst candida makes up part of the normal vaginal flora, symptomatic infection is usually predisposed by a change in the environment of the vagina or a compromised immune system and thus increased susceptibility to infection. Candida is estimated to affect around 75% of women during their reproductive years, with a peak incidence at 20–40 years. Risk factors for vaginal candidiasis include diabetes, pregnancy, broad spectrum antibiotic treatment, chemotherapy or foreign body presence. Candidiasis often presents with a white 'cheesy' discharge, associated with itching, burning or severe irritation. Other common presenting complaints include dysuria or dyspareunia.
Diagnosis is usually clinical, and routine culture is not required. Severe or resistant infection may indicate culture swabs from the anterior fornix or lateral vaginal wall.
Anti-fungal treatment is often accompanied by general hygiene advice, including avoidance of topical irritants. Drug treatments include application of topical azoles, i.e. clotrimazole, oral triazoles i.e. fluconazole or single high-dose oral triazole.