Tricky ten minutes – ‘why do I keep getting thrush?’

Candida is considered part of the normal vaginal flora and can be found in about 40% of adult women at any given point. About half of these women will have at least one episode of symptomatic candidiasis and a minority of those who have an episode will have recurrent symptoms.¹

True recurrent vulvovaginal candidiasis is thought to occur in 5% of healthy women.²

History

Many of the symptoms of thrush overlap with other causes of vulvovaginitis and so are not specific to candida. Some of the women who self-diagnose and treat with over-the-counter preparations will have other causes for their symptoms – none of the symptoms or signs of thrush are pathognomonic. A good history, supported by corroborative laboratory evidence, is essential if a women presents with recurrent thrush. It is important to go through the following questions to establish diagnosis and exclude other causes.  

• What are the symptoms and when did they start?^{2, 3} Episodes of symptomatic thrush typically present with vulval itching, soreness and vaginal discharge (although discharge may be absent). There might be superficial dyspareunia and external dysuria, especially if there are erosions and fissures secondary to scratching. There is typically no malodour.
• What is the sexual history and why has the patient attended now? Has there been a change in symptoms? Are there underlying concerns, for example about STIs?
• How frequently do the symptoms occur? Recurrent vulvovaginal candida is defined as four or more episodes of symptomatic infection annually. There is at least partial resolution of symptoms between episodes. Positive microscopy or a moderate to heavy growth of candida should be documented on at least two occasions when symptomatic.³

Differential diagnoses

Establish whether a formal diagnosis has ever been made. Other causes need to be excluded. These include infections causing vaginal discharge such as bacterial vaginosis, trichomoniasis, genital tract chlamydia, gonorrhoea and genital herpes. Non-infective conditions, like irritants, vulval eczema, psoriasis, lichen simplex and sclerosus, and atrophic vaginitis² also need to be excluded.

Examination and investigation

Examination may reveal a thick, white discharge. Depending on severity, there may be signs of vulvovaginal inflammation with erythema, oedema, vulval excoriation and satellite lesions. Vaginal discharge may be normal in appearance or may be typically ‘curdy-white’. Speculum examination is needed and swabs should be taken as follows:

• Gram stain or ‘wet film’ (saline and/or potassium hydroxide preparation) examination of a vaginal swab taken from anterior fornix or lateral vaginal wall is needed. Blastospores and pseudohyphae are looked for. The sensitivity of each of these tests would be no more than 65% to 70% at best. If two of the tests were done, sensitivity would be increased and bacterial vaginosis can be picked up as well.
• Culture of above specimen in Sabouraud’s media should be considered in all cases of recurrent candidiasis as this would give information on species.
• A swab should be taken from the posterior fornix and examined for trichomonas (refer to local laboratory guidance).
• Chlamydia trachomatis and Neisseria gonorrhoeae nucleic acid amplification tests should be offered.
• Visualisation of the cervix is useful.

Referral to a GUM clinic would mean that full microbiological tests can be done to establish an accurate diagnosis. As microscopy is routinely done, an immediate diagnosis may be available for many patients. 

Management

Once the diagnosis is confirmed, any predisposing conditions should be identified.  These include diabetes mellitus, which should be excluded, use of antibiotics and systemic immunosuppression or immunodeficiency, for example because of steroid use or HIV infection. Hyperoestrogenemia, because of use of HRT or the combined oral contraceptive pill, may contribute. 

The pathogenesis of recurrent disease probably involves host factors that find it difficult to tolerate the resident yeast. Current guidelines advocate an induction regimen consisting of vaginal imidazole or oral fluconazole. This should be followed immediately by a maintenance regimen – weekly maintenance with either a clotrimazole pessary (500mg) or oral fluconazole (150mg) to suppress clinical attacks. It is generally given for a period of six months and reviewed. Symptoms may recur after treatment is stopped.

Speciation and sensitivity testing is important to guide management. If resistant Candida albicans or Candida glabrata is identified, longer courses or alternative treatments may be needed. Prevalence of the latter is thought to be 10–15% in women with recurrent symptomatic candidiasis.

General advice should be given regarding symptomatic relief, genital skin care and use of emollients.

There is no evidence to support the treatment of asymptomatic male sexual partners.

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