Mycology update and GP’s Q&A

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By Dr Riina Richardson, DDS, PhD, FRCPath (Medical Microbiology), FECMM, PGCertMedEd
Clinical Head of Service for the NHS Mycology Reference Centre Manchester
October 2022

What is new about Candida and dermatophyte infections?

  • Genetic analyses of fungi have resulted in many changes in the names of fungal species and genera. Examples of common yeasts and moulds:
Old name New name
Candida glabrata    Nakaseomyces glabrata
Candida krusei    Pichia kudriavzevii
Saphrochaete clavata Magnusiomyces clavatus

Fungi will be reported with the new names but the previous names will also be provided.

For practical reasons, infections caused by yeasts previously in the genus Candida will continue to be called candidiasis.

  • British Association of Sexual Health and HIV (BASHH) has updated the national Vulvovaginal Candidiasis guideline. This was a significant update highlighting the importance of vulval skin care in the management and prevention of recurrent disease as well as consideration of alternative or dual pathology. More detail below.

 

  • Antifungal resistance in dermatophytes is an increasing problem. If you suspect resistance due to poor response to standard treatment, please let the laboratory know and request susceptibility testing.

Questions and answers

We have compiled responses to the most common GP enquiries about fungal infections below. If you have any other questions, please contact the laboratory via email at mrcm@mft.nhs.uk or by phone at 0161 291 5839.

Vulvovaginal candidiasis is not responding to standard treatment – what should I do?

In the first instance, a high vaginal swab should be sent for microscopy, and fungal culture and identification. Antifungal susceptibility testing should also be requested. Some yeasts are innately resistant to fluconazole such as Nakaseomyces glabrata (previously Candida glabrata) and Pichia kudriavzevii (previously Candida krusei). If this is the case, recommended treatment are nystatin pessaries or Boric acid vaginal suppositories (available off licence). See more information on treatment.

If there is no fungal growth, or no clinical improvement after introduction of an antifungal to which the identified isolate is susceptible, it indicates the problem must be elsewhere.  The patient should undergo further investigation, including a complete gynaecological examination, to rule out alternative or additional aetiologies for their symptoms. A large array of dermatological and other conditions can present similarly to and/or concomitantly with VVC such as vulval eczema, lichen sclerosus, vulval atrophy and vulvodynia. It is also useful to keep in mind that topical treatment can cause local irritation, in case of adverse response to treatment.

If the patient responds to treatment but the symptoms recur repeatedly (at least 4 episodes within 12 months, of which at least 2 have been confirmed by mycology), suppression with once weekly fluconazole for 6 consecutive months should be considered.  The patient should remain asymptomatic whilst on suppression, and any breakthrough symptoms should be fully investigated (examination + HVS). After this, instead of stopping the suppression altogether, extending the time between antifungal doses (once fortnightly in the first instance) and/or timing them with the times the patient would typically flare (normally last 2 weeks of the cycle) should be considered.

Good daily skin care is the cornerstone in the management and prevention of vulvovaginal candidiasis. There is a lot of over-washing and unnecessary use of feminine and other products. Washing (even with water) dries the skin and dry skin is always itchy. It is also more vulnerable and prone to infection.

Strategies to prevent recurrence include:

  • Use emollient cream (i.e. doublebase gel, dermol, E45) at least twice daily and before exercise
  • Avoid vaginal douching and the use of other feminine hygiene products
  • Replace soap with emollient cream for daily genital hygiene
  • Avoid the use of sanitary pads and pantyliners; tampons or menstrual cups are preferred
  • Avoid tight clothes, favour loose and breathable fabrics like cotton
  • Use water-based lubricant during sexual intercourse

The patient needs to be referred to a GUM clinic if the diagnosis is uncertain, treatment is unsuccessful or if the Candida species is resistant to fluconazole (off licence treatment required). Withington Hospital GUM service has special expertise and interest in these patients.

 

Oral/oropharyngeal candidiasis is not responding to standard treatment – what should I do?

Firstly, a significant percentage of adults are colonised with Candida species, with counts fluctuating from day to day and week to week.  At the same time, symptoms of oral candidiasis are non-specific and many other infectious and non-infectious conditions present similarly. Therefore, the diagnosis has to build on the combination of symptoms, clinical findings, culture results and response to treatment. A positive swab from an asymptomatic patient reflects colonisation which does not require treatment.

The key risk factors for oral, oro-pharyngeal and oesophageal candidiasis are poor oral hygiene, high carbohydrate diet, weak immune defences (eg lack of saliva and the use of steroids and other immunosuppressants) and acidic environment favouring the growth of Candida (silent GORD, acidic diet). In order to gain a better control of the recurrences, it is important to address each of these factors.

Setting a high standard for oral hygiene is particularly important as biofilms are resistant to all antifungals. Patients should brush their teeth twice daily, floss or use an interdental brush daily, and use a tongue scraper. If they wear dentures or other appliances these need to be brushed and disinfected daily. Any oral health issues such as chronic gingivitis or periodontitis and dental caries will promote Candida growth as they harbour mixed bacterial-candidal biofilms.

Patients should also be assessed for GORD, including silent reflux. A PPI trial is recommended. Patients should also be advised to stay hydrated and drink enough water daily as saliva is the main defence against Candida. Medications should be reviewed, and ideally drugs causing dry mouth should be replaced. Inhaled steroids must be used with a spacer and mouth rinsed afterwards. Smoking cessation advice is essential, and reducing alcohol, coffee and tea intake and consumption of acidic drinks and food (fizzy drinks, sour pastilles) will also help to control oral thrush. Other or additional aetiologies for  recurring oral symptoms should be ruled out (e.g. gingivitis, hairy tongue, leucoplakia, burning mouth syndrome).

When choosing antifungal treatment, the three main factors that need to be taken into account are (1) level of saliva production, (2) antifungal history (risk for azole resistance) and (3) level of oral hygiene. In patients with minimal saliva production, the levels of systemic antifungals will be very low in the oral cavity and topical antifungals are preferred. The risk for azole antifungal resistance is high in patients who have been prescribed prolonged courses of low dose (50mg OD) fluconazole, particularly if they have reduced saliva production. In these cases, topical polyenes (nystatin or amphotericin B) are a good option as polyene resistance is extremely rare. Amphotericin B lozenges are off-licence but can be resourced; they are often more efficient than nystatin solution as they last in the mouth longer. Patients whose oral hygiene is poor and is unlikely to improve, twice daily chlorhexidine mouth rinse could be considered due to its antifungal, antibacterial and antibiofilm properties. This is in contrast to many other mouth rinses with no or minimal antifungal effect which can thus promote fungal growth similarly to antibiotics. Chlorhexidine should, however, be avoided in patients with large erosive mucosal lesions due to the risk for allergic reactions.

The patient needs to be referred to an Oral Medicine specialist if the diagnosis is uncertain or microbiologically effective treatment does not resolve their symptoms.

 

Tinea is not responding to standard treatment – what should I do?

Tinea is a generic name for superficial skin, nail and hair infection caused mainly by dermatophytes. Dermatophytes (e.g. Trichophyton, Microsporum, Epidermophyton spp.) are fungi with the ability to metabolise the keratin found in hair, nails, and epidermis. Tinea can also be caused by non-dermatophyte moulds and yeasts like Candida. This is particularly the case with onychomycosis (tinea unguium), tinea versicolor and tinea nigra.

Due to the broad spectrum of pathogens involved, direct microscopy and fungal culture are important in making the diagnosis. Instructions on how to collect skin scrapings, hair samples and nail clippings can be found in the guidelines mentioned below. False negative microbiology is often due to too superficial sample collection (eg. a swab).

The choice of antifungal treatment depends on the extent and depth of the infection. Terbinafine 1% cream and clotrimazole 1% cream can only be used to treat superficial cutaneous infection. Systemic antifungals like terbinafine, itraconazole, and griseofulvin are used to treat hair follicle infection, extensive cutaneous infection, or resistant or refractory disease.  Nystatin is an effective treatment for infections caused by Candida and Candida-like species but it is important to note that dermatophytes are resistant to Nystatin. In case of onychomycosis, monotherapy with topical agents is limited to early, localised onychomycosis. Terbinafine and itraconazole are the most commonly used systemic oral antifungals (see guidelines for dosing).

In case of poor response to treatment, it is important to repeat fungal culture to confirm the presence of a fungal pathogen and test the isolate for resistance (this has to be specifically mentioned on the request form). It is also important to assess adherence to treatment and instructions given regarding preventive measures (washing and disinfecting clothes and shoes, not sharing towels, sport gear, clothes, combs, or hairbrushes, use of desiccating powder and wearing of footwear in public areas, including gym, pool, and public showers). It is also good practise to assess household members for superficial fungal infection and to treat accordingly. It is important to ask about pets and their skin/fur issues (e.g. patches of missing fur) as well, and refer to veterinary medicine if needed.

A number of skin diseases can present similarly to and/or concomitantly with tinea whereby it is important to assess for presence of non-fungal underlying skin disease. The following diagnoses need to be considered in case of failure to respond to treatment: annular psoriasis, atopic dermatitis, seborrheic dermatitis, contact dermatitis, erythema multiforme, and in case of onychomycosis, repeated trauma, nail psoriasis, lichen planus, yellow nail syndrome and squamous cell carcinoma of the nail.

A referral to a dermatology clinic should be considered if oral antifungal treatment is required for a child, diagnosis is uncertain and treatment is unsuccessful, or if the patient is immunocompromised. In case of onychomycosis, a referral to a podiatrist is recommended. In some cases, the patient fails to improve despite multiple courses of antifungal therapy, or the fungal pathogen is resistant to all available antifungals. In these cases, surgical avulsion remains a treatment option to be discussed with the patient.

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