Fungal nail infections (onychomycosis)
Fungal infection of nails is a common health problem which can be difficult to treat. The majority of sufferers don’t seek treatment, maybe don’t even recognise the existence of a problem. Surveys have shown that up to 30 % of people have onychomycosis with toenails more commonly affected than fingernails. Three groups of fungi cause this disease and these are known as dermatophytes (for example,Trichophyton rubrum), yeasts (for example, Candida albicans) and non-dermatophyte moulds (for example, Scopulariopsis brevicaulis); 85 – 90 % of fungal nail diseases are caused by the dermatophyte group of fungi. There is wide geographical and ethnic variation in the fungi that cause onychomycosis and an increase in foreign travel has lead to the introduction of some exotic species. In addition, fungi that were previously thought to be non-pathogenic may now occur as pathogens in patients with immune system deficiency, such as those with AIDS or leukaemia. Onychomycosis can be fatal in patients with a deficient immune system if the fungus infects tissue surrounding the nail and gains entry into the body.
Fungal nail infections look different depending on which fungi cause the infection however, when a fungal nail infection is suspected specimens should be taken to confirm the diagnosis and to identify the fungus involved. This is important because there are some dermatological conditions that look like onycomycosis, but in fact have a completely different cause and not all onycomycosis-causing fungi respond to all therapies.
Many localised nail infections caused by the dermatophyte fungi, non-dermatophyte fungi and Candidayeasts are treated with nail paints containing antifungal agents for example, tioconazole; these nail paints have a 40 % cure rate. If the surrounding tissue or nail bed is involved then the infection is very unlikely to respond to a nail paints. Terbinafine (Lamisil) is taken orally and is more effective than the nail paints. It will also treat infections where the surrounding tissue is affected and the cure rate for Terbinafine is 80-95 % for dermatopyte infections although it is less active against Candida yeasts and its activity against the non-dermatophyte moulds is unknown. Another group of drugs called the azoles can be taken orally for fungal nail infections. One of these drugs – itraconazole – has cure rate similar to terbinafine and is active against Candida yeasts, it is also active against some non-dermatophyte moulds. Griseofulvin can also be taken orally, but is only useful in dermatophyte infections, it has a cure rate of 90 % for fingernail infections, but only 40 % for toenail infections.
Some precautions can be taken to help prevent the development of fungal nail infections:
- Wash feet with soap and water and remember to dry thoroughly. Wear shower shoes in public areas and change socks daily.
- Nails should be clipped straight across so that the nail does not extend beyond the tip of the digit.
- Wear shoes that fit well and are made of materials that breathe.
- Avoid wearing excessively tight hosiery, which promotes the build up of moisture. Socks made of synthetic fiber tend to “wick” away moisture faster than cotton or wool socks, especially for those with more active life styles.
- The presence of an artificial nail or a polish impedes the evaporation of moisture from underneath the nail and the water trapped below can become stagnant and unhealthy, ideal for fungi and similar organisms to thrive.
- Always use preventive measures when applying polishes. Disinfect home pedicure tools and don’t apply polish to nails suspected of infection those on toes that are red, discolored, or swollen, for example.
Deep Candida infections
These infections are caused by Candida yeasts and occur deep inside the body. They are increasingly a cause of death in neonatal and paediatric patients.
Surgical and intensive care patients
Patients of this group are most likely to experience a deep Candida infection if they are kidney and cancer patients, they have had gastrointestinal, pancreatic or thoracic surgery or they are receiving nutrition intravenously. A deep Candida infection can have serious consequences and it is estimated that 38 % of patients with a deep Candida infection die as a direct result of this fungal infection. The majority of these infections are caused by the yeast Candida albicans, although other Candida yeasts are also implicated, these include Candida torulopsis, Candid krusei and Candida parapsilosis. Accurate diagnosis of the Candida yeast species is important because different species have different susceptibilities to antifungal drugs.
There are several established antifungal agents useful against this disease and these are, amphotericin B, itraconazole, flucytosine and fluconazole. Amptericin B is also available in safer lipid formulations called Ambisome, Amphocil and Abelcet.
Vaginal candidiasis (Vaginal thrush)
Up to three quarters of all women will suffer at least one episode of vaginal thrush during their lifetime. Most of these women experience infrequent attacks and respond well to drug therapy, however in some the infection is recurrent or persistent and does not respond to drug therapy. 95 % of genital candidiasis is caused by the yeast Candida albicans with a further 5 % is caused by the yeast Candida glabrata; infections with Candida glabrata tend to be milder. Candida albicans has been isolated from vaginal swabs in women who do not complain of symptoms and who do not have clinical signs of disease. This suggests that some change in the vaginal environment needs to occur for the yeast to cause disease. These factors are unknown, but vaginal candidiasis is associated with pregnancy, diabetes and antibiotic treatment.
Symptoms of thrush include vaginal discharge, intense vaginal and vulval itching (pruritis), painful or difficult urination (dysuria) and difficult or painful sexual intercourse (dyspareunia). In women who are not pregnant infection tends to begin the week before menstruation. Thrush is so common that often a woman can obtain treatment from a doctor without genital examination. If symptoms persist despite antifungal treatment it is necessary to perform a genital examination and obtain specimens for laboratory diagnosis. This allows the doctor to eliminate other causes of disease such as bacterial infection and to test for drug resistance in any Candida yeasts isolated. More info
Most women with thrush respond to topical treatment with the antifungal drug nystatin or an antifungal drug from the imidazole family – clotrimazole, econazole, isoconazole, ketoconazole or miconazole. Clotrimazole, econazole, ketoconazole and miconazole are sold as creams and clotrimazole, econazole, isoconazole and miconazole are sold as pessaries. The imidazole drugs have a higher cure rate than nystatin with shorter courses of treatment. Two other drugs, itraconazole and fluconazole are available in an oral form for the treatment of thrush. Fluconazole is given in a single oral dose and itraconazole in two doses 8 hours apart. Fluconazole and itraconazole are much more expensive than the other drugs, but are easier and less painful to administer. If a patient does not respond to one of these drug treatments, their doctor will try another.
Women with recurrent thrush may suffer from depression and psychosexual problems and it is important to obtain a cure as quickly as possible. It is often helpful for the patient to think of factors that may trigger the infection. It is also important for a patient to consider that their sexual partner may be colonised with Candida yeasts (this can occur without symptoms) and may pass the infection on to them during sexual intercourse. It is not necessary to investigate oral or intestinal colonisation with Candida yeasts. In the past doctors thought women had recurrent vaginal thrush because they were reinoculated from a persistent intestinal reservoir; this is now known to be false.
Recurrent thrush can be controlled in most women using doses of oral antifungals combined with topical treatments. After symptoms of thrush have been suppressed for six months, drug treatments are discontinued and the patient is reassessed. Many women do not revert to the previous pattern of recurrent disease. Some women find that yoghourt douches or special diets help them. It is also recommended that women with recurrent thrush wear loose fitting cotton underwear and do not wear tights. Finally, it is very important to take medications exactly as prescribed by your doctor – this greatly improves the chances they will work.
Penile candidiasis (Penile thrush)
Most men with penile candidiasis experience an inflamed penis apex and foreskin and sometimes they have a discharge from underneath the foreskin. The apex of the penis is often red with spots and the skin on the penis and in the groin is sometimes itchy and scaly. A specimen will often be taken for laboratory diagnosis as these symptoms can result from other infections. Penile candidiasis is treated with saline washes or application of antifungal cream. Female partners should be examined in case they are the source of the infection. If a man has a persistent infection, he should be investigated for diabetes as diabetes sufferers are prone to penile candidiasis. In addition men who have a penile catheter inserted for a long time are prone to recurrent penile candidiasis.
Oral candidiasis (Oral thrush)
Newborn bottle fed infants and individuals taking antibiotics are most susceptible to oral thrush which is caused by Candida yeasts. Oral thrush appears as curdy, white patches or membranes covering the inside of the mouth. Sloughing of the membrane exposes a reddened, irritated surface. Oral thrush responds well to treatment which is usually oral nystatin, ketoconazole, fluconazole or amphotericin B. More info
Chronic Mucocutaneous Candidiasis (CMC)
CMC is a rare condition caused by the yeast Candida. Most people can fight off Candida infections with the use of antifungal treatment, but in a small number of people these infections recur and are difficult to cure. CMC is a disease in which individuals have frequent, usually continuous oral thrush which is difficult to treat. Most cases of CMC are recognised in childhood where babies or children have repeated episodes of oral thrush and sometimes thrush of the gullet (oesophagus). The immune cells (lymphocytes) of these children can be tested and are found not to respond Candida yeast. When CMC is found in children it is usually genetic, although the exact genetic defect has not been identified it is thought that affected children have two copies of a defective gene, one from each parent. Occasionally there are other reasons for recurrent thrush and blood tests are needed to eliminate these. In some people with genetically acquired CMC other health problems occur as the children get older. The immune systems of these people, although unable to fight offCandida, are overactive in certain body tissues. Damage to endocrine organs like the adrenal glands and ovaries and also to the skin can occur in adolescence or early adulthood. Some patients develop patches on their skin (vitiligo) and others lose some or all of their hair, other patients need various forms of hormone replacement. The exact reason for these additional problems is not known. More info
Although most cases of CMC occur in childhood, there are some cases that first appear in adults even as late as 50 years of age. These cases are not so clearly linked to a genetic defect and the cause(s) of CMC in adults is unknown. People who develop CMC as adults are unlikely to experience the additional problems that people who develop CMC as children can experience.
CMC is usually treated with courses of oral anti-fungal antibiotics such as fluconazole and itraconazole. Often long term therapy with these drugs is required, but the drugs have few side effects and patients have been treated with them for many years at a time quite safely. A slight concern is that anti-fungal drug resistance may occur over time, although this is very uncommon in CMC patients. With more research into this disease it may be possible to identify the exact genetic abnormality and then to develop a gene replacement therapy and a cure.
CMC contact group – Andrea Holroyd, Hillcrest, Park Road, Menston, Nr Ilkley, U.K. LS29 6LN Tel – +44 (0)1943 870296