Fungal Foot Infection The evidence. Types of Fungi. Epidemiology. Why is it so common? Epidemiology of Fungal foot Infection (FFI)

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1 Fungal Foot Infection The evidence Epidemiology of Fungal foot Infection (FFI) Ivan Bristow True data difficult to ascertain due to methodological differences. Many studies focus on specific populations European data suggests fungal foot infection prevalence of 34.9% in an out-patient population Prevalence in HK around 31% Burzykowski et al. (2003) Chan et al. (2002) Epidemiology Types of Fungi Seldom seen in children under 10 years. Prevalence rises steadily from teens Peak prevalence in 60-70s More common in males. Around 90% are due to dermatophytes: T.rubrum T.mentagrophytes E.floccosum (Summerbell et al. 1989, Merlin 1998, Rinaldi 2000, Lange 2004) Why is it so common? Fungus has a high prevalence in communal areas Arthroconidia very stubborn Thrives in high humidity Poor hygiene Occlusive footwear Despite the condition being treatable the prevalence remains high suggesting that either: it is not being recognition OR it is not being treated effectively 1

2 T rubrum the hidden menace! Many patients have Chronic Dermatophytosis Lifelong condition Fungal pool resides on plantar surface Zaias & Rebell (1996) Chronic Dermatophytosis Failure to recognise FFI Consistently studies highlight the lack of awareness of the condition (Gill & Marks 1999, Ogasawara 2003, Mayser 2004) 2

3 Why is it not recognised? Why is it not being treated? A study compared treatment seekers and nontreatment seekers The main driving force for seeking treatment was the itching and erythema Symptoms of blistering and fissuring were generally ignored Maruyama (2003) It has been suggested that although tinea pedis is treated the regime is not continued for long enough in many cases so relapse occurs (Murray & Dawber 2001) Increased Fungal Skin disease in diabetes In one study fungal skin infection was found in 32% of Diabetics v 7% of controls. Yosipovitch (1998) ARE FUNGAL FOOT INFECTIONS MORE COMMON IN PEOPLE WITH DIABETES? In another study, infection rates in diabetics were 1.5 higher. Burzykowski (2003) Diabetes & Onychomycosis Main Results Survey of 550 subjects with DM & onychomycosis Assessed using: Duration and type of disease HBA1c Medication Proteinuria and lipid levels Neuropathy (10g monofilament) Pulse presence, ABPI and CRT Prevalence 3 times higher in males Increases with age in both sexes Diabetic subjects have 2.77 risk for o/mycosis compared with non-diabetics Other main risk factors Immuno-suppression Gupta et al. (1998) 3

4 Dermatophytes in other at-risk groups Onychomycosis and HIV infection Fungal nail infection has been correlated to other conditions. Smoking the more packs smoked per day, the greater the risk. Having PVD increases chances of onychomycosis threefold. In a controlled study the prevalence rate of fungal nail infection in HIV patients was 30% compared with just 12.6% in controls Also wider variety of fungi and was isolated in these patients Cribier et al. (1998) Gupta et al. (2000) Proximal sub-ungual onychomycosis Fungal Infection and Obesity Onychomycosis and Immunosuppression Patients who suffer with obesity have a slightly increased risk of FFI. Odds ratio = 1.38 Burzykowski (2003) Patients who have undergone renal transplants have a higher than normal rate of onychomycosis. Typically this is a white sub-ungual presentation Virgili et al. (1999) 4

5 Cancer and Onychomycosis Pathology Patients with a history of cancer have a 3.5 increased risk of developing onychomycosis Sigurgeirsson & Steingrimsson (2004) Adherence Activation of hyphae and DNA transcription Invasion of St Corneum Establishment and secretions Suppression and protection Immune response (variable) Brasch (2010) What happens if it remains untreated? Complications of fungal infection Dermatophytes rarely invade further than the epidermis. However, they may cause fissuring and skin breakdown leading to secondary (bacterial) infection. Skin barrier breakdown is the main identifiable risk factor for the development of cellulitis Local secondary infection Fungal infection and cellulitis 5

6 Cellulitis and Tinea Pedis Risk factors for cellulitis In a study of 60 hospital admissions for cellulitis, 32% had skin changes signs suggestive of tinea pedis. In patients with recurrent cellulitis, skin changes suggestive of tinea pedis were 73% Koutkia et al. (1999) A case control study was conducted (167 v. 294 controls) Strong association found between interdigital maceration and erysipelas. The more webs affected the higher the odds ratio. 60% of cases attributable to ID tinea pedis Dupuy et al. (1999) Fungal infections and cellulitis In a study of 30 adults with leg cellulitis, (13) 43% had mycologically proven tinea pedis Of those who suffered with recurrent cellulitis, 75% had tinea Roldan et al. (2000) Latest Evidence Diagnosis Foot dermatomycosis a significant risk factor for the development of cellulitis. ID tinea (OR 3.2) Onychomycosis (OR 2.2) Visual Prediction (Fletcher et al. 2004, Walling & Sniezek 2007) Microscopy and culture Histological examination Bristow & Spruce (2009) (Lawry et al 2004) 6

7 Clinical Tip TREATMENT OF FFI Skin Infection Most of the proprietary topical anti-fungal creams appear effective against common organisiums causing tinea pedis Terbinafine cream however, appears to have a faster cure time and a slightly broader spectrum than azoles such as clotrimazole and miconazole Hart et al. (1999) Terbinafine Single Application Film Forming Solution Early evidence suggests terbinafine FFS to be effective as other preparations in the treatment of tinea pedis. Cure rate 61% v 18% placebo De Chauvin (2007) Onychomycosis Terbinafine & high risk populations Itraconazole & terbinafine have been found effective in toenail onychomycosis. Terbinafine shows slight superiority and should be considered as first line. Mycological cure rates of 70-80% can be expected with toenail infections Roberts et al. (2003) Limited number of studies identified Cure rates in these patients 68-78% Few adverse event reported Generally safe and well tolerated. Cribier & Bakshi (2004) 7

8 Long Term Effectiveness Who is less likely to be cured? 151 patients were followed up for 5 years after taking single course of terbinafine or Itraconazole and being mycologically cured. After 5 years Terbinafine Itraconazole 46% remained cured 13% remained cured Sigurgeirsson et al. (2002) People with diabetes >50% nail involvement Immuno-suppressed Patients with PVD Lateral nail spike disease Scher & Baran (2003) Arresse & Pierard (2003) How can cure rates be improved? Combination Therapy Basic hygiene advice (Wantabe 2000, Tanaka 2006) Combination therapy Nail reduction prior to therapy Adequate prophylactic treatment of skin and nails Use of oral and topical anti-fungal agents Parallel or serial treatment. Improved cure rate and early evidence of cost effectiveness. More long term follow up required. (Bristow & Baran 2006) Dermatophytoma (Biofilm) Resection of the nail 8

9 Urea Cream Nail Reduction Antifungal Socks? Found to be effective Nail reduced prior to therapy Allows greater penetration of topical agents Reduces fungal load (Fukuda 2001, Malay 2009, Sumikawa 2007) Early evidence suggests antifungal socks as a useful adjunct in the treatment of patients with recurrent tinea pedis. Bristow and Turner (2009) Prophylactic Nail Lacquer In conclusion Two groups cured of Onchomycosis One group amorolfine lacquer every 2/52 3 year follow up Lacquer group delayed OM recurrence by 200 days on average (31% v 8%) Sigurgeirsson et al (2010) FFI is common and often missed or trivialised Decide if treatment is appropriate. Combination therapy in difficult cases of onychomycosis. If treatment is to be implemented, treat the skin good skin care may prevent cellulitis 9