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Fungal nail infections

Onychomycosis is a fungal nail infection that causes discolouration, thickening and separation from the nail bed ( Westerberg 2013 )

How common

Happens in 10 % of general population 0.7 % in patients younger than 19 20 % in those older than 60 50 % of those older than 70 Men are affected more than women Only 50 % of nail problems are caused by onychomycosis

What is the cause

Dermatophyte fungi 
( ringworm) Nondermatophyte fungi Yeasts cause about 5 % of infections

Dermatophyte-Trichophyton.rubrum- responsible for > 70 % infections T.mentagrophytes about 20 % T. interdigitale T.tonsurans E.floccosum. Dermatophytes are the most common cause of fungal nail infections mostly Trichophyton rubrum

Yeasts-Majority caused by Candida albicans- occurs in conjunction with chronic muco-cutaneous candidiasis True infection with yeasts are rare and more↑ likely to affect the fingernail or nail folds

NON-DERMATOPHYTE
 ( Rare )
 Usually follow nail trauma, immunosuppression or underlying dermatophyte infection Discuss management with microbiologist or dermatologist Diagnosis requires positive direct microscopy, isolation of organism in pure culture and ideally on repeated occasions

Morphological Types -Distal and lateral subungal 
( most common ) Proximal subungal White or Black superficial Midplate type Total dystrophic

Risk Factors -Diabetes ( 3 times ↑ likely ) Age and ↑ frequently in men Hyperhidrosis Genetics Psoriasis immunodeficiency- eg HIV ( T cell ct 400) Smoking Peripheral arterial disease ↑ participation in physical activity Exposure to wet work Ill-fitting shoes Commercial swimming pools Working with chemicals Walking barefoot Nail biting Occupation ( athletes )

Complications -Psychological distress Treatment failure Relapse after treatment ( high relapse rate of 40-70 % ) Problems with walking, exercising, shoewear Potential for spread Secondary bacterial infection and cellulitis Source of injury to surrounding skin Dermatophytoma

History/ Examination -Duration – how long Pain? Any other skin condition? e.g
○ eczema
○ psoriasis
○ lichen planus H/O nail trauma Family h/o fungal nail infection H/O any previous treatment is the patient immunocompromised Diabetic Peripheral vascular disease Occupation Check the distribution of fungal infection Secondary infection ( e.g cellulitis ) Any obvious
◘ deformity
◘ abnormal pigmentation
◘ footwear trauma
◘ check adjacent toes

What happens? Begins with invasion of stratum corneum of the hyponychiumn in distal nail bed whitish to brownish-yellow opacification of the distal edge of nail infection spreads proximally up the nail bed to ventral nail plate subungal keratosis
hyperproliferation of nail bed ►progressive nail dystrophy

Differential diagnosis -Psoriasis Lichen planus Trauma Eczema Bacterial infection Viral warts Yellow nail syndrome Lamellar onychoschizia Periungual squamous cell carcinoma / Bowen’s disease Subungal melanoma Myxoid cyst

Podiatry referral -Lifestyle advice for foot care and hygiene If nails traumatised by footwear or deformed nails causing injury to adjacent toes Thickened toenails cause discomfort on walking

Oral treatment -Treatment cure rates approx 60-80 % Drugs need to be taken for several months or longer for resistant nails May not restore the nail completely Oral treatment may not be appropriate for the elderly or people on polypharmacy Oral treatment is more effective than topical A complete cure ( clinical and
 mycological ) is often unattainable Psoriasis or injury may look like fungal nail infection – always send sample before starting long term oral treatment

Dermatology referral -Diagnosis uncertain Treatment failure Co-existant nail disease such as psoriasis and lichen planus Immunocompromised patient

Self care / Pharmacist– Treatment not necessary for
everyone and maybe inappropriate for e.g in the elderly Medicated nail paint or lacquer Amorolfine 5 % -For mild or superficial infections once or twice a week
synthetic fungicidal with high sensitivity against
Weak evidence but recommended first line6 months for fingernail and 9-12 months for toenail Topical Rx- low efficacy as the drug is unable to reach the nail bed where the infection resides

Terbinafine –
 1st or 2nd line 6 weeks to 3 months in fingernail 3-6 months into nail Improvement expected end of 2 months ( fingernail ) and 3 months (toenail )

Mechanism of action
Keratophilic medication- both fungistatic and fungicidal Inhibits fungal enzyme (squalene epoxidase ) → accumulation of sterol squalene →toxic to organism Reduces ergosterol → prevents synthesis of fungal cell membrane
 
Side effects GI SE as dyspepsia , nausea and diarrhoea ( common) Skin reactions as morbilliform rash , urticaria ( common ) Taste disturbance ( common ) Rare but serious skin reactions as Stevens-Johnson syndrome , toxic epidermal necrolysis , drug hypersensitvity syndrome Psoriasis may be aggravated by terbinafine treatment

Do not use + also check for interaction Existing liver disease and also warn of any symptom that may suggest liver toxicity as anorexia , nausea, vomiting and fatigue

Other optionsCiclopirox ( topical Rx- not available in UK ) Itraconazole ( first or second line ) Fluconazole ( third line ) Griseofulvin ( fourth line ) Combination treatment for e.g combining systemic therapy with topical – may provide synergistic activity Photodynamic therapy -combines light irradiation and a photosensitising drug to cause selected hyphal cell destruction Laser devices – cosmetic Rx only Iontophoresis ( needs further study ) Ultrasound – has shown fungistatic activity , the device itself is overly complicated, cumbersome and expensive Surgical nail avulsion -if treatment fails considering referral to podiatry who may consider to carry out a chemical or surgical nail avulsion

Advice to patients – sample collection

Wipe off any treatment creams before sampling Send most proximal part of diseased nail- with chiropody scissors Also sample debri from under the diseased part of nail In superficial infections scrape surface of the diseased nail plate with scalpel blade ►►Samples should be kept at room temp and collected into folded dark paper squares (secure with clip and place in a plastic bag ) Commercial collecting kits available- Mycotrans , Dermpak

LINKS AND RESOURCES

Dermnetz is a very useful resource from Newzealand https://dermnetnz.org/topics/fungal-nail-infections/

Dermnet is another fabulous resource for reference images http://www.dermnet.com/moduleSearch.php

British Association of Dermatology has a useful leaflet for patients which can be downloaded in pdf form via http://www.bad.org.uk/for-the-public/patient-information-leaflets/fungal-infections-of-the-nails/?showmore=1&returnlink=http%3A%2F%2Fwww.bad.org.uk%2Ffor-the-public%2Fpatient-information-leaflets#.Xejibej7T-g 

The Pharmaceutical Journal has a useful article which is available here https://www.pharmaceutical-journal.com/cpd-and-learning/learning-article/how-to-treat-fungal-nail-effectively/20205630.article

Primary Care Dermatology Society has a useful section on fungal infections http://www.pcds.org.uk/clinical-guidance/tinea-pedis-feet-manuum-hands-and-unguium-nails

CDC has a very useful section on fungal infections ( for both patients and professionals ) https://www.cdc.gov/fungal/nail-infections.html

Terbinafine PIL – from Medicines. org.uk – print and document https://www.medicines.org.uk/emc/files/pil.1031.pdf

in USA information about Terbinafine https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/020539s021lbl.pdf

References
; see useful links for for further reading
 Medicine compendium www.medicine.org.uk CKS Fungal nail infection accessed via http://cks.nice.org.uk/fungal-nail-infection Fungal nail infection : diagnosis and management BMJ 2014 ; 348 : g1800 Onychomycosis : Current Trends in Diagnosis and Treatment Dyanne P.Westerberg et al Am Fan Phyician 2013 Dec 1;88 (11) : 762-770 Fungal Nail Infections ( Onychomycoses ) : Diagnosis , Lab Investigations and Treatment Quick Reference Guide for Primary Care Aneurin Bevan Health Board British Association of Dermatologists’ guidelines for the management of onychomycosis 2014 M.Ameen et al British Journal of Dermatology July 2014 Onychomycosis : Diagnosis and management Archana Singal, Deepshikha Khanna ; Indian Journal of Dermatology Venereology and Leprology 2011 Vol 77 Issue 6 Page : 659-672 Management of fungal nail infections by Dr Amanda Oakley , Specialist Dermatologist and Clinical Associate Professor , Tristam Clinic , Hamilton BPAC 18 BPJ Issue 19 Fungal Nail Infections ( Onychomycosis ) : A Never- Ending Story ? Mahmoud Ghannoum , Nancy Isham Center for Medical Mycology , University Hospitals of Cleveland , Cleveland Ohio , USA PLOS Pathogens June 2014, Volume 10, Issue 6 e1004105 http://www.plospathogens.org How to treat fungal nail effectively The Pharmaceutical Journal20 NOv2018 By Marion Yau et al the Pharmaceutical Journal

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