Episode 62: Onychomycosis (nail fungus).
Future doctors Gabrielle and Jeanette discuss with Dr Arreaza the diagnosis and treatment of onychomycosis, AKA nail fungus.
By Gabrielle Robinson, MS3, and Jeanette Adereti, MS3
Ross University School of Medicine
Facilitated by Hector Arreaza, MD
This is Rio Bravo qWeek, your weekly dose of knowledge brought to you by the Rio Bravo Family Medicine Residency Program from Bakersfield, California. Our program is affiliated with UCLA, and it’s sponsored by Clinica Sierra Vista, Let Us Be Your Healthcare Home.
What is onychomycosis?
-Onychomycosis is a fungal infection that resides in the finger and toenails. The nails become discolored, have onycholysis (painless separation of nail bed), splitting of nail bed, thickened. There are various causes of onychomycosis and examples include the following: dermatophytes, yeast, non-dermatophyte molds.
-Onychomycosis occurs in 10% of the general population.
Microbiology:
Dermatophytes such as Tinea rubrum, account for most onychomycosis infections (~60-70%) while candida account for most of yeast causes of onychomycosis. Non-dermatophyte molds include fusarium, aspergillus, acremonium, scytalidium, Scopulariopsis brevicaulis.
The type of organism involved has an association for the type of infection it causes. Yeast infects fingernails preferentially while the dermatophytes prefer to infect toenails.
Diagnostic testing including culture, KOH preparation and PAS staining can help with confirming fungal infection, but culture not required for empiric treatment with oral terbinafine.
Severity of onychomycosis:
-Mild-moderate: ≤50 percent involvement of the nail and sparing the matrix/lunula
-Moderate-severe: involving >50 percent of the nail or involving the matrix or lunula, including further spread throughout nail.
-It’s common to have multiple nails affected at the same time. Toenails and fingernails can both be affected. Remember to check all nails in your patients. Nails can show signs of local but also systemic diseases.
Risk factors:
-Health conditions: Diabetes, immune suppression, venous insufficiency, peripheral artery disease, or even just having slow growth of the nails. This makes sense because there is decreased blood flow to those areas resulting in decreased immune surveillance of that area. Patient s with PAD are at risk for onychomycosis. Nails normally grow slower in male. Hormones play a role in that growth.
-Exposure: smoking, trauma to the nail, sports, wearing sweaty shoes, being barefoot in communal areas such as swimming pools, college showers, jail house showers, and gyms.
-Dermatological diseases: tinea pedis (athletes’ foot), excessively sweaty hands (hyperhidrosis), psoriasis
-Other factors: old age, having family members whom the patient shares a living space with, bunion (hallux valgus).
Effects on mental health
Unfortunately, the infection takes a toll on the patient because the infection is unsightly it results in psychosocial disturbances. The patients may not want to wear sandals, get pedicures, or shower during gym class if they are school age. These types of feelings can cause patients to not want to go to work or do things they enjoy due to feelings of embarrassment.
Management
Treatment of dermatophyte onychomycosis is guided by causative organism, severity, treatment availability, and cost.
Oral agents
-Oral treatment is generally the gold-standard for onychomycosis due to shorter course and greater efficacy compared to topical.
-Oral terbinafine is the preferred oral agent. Itraconazole can be used in patients not able to tolerate/respond to terbinafine.
-Terbinafine and itraconazole both work by blocking important enzymes in fungal synthesis.
-A randomized double-blind trial showed that terbinafine is more effective outcomes and better long-term cure rates than itraconazole.
-Adult dosing of terbinafine: fingernail onychomycosis =250 mg per day for 6 weeks. Toenail onychomycosis= 250 mg per day for 12 weeks.
-Some side effects of oral terbinafine include headache, dermatitis, GI distress, taste disturbances, and liver enzyme abnormalities. Adverse effects of Itraconazole include headache, GI disturbances, liver enzyme abnormalities.
-In patients receiving continuous therapy, monitoring of transaminase levels is typically performed at baseline and repeated at six weeks if therapy will continue beyond six weeks. A medication interaction check is recommended before starting treatment with oral agents.
-Mycotic cure rates of 76% for terbinafine, 63% for itraconazole with pulse dosing, 59% for itraconazole with continuous dosing, and 48% for fluconazole, topical cure rate is about 40%.
-Recurrence of infection ranges 10-50% (reinfection or persistent infection). Patients need to wait for up to 1 year to see full effect of treatment. Treatment is highly recommended in patients with diabetes, treatment in other patients is cosmetic.
Compliance
Patient compliance is difficult because while taking oral medications, you cannot drink alcohol, and this becomes a problem due to the length of the treatment.
Topical agents
-Efinaconazole, Amorolfine, Tavaborole, Ciclopirox
-Patients who have contraindications to systemic antifungal therapy, who are at risk for drug-drug interactions with systemic antifungal drugs, or who prefer to avoid systemic treatment can be treated with topical therapy. Similarly, to oral agents, these medications work by blocking important processes in fungal synthesis. These agents come in solutions or nail lacquer. Possible side effects include local skin irritation or ingrown nails.
Alternatives
-Less common therapeutic interventions for onychomycosis include oral antifungal agents other than terbinafine and itraconazole, laser therapy, photodynamic therapy, and surgical nail removal.
-Patients with pain or discomfort from infected nails may benefit from removal of hyperkeratotic nail debris. Application of topical urea under occlusion can help with debridement of the nail and symptom improvement.
-Recurrence after treatment of onychomycosis is common.
Prevention:
Now that we have gone over a lot of material about onychomycosis, we should discuss how we can prevent these types of infections from occurring. Having good “foot hygiene” can help reduce the of infection and re-infection.
Wash your hands and feet frequently, especially after encountering someone who is infected.
Clip nails straight across and file afterward making sure to sterilize clippers before and after each use. Do not share nail clippers with others.
If you have a history of sweaty feet, consider using sweat absorbing socks or wearing “breathable shoes” to prevent sweat from accumulating.
Throw out old shoes or disinfect them using antifungal powders.
Wear sandals in communal shower areas and at the pool.
Pay attention to the cleanliness of your nail salon.
Joke: Do you want to know how a person with toenail fungus feels? Just step into their shoes.
Conclusion: Now we conclude our episode number 62 “Onychomycosis (nail fungus).” Future doctors Robinson and Adereti gave a very good summary about symptoms, diagnosis, and treatment of this common infection. Remember, not all patients need to be treated, but patients with diabetes or other risks are highly encouraged to receive treatment to prevent future complications. Even without trying, every night you go to bed being a little wiser.
Thanks for listening to Rio Bravo qWeek. If you have any feedback about this podcast, contact us by email RBresidency@clinicasierravista.org, or visit our website riobravofmrp.org/qweek. This podcast was created with educational purposes only. Visit your primary care physician for additional medical advice. This week we thank Hector Arreaza, Gabrielle Robinson, and Jeanette Adereti. Audio edition: Suraj Amrutia. See you next week!
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References:
Goldstein, Adam O et al, Onychomycosis: Epidemiology, clinical features, and diagnosis, Up to Date, last updated: Apr 30, 2019. https://www.uptodate.com/contents/onychomycosis-epidemiology-clinical-features-and-diagnosis?search=onychomycosis&source=search_result&selectedTitle=2~92&usage_type=default&display_rank=2.
Bai, Jennifer, MD, Consult Corner: Laceration through the nail bed, American Society of Plastic Surgeons, January 1, 2020. https://www.plasticsurgery.org/for-medical-professionals/publications/plastic-surgery-resident/news/consult-corner-laceration-through-the-nail-bed.
Goldstein, Adam O et al, Onychomycosis: Management, Up to Date, last updated: Nov 20, 2020. https://www.uptodate.com/contents/onychomycosis-management?search=onychomycosis&source=search_result&selectedTitle=1~92&usage_type=default&display_rank=1.
Rodgers P, Bassler M. Treating onychomycosis. Am Fam Physician. 2001 Feb 15;63(4):663-72, 677-8. Erratum in: Am Fam Physician 2001 Jun 1;63(11):2129. PMID: 11237081. https://www.aafp.org/afp/2001/0215/p663.html.
Mayo Clinic, Patient and Health Information, Nail Fungus, https://www.mayoclinic.org/diseases-conditions/nail-fungus/symptoms-causes/syc-20353294
