Mycological sampling: onychomycosis, tinea
BioMG follows French guidelines. Adapt it to the guidelines and the tests available where you practise.
Onychomycosis (before any treatment)
Mycological examination
- Mycological sample from the affected nail (direct examination and culture), in an experienced laboratory
- Mycological sample from associated skin lesions (intertrigo, sole) if presentif neededAssociated skin lesions of the foot or of any other site suggesting a fungal infection: they must also be sampled, as their presence enters the therapeutic decision [1].
- Conditions: no topical antifungal for 3 months (film-forming solution, lacquer) and no oral antifungal; nails scrubbed with soap on the day of sampling.
Also consider
- Terbinafine planned? Before terbinafine, look for liver disease: see the "Treatment: terbinafine" page.
Do not order
Tinea capitis (child, contacts)
Mycological examination (before treatment)
- Mycological sample from the scalp (scales and hairs; direct examination and culture)
- Mycological sample from the scalp of people living under the same roof and close contacts (anthropophilic tinea, notably T. tonsurans)if neededIndex case of tinea capitis due to Trichophyton tonsurans: mycological screening of all family members and close contacts, and treatment of positive carriers [8]. The HCSP guide recommends that contacts consult for screening [9].
- Contacts (family, community): clinical examination and screening of contacts.
At the end of treatment
- Follow-up mycological sample from the scalp
Do not order
- Antifungal susceptibility testing on tinea capitis: not indicated; the laboratory does the direct examination, culture and species identification [8].
Extensive skin dermatophytosis or not healing on terbinafine (Trichophyton indotineae)
Mycological examination (before changing antifungal)
- Mycological sample from skin lesions (direct examination, culture and species identification)
- State on the request: extensive lesions, terbinafine failure, origin from or recent stay in the Indian subcontinent.
Sources (14)
- Société française de dermatologie. Onychomycoses : modalités de diagnostic et prise en charge. Ann Dermatol Venereol. 2007;134(5 Pt 2):5S7-16.
- Velasquez-Agudelo V, Cardona-Arias JA. Meta-analysis of the utility of culture, biopsy, and direct KOH examination for the diagnosis of onychomycosis. BMC Infect Dis. 2017;17(1):166.
- Stolmeier DA, Stratman HB, McIntee TJ, Stratman EJ. Utility of laboratory test result monitoring in patients taking oral terbinafine or griseofulvin for dermatophyte infections. JAMA Dermatol. 2018;154(12):1409-16.
- US Food and Drug Administration (DailyMed). Terbinafine tablets, USP 250 mg (Cipla USA) : prescribing information, rubrique 1 (Indications and usage), version du 19 septembre 2025.
- Caplan AS, Gold JAW, Smith DJ, Ely JW. Diagnosis and management of tinea infections. Am Fam Physician. 2025;112(4):382-392.
- Frazier WT, Santiago-Delgado ZM, Stupka KC 2nd. Onychomycosis: rapid evidence review. Am Fam Physician. 2021;104(4):359-367.
- Nenoff P, Reinel D, Mayser P, et al. S1 Guideline onychomycosis. J Dtsch Dermatol Ges. 2023;21(6):678-692.
- Fuller LC, Barton RC, Mohd Mustapa MF, Proudfoot LE, Punjabi SP, Higgins EM. British Association of Dermatologists' guidelines for the management of tinea capitis 2014. Br J Dermatol. 2014;171(3):454-63.
- Haut Conseil de la santé publique. Survenue de maladies infectieuses dans une collectivité. Guide des conduites à tenir en cas de maladies infectieuses dans une collectivité d'enfants ou d'adultes. Rapport du 28 septembre 2012 ; fiche « Teignes du cuir chevelu et de la peau ».
- Mayser P, Abeck D, Bosshard PP, et al. Consensus-based guideline on tinea capitis. J Dtsch Dermatol Ges. 2026;24(10):e1510-e1522.
- Ely JW, Rosenfeld S, Seabury Stone M. Diagnosis and management of tinea infections. Am Fam Physician. 2014;90(10):702-710.
- Jabet A, Brun S, Normand AC, et al. Extensive dermatophytosis caused by terbinafine-resistant Trichophyton indotineae, France. Emerg Infect Dis. 2022;28(1):229-33.
- Dellière S, Joannard B, Benderdouche M, et al. Emergence of difficult-to-treat tinea corporis caused by Trichophyton mentagrophytes complex isolates, Paris, France. Emerg Infect Dis. 2022;28(1):224-8.
- Gupta AK, Talukder M, Saunte DML, et al. Consensus recommendations for Trichophyton indotineae: a modified Delphi study. J Eur Acad Dermatol Venereol. 2026 (publié en ligne le 25 septembre 2026).