Nail Scraping for C/S

Function

Nail Scraping for Culture and Sensitivity (C/S) is the definitive method for identifying the specific pathogens responsible for nail infections. While visual inspection can suggest a fungal infection, a culture is necessary to distinguish between dermatophytes, yeasts, and non-dermatophyte molds, as well as to rule out bacterial involvement.

Why it is Ordered

This test is ordered when a patient presents with onychomycosis (fungal nail infection) symptoms: thickened, brittle, ragged, or distorted nails with discoloration (yellow, brown, or white). Since long-term oral antifungal therapy (like Terbinafine) carries risks of liver toxicity, clinicians use C/S to confirm the diagnosis and ensure the organism is sensitive to the prescribed medication before starting treatment.

Associated Conditions

• Onychomycosis: The most common cause of nail plate destruction.
• Tinea Unguium: Fungal infection specifically caused by dermatophytes.
• Paronychia: Bacterial or fungal infection of the nail fold.
• Psoriasis of the Nail: Can mimic fungal infections; a negative culture helps differentiate the two.

Methodology

The laboratory places the scrapings on specialized media (like Sabouraud Agar). Because fungi grow slowly, the culture may be monitored for up to 3-4 weeks. If bacteria are suspected, a separate aerobic culture is performed to determine antibiotic sensitivity.