What is the management of an infected nail bed?

Management of Infected Nail Bed

For bacterial nail bed infections, initiate cephalexin as first-line antibiotic therapy while keeping the area clean and dry, and perform drainage if an abscess is present. 1

Distinguishing Bacterial from Fungal Infection

Before initiating treatment, it is critical to differentiate between bacterial and fungal nail bed infections, as management differs substantially:

• Bacterial infections typically present with acute onset, pain, erythema, purulent discharge, and potential abscess formation 2
• Fungal infections (onychomycosis) present with gradual nail discoloration, thickening, friable texture, and minimal pain 1
• Obtain bacterial cultures if bacterial infection is suspected to guide appropriate antibiotic selection 1
• Perform KOH preparation and fungal culture on Sabouraud's glucose agar to confirm fungal infection, as 50% of dystrophic nails are non-fungal despite similar appearance 3

Management of Bacterial Nail Bed Infections

Immediate Interventions

• Drain any abscess before initiating antibiotic therapy—this is mandatory for treatment success 1
• Partial or total nail avulsion may be required if painful hematoma or subungual abscess is present, particularly in immunocompromised patients 1
• Clean the nail bed and obtain cultures at the time of drainage 2

Antibiotic Therapy

• Cephalexin is the first-line antibiotic for mild to moderate bacterial nail bed infections, particularly effective against Staphylococcus aureus and Streptococcus pyogenes 1
• Keep the affected area clean and dry between soaks 1
• Avoid manipulation of cuticles and nail biting to prevent further infection 1

Special Considerations

• For Pseudomonas infections (presenting with green or black nail discoloration), treat with ciprofloxacin 4
• Apply topical antiseptics (octenidine) or topical antibiotics (nadifloxacin, gentamicin) as adjunctive therapy 4
• Topical povidone iodine 2% twice daily can be used for bacterial infections while keeping the area dry 3

Follow-Up

• Reassess after 2 weeks of treatment 1
• If infection worsens or does not improve, consider alternative antibiotics based on culture results or surgical intervention 1

Management of Fungal Nail Bed Infections (Onychomycosis)

If fungal infection is confirmed, management differs entirely:

First-Line Systemic Therapy

• Terbinafine 250 mg daily is the preferred first-line treatment for dermatophyte onychomycosis: 6 weeks for fingernails, 12-16 weeks for toenails 2, 5
• Itraconazole pulse therapy (400 mg daily for 1 week per month): 2 pulses for fingernails, 3 pulses for toenails—equally effective as first-line treatment 2
• Baseline liver function tests and complete blood count are recommended before initiating terbinafine 2

Alternative Systemic Therapy

• Fluconazole 150-450 mg weekly for 3 months (fingernails) or longer duration (toenails) may be useful in patients unable to tolerate terbinafine or itraconazole 2
• Azoles are preferred when onychomycosis is caused by Candida species 3

Adjunctive Measures

• Remove dermatophytomas (dense white lesions beneath the nail) mechanically, as these can be resistant to antifungal treatment alone 2
• Apply topical emollients daily to periungual folds, matrix, and nail plate 2
• Keep nails as short as possible and avoid sharing nail clippers 2

Common Pitfalls to Avoid

• Do not assume fungal infection without laboratory confirmation, as 50% of dystrophic nails are non-fungal 3
• Do not initiate antibiotics for fungal infections or antifungals for bacterial infections—misdiagnosis leads to treatment failure 1
• Inadequate duration of antibiotic therapy leads to recurrence—complete the full treatment course 1
• Do not overlook examination of family members for fungal infections, as household transmission is common 3
• Avoid prolonged soaking in water, exposure to solvents, and application of artificial nails during treatment 2