A 28-year-old man with a 4-week history of tinea pedis (interdigital type) presents with maceration, erosions, and secondary bacterial infection (purulent drainage, mild cellulitis of the foot). He has been using topical terbinafine for 2 weeks without improvement. What is the most appropriate next step in management?

Question

Accepted Answer

C. Start oral terbinafine 250 mg daily AND oral antibiotics (amoxicillin-clavulanate) for the secondary infection. ## Clinical Scenario Breakdown

This patient has **tinea pedis with secondary bacterial superinfection**:
- **Primary pathology**: Dermatophyte infection (interdigital tinea pedis)
- **Complication**: Maceration → erosions → bacterial colonization (purulent drainage, cellulitis)
- **Treatment failure**: Topical terbinafine × 2 weeks without improvement

## Why Oral Terbinafine + Oral Antibiotics Is Correct

**Key Point:** When tinea pedis is complicated by secondary bacterial infection and cellulitis, **both the fungal and bacterial infections must be treated simultaneously** with systemic agents.

**High-Yield:** Tinea pedis with secondary bacterial infection requires:
1. **Oral antifungal** (terbinafine) — because:
   - Topical penetration is poor in interdigital spaces (moisture, occlusion)
   - Systemic therapy achieves higher skin concentrations
   - Fungicidal action (terbinafine) is faster than topical azoles

2. **Oral antibiotic** (amoxicillin-clavulanate or cephalexin) — because:
   - Cellulitis is present (spreading erythema, warmth, purulent drainage)
   - Systemic antibiotic is needed to control bacterial spread
   - Topical antibiotics alone are insufficient for cellulitis

**Clinical Pearl:** The **maceration and erosions in tinea pedis create a portal of entry** for bacteria (usually *Staphylococcus aureus* or *Streptococcus pyogenes*). Treating only the fungus will not resolve the bacterial superinfection; treating only bacteria will allow the fungus to persist and re-seed the infection.

## Dosing for Concurrent Infection

| Agent | Dose | Duration | Indication |
|-------|------|----------|------------|
| **Terbinafine** | 250 mg daily | 2–4 weeks | Dermatophyte |
| **Amoxicillin-clavulanate** | 500/125 mg TDS | 7–10 days | β-lactamase-producing bacteria |
| Cephalexin | 500 mg QID | 7–10 days | Alternative if penicillin allergy |

## Management Algorithm for Tinea with Superinfection

```mermaid
flowchart TD
  A[Tinea pedis with maceration/erosions]:::outcome --> B{Signs of bacterial infection?}:::decision
  B -->|No| C[Oral terbinafine 250 mg daily]:::action
  B -->|Yes: purulent drainage, cellulitis| D[Oral terbinafine + oral antibiotic]:::action
  C --> E[Review at 2-4 weeks]:::action
  D --> F[Antibiotic x 7-10 days; antifungal x 2-4 weeks]:::action
  F --> G[Reassess at 1-2 weeks]:::action
  G --> H{Cellulitis resolved?}:::decision
  H -->|Yes| I[Continue antifungal until cure]:::action
  H -->|No| J[Consider resistant organism or poor compliance]:::urgent
```

**Mnemonic:** **BOTH for BUGS + FUNGI** — When tinea is complicated by bacterial infection, treat **B**oth organisms **O**rally **T**ogether **H**olistically.

![Dermatophytosis — Tinea diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/4107.webp)

Answer

A. Discontinue all antifungals and treat only the bacterial infection with systemic antibiotics

Answer

B. Perform bacterial culture and await sensitivity results before starting antibiotics

Answer

D. Continue topical terbinafine and add topical antibiotics (mupirocin)

Explanation

Clinical Scenario Breakdown

Why Oral Terbinafine + Oral Antibiotics Is Correct

Dosing for Concurrent Infection

Management Algorithm for Tinea with Superinfection

Practice similar questions

Join our NEET PG community

Agent	Dose	Duration	Indication
Terbinafine	250 mg daily	2–4 weeks	Dermatophyte
Amoxicillin-clavulanate	500/125 mg TDS	7–10 days	β-lactamase-producing bacteria
Cephalexin	500 mg QID	7–10 days	Alternative if penicillin allergy