Can paronychia be caused by a fungal infection?

Fungal Etiology of Paronychia

Yes, paronychia can definitely be caused by fungal infections, particularly Candida species, which are a common cause of chronic paronychia. 1

Types of Paronychia and Fungal Involvement

Acute Paronychia

• Primarily caused by polymicrobial infections (bacteria) after breach of the protective nail barrier 2
• Usually not fungal in origin, but rather bacterial pathogens

Chronic Paronychia

• Characterized by symptoms lasting at least six weeks 2
• Fungal involvement is significant, with Candida species being important pathogens
• According to the British Association of Dermatologists' guidelines, chronic paronychia with secondary nail dystrophy is one of the four ways Candida can affect the nail apparatus 1
• Common in people with wet occupations (housekeepers, dishwashers, bartenders) and children who suck their thumbs 1

Pathophysiology of Fungal Paronychia

The mechanism of fungal paronychia development follows a specific pattern:

1. Swelling of the posterior nail fold occurs due to chronic immersion in water or allergic reactions
2. The cuticle becomes detached from the nail plate, losing its water-tight protective properties
3. Microorganisms, including Candida yeasts and bacteria, enter the subcuticular space
4. This leads to further cuticular detachment, creating a vicious cycle
5. Infection and inflammation in the nail matrix area eventually lead to proximal nail dystrophy 1

Common Fungal Pathogens in Paronychia

• Candida species are the most common fungal pathogens in paronychia
• Specifically, C. parapsilosis and C. guilliermondii are more frequently isolated than C. albicans in nail infections 3
• Nail and nail fold infections with Candida are more common in:
  • Women than men
  • Fingernails rather than toenails
  • Dominant hand
  • Thumbs and middle fingers more than fourth and fifth fingers 1

Clinical Presentation of Fungal Paronychia

When Candida causes paronychia, the presentation typically includes:

• Swollen, erythematous, and painful periungual skin
• A prominent gap between the nail fold and nail plate
• White, green, or black marks in proximal and lateral portions of the nail
• Increased opacity of the nail
• Transverse or longitudinal furrowing or pitting
• Nail friability and possible detachment from its bed
• Pain with pressure or movement (unlike dermatophyte infections) 1

Important Clinical Considerations

1. Bacterial superinfection is common in fungal paronychia, making it difficult to determine which organism is causing the nail damage 1

2. Fungal involvement in chronic paronychia is controversial - some studies suggest that chronic paronychia is not a type of onychomycosis but rather a form of irritant dermatitis, with Candida as a secondary colonizer rather than the primary cause 4, 5

3. Diagnosis should include proper mycological examination to confirm fungal etiology, as treatment approaches differ significantly between bacterial and fungal causes 3

Treatment Implications

Understanding the fungal etiology of paronychia is crucial for treatment selection:

• For confirmed fungal paronychia, antifungal therapy may be indicated:

  • Topical antifungals like amorolfine or ciclopirox for limited disease 3
  • Systemic antifungals (fluconazole for yeast infections) when more extensive 3

• However, some research suggests topical steroids may be more effective than antifungals in chronic paronychia, supporting the view that it may be primarily an inflammatory condition 4

The multifactorial nature of chronic paronychia requires addressing both the fungal component and the underlying factors that create the environment for infection, including excessive moisture exposure and barrier disruption 5.