How do you differentiate and treat fungal vs bacterial infections under an acrylic nail?

Differentiating and Treating Fungal vs Bacterial Infections Under Acrylic Nails

Laboratory confirmation is essential to differentiate between fungal and bacterial infections under acrylic nails, as clinical features alone are insufficient for accurate diagnosis and treatment selection. 1

Clinical Differentiation Features

Fungal Infection (Onychomycosis)

• Common Presentation:
  • Thickened, discolored, brittle nails
  • Soft and friable nail surface
  • Subungual hyperkeratosis
  • Onycholysis (separation of nail from nail bed)
  • Usually painless unless advanced 2
  • More common in toenails (80% of dermatophyte infections) 2

Bacterial Infection

• Common Presentation:
  • Green or black discoloration (especially with Pseudomonas aeruginosa) 2
  • Swollen, erythematous, and painful periungual skin 2
  • Pain with pressure or movement of the nail 2
  • More common in fingernails 3
  • Often follows trauma or prolonged water exposure 3
  • Artificial nails can harbor bacteria 3

Diagnostic Approach

1. Visual Examination:

   • Assess pattern of involvement (distal, proximal, superficial)
   • Check for green/black discoloration (suggests Pseudomonas)
   • Evaluate periungual tissue for inflammation 2

2. Sample Collection:

   • Remove acrylic nail completely if possible
   • Collect material from discolored, dystrophic parts
   • Include crumbly material and subungual debris
   • Cut affected nail as far back as possible 1

3. Laboratory Testing:

   • For fungal infection:

     • Direct microscopy with KOH preparation or calcofluor white (preferred)
     • Fungal culture (takes 2-6 weeks)
     • PCR testing if available (faster results) 1

   • For bacterial infection:

     • Gram stain
     • Bacterial culture and sensitivity testing 4

Treatment Algorithm

Fungal Infection Treatment

1. Topical Treatment (for mild cases with <50% nail involvement):

   • Amorolfine 5% nail lacquer applied once or twice weekly for 6-12 months
   • Effective in approximately 50% of cases 2
   • Remove diseased nail areas by gentle filing before application

2. Oral Treatment (for moderate to severe cases with >50% nail involvement or >3 nails affected):

   • For dermatophyte infections: Terbinafine 250mg daily for 6 weeks (fingernails) or 12 weeks (toenails) 5, 4
   • For yeast infections (Candida): Fluconazole 4
   • Alternative: Itraconazole 4

Bacterial Infection Treatment

1. For Pseudomonas infections:

   • Topical antiseptics (octenidine)
   • Ciprofloxacin for systemic treatment if needed 4

2. For other bacterial infections:

   • Topical antiseptics
   • Topical antibiotics (nadifloxacin, gentamicin)
   • Systemic antibiotics based on culture and sensitivity 4

3. For severe acute infections:

   • Surgical drainage may be necessary
   • Caution: herpetic whitlow (viral) can mimic bacterial abscess but requires non-operative treatment 3

Prevention After Treatment

1. Remove predisposing factors:

   • Avoid prolonged water exposure
   • Allow time between acrylic nail applications
   • Ensure proper hygiene of nail tools 2

2. Follow-up:

   • Clinical improvement may lag behind mycological cure
   • Complete nail regrowth takes 6-12 months
   • Monitor for relapse (approximately 15% relapse rate) 5

Common Pitfalls

1. Misdiagnosis: Many conditions mimic nail infections (psoriasis, trauma, lichen planus) 2

2. Treating without confirmation: Laboratory testing is essential before initiating treatment 1, 6

3. Mixed infections: Bacterial and fungal infections can coexist, requiring combination therapy 2

4. Inadequate treatment duration: Nail infections require prolonged therapy due to slow nail growth 5

5. Failure to remove artificial nails: Treatment will be ineffective if acrylic nails remain in place 3