Green Nail Syndrome (Pseudomonas Nail Infection)
Topical antiseptic agents and topical antibiotics are first-line treatment for green nail syndrome, with oral ciprofloxacin reserved for more extensive infections or treatment failures. 1
Diagnosis and Clinical Recognition
Green nail syndrome presents with characteristic green, green-yellow, green-blue, or green-brown discoloration of the nail plate, which is sufficient to make a working diagnosis without laboratory confirmation in typical cases. 2
The infection most commonly affects a single digit (79.4% of cases), particularly the big toe or thumb (85.3%), and frequently occurs with concurrent fungal infection (67.6%). 3
Important caveat: Bacterial culture results are inconsistent in 64.7% of cases, with no evidence of P. aeruginosa detected despite classic clinical presentation—this does NOT change management, as these cases respond equally well to standard fluoroquinolone treatment. 3
Risk factors to identify include use of acrylic nails, chronic moisture exposure, recent water immersion, or immunocompromised status. 1, 2
Treatment Algorithm
First-Line: Topical Therapy
Apply topical antiseptic agents (such as octenidine) or topical antibiotics (nadifloxacin, gentamicin) to the affected nail. 4
Topical ciprofloxacin solution applied daily is highly effective, with typical improvement within one week and complete resolution in 8 weeks. 2
Topical ozenoxacin 1% cream daily for 12 weeks is an alternative option, particularly effective for multidrug-resistant P. aeruginosa or co-infections with Achromobacter species. 5
Adjunctive measures include keeping nails dry, avoiding prolonged moisture exposure, and removing artificial nails if present. 1
Second-Line: Oral Antibiotics
Oral ciprofloxacin (500-750 mg twice daily) is indicated for more extensive infections, treatment failures, or when topical therapy is impractical. 1, 4
Treatment duration is typically 1-2 weeks for oral therapy, though topical therapy may continue for 8-12 weeks until complete nail regrowth. 1, 2
Special Populations Requiring Aggressive Treatment
Diabetic patients: Require early intervention and more aggressive treatment due to increased risk of complications—consider starting with oral ciprofloxacin rather than topical therapy alone. 1
Immunocompromised patients: Require longer duration of therapy and closer monitoring, with lower threshold for oral antibiotics. 1
Monitoring and Follow-Up
Reassess clinical response after 2 weeks of appropriate therapy—if no improvement, obtain repeat cultures and sensitivity testing. 1
Expect visible improvement within 1 week and complete resolution in 8 weeks with effective treatment. 2
Prevention of recurrence requires addressing underlying moisture exposure and maintaining dry nail environment. 1
Critical Pitfalls to Avoid
Do not delay treatment waiting for culture confirmation—the characteristic green discoloration is diagnostic, and negative cultures occur in the majority of cases but do not alter management. 3
Do not assume all isolated Pseudomonas requires systemic antibiotics—topical therapy is first-line for uncomplicated nail infections, unlike severe systemic or deep tissue infections. 1, 4
Do not empirically target Pseudomonas without clinical confirmation in other body sites, but the characteristic green nail discoloration IS sufficient clinical confirmation for this diagnosis. 1
Failure to address chronic moisture exposure or artificial nail use will lead to recurrence despite appropriate antibiotic therapy. 1, 2