Background: Pseudomonas aeruginosa is the most common pathogen causing bacterial nail infections, producing a classic blue-green pigment, known as chloronychia. Clinical examination and dermoscopic findings, as well as diagnosis and treatment, have not been well characterized.
Objective: The aim was to characterize the clinical and dermoscopic findings of P. aeruginosa infection of the nails and assess treatment efficacy.
Methods: This is a retrospective study of patients with P. aeruginosa nail infection diagnosed between January 27, 2017 and May 28, 2019. Demographics, history, clinical and dermoscopic findings, diagnostics tests, and treatment were documented and analyzed.
Results: Twenty-six patients with P. aeruginosa nail infections were analyzed, with 21 patients completing treatment, two lost to follow-up, and three still undergoing treatment. Clinical examination findings were notable for onycholysis in 76.9% of patients. Green discoloration was seen in 38.5% of patients and green-brown discoloration in 30.8%. A majority of the patients had only one nail involved (73.1%). Dermoscopic findings were significant for greenish pigmentation in 37.5% of patients and 88.9% of cases presenting with a fading border. Wound cultures of nail plates were more sensitive (40%) than dermatopathology (16.7%), but the difference was not statistically significant (p value = 0.1596). All patients were treated with ophthalmic 0.3% gentamicin topical solution nightly for a 3-month period and those who completed therapy had complete resolution of their infection.
Limitations: The limitations of the study were the retrospective design and the small cohort size.
Conclusion: Clinical examination findings of onycholysis coupled with a green or green-brown discoloration involving one or more digits and dermoscopic findings of greenish discoloration with a fading border are consistent with a diagnosis of Pseudomonas nail infection. Gentamicin topical solution is an effective, inexpensive, easy-to-use treatment for this condition. Larger randomized clinical trials are necessary to compare efficacy with other therapeutic options.