Pseudomonas Aeruginosa Infection of the Nail

This post is an answer to the Case – Green Nails

Bacteriologic examination of nail scrapings revealed the presence of fluoroquinolone-sensitive Pseudomonas aeruginosa and Klebsiella pneumoniae. After 2 weeks of treatment with topical nadifloxacin, the nail color returned to normal.

Green nails, a form of chromonychia, may be caused by bacterial infection with P. aeruginosa. This syndrome is typically seen in patients with nail disease such as onycholysis, onychotillomania, or paronychia, particularly in those whose abnormal nails have been exposed to moist environments. The green color is caused by the fluorescent siderophore pyoverdin, produced by P. aeruginosa.

The infection may have been acquired when the patient was gardening or even at work, despite the wearing of gloves when caring for patients. As seen in this case, topical antibiotic therapy treats the bacterial infection and results in normalization of the nail color.