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One of the authors suffered “black toe” on a skiing trip.1 Vigorous fore-aft movements of the feet caused the halluces to strike repeatedly the ends of the ski boots resulting in recurrent micro-trauma and, eventually, subungual haematoma formation and onycholysis. Examination 3 months later revealed the nail of the right hallux to have developed a green discolouration accompanied by non-tender paronychia (fig 1). Microscopy and culture of nail cuttings for fungi were negative but a swab from the nail bed grew Pseudomonas aeruginosa.
Green nail syndrome, or chloronychia, is typically associated with nail infections caused by P aeruginosa.2 The same green colouration may be exhibited by colonies of P aeruginosa grown on agar (fig 2) and results from production of the diffusible pigments pyoverdin and pyocyanin.3 Treatment options for Pseudomonas chloronychia include trimming the affected nail and applying topical astringents and antibiotics or, as in this case, systemic treatment with an oral quinolone.
P aeruginosa is a ubiquitous opportunistic pathogen favouring warm, moist environments. Onycholysis results in disruption of the hyponychium (the region immediately beneath the free edge of the nail), which normally forms a tough, waterproof barrier protecting the nail bed. This allows secondary Pseudomonas infection, which may, therefore, accompany onycholysis of any aetiology—particularly when the nails are also exposed to moisture. This is the first case report of Pseudomonas chloronychia in a skier, where the combination of repeated micro-trauma, causing onycholysis, and perspiration, causing a moist environment, makes ski boots a particularly conducive milieu.
Competing interests: none.
Patient consent: Patient/guardian consent was obtained for publication.
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