Pseudomonas aeruginosa is an opportunistic Gram-negative bacillus that can contaminate skin diseases or open wounds or may cause characteristic cutaneous lesions.
Pseudomonas nail infection represents an unpleasant nail disease for the patients due to the green discoloration of the nail. Although commonly seen, the treatment for this disorder remains challenging, and this is further punctuated in HIV infection, as there are no controlled studies assessing systemic or topical treatments [1,2].
We present two HIV-positive patients with Pseudomonas nail infection of the fingernails of 2 and 3 weeks duration (Fig. 1) that were examined in our department 3 years ago (Table 1). They were both men (aged 39 and 46 years) and under highly-active antiretroviral therapy (HAART). They reported that their hands were frequently immersed in water owing to their occupation. At the time of the diagnosis of the nail infection, their CD4 cell counts were 566 and 943 cells/μl, respectively, whereas their viral load was less than 50 copies/ml.
Mycological examination of the affected nail scrapings was performed and fungal infection was excluded by microscopy and culture. Bacteriologic examination that was also performed was positive and revealed the presence of P. aeruginosa. The patients were treated topically with nadifloxacin . No other topical or systemic antimicrobial was administered during the application period.
Nadifloxacin was applied once daily on the affected nails and complete resolution was achieved within 4–6 weeks (Fig. 2). Although it is not certain whether there is a true invasion of pseudomonas in nail plate or just a diffusion of the pyocyanin staining that is produced by Pseudomonas, we consider as cure the complete clearance of the nail [2,3]. No adverse effects were noticed during the application period and no recurrence was reported after 3.4 and 3.1 years, respectively (Table 1).
Pseudomonas nail infection is presented clinically by a typical triad: a characteristic greenish or black discoloration associated with proximal chronic paronychia and disto-lateral onycholysis . The pathogenesis of the nail infection is not yet known. The bacteria are incapable of attacking a healthy nail plate, thus the colonization of pseudomonas is taking place when predisposing factors are present, such as onycholysis, onychotillomania, microtraumatisms, chronic paronychia, moist environment and associated nail disorders such as psoriasis [2–4]. The disease commonly is restricted to one or two nails , as in our cases.
The treatment of nail diseases is not always easy and topical treatment is usually ineffective; however, Pseudomonas nail infection can be treated with brushing of the nail bed with a 2% sodium hypochlorite solution twice daily , topical application of diluted acetic acid or polymyxin B  or chlorhexidine solution  or octenidine dihydrochloride 0.1% solution  for a few weeks. Administration of systemic antibiotics is unnecessary.
To our knowledge, this is the second report  of the successful treatment of Pseudomonas nail infection with topical nadifloxacin and the first in HIV-positive patients.
On the basis of our cases, topical nadifloxacin seems to represent an interesting and efficacious therapeutic choice for the treatment of Pseudomonas nail infection in HIV-positive patients.
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