You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
green nail syndrome ( gns ) is characterized by greenish chromonychia caused by pyocyanin , a metabolite produced by p. aeruginosa .
predisposing factors are onychomycoses , nail diseases , working in wet conditions , diabetes mellitus , paronychia and immunosuppression , among others [ 1 , 4 , 5 ] .
p. aeruginosa can be transmitted from gns to wounds or surgical sites [ 6 , 7 ] and thus lead to local and possibly systemic complications in immunocompromised individuals .
reported treatment options are systemic fluoroquinolones , topical octenidine 0.1% , topical aminoglycoside   and nail extraction [ 1 , 8 ] .
moreover , three patients with gns successfully treated with topical nadifloxacin have been reported [ 3 , 4 ] .
nadifloxacin is a topical fluoroquinolone approved for the treatment of acne vulgaris in some countries ( germany , italy , spain , china , japan and india , among others ) .
it has a broad - spectrum activity against gram - positive ( including methicillin - resistant staphylococcus aureus ) , gram - negative and anaerobic bacteria .
hence in some countries ( e.g. india , japan ) it is also approved for the treatment of skin infections .
a 64-year - old otherwise healthy female developed an asymptomatic greenish discoloration of the nail plate of the right middle finger within 2 months .
treatment with topical acetic acid and ethyl lactate during 1 month showed no effect . at first visit a greenish discoloration and mild onychodystrophy of the entire nail plate with distal onycholysis exclusively on the right middle finger
koh preparation ( direct mycological microscopy ) of nail scrapings was negative , but the culture was positive for candida parapsilosis .
nadifloxacin ( nadixa cream ) was applied once daily on the nail plate for 6 weeks .
the coinfection with c. parapsilosis was treated with itraconazole 100 mg twice daily on weeks 1 and 5 .
the nail plate was cured within 6 months after the initiation of treatment ( fig .
2 ) . a 49-year - old female with bulimia suffered from recurrent onycholysis of the big toes due to tight shoes .
moreover a yellow - greenish discoloration persisted for several weeks on the right big toe .
lateral yellow - greenish discoloration , distal onychodystrophy and onycholysis exclusively on the right big toe without signs of paronychia ( fig .
nadifloxacin ( nadixa cream ) was applied once daily on the nail plate for 6 weeks .
the nail plate was cured within 4 months after the initiation of treatment ( fig .
a 64-year - old otherwise healthy female developed an asymptomatic greenish discoloration of the nail plate of the right middle finger within 2 months .
treatment with topical acetic acid and ethyl lactate during 1 month showed no effect . at first visit a greenish discoloration and mild onychodystrophy of the entire nail plate with distal onycholysis exclusively on the right middle finger
koh preparation ( direct mycological microscopy ) of nail scrapings was negative , but the culture was positive for candida parapsilosis .
nadifloxacin ( nadixa cream ) was applied once daily on the nail plate for 6 weeks .
the coinfection with c. parapsilosis was treated with itraconazole 100 mg twice daily on weeks 1 and 5 .
the nail plate was cured within 6 months after the initiation of treatment ( fig .
a 49-year - old female with bulimia suffered from recurrent onycholysis of the big toes due to tight shoes .
moreover a yellow - greenish discoloration persisted for several weeks on the right big toe .
lateral yellow - greenish discoloration , distal onychodystrophy and onycholysis exclusively on the right big toe without signs of paronychia ( fig .
nadifloxacin ( nadixa cream ) was applied once daily on the nail plate for 6 weeks .
the nail plate was cured within 4 months after the initiation of treatment ( fig .
the clinical presentation of these two cases with p. aeruginosa nail infection in only one nail is typical . in both cases
a predisposing factor was prevalent ( onychomycosis in case 1 , nail trauma in case 2 ) .
the observation of successful treatment with nadifloxacin is in line with previous reports [ 2 , 3 , 4 ] .
easy - to - handle , effective , nail - preserving and low - priced treatment option of gns .
as nadifloxacin is not approved for this indication , insurance confirmation of coverage should be provided .
pseudomonas is not sensitive to itraconazole , hence the treatment effect on gns in case 1 can be attributed to nadifloxacin .
however , the treatment of the coinfection ( c. parapsilosis ) with itraconazole in this case contributed to the cure of the nail .
thus , screening for fungal coinfections and if needed antifungal treatment in patients with gns is crucial .
green nail syndrome ( gns ) caused by pseudomonas aeruginosa is the most common bacterial nail infection . 
 the treatment of gns is challenging in many cases and recommendations based on clinical trials are lacking . 
 we report two cases with gns successfully treated with off - label use of topical nadifloxacin , a fluoroquinolone approved for acne and bacterial skin infections in some countries .