Green nail syndrome: causes, symptoms, diagnosis, and treatment

Green nail syndrome is characterized by the bluish green nail, caused by bluish green pigments in the nail plate produced by subungual pseudomonas aeruginosa, mostly in patients with oncholysis or chronic paronychia persistently immersed in water.


Pseudomonas aeruginosa is an aerobic Gram-negative bacillus, is widely present in moist natural environments, mainly in the soil, water, and intestines of few persons, and can also temporarily parasitize the anus, genitals, armpits, and external auditory canal. Under normal circumstances, its growth is inhibited by Gram-positive cocci, generally nonpathogenic. However, the bacterium can quickly reproduce in the burns, ulcers, and moist skin, causing skin infections. Systemic infections usually occur in persons with low immunity, such as patients whose normal microflora being inhibited by antibiotics or glucocorticoids, tumor patients, patients with granulocytopenia caused by various causes, patients with immunodeficiency caused by chronic wasting diseases, frail old adults, and malnourished infants. If a healthy person is immersed in water for a long time, the infection of the bacteria can also occur. The bacteria can also cause nosocomial infections by contamination of hospital bedpans and sheets, and has become one of the main pathogens of nosocomial infections in recent years.

Studies have shown that the pathogenicity of the bacteria is mainly caused by the secreted exotoxin, and the collagenase, elastase, and phospholipase secreted by the bacteria are involved in the disease. A typical strain produces two pigments of blueish green pyocyanin and yellowish green pyoverdin.

Systemic pseudomonas aeruginosa infection can cause sepsis, and patients present with fever, jaundice, splenomegaly, pneumonia, urinary tract infection, and meningitis. Cutaneous pseudomonas aeruginosa infection often occurs in the persistently moist lesion sites, especially on the periumbilical and burned surfaces of infants, as well as in macerated toes, external auditory canal, and auricle.

Signs and Symptoms

The characteristic manifestation is oncholysis in the distal nail and the bluish green nail plate. Since the pathogen does not enter the horny layer of nail, bacterial growth in the nail culture cannot be seen. However, pseudomonas aeruginosa can be isolated in the free margin of the nail.

The disease often occurs in patients who are often immersed in water or with paronychia, and may also be secondary to fungal infections.


On the basis of typical clinical manifestations, diagnosis is not difficult.


One hour of immersion of the infected finger in 1% acetic acid solution or 0.1% polymyxin B solution twice daily is effective. After trimming the separated nail plate, topical neosporin solution or silver sulfadiazine cream is beneficial for treatment. If local undulation of paronychia is present, incision and drainage, or nail extraction, should be performed.