Case Study : Infection and Sepsis

81. Green nail syndrome

Gratefully sourced with permission from Photo Rounds in The Journal of Family Practice

81. Green fingernail

A 34-year-old woman came to our clinic because she was concerned about her thumbnail, which had turned green.

Although her finger didn’t hurt, she was bothered by its appearance.

Several months earlier, the woman had sought care at a different clinic because the same nail had become brittle and come loose from the nail bed, which was spongy.

The physician advised her that she had onychomycosis and prescribed ciclopirox lacquer, but it didn’t help.

Over the next 3 weeks, she noticed a faint green hue developing at the tip of the nail, which expanded and intensified in color (FIGURE).

The patient was a mother who worked at home, washed dishes by hand daily, and bathed her children.

Her past medical history was significant for type 1 diabetes mellitus and Hashimoto’s thyroiditis.

She had no other symptoms.

Green nail syndrome caused by Pseudomonas Aeruginosa

This patient had green nail syndrome (GNS), an infection of the nail bed caused by Pseudomonas aeruginosa.

These bacteria produce pyocyanin, a blue-green pigment that discolors the nail. (1)


GNS often occurs in patients with prior nail problems, such as onychomycosis, onycholysis, trauma, chronic paronychia, or psoriasis.

Nail disease disrupts the integumentary barrier and allows a portal of entry for bacteria.

Scanning electron microscopy of patients with GNS has shown that fungal infections create tunnel-like structures in the nail keratin, and P aeruginosa grows in these spaces.(2)

Nails with prior nail disease that are chronically exposed to moisture are at greatest risk of developing GNS,(3),(4) and it is typical for only one nail to be involved.(5)

Pseudomonas is the most common bacterial infection of the nails, but is not well known because it is rarely reported and patients often don’t seek care.(6)


In our patient’s case, her prior onychomycosis helped to create a favorable environment for the growth of the bacteria. Onycholysis—characterized by separation of the nail plate from the nail bed—was also present in our patient, based on her description of a “spongy” nail bed and loose nail, allowing moisture and bacteria to infiltrate the space.

Onycholysis is associated with hypothyroidism, which the patient also had.(7)

The frequent soaking of her hands during dishwashing and bathing her children helped to provide the moist environment in which Pseudomonas thrives.

As was the case in this patient, GNS is often painless, or may be accompanied by mild tenderness of the nail.

Patients may seek treatment primarily for cosmetic reasons.

GNS can be diagnosed by clinical observation and characteristic pigmentation along with an appropriate patient history.(4) Culture of the nail bed may be helpful if bacterial resistance or co-infection with fungal organisms is suspected.

Changes in nail color can be a sign of many conditions.

Nail discoloration, or chromonychia, can present in a variety of colors.

Nail findings may represent an isolated disease or provide an important clinical clue to other systemic diseases.(8)

The specific shade of discoloration helps to differentiate the underlying pathology.

  • Yellow nail syndrome

    • clinical triad: hypoalbuminemia, pleural effusion, and lymphedema.

    • Bronchiectasis, internal malignancies, immunodeficiency, and rheumatoid arthritis (8)

  • Nail bed hematoma

    • reddish-black, depending on the age of the bleed

    • will often have streaks at the distal margin of the lesion.(9)

  • Subungual melanoma

    • may form a longitudinal band in the nail.(9)

    • is a common variant in African American individuals.(10)

    • brown-lack

  • Medication induced effects

    • minocycline

    • colloidal silver, which is still sold as a dietary supplement or homeopathic remedy to treat a wide range of ailments.(6)

  • Glomus tumour

    • accompanied by localized tenderness, cold sensitivity, and paroxysms of excruciating pain that are disproportional to the size of the tumor.

  • Exogenous pigmentation

    • frequent culprits include eosin, methylene blue, henna, hair dye, and tobacco.(9)


Antibiotics and measures to keep the nail dry will help resolve infection

When chronic nail wetness is a contributing factor, treatment begins with measures to keep the nails dry.

In addition, either topical or systemic antibiotics may be used to eradicate the infection.

Topical applications with agents such as nadifloxacin have been shown to be effective in several case reports,(3) but large-scale controlled trials are lacking.

Fluoroquinolones are regarded as first-line systemic treatment.(5)

Briefly soaking the nail in a diluted sodium hypochlorite (bleach) solution also helps to suppress bacterial growth.

Nail extraction may be required in refractory cases.

For our patient, we prescribed ciprofloxacin 500 mg twice a day for 10 days, plus bleach soaks (one part bleach to 4 parts water) twice a day.

We recommended that our patient wear gloves for household tasks that involved immersing her hands in water, and drying her finger with a hair dryer after bathing.


1. Greene SL, Su WP, Muller SA. Pseudomonas aeruginosa infections of the skin. Am Fam Physician. 1984;29:193-200.


2. de Almeida HL Jr, Duquia RP, de Castro LA, et al. Scanning electron microscopy of the green nail. Int J Dermatol. 2010;49:962-963.

3. Hengge UR, Bardeli V. Images in clinical medicine. Green nails. N Engl J Med. 2009;360:1125.


4. Chiriac A, Brzezinski P, Foia L, et al. Chloronychia: green nail syndrome caused by Pseudomonas aeruginosa in elderly persons. Clin Interv Aging. 2015;10:265-267.


5. Müller S, Ebnöther M, Itin P. Green nail syndrome (Pseudomonas aeruginosa nail infection): Two cases successfully treated with topical nadifloxacin, an acne medication. Case Rep Dermatol. 2014;6:180-184.


6. Raam R, DeClerck B, Jhun P, et al. That’s some weird nail polish you got there! Ann Emerg Med. 2015;66:585-588.

7. Gregoriou S, Argyriou G, Larios G, et al. Nail disorders and systemic disease: what the nails tell us. J Fam Pract. 2008;57:509-514.


8. Fawcett RS, Linford S, Stulberg DL. Nail abnormalities: clues to systemic disease. Am Fam Physician. 2004;69:1417-1424.


9. Braun RP, Baran R, Le Gal FA, et al. Diagnosis and management of nail pigmentations. J Am Acad Dermatol. 2007;56:835-847.


10. Buka R, Friedman KA, Phelps RG, et al. Childhood longitudinal melanonychia: case reports and review of the literature. Mt Sinai J Med. 2001;68:331-335.


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Ireland notes.png

Nadifloxacin (potent topical quinolone) is N/A in Ireland.

Alternatively, topical antibiotics, such as bacitracin or polymyxin B, applied two to four times per day will cure most patients if continued for one to four months.

Cream containing both bacitracin and polymyxin B is available in Ireland as Polyfax.

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