What is Chloronychia?
Chloronychia, commonly known as Green Nail Syndrome, is a bacterial infection of the nail. It is characterized by a striking blue-green, dark green, or blackish-green discoloration of the nail plate. Unlike fungal infections, which take months to develop, green nail syndrome can appear very suddenly.
The Bacterial Culprit
The condition is almost exclusively caused by a specific bacterium called Pseudomonas aeruginosa.
Where it lives
- Pseudomonas thrives in damp, wet environments.
- Commonly found in soil, sinks, hot tubs, and sweaty shoes.
Why it turns green
- The bacteria produces toxic pigments called pyocyanin (blue) and pyoverdine (green).
- These pigments dye the underside of the hard keratin nail plate.
How Does it Develop?
Pseudomonas cannot infect a healthy, attached toenail. It requires an "entry point" and a safe place to colonize.
- Pre-existing Onycholysis: The most common scenario. Trauma (like a tight shoe) lifts the toenail slightly from the bed, creating a microscopic pocket. Water gets trapped in this pocket, creating the perfect dark, damp home for the bacteria.
- Moisture Exposure: People whose feet are chronically wet (swimmers, dishwashers, or those with highly sweaty feet in non-breathable boots) are at much higher risk.
Treatment Protocol
Because the bacteria are trapped under the nail plate, topical creams often cannot penetrate deeply enough to kill them. Podiatric treatment typically involves cutting away (debriding) the lifted, green portion of the nail to expose the nail bed. Once exposed, the bacteria is easily treated with topical antibiotics (like polymyxin B or gentamicin) or simple diluted white vinegar soaks, which alter the pH and kill the bacteria rapidly.