pseudomonas [sue-de’mo-nus] n: a common household bacteria that thrives in many environments, including water and moist soil. It is the main culprit of the unwelcome phenomenon known to nail techs as “green nails.”

Pseudomonas is the name given to a common, run-of-the-mill bacterium that announces itself to nail clients by turning their nails green. Most of the time, the nail bed and the nail plate do not provide a sustainable environment for these bacteria to grow. There are times, however, when conditions are perfect, and happy bacteria make a home either on top of the nail bed and under the natural nail, or on top of the natural nail and under an enhancement. Advanced cases will appear as dark green or even black spots on the nail. This is not mold.

Mold is a fungus; green spots are bacterial — and the bacteria “pseudomonas” that causes the majority of green nails can be present almost anywhere — on plants and animals, in soil, even in water. Because these bacteria are so prevalent, people can develop green nails from a pseudomonas infection even if they don’t have nail enhancements. All it takes is for the skin under their nail to be compromised and then exposed to the pseudomonas bacterium.

Given that green nails can develop even without enhancements, techs need to be vigilant about thoroughly cleaning their implements, all salon surfaces, their own hands, and the hands and nails of their clients. Careful cleaning and disinfection of the nail surface is essential before applying product. Otherwise, techs could unknowingly trap bacteria between the product and the natural nail. When product is applied over a nail plate that holds pseudomonas bacteria, “it creates a nearly oxygen-free environment — which these bacteria just love,” says Doug Schoon, chief scientific advisor at CND. “They eat the oils and excrete an extremely dark substance. This is what we see when the nail turns green.”

Schoon reminds us that green spots are not caused by moisture. “That’s like saying a flower will grow because you watered the ground every day. Of course that won’t happen unless flower seeds were in the ground,” he says. So in the case of the pseudomonas bacteria causing green spots under nail product, the cause is always one of two things: either these bacteria were on the nail plate when the product was applied (due to dirty implements or poor prep), or product adhesion was insufficient. When adhesion is insufficient, pseudomonas bacteria can find their way under the product through a chip, crack, or lift. Even the most experienced tech can be counted among pseudomonas victims. The reason for this is that even after careful preparation, clients can be exposed to these bacteria while sitting in the salon. “For example,” says Schoon, “if a client touches her nails to her face and the nail plates aren’t re-cleaned,” her chances of infection have increased.

The treatment for green nails is to remove the enhancement, and trim, clean, and disinfect the nail to kill the pseudomonas bacteria. Some doctors will suggest a 1% acetic acid treatment, an antibiotic, or an antifungal cream. There was a time when techs were taught to treat the nail to remove a green spot. Some techs may even remember the days we were told to reapply product over the stain left behind from a green spot. Those days are gone. “If a nail is infected, it’s out of your hands,” says Schoon. “The client needs to be under a doctor’s supervision.”

What’s a Tech to Do to Deal with Pseudomonas?

Prevention is the best treatment. The first step in prevention is a clean environment and proper application. Protect yourself and your client by holding to industry standards. Short cuts can result in infection.

Next, educate your clients about nail care. During a client’s first appointment, instruct her not to pick, pry, or glue her nails. Don’t wait until she has glued a cracked or broken nail to tell her about trapped bacteria and green spots. When a client glues the nail, she increases the risk of trapping bacteria under the nail.

If a green spot appears on the nail, techs can’t treat the infection. “Green spots are considered to be a medical disorder,” says Doug Schoon, “and not something nail technicians are allowed to treat.” Refer the client to a doctor. Techs may want to remove the product from the nail, but if the nail has an infection, techs are legally bound to avoid any form of treatment. If you nick the skin while removing the nail, you could worsen the infection. If any of your implements came into contact with the infected nail, immediately clean and disinfect it, wash your hands, your client’s hands, and the surface of your work area.

The natural nail underneath the enhancement will likely be stained, with colors ranging from a dull green to an unsightly black, and it could be soft from being moist; do not apply polish or product over the nail to hide the color until the client has seen a doctor and the infection is completely clear. Once treated by a doctor, the stained nail will eventually grow out, and a soft nail will “harden” back up as it’s exposed to air.