In the medical and scientific world it’s known as pseudomonas. In the salon, it’s more commonly referred to as “greenies.” Whatever the name, it’s an unsightly bacterial infection that makes clients and nail techs see green — literally.

Pseudomonas bacterial infection can occur between the natural nail plate and the nail bed, or between an artificial nail coating and the natural nail plate. Some people mistakenly categorize pseudomonas as a mold, but in reality mold is not a human pathogen.

For years, the term “mold” has been used in the nail industry to describe what are most likely pseudomonas bacteria. The green color visible on the nail that’s often mistaken for mold is a byproduct of the infection and is caused primarily by iron compounds.

This type of bacteria is commonly associated with nails, but it can also settle into other parts of the body, including the eyes. It is common in the environment and sometimes even found in hot tubs, says Phoebe Rich, a clinical associate professor of dermatology at the Oregon Health Sciences University in Portland, Ore.

The risk of pseudomonas can be increased by moisture entrapment. Before a nail infection can occur the surface of the nail plate must be contaminated with bacteria. Once a nail enhancement enters the picture bacteria can become trapped between the natural and artificial nail and grow. Covering the nail plate with an enhancement creates a nearly oxygen-free environment in which these bacteria thrive. They produce a dark green substance — the green color you see visible on the nail.

Pseudomonas can form if the bacteria were on the nail plate and were not thoroughly removed before a coating was applied on the nail, or if bacteria somehow got between the nail plate and the product after the client left the salon.

According to Dr. Rich, pseudomonas usually affects a nail that is already damaged or has onycholysis (separation from the nail bed) or paronychia (a condition that often results in inflammation, pus, and pain in and around the cuticle).

According to Doug Schoon, vice president of science and technology for Creative Nail Design, the vast majority of infections that occur on nails with no signs of lifting are often caused by the nail tech. For example, if a client touches her nails to her face and the nail plates aren’t re-cleaned the chances of an infection go up tremendously.

That’s why it’s important for both nail techs and clients to wash their hands before every service. Nail techs should also individually clean the nail plates just before applying product. If you get rid of surface moisture and oils (and the bacteria) before product is applied, it will be highly unlikely for your client to get infections.

If the client has product lifting and bacteria get under the nails, usually no infections occur, says Schoon. But if the client glues her own lifted nails, the chance of infection increases because there’s no oxygen, giving the bacteria a chance to thrive.

Instruct your clients to come to you if they experience lifting and not to attempt to take care of the problem themselves and avoid a nasty infection.

Also, educate your clients to not fear artificial nails and assume they’re the culprits that help make it easier for pseudomonas to thrive. As long as you take the proper sanitary precautions when you’re working on your client she should be fine.

When a client comes to you with green stains on her nails don’t panic and tell her you won’t work on her nails. It is possible to work on a client with pseudomonas. According to Dr. Rich, the infection is not easily transmitted from person to person in a salon. However, as a precaution, once you use a file on an infected nail, don’t use it on another nail. Wrap it in plastic wrap and toss it in the trash.

To help rid the nail plate of the infection, remove the enhancement, lightly buff the stain to open up the nail plate cells, and remove all moisture and some of the surface oils. If the stain is very dark, you might consider leaving product off for a period of time to allow the nail plate to “harden” before applying any more product. Instruct the client to keep the plate clean and dry at all times, and wear gloves when having her hands in water or using household cleaning solutions.

Dr. Rich suggests also having the client soak the nail in vinegar several times a day for a few days. It will take several months for the green stain to grow out with the nail. If it spreads out or does not begin to grow out in three to four weeks, urge your client to visit her doctor.

So the next time one of your clients appears to have a case of the “greenies,” fear not. You’re not dealing with mold or fungus. It’s a bacteria that although may be a nuisance can be treated and eventually gotten rid of.