In 2002, the United States Centers for Disease Control and Prevention (CDC) developed guidelines on hand hygiene in healthcare settings. According to these recommendations, medical personnel in contact with high-risk patients (for example, intensive care unit staff, intensive care unit, transplant department, operating room staff) should not use artificial nails and have long nails. This recommendation is classified as AI, that is to say "highly recommended for implementation and confirmed in a reliable manner by properly planned experimental, clinical or epidemiological studies".

In 2003, the CDC launched a campaign to prevent antibiotic resistance in healthcare settings, which included the introduction of "12 steps to prevent antibiotic resistance in surgical patients". Step 12, concerning hand hygiene, contains the instruction "Medical personnel must not have artificial nails".

A large number of bacteria are found in the subungual spaces (on the hands), mainly coagulase-negative staphylococci, Gram-negative bacilli (including Pseudomonas), Corynebacterium and yeasts. The recently applied nail polish does not increase the number of bacteria on the skin surrounding the nail, but the cracked nail polish can contribute to the growth of microorganisms on the nail plates. Even after careful hand washing or the use of surgical brushes, a significant amount of potentially pathogenic microorganisms are found in the sub-sexual spaces of staff hands.

It is not known whether artificial nails contribute to the transmission of nosocomial infections. However, gram-negative microorganisms are more often found on the fingers of people with artificial nails than people with natural nails, before and after washing their hands. The influence of the length of natural and artificial nails on the risk of infection is also unknown, since the growth of bacteria occurs mainly in an area of 1 mm wide, where the nail plate adjoins the skin in the sub-ungueal space.

There is epidemiological evidence that staff with long, natural or artificial nails have caused outbreaks of nosocomial infections.

The fungi that affect the nails multiply in the thickness of the nail plate. The nail protects the growing fungi. Protected from light places and humid conditions are most favorable for the growth of fungi. This is what the difficulty of treating nail fungus is associated with. Nail polish, plastic and acrylic nails can trap moisture and contribute to nail fungal damage.

7B. Qualification of all identified cases of unforeseen death and severe persistent dysfunction associated with nosocomial infection as signaling events.

Note that the recommendations on the undesirability of artificial nails are classified as AI in the CDC guidelines, and this rule must be followed by caregivers who are at high risk of contracting infections.

The Nursing Association Guidelines for Surgical Hand Disinfection and General Hand Hygiene contains the following provisions for nails:

Studies have shown that cracked nail polish can promote the growth of microorganisms on the nails. Although the relationship between recent nail polish and infection has not been proven, it can be assumed that people with recent manicures can avoid strict hand hygiene to avoid damaging the nails. Lax hygiene can lead to transmission.

If nail polish is used, it should not be worn for more than 4 days. After 4 days, the varnish must be removed or reapplied.

Regarding the use of acrylic (artificial) nails, the Association of Operating Sisters notes that artificial nails should not be used.

Many studies have shown that at the fingertips of people with artificial nails before and after washing their hands, more bacteria are found.

The National College of Beauticians in the United States reports that nail fungal lesions often develop under artificial nails.

According to the World Health Organization recommendations on hand hygiene, the use of artificial acrylic nails can help maintain hand contamination after the use of alcohol-containing soaps or gels. Given all of the above recommendations and cautions for long nails, nail polish, and acrylic nails, healthcare professionals should be aware that failure to follow simple rules puts patients at risk for develop nosocomial infections.