Thousands of pathogenic organisms can survive under and around fingernails.
Clean areas under fingernails if they are visibly dirty and pay special attention to these areas when you wash or use alcohol handrubs for cleaning hands.
Freshly applied nail polish does not increase the numbers of germs present, but chipped nail polish may harbor bacteria.
Persons with artificial nails are more likely to harbor higher bacterial counts than those who do not wear them.
For this reason healthcare personnel should not wear artificial nails.
In a 1998 study published in the journal Nursing Research, healthcare workers who wear artificial nails are more likely to have gram-negative pathogens on their fingertips than those who have natural nails, both before and after hand hygiene.
More recently, an outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit was attributed to two nurses, one with long natural nails, and one with long artificial nails, who carried the implicated strain of the bacteria on their hands.
In June 2010, the CDC stated that artificial nails were a Level I issue.