not to be used for advertising or in a defamatory context Paronychia infection. Swelling at the base and sides of the fingernail of a 14-year-old girl. Such an infection is normally caused by bacteria. It usually occurs in the folds of skin that surround the nails of the hands and feet. Treatment is with antibiotic drugs. If an abscess (area containing pus) has developed, the area may require surgical drainage.