Acute bacterial paronychia is an acute infection, usually by Staphylococcus aureus, of the paronychial tissues of a digit. It may result from local injury, e.g. a thorn prick in a lateral nail groove, a splinter, torn hangnails or nail biting, but also occurs frequently as an episode during the course of chronic paronychia, when other organisms may be involved, including streptococci, Pseudomonas aeruginosa, coliform organisms and Proteus vulgaris.