Which condition is characterized by inflammation at the base of the nail with pus usually present?

The condition characterized by inflammation at the base of the nail with pus usually present is known as paronychia. This condition occurs due to bacterial or fungal infections that affect the tissue surrounding the nail. When paronychia occurs, the inflamed area can become red, swollen, and painful, often with the presence of pus, indicating an infection.

Onychia, while it also involves inflammation related to the nail, primarily refers to inflammation of the nail matrix itself rather than the surrounding tissue. This distinction is crucial because paronychia specifically involves inflammation and infection around the sides and base of the nail, which is typically more visibly swollen and painful with pus.

Onychocryptosis refers to an ingrown nail and does not primarily involve pus or significant inflammation. Onychophagy involves nail-biting behavior, which can damage the nails but does not typically present with inflammation or infection similar to paronychia. Thus, paronychia is the direct answer for its hallmark features of inflammation and pus at the nail's base.