What causes an infected Bartholin's gland in the labia minor?

Infected gland. An infected bartholin's gland can be caused by many different bacteria. These can result is severe pain if left untreated till the cystic structure can enlarge greatly.
Bartholins infection. Infection in the bartholin's gland is most often the result of bacteria being trapped inside the gland do to a blocked duct. Infections are usually very painful and consistent with an abscess, whereas bartholin's cyst are generally not painful.