Infection and immune-mediated meningococcal-associated arthritis: combination features in the same patient

we present a case of a 16-year-old male patient with sudden-onset, rash, arthritis and meningitis by neisseria meningitidis one week after an acute upper respiratory infection. on the 10th day of treatment followed by neurological and arthritis clinical improvement, he presented once again a tender and swollen left knee with a moderate effusion, and active and passive range of motion was severely limited secondary to pain, and when he was submitted to surgical drainage and synovial fluid analysis he showed inflammatory characteristics. a non-steroidal anti-inflammatory drug was taken for five days with complete improvement of symptoms. the case is notable for its combination of features of septic and immune-mediated arthritis, which has rarely been reported in the same patient.