Objective. To assess the outcome and adverse prognostic factors of bacterial arthritis (BA).

Methods. In a prospective community survey of BA, data were collected at the time of diagnosis and at a mean of 2 years later. A poor patient outcome was defined as death due to BA or severe overall functional deterioration. A poor joint outcome was defined as amputation, arthrodesis, prosthetic surgery, or severe functional deterioration. Possible prognostic factors were analyzed by univariate analysis.

Results. BA was diagnosed in 154 patients, 121 adults and 33 children. One-half of the adults had a preexisting joint disease and 29% of the infected joints contained synthetic material. The patient outcome was poor in 21% of all patients, and the joint outcome was poor in 33% of the surviving patients. Adverse prognostic factors were an older age, preexisting joint disease, and an infected joint containing synthetic material. These factors were interrelated. There was no association between a poor outcome and young age, comorbidity, immunosuppressive medication, functional class, multiple infected joints, type of microorganism, or treatment delay.

Conclusion. BA had a poor outcome in almost one-half of the patients. Patients who were older, had a preexisting joint disease, and/or had an infected joint containing synthetic material had the poorest prognosis.