[Septic arthritis in rheumatoid polyarthritis. 24 cases and review of the literature]. / Les arthrites septiques au cours de la polyarthrite rhumatoïde. Vingt quatre observations et revue de la littérature.

Twenty-four cases of septic arthritis in rheumatoid arthritis patients were compared with 99 cases of septic arthritis in patients without rheumatoid arthritis. In addition, 238 previously published cases of septic arthritis with rheumatoid arthritis were analyzed. Fifteen percent of our patients with septic arthritis had rheumatoid arthritis, which was typically of long duration (mean 15 years), erosive, and seropositive. Fifty-four per cent (28% in the literature) and 9% of patients with and without rheumatoid arthritis, respectively, had pyarthrosis of multiple joints. The knee represented one-third of infected joints and the elbows and wrists were more often infected in patients with than without rheumatoid arthritis. S. aureus was recovered in 80% versus only 60% of patients with and without rheumatoid arthritis, respectively. The source of sepsis was often a skin lesion, in particular at the foot, emphasizing the need for early orthopedic treatment of deformities responsible for skin lesions. Monoarticular infection was more likely to be due to an intraarticular injection. Mortality rate was 17% in patients with rheumatoid arthritis (23% in the literature) versus 7% in patients without rheumatoid arthritis. Staphylococcal infection and infection of multiple joints were associated with higher mortality rates (35% and 49%, respectively). The mortality rate in polyarticular infections has failed to decline over the last 35 years. Initial failure to distinguish septic arthritis from an exacerbation of rheumatoid arthritis contributes to the high mortality rate. The diagnosis of septic arthritis rests on a high index of suspicion. Septic arthritis cannot be ruled out based on absence of local inflammation, fever, or hyperleukocytosis or on presence of inflammation of multiple joints. Joint fluid specimens should routinely be sent to the microbiological laboratory and should be inoculated in blood culture bottles at the least suspicion.

Polyarticular septic arthritis.

Twenty-five cases of polyarticular septic arthritis (PASA) were observed in our department over a 13-year period. They accounted for 16.6% of all septic arthritis (15% on average in the literature). A male predominance was noted in our patients, as well as in the literature. The knee was the most frequent location followed by the elbow, shoulder, and hip, in varying order depending on the series. An average of 4 joints was involved. The causative microorganism was Staphylococcus aureus in 20/25 of our patients and in about 50% of published cases. Other frequently causative organisms were streptococci and gram-negative bacteria. Blood cultures and joint aspirations were positive in 19/22 and 23/25 of our cases, respectively. Other septic lesions were noted in 10/25 of our cases. Fever and severe leukocytosis were absent at admission in 5/25 (literature, 37%) and 10/25 of our 25 patients, respectively. The underlying disease was rheumatoid arthritis in 13/25, while 9 of the other patients had immunodepression caused by drugs or by concurrent illness. Typically, rheumatoid arthritis was long-standing and erosive, patients having ulcerated calluses on the feet. This skin source was also noted in 23/36 published cases of PASA in rheumatoid arthritis. Systemic lupus erythematosus was an uncommon disease in PASA, but its presence promoted gram-negative infection. Despite effective therapy with 2 antibiotics, 8/25 patients died, a prognosis that is equally severe in cases reported in the literature (30%) and one that has remained surprisingly stable over the last 40 years. For comparison, the death rate was only 4% in our patients with MASA. Factors contributing to a poor prognosis were age greater than 50 years, rheumatoid arthritis as an underlying disease, and disease of staphylococcal origin. Septic polyarthritis should be considered even when the clinical picture is not florid--when patients have low fever and normal white blood cell counts. Nor should the simultaneous involvement of distant joints rule out infection. Indeed, the frequency of underlying rheumatic disease and its treatment may further confuse the clinical presentation. Joints suspected of harboring infection should be aspirated, including those previously affected by the concurrent rheumatism.