A prospective study of the incidence and characteristics of septic arthritis in a teaching hospital in Riyadh, Saudi Arabia

To find the incidence, characteristics, method of treatment, and outcome of synovial fluid culture-positive septic arthritis, all newly admitted cases of synovial fluid culture-positive septic arthritis to King Khalid University Hospital, Riyadh, Saudi Arabia were studied prospectively during August 2005 to July 2006 and only those with positive synovial fluid culture septic arthritis were included in the analysis. Demographic, clinical, hematological, biochemical, microbiological, radiological, and histopathological data along with the interventional and surgical procedures and the functional outcome related to the joint involved were recorded. Of the 42 patients admitted, only 12 fulfilled the study criteria of having positive synovial fluid culture. Annual incidence was estimated to be 2.13 per 100,000 inhabitants. The mean disease duration before diagnosis and treatment was 10.42 +/- 2.9 days. The affected joints were six knees, three hips, two shoulders, and one with hip and knee involvement. Two patients had rheumatoid arthritis, two had osteoarthritis, and one had sickle cell disease. The most common infecting organism was Staphylococcus aureus, which caused eight of the infections (66.7%), one Salmonella, one Staphylococcus epidermidis, one Enterobacter cloacae, and one Mycobacterium tuberculosis. The septic arthritis in 4 (33.3%) cases followed previous orthopedic intervention. Blood cultures were positive in three patients, all with S. aureus. White blood cell count was elevated in 3 (25%) patients. All patients received intravenous antibiotic for the initial 2 weeks, the most commonly used antibiotic was flucloxacillin. There were no deaths due to septic arthritis. The functional outcome was excellent to good. Septic arthritis is less prevalent in our community, and the most frequent organism is Staphylococcus. However, special risk factors favor other organisms such as Salmonella and Enterobacter. Previous orthopedic intervention is an important risk factor. Mortality due to septic arthritis is lower than reported elsewhere.