Retroperitoneal infections by community acquired methicillin resistant Staphylococcus aureus.

PURPOSE: We describe the clinical presentation and response to treatment of community acquired, methicillin resistant Staphylococcus aureus retroperitoneal infections. MATERIALS AND METHODS: A total of 13 patients with unusual retroperitoneal infections who fulfilled Centers for Disease Control criteria for community acquired, methicillin resistant S. aureus were included in this multicenter study, which was done from May 2004 to June 2005. Distinctive features of these infections were noted and treatment alternatives are proposed. RESULTS: Mean patient age was 32 years and 85% of the patients were male. All 13 patients presented with back pain and fever. Infected skin lesions were the presumed portals of entry for bacteria in all cases. Mean time between skin infection and lumbar pain was 48 days. After lumbar pain was established a retroperitoneal abscess was diagnosed at a mean delay of 11 days. An association of foci (kidney, perinephric tissue and psoas) occurred in 85% of cases. Perinephric tissue was the most affected site. Of note, all patients presented with anemia and low serum prothrombin, and required drainage of the retroperitoneal collection. Open drainage was performed in all except 1 patient, in whom percutaneous drainage and antibiotic treatment were sufficient. In 1 patient nephrectomy was necessary. Specific antibiotics were administered as soon as culture results were obtained. Sensitivity was 100% to vancomycin, trimethoprim-sulfamethoxazole, ciprofloxacin and gentamicin. There were no deaths. CONCLUSIONS: Three characteristics shared by our patients should be given special consideration, including an infected skin lesion as the possible portal of entry, anemia plus hypoprothrombinemia and frequent involvement of the perinephric region. Treatment with drainage and antibiotic therapy was effective in all cases.