Infection of the ankle joint is a serious problem that can have a debilitating outcome if not identified and treated appropriately. The purpose of this retrospective study is to present epidemiologic data aimed at better characterising the clinical diagnosis of septic ankle guiding empiric therapy. All admissions to Los Angeles County+USC Medical Center between 1996 and 2005 were screened to identify patients with ankle infection, shown by a synovial WBC count >
50,000, frank purulence in the joint, or positive synovial culture. Forty-two patients (33 male, 9 female) with a mean age of 44.8 (23 to 67 years) were identified. Twelve out of forty-two patients had indwelling hardware and were excluded from further analysis. Of the 30 patients with hematogenous septic ankle arthritis, 87% reported ankle pain, 70% ankle swelling, and 50% demonstrated decreased range of motion at the ankle joint. Cultures grew Staphylococcus aureus (43%), streptococci (30%), and gram-negative rods (7%). Twenty-three percent of cases were polymicrobial; no cases of Neisseria gonorrhea were identified. There were 3 cases of M. tuberculosis, and 1 case each of Coccidioides immitis and Aspergillus sp. Forty-four percent of the Staphylococcus aureus were methicillin-resistant (MRSA); no change was observed in prevalence of resistant organisms over time. Only 48% had an elevated WBC count; C-reactive protein and ESR were elevated in 100% of patients. Adjacent osteomyelitis was found in 30% of patients. Open irrigation and debridement was performed in 73% of cases; five patients required multiple surgical procedures and 1 amputation. Septic ankle arthritis presents non-specifically; a high index of suspicion is essential to ensure prompt identification and treatment. Empiric antibiotic therapy should cover Staphylococcus aureus (including MRSA) and streptococcus. Patients should be evaluated for adjacent osteomyelitis.
Drug injection often results in soft tissue infections of the upper extremity. The purpose of this study was to determine the distinct bacteriologic features of soft tissue abscesses in injecting drug abusers in order to provide guidelines for optimal empiric antibiotic therapy. Admissions to the musculoskeletal infection ward at our institution from 1993 to 2005 were screened to identify patients with a history of injecting illicit drugs and a diagnosis of a soft tissue abscess. Eight hundred fifty-five patients met these criteria and were included in this retrospective study. There were 638 male and 217 female patients with a mean age of 41.5 years (18 to 75 years). In the 694 patients with positive cultures the most common organism was Staphylococcus aureus, identified in 359 patients (52%). A progressive increase in the prevalence of ORSA was observed; ORSA comprised 5% of Staphylococcus aureus infections in 1999, 50% in 2001, 56% in 2003, and 82% in 2005. Microaerophilic Streptococcus was present in 37% of culture-positive cases and other anaerobes in 10%. Infections were monomicrobial in 366 of 694 patients (53%) and polymicrobial in 328 of 694 patients (47%). Staphylococcus aureus is the most common pathogen in soft tissue abscesses in injecting drug abusers with an increasing proportion of ORSA. In addition to surgical decompression of abscesses, broad-spectrum empiric antibiotic therapy may be necessary.