Retroperitoneal abscess due to Achromobacter xylosoxidans presenting as femoral pain

We describe the case of a 65-year-old patient who presented to our hospital with femoral pain. MRI and CT scan revealed a retroperitoneal abscess. We treated him with early surgical drainage and antibiotic treatment. The urine and draining pus cultures grew Achromobacter xylosoxidans. An iliopsoas abscess may show unique signs depending on its volume. To the best of our knowledge, this is the second reported case of retroperitoneal abscesses due to A. xylosoxidans. Surgical drainage appears to be effective when abscess is large.