1561 - Recurrent Bilateral Culture Negative Abscesses Mimicking a Diabetic Foot Infection

Background: The aim of this study is to present a novel case of recurrent bilateral culture negative pedal abscesses, mimicking a diabetic foot infection, as an extra-intestinal manifestation of previously undiagnosed ulcerative colitis. Culture negative abscesses may develop as a rare sequela of ulcerative colitis, with less than 40 cases documented within current literature. They often demonstrate a large neutrophilic predominance, negative cultures, and negative serology testing. The diagnosis was achieved utilizing a multi-specialty team approach with podiatry serving as the primary service coordinating the patient care.

Methods: Multiple incision and drainage procedures were performed with copious purulence expressed from the plantar medial pedal compartment. The patient was initiated on broad spectrum antibiotics post-operatively without a clinical response. Advanced microbiological and rheumatologic testing was performed.

Results: Serial aerobic, anaerobic, acid fast, and fungal cultures as well as 16s rDNA testing remained negative for infection throughout the admission. Rheumatologic work-up consisted of broad autoimmune serologic testing (Table 1).  Greatly elevated levels of calprotectin were identified, resulting in a colonoscopy for confirmation of the diagnosis of ulcerative colitis. The patient was then placed on infliximab and has remained free of recurrent abscesses for the 15 months of follow up.Table 1: Workup Results


Conclusion: The differential diagnosis of a culture negative abscess is broad and a multi-specialty team approach must be considered. Criteria for the diagnosis has previously been proposed and includes: deep abscess with neutrophilic features, negative serologic testing, failure of broad-spectrum antibiotic therapy, and rapid improvement on steroids or other DMARDs with subsequent radiologic evidence of abscess resolution. To our knowledge no bilateral cases have been documented within the foot.