Background:

Focal extraintestinal infections from nontyphoid salmonellae have increased in incidence during the past decade. Isolated salmonella soft tissue infections are relatively rare, occurring mostly in adults with chronic underlying conditions, such as diabetes mellitus and cell-mediated immunity defects. Patients treated with anti TNF-a antibodies exhibit increased susceptibility to infections caused by intracellular microbes, such as Salmonella.

Purpose:

To present a female patient with rheumatoid arthritis on antiTNF-a treatment with a postoperative soft tissue and joint infection due to Salmonella enteritidis.

Case presentation:

A 52-year-old female patient with rheumatoid arthritis, initially treated with corticosteroids and naproxen, was operated for a right knee ruptured Baker's cyst. Two weeks postoperatively, arthritis symptoms rapidly deteriorated, and leflunomide plus infliximab were added. Despite prompt clinical response, she developed a painful, inflammatory swelling of the right popliteal area, which was automatically ruptured, draining pus and serosanguinous material. Cultures revealed Salmonella enteritidis, and markedly elevated ESR and CRP were noted. Steroid-induced diabetes mellitus was also discovered. The patient had no gastrointestinal symptoms and stool cultures were negative for Salmonella spp. At that point, the patient was referred to our clinic. MRI of the affected area showed a marked inflammatory process of the surrounding soft tissue with increased intra-articular fluid collection and thickening of the synovium. No radiological sign of osteomyelitis was evident. Immunomodulatory agents were stopped and ciprofloxacin 750 mg q12 h and glibenclamide were administered. Inflammatory markers soon dropped and optimal glucose control was achieved. Surgical debridement and reconstruction of the knee joint was performed under antibiotic coverage uneventfully. The patient completed a 12-week course of ciprofloxacin without adverse events, and infliximab is scheduled to be restarted.

Conclusion:

Salmonella spp. although rare, should always be considered as a potential pathogen in soft tissue and joint infections in patients with certain comorbidities (e.g. diabetes) or under immunosuppressive medications (such as antiTNF-a antibodies). Opportunistic infections during antiTNF-a regimens do not necessarily preclude its future use in the same patient, once infection is treated, although secondary prophylaxis could be an issue.