A 67-year-old man presents to the office with a 2-week history of a swollen first toe. The patient was diagnosed with gout 4 years ago, and he states that he was treated for a gouty tophi on the medial boarder of his first metatarsophalangeal (MTP) joint 2 weeks ago. The swelling and erythema have increased over the last week following debridement of the tophi. It is unclear whether the erythema, swelling, and pain are caused by gout, an acute infection, or both.
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Gout affects the first MTP joint in 50% of cases and more frequently affects men than women.1 Symptoms of a gouty attack including swelling, erythema, warmth, and joint pain, all of which can mimic the symptoms of a septic joint. Clinicians must pay close attention to key diagnostic factors to distinguish between a septic joint and a gout attack, keeping in mind the possibility that the 2 conditions can occur simultaneously.
Gout is often associated with the formation of tophi, which can break down skin and introduce infection. For concurrent gout and septic arthritis, Staphylococcus aureus is the most common pathogen, although gram-negative bacilli have been found in 30% of cases.2
Synovial fluid analysis from a joint aspiration is the best diagnostic tool to differentiate gout from a septic joint; however, this is impractical for the first MTP joint. Erythrocyte sedimentation rate and peripheral white blood cell count can be elevated in the setting of either condition. Serum uric acid level is usually elevated during a gouty attack. Septic arthritis generally has a more gradual onset of pan and erythema. Ultimately, wound culture must be obtained to rule out a septic joint and wound infection. Antibiotic treatment should not be initiated until a wound culture is obtained.1-4
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
2. Yu KH, Luo SF, Liou LB, et al. Concomitant septic and gouty arthritis — an analysis of 30 cases. Rheumatology (Oxford). 2003;42(9):1062-1066.
3. Rogachefsky RA, Carneiro R, Altman RD, Burkhalter WE. Gout presenting as infectious arthritis. Two case reports. J Bone Joint Surg Am. 1994;76:269-273.
4. Lee KH, Choi ST, Lee SK, Lee JK, Yoon BY. Application of a novel diagnostic rule in the differential diagnosis between acute gouty arthritis and septic arthritis. J Korean Med Sci. 2015;30(6):700-704.