Case Report: RA, Diabetes and a Rare Infection

In a case report published in the American Journal of Orthopedics, physicians report a rheumatoid arthritis patient with diabetes mellitus and a rare, but serious, fungal joint infection.

A septic arthritis diagnosis is often delayed or missed altogether in immune compromised patients with diabetes mellitus who, by nature of their comorbidities, have an especially high risk of atypical infections, including mycotic subtypes. A delayed diagnosis of septic arthritis caused by a Candida albicans infection can lead to increased morbidity making it very difficult, if not impossible, to treat in some cases.

This case highlights the complexities of treating infections in immunocompromised patients.

“This case reflects the complexities of septic arthritis caused by atypical pathogens and highlights the need for clinical vigilance in the setting of comorbidities, such as type 2 diabetes and rheumatoid arthritis. Failure to consider the diagnosis early on might result in delayed and inadequate treatment, increased joint destruction, and, potentially, osteomyelitis with subsequent increased morbidity. Early diagnosis (based on joint aspirate findings), surgical debridement, and prolonged aggressive treatment with antifungal medication are the mainstays of treatment,” writes Adam Tucker and colleagues.

Case

A 52-year-old female with rheumatoid arthritis and insulin-dependent type two diabetes mellitus sought emergency treatment at a local hospital for right ankle pain. Four weeks earlier, she received a steroid injection into the subtalar joint by a rheumatologist. She reported having purulent discharge from the peroneal sheath for about two weeks. She was being treated with prednisolone for rheumatoid arthritis maintenance therapy.

The patient presented with painful range of motion, fever and elevated C reactive protein. Clinically, the joint was not erythematous, but active and passive movements were painful. Blood tests revealed a C-reactive protein level of 98 mg/dL and a white blood cell (WBC) count of 11.3 × 109/L.

Joint aspirates at admission and one week post ED visit showed mycotic organisms, specifically C albicans. The patient underwent debridement of the joint and was put on a six-week course of anti-fungal therapy with anidulafungin.

Likely contributing factors include the prior injection to the joint, poor peripheral oxygen supply secondary to diabetes mellitus, and high blood sugars, which hinder antibody function. Left untreated, septic arthritis can lead to osteomyelitis and joint destruction.

The patient made good progress and was able to bear weight on her ankle before being discharged from the hospital.

Discussion

Infection of a joint capsule is considered an emergency. Having an infected joint is debilitating and most often caused by staphylococcus aureus bacteria. Time is of the essence in making a diagnosis before joint damage ensues.

Septic arthritis is serious and requires prompt diagnosis and treatment, which can be facilitated by utilizing the Kocher diagnostic criteria:

• Inability to bear weight
• White blood cell count > 12,000
• Sedimentation rate > 40mm/h
• Fever > 38.5 C

The Kocher criteria confer a predictive value of 99.6% when all conditions are met.

While C albicans is not a common cause of septic arthritis, reports indicate higher risk in immune compromised patients such as those with rheumatic conditions, on steroid therapy and particularly when they also have diabetes. The most common pathogenic cause is S aureus, but streptococcus, neisseria and pseudomonas also are common.

The physicians write that Candida parapsilosis and Candida glabrata have also been reported in other case reports of Candida septic arthritis of the ankle.

Without treatment, this infection can lead to articular cartilage destruction and erosion, and progressive deformity and functional debilitation. A delayed diagnosis or suboptimal treatment could lead to fungal osteomyelitis, which typically is associated with poor outcomes.

Early aggressive treatment is essential. Candida septic arthritis is typically treated with an anti-fungal medication that may or may not require surgical debridement.

Key Points

• Immunosuppressed patients, such as those with rheumatologic disease, on steroid therapy, and or with diabetes mellitus, are a higher risk for developing intra-articular fungal infections.
• Early diagnosis, early treatment and possibly surgical intervention are crucial to prevent further joint or bone damage.
• The Kocher criteria may be useful in establishing an early diagnosis.
• Treatment should consist of a broad-spectrum antifungal until speciation and sensitivities can be confirmed.

References:

Adam Tucker  MRCS; Scott Matthews  MRCS; Alister Wilson  FRCS. "Mycotic Septic Arthritis of the Ankle Joint," American Journal of Orthopedics. November 2016. 45(7):E478-E480