# Polyarticular Septic Arthritis in an Immunocompromised Adult: A Case Report

## TL;DR

A 61-year-old immunocompromised woman with rheumatoid arthritis developed a severe infection involving multiple joints and was successfully treated with surgery and long-term antibiotics.

## Contribution

This case highlights the rare and severe presentation of polyarticular septic arthritis in an immunocompromised adult with rheumatoid arthritis.

## Key findings

- The patient had invasive methicillin-sensitive Staphylococcus aureus infection affecting five major joints and causing systemic complications.
- Arthroscopic debridement and a three-month course of combination antibiotics led to full clinical and laboratory recovery.
- The case emphasizes the challenges in diagnosing and treating polyarticular septic arthritis in immunocompromised individuals.

## Abstract

Septic arthritis is an inflammatory process affecting one or more joints due to infection, most commonly of bacterial origin. Polyarticular involvement is a rare but severe form of the disease, frequently associated with preexisting joint pathology, involving an average of 3.5 joints and carrying increased morbidity and mortality. We report the case of a 61-year-old woman with rheumatoid arthritis and long-term immunosuppression who was admitted with invasive methicillin-sensitive Staphylococcus aureus infection, complicated by polyarticular septic arthritis involving five major joints (left hip, knees, and shoulders), intramuscular abscess formation, and cervical spondylodiscitis. Arthroscopic washout and debridement of the affected joints were performed, and combination antibiotic therapy with flucloxacillin, doxycycline, and rifampicin was initiated and maintained for a total of three months. The patient showed excellent clinical and laboratory improvement, with full recovery from systemic dysfunction. The clinical course, diagnostic work-up, treatment, and outcome are discussed, emphasizing the diagnostic challenges and therapeutic considerations in immunocompromised hosts.