An Unusual Case of Haemophilus influenzae Associated Polyarthritis: Diagnostic and Therapeutic Challenges in Concurrent Septic and Reactive Arthritis

Septic arthritis and reactive arthritis are both recognized as distinct causes of swollen joints; however, they can, at times, overlap as causes of acute polyarthritis. Septic arthritis is an orthopedic emergency, typically caused by bacterial infection, and requires urgent antibiotic treatment and joint drainage to prevent irreversible joint damage. In contrast, reactive arthritis is a sterile, immune-mediated arthritis that occurs following infections and is managed with anti-inflammatory treatments such as corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs). We report the case of a 47-year-old, previously healthy male presenting with acute severe polyarthritis, including both large and small joints, fever, and flu-like symptoms. Blood cultures were positive for <i>Haemophilus influenzae</i>, leading to targeted antibiotic treatment for septicemia. However, given the rapid progression of asymmetrical polyarthralgia and systemic features, reactive arthritis was also suspected, and corticosteroids were commenced. Despite this, persistent fever and worsening joint symptoms raised concerns for septic arthritis in the left knee. Arthroscopy of the left knee revealed synovitis; however, the joint fluid culture was sterile on culture. Ultimately, polymerase chain reaction (PCR) of the fluid confirmed <i>Haemophilus influenzae</i> septic arthritis. Steroids were discontinued, and arthroscopic washout alongside targeted antibiotic therapy led to improved symptoms and inflammatory markers. However, despite gradual clinical improvement, the patient continued to have persistent polyarthralgia, raising the possibility of concurrent reactive polyarthritis alongside septic arthritis. On follow-up, rheumatology is managing chronic reactive arthritis. This case underscores the diagnostic challenges in distinguishing septic arthritis from reactive arthritis in atypical presentations, such as <i>H. influenzae</i> infection. Concurrent arthropathies must also be considered, and no guidelines have been found to address this possibility. This raises the challenge of implementing conflicting therapies, such as corticosteroids for reactive arthritis, that could potentially worsen septic arthritis outcomes. Recognizing the potential consequence of sepsis and septic arthritis, early antibiotic therapy was initiated. Furthermore, a persistent suspicion of septic arthritis, even in the presence of features suggestive of reactive arthritis, led to diagnosis and effective treatment. Further evidence-based guidelines are needed to aid clinicians in managing two or more co-presenting arthropathies.