Group A Streptococcal Septic Arthritis and Osteomyelitis Presenting As Acute Rheumatic Fever: A Diagnostic Dilemma

Historically, it has been difficult to differentiate between acute rheumatic fever (ARF) and poststreptococcal reactive arthritis (PSRA), given their overlapping systemic symptoms and antecedent Streptococcus pyogenes (Group A Streptococcus (GAS)) diagnosis.We report the case of a five-year-old girl who presented with fever, chills, body aches, and swollen joints.A positive throat qualitative polymerase chain reaction (PCR) test for GAS and significant right knee and bilateral elbow pain prompted admission.The child met the Jones diagnostic criteria for ARF; however, arthrocentesis and imaging later confirmed a septic left elbow and adjacent radial and olecranon osteomyelitis.In the context of this finding, and given the patient's additive, non-suppurative polyarthritis in other afflicted joints, it was deemed more likely that the patient had simultaneous PSRA and septic arthritis rather than ARF.Our case demonstrates how concurrent infection can misrepresent clinical indicators under the Jones criteria, emphasizing the need for a nuanced, riskaverse approach to managing poststreptococcal complications.