Case Report: Austrian syndrome with multifocal septic arthritis in the immunocompetent elderly: expanding the clinical spectrum.

INTRODUCTION

Austrian syndrome, defined by the triad of pneumococcal pneumonia, meningitis, and infective endocarditis (IE), represents a rare but severe form of invasive pneumococcal disease (IPD). Despite advances in vaccination and antimicrobial therapy, it remains associated with high morbidity and mortality due to diagnostic delays. We report a diagnostically challenging case of Austrian syndrome in an immunocompetent elderly male, complicated by multifocal septic arthritis and delayed recognition of IE.

CASE DESCRIPTION: A 71-year-old man with no history of pneumococcal vaccination, smoking, or alcohol use initially presented with acute monoarthritis of the right knee. Both blood and synovial cultures yielded Streptococcus pneumoniae serotype 19A with reduced susceptibility to penicillin. During hospitalization, he developed acute confusion and right wrist arthritis. Chest imaging revealed right lower lobe consolidation, and brain magnetic resonance imaging demonstrated leptomeningeal enhancement consistent with meningitis. Transthoracic echocardiography was initially negative. However, subsequent transoesophageal echocardiography revealed aortic valve vegetations with annular abscess, confirming definite IE according to modified Duke criteria. The combination of pneumonia, meningitis, and IE established the diagnosis of Austrian syndrome. The patient was managed with prolonged targeted intravenous antibiotics, achieving full clinical and microbiological recovery without surgical intervention.

CONCLUSION

This case illustrates the diagnostic complexity of Austrian syndrome in an immunocompetent elderly patient lacking classical risk factors or respiratory symptoms. It underscores the pivotal role of transoesophageal echocardiography in IE diagnosis, highlights the therapeutic potential of prolonged targeted antimicrobial therapy, and reinforces the importance of pneumococcal vaccination to prevent severe IPD.