23 Sept 2026
Patient history
A 46-year-old man has six weeks of low-grade evening fevers, night sweats, aching muscles and 6 kg of weight loss, twice treated as a viral illness. He had a molar extracted two months ago, and was told as a teenager of a murmur needing no treatment.
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Infective endocarditis
IV benzylpenicillin (penicillin G) with gentamicin
A murmur that has changed character is what turns six weeks of vague fevers into an emergency. His old records describe a soft mid-systolic click, the sound of mitral valve prolapse; what he has now is a pansystolic murmur radiating to the axilla, severe regurgitation through a leaflet eaten away since. Being twice labelled a viral illness is the ordinary history here, and the molar extracted two months ago is the portal of entry for viridans group streptococci, low-virulence mouth commensals that settle on valves already abnormal. The peripheral stigmata are immune and embolic phenomena of persistent bacteraemia: splinter haemorrhages, painless Janeway lesions, a Roth spot. Microscopic haematuria with a sterile urine reflects immune-complex glomerulonephritis, not urinary infection, and a positive rheumatoid factor in this setting is another immune-complex phenomenon rather than evidence of rheumatoid arthritis. He meets both modified Duke major criteria, persistently positive cultures with a typical organism across three separate sets and echocardiographic vegetation, which is sufficient for a definite diagnosis. Two practical points. Cultures must come from separate sites before antibiotics, since prior antibiotics are the commonest cause of culture-negative endocarditis. And a normal transthoracic study does not exclude endocarditis: sensitivity is roughly 60–70%, so transoesophageal imaging is required when suspicion is high. A penicillin MIC of 0.06 mg/L puts the organism in the fully susceptible range, which decides the regimen: intravenous benzylpenicillin for four weeks alone, or two weeks with gentamicin for synergy, the shorter course being reasonable because the disease is uncomplicated native-valve with no annular abscess. Ceftriaxone is the outpatient alternative. Surgery is reserved for heart failure, uncontrolled infection, abscess or recurrent embolism, and the perforated leaflet with severe regurgitation is why this valve needs watching for the first of those.