We describe the case of a 25-year-old male patient admitted to the emergency department of our hospital. The patient was a resident of a rural area in contact with various farmyard animals, with a history of Down syndrome, severe mental retardation and chronic renal failure (left renal atrophy). He consulted for intermittent fever of 3 months' evolution, weight loss and nocturnal diaphoresis. In the last week, he became dyspnoeic, which is why his relatives decided to consult him.

Physical examination findings: blood pressure 120/80mmHg, heart rate 100lpm, respiratory rate 22min and oxygen saturation: 88%. Teeth in good condition, no jugular distension, no cervical lymphadenopathy. Systolic heart murmur grade 2/4 in mitral focus, as well as cramp in both lung bases. Abdomen without alterations. Oedema in the lower limbs, without skin lesions or neurological focalisation.

The initial diagnostic impression was sepsis of pulmonary origin. Treatment was started with piperacillin tazobactam 4.5g iv every 8h (after taking blood cultures) for 4 days.

Paraclinical tests showed normocytic normochromic anaemia (haemoglobin: 9g/dl) associated with thrombocytopenia (100,000/mm3), hypoalbuminaemia (3g/dl), microscopic haematuria, proteinuria and renal failure (creatinine: 1.6mg/dl), which led to glomerulonephritis; in addition, the chest X-ray and later a chest CT scan ruled out not only pulmonary infection, but also lymphadenopathy and hepatosplenomegaly, although they showed signs of pulmonary congestion. Subsequently, the patient underwent transesophageal echocardiography, which showed: prolapse of the anterior leaflet of the mitral valve, with severe insufficiency and an image of 2.1×1.1cm in the distal third, compatible with endocardial vegetation.

Blood cultures taken on admission reported growth in the 2 bottles (19 and 20h incubation) of Gram-positive catalase-negative cocci, of which phenotypic identification of the species was performed in VITEK2® automated equipment (bioMérieux) as S. pluranimalium, with in vitro sensitivity to penicillin, clindamycin, erythromycin, linezolid, cefotaxime and vancomycin by the Kirby-Bauer method. Based on the modified Duke criteria1 , a diagnosis of infective endocarditis was made, meeting one major criterion (presence of vegetation on echocardiography) and four minor criteria (predisposing cardiac condition, fever, glomerulonephritis and positive blood cultures of a germ that did not meet the characteristics of the major criterion).

Because the patient had severe mitral insufficiency with signs and symptoms of heart failure, and the size of the vegetation was greater than 15mm, transfer to surgery for mitral valve replacement (biological valve) was considered. It should be noted that despite being a young patient, biological valve implantation was decided because the patient's social conditions (severe mental retardation and living in a rural area) made it very difficult for him to travel to attend anticoagulation check-ups. Control blood cultures were performed 8 days after the start of antibiotic therapy with no microbiological growth, and antibiotic treatment was completed with ampicillin sulbactam adjusted according to the sensitivity profile for up to 28 days, in accordance with the recommendation of the guidelines for the treatment of streptococcus. He did not receive gentamicin due to renal compromise. The patient was discharged without complications or sequelae.
