Adverse reaction to amoxicillin: a vasculitis case report

Abstract

Introduction: Vasculitis is a heterogeneous group of immune-mediated diseases defined by the inflammation of blood vessels. They can affect vessels of any caliber, resulting in various signs and symptoms, making the diagnosis difficult. This case report shows the importance of anamnesis and careful objective examination, paying attention to potential triggering factors, namely medication intake.

Case description: Male, 71 years old, with a personal history of arterial hypertension, hypertriglyceridemia, and benign prostatic hypertrophy, medicated with losartan + amlodipine and dutasteride + tamsulosin. The patient sought consultation due to a condition compatible with an uncomplicated lower respiratory infection. A diagnosis of community-acquired pneumonia was made, and he was medicated with amoxicillin 500mg 8/8h for seven days, with improvement of the symptoms. However, on the tenth day after starting antibiotic treatment started with progressive worsening, with prostration, bilateral subconjunctival haemorrhage, and the appearance of new macular lesions, painful to the touch, dispersed in the palms of the hands and ventral face of the wrists. In the blood tests alterations suggestive of inflammation and autoimmunity were highlighted, which led to a presumed diagnosis of amoxicillin hypersensitivity vasculitis and was medicated with corticosteroid therapy with symptomatic improvement.

Comment: In this case, the multisystemic presentation and the positive response to corticosteroid therapy points to a diagnosis of vasculitis. Skin lesions associated with episcleritis, and asthenia are more suggestive of small vessel vasculitis. This is potentially secondary to a hypersensitivity reaction to the medication with amoxicillin, considering the temporal evolution of the condition, suggestive of an association. To carry out this difficult diagnosis, the general practitioner, by the nature of his work, accompanying the patient longitudinally, is uniquely qualified to identify cases with temporal evolution and associations between pathologies and previous medications.