Co-trimoxazole induced acute thrombocytopenic purpura

A 58 year old man presented to the emergency department with rhinorrhagia, haematuria, and generalised petechiae and ecchymoses (fig 1). Two weeks before his admission, a 10 day course of co-trimoxazole double strength tablets (trimethoprim 160 mg and sulfamethoxazole 800 mg) twice daily was prescribed as treatment for a urinary tract infection caused by E coli . He stopped taking the drugs on his physician’s advice two days before completion of treatment after he noticed easy bruising. The subsequent development of extensive purpuric lesions and rhinorrhagia brought him to the hospital. His medical history was notable only for moderate prostatic enlargement. On admission, his spleen was not palpable. A peripheral blood sample revealed a very low platelet count (<5×109/l) and a …