A 25 year old, human immunodeficiency virus (HIV) seropositive, severe haemophilic patient was treated for suspected Pneumocystis carinii infection with high dose intravenous cotrimoxazole and subsequently with prednisolone. When he improved he was discharged on oral treatment only to return two days later, extremely unwell, with headaches, fever, sweats, tachycardia and hypotension. A lumbar p...