590 A Case of Chronic Urticaria Complicated by Raoultella Ornithinolytica Urinary Tract Infection, Bronchospasm and Angioedema

BACKGROUND: Raoultella ornithinolytica (formerly Klebsiella ornithinolytica) has been recovered from water, soil, plants and occasionally mammalian mucosae. It is one of the organisms that cause histamine fish poisoning by converting histidine to histamine as it possesses the enzyme histidine decarboxylase. METHODS: We report a case of a 51 year old woman with a history of rheumatic heart disease, allergy to aspirin and penicillin, reflux oesophagitis, atopic dermatitis, stress incontinence and a cystocele attributed to chronic obstructive pulmonary disease. She presented to the emergency unit with a 5 years history of urticaria of unknown cause, complicated by symptoms of a urinary tract infection and 3 episodes of angioedema in the preceding 10 days. She was not on regular medication but on intermittent prednisone, promethazine and was recently treated with omeprazole and sucralfate for reflux oesophagitis. She denied previous use of angiotensin converting enzyme inhibitors. Urine culture grew Raoultella ornithinolitica (>100 000 CFU/mL) after 3 days. RESULTS: The angioedema resolved on treatment of the UTI with oral ciprofloxacin. She was lost to follow-up and when seen 3 years later she still had intermittent flares of urticaria, but had had no episodes of angioedema. CONCLUSIONS: R ornithinolytica, most commonly described as a causative agent of histamine fish poisoning in humans, possesses histidine decarboxylase, an enzyme that converts histidine into histamine. The resulting elevated levels of histamine usually do not cause severe disease but complications can arise in people with chronic histamine mediated diseases.