Acute focal bacterial nephritis in an occupational allergy

A 50-year-old male professional noodle maker with an allergy to soba (buckwheat noodles) was admitted to the emergency room with high fever. 2 months earlier he had a mild stiff shoulder for a week. At the time of admission, the patient had a temperature of 38·8°C and oliguria. Laboratory fi ndings showed a white-blood-cell count of 18 800 per μL (normal value 4400–11 000 per μL), C-reactive protein 16·3 mg/dL (<0·3 mg/dL), procalcitonin 2·44 μg/L (<0·1 μg/L), creatinine 147·5 μmol/L (60–110 μmol/L), plasma glucose 56·4 mmol/L (5·6 mmol/L), HbA1c 14·7% (<5·7 %), and 100 urinary leucocytes cells per high-power fi eld without red blood cells and sediment. Contrast-enhanced CT showed wedge-shaped masslike hypodense lesions, resembling acute focal bacterial nephritis (AFBN; fi gure part A). Meticillin-sensitive Staphylococcus aureus (MSSA), common in skin infections, was found in blood (arterial and venous) and urine samples. Levofl oxacin 500 mg per day and intravenous insulin were started, leading to substantial clinical improvement. However, 7 days after starting levofl oxacin treatment, the patient developed rapidly worsening pain of the left acromioclavicular joint with high fever. A subsequent CT scan showed extensive masses in the deltoid muscle and lateral humeral condyle that extended downwards into the brachioradialis muscle (fi gure part B). Cultured glenohumeral joint fl uid repeatedly grew MSSA. The results of a gallium-67 scan showed diff use uptake at the glenohumeral joint to the lateral humerus (fi gure part C). The antibiotics were changed to cefazolin 6 g/day continuously for 6 weeks for osteomyelitis according to WHO guidelines. He recovered during the 6 weeks and all infected lesions healed. Although MSSA is a common pathogen of bacterial soft-tissue infection, there was no remarkable skin manifestation. Therefore, hypersensitive reaction to soba and diabetes might be relevant in the pathogenesis of blood-borne AFBN. The patient with skin allergy had enhanced colonisation of S aureus, increasing production of potent exotoxin; toxin might act as a risk for blood-borne AFBN adding to diabetes.