Macroscopic amoxicillin crystalluria

Excerpt

A 36-year-old woman was admitted in intensive care unit (ICU) for coma secondary to pneumococcal meningitis complicated by acute obstructive hydrocephalus requiring emergency external cerebrospinal fluid drainage. She weighed 100 kg. Dexamethasone and antimicrobial therapy (cefotaxime, 24 g/day) were started at ICU admission. After 36 h, cefotaxime was switched to amoxicillin (20 g/day administered in six infusions of 60 min) based on the bacterial minimum inhibitory concentration. 36 h later, the urine was white yellowish and turbid, with white particles in the urinary catheter (Fig. 1a) that sedimented in the urine collection recipient (Fig. 1b). Crystalluria was suspected and amoxicillin was switched back to cefotaxime, pending the result of plasmatic antibiotic concentrations. Microscopic urine examination confirmed a massive crystalluria with characteristic amoxicillin crystals (Fig. 1c), associated with microscopic hematuria and a urinary pH of 5.8. Amoxicillin trough concentration was 5.2 mg/l. Hydration and alkalization were initiated, and macroscopic crystalluria disappeared. The patient never developed acute renal failure (glomerular filtration rate of 110 mL/min/1.73 m²). She was extubated at day-6 and discharged from ICU at day-12.

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