Falsely elevated serum tobraycin levels in a patient receiving nebulised tobramycin

Abstract It is common when treating patients with respiratory exacerbations of cystic fibrosis to use both nebulised and intravenous antibiotics. Aminoglycoside drug levels are often measured from finger-prick blood samples. We describe a case of a 14-year-old girl treated simultaneously with IV and nebulised tobramycin in whom drug levels, measured from finger prick blood samples, were erroneously high due to finger contamination by the nebulised drug. Special precautions or direct venepuncture is essential when assessing antibiotic levels in such patients.