Procalcitonin and neopterin levels do not accurately distinguish bacterial from viral infections in ill-returned travellers with fever.

The diagnostic performance of procalcitonin and neopterin as markers for bacterial and viral causes of fever was evaluated in a cohort of 69 febrile travellers with known etiological agents. Our aim was to establish a decision rule to minimize empirical antibiotic treatment. Compared with C-reactive protein (CRP) and leukocyte (differential) counts, procalcitonin and neopterin had a disappointing diagnostic accuracy. Refraining from antibiotics in case of combined presence of lymphocytosis and/or CRP ≤10 mg/l would result in an 85% reduction in unwanted antibiotic treatment in patients with viral disease but in adequate antibiotic coverage of all patients with bacterial disease.