Leukopenia, neutropenia, and procalcitonin levels in young febrile infants with invasive bacterial infections

Background and objective Serum procalcitonin (PCT) is a highly accurate biomarker for stratifying the risk of invasive bacterial infections (IBIs) in febrile infants ≤60 days old. However, PCT is unavailable in some settings. We explored the association of leukopenia and neutropenia with IBIs in non–critically ill febrile infants ≤60 days old, with and without PCT. Methods We conducted a secondary analysis of a prospective observational cohort consisting of 7407 non–critically ill infants ≤60 days old with temperatures ≥38°C. We focused on the risk of IBIs in patients with leukopenia (white blood cell [WBC] count