Association between low eosinophil count and acute bacterial infection, a prospective study in hospitalized older adults

Abstract Background The incidence of sepsis increases significantly with age, including a high incidence of bacterial infection in the old adults. Eosinopenia and the CIBLE score have been proposed in critically ill adults and in internal medicine wards. This study aimed to assess whether a low eosinophil count was associated with acute bacterial infection among hospitalized older adults, and to find the most efficient eosinophil count cut-off to differentiate acute bacterial infection from other inflammatory states. Methods This was a prospective study from July 2020 to July 2022 in geriatric wards of the University Paul Brousse Hospital (Villejuif, France) including patients aged of 75 y/o or over suffering from fever or biological inflammation. Acute bacterial infection was assessed using biological identification and/or clinical and radiological data. Results A total of 156 patients were included. Eighty-two (53%) patients suffered from acute bacterial infection (mean age (SD) 88.7 (5.9)). Low eosinophil count was independently associated with acute bacterial infection: OR [CI95%] 3.03 [1.04–9.37] and 6.08 [2.42–16.5] for eosinophil count 0–0.07 G/L and 0.07–0.172 G/L respectively (vs. eosinophil count > 0.172 G/L). Specificity and sensitivity for eosinophil count