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

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 < 0.01 G/L and CIBLE score were 84%-49% and 72%-62%, respectively with equivalent AUCs (0.66 and 0.67). CONCLUSION: Eosinophil count < 0.01 G/L is a simple, routinely used and inexpensive tool which can easily participate in antibiotic decisions for older adults. Further studies are needed to assess clinical benefits. TRIAL REGISTRATION: The study was registered at Clinical trial.gov (NCT04363138-23/04/2020).

Persistence of Neutralizing Antibodies and Clinical Protection up to 12†Months After Severe Acute Respiratory Syndrome Coronavirus 2 Infection in the Elderly.

Background: Coronavirus disease 2019 (COVID-19) has severely affected the elderly, who are expected to display decreased immune responses due to immunosenescence. Methods: This study retrospectively assesses neutralizing antibody (NAb) production up to 12 months after infection in long-term care patients. We used Roche Diagnostics immunoassay to quantify anti-spike (S) antibodies and a competitive immunoassay from YHLO as a surrogate test for NAb. Results: We included 91 patients (mean age, 86 years). There was no significant variation in anti-S titers over time. There was a significant decrease of NAb titers between month 3 and month 6 but no further significant change up to month 12. Overall, 75 of 91 (82%) and 52 of 91 (57%) patients had, at least once, anti-S titers >75 U/mL and NAb titers >50 AU/mL, respectively, corresponding to a significant neutralizing activity in vitro. All 68 patients studied at M12 had detectable anti-S antibodies and 60 (88%) had detectable NAb; 60 of 68 (88%) and 29 of 68 (42.6%) still had anti-S titers >75 U/mL and NAb titers >50 AU/mL. Higher NAb titers were correlated with severe infection, higher levels of C-reactive protein, and lower lymphocyte counts. No patient developed reinfection. Conclusions: Elderly people can display robust and persistent humoral response after severe acute respiratory syndrome coronavirus 2 infection, with NAb lasting up to 12 months.