Empirical antibiotic therapy modalities for Enterobacteriaceae bloodstream infections in older patients and their impact on mortality: a multicentre retrospective study

Purpose: Enterobacteriaceae (EB) bloodstream infections (BSI) are frequent and serious in older patients. Physicians are faced with the dilemma of prescribing early appropriate empirical antibiotics to limit the risk of death, and sparing broad-spectrum antibiotic prescription. The aim of the study was to assess the rate of appropriate empirical antibiotics prescription to treat EB BSI in older patients and its impact on survival.

Methods: This study conducted in 49 centres enrolled retrospectively up to the 10 last consecutive patients aged 75 years and over and treated for EB BSI. Factors related to in-hospital death were investigated using logistic regression.

Results: Among the 487 enrolled patients (mean age 86 ± 5.9 years), 70% had at least one risk factor of being infected by third-generation cephalosporins (3GC)-resistant strain; however, only 13.8% of EB strains were resistant to 3GC. An empirical antimicrobial treatment was initiated for 418 patients (85.8%), and for 86% (n = 360/418) of them, it was considered appropriate. In-hospital mortality was 12.7% (n = 62) and was related to the severity of infection (OR 3.17, CI 95% 1.75-5.75), while a urinary portal of entry was protective (OR 0.34, CI 95% 0.19-0.60). Neither the absence of nor inappropriate empirical antibiotics prescription was associated with increased mortality.

Conclusion: While patients enrolled in this study were at risk of being infected by multidrug-resistant bacteria, yet mainly treated with 3GC, empirical antibiotics prescription was appropriate in most cases and did not influence mortality.