BACKGROUND: The absence of fever in bacteremia in patients who are older is known to delay diagnosis. Our objective was to determine whether atypical presentation was associated to mortality as a result of bacteremia in this patient cohort as well as possible factors associated with this atypical presentation. METHODS: We conducted an observational prospective study in 2 French university hospitals in 2016-2017 including patients ages >/=75 years with bacteremia. Atypical presentation was defined as the absence of a temperature >/=38.3 degrees C or <36 degrees C, chills, or hypotension. Mortality and dependence for activities of daily living (ADL) were recorded at 1 week (D7) and 3 months (D90). RESULTS: Among the 151 patients (mean age 85.4+/-5.8 years) enrolled, atypical presentation prevalence was 21.2%. D7 and D90 mortality rates were 7.9% and 40.0%, respectively. Atypical presentation was independently associated with D7 (odds ratio (OR) 4.46, 95% confidence interval (CI) 1.04-19.24) and D90 mortality (OR 3.76, 95% CI 1.30-10.92) after controlling for other prognostic factors. Patients with diabetes and those infected with Staphylococcus aureus were more likely to have atypical signs of infection. ADL score decreased from 3.6+/-2.0 before bacteremia to 2.8+/-2.1 at D90 (P <0.001). CONCLUSION: Patients who are older with bacteremia have poor vital and functional prognoses in the short and long terms. The absence of typical signs of infection is associated with mortality. Blood culture should be considered for patients who are older, especially with diabetes with acute unexplained clinical manifestations.< Réduire