Sex-Related Differences in Clinical Characteristics and Outcomes Among Patients Clinically Managed for Suspected Bacterial Infection in the Emergency Department

Background and Objectives: Suspected bacterial infection is one of the leading presentations to the Emergency Department (ED) and is still associated with considerable morbidity and mortality. There is increasing evidence that biological sex may influence host immune responses, disease manifestations, therapeutic requirements, and clinical outcomes in infectious diseases. However, sex-specific differences among patients clinically managed for suspected bacterial infection in ED remain incompletely defined. This study, therefore, aimed to assess demographic characteristics, clinical presentation, and clinical management as well as short-term outcomes related to sex among these patients. Materials and Methods: This retrospective single-center observational study included consecutive adults presenting with suspected bacterial infection to the ED between 1 June and 31 August 2025. Demographic, clinical, laboratory, treatment, infection-source, and outcome data were extracted from medical records. Between-group comparisons were followed by planned age-adjusted analyses and multivariable logistic regression. Results: A total of 213 patients were included, comprising 100 women (46.9%) and 113 men (53.1%). Women were older than men (median 77.0 vs. 67.0 years, p < 0.001), had lower diastolic blood pressure (70 vs. 75 mmHg, p = 0.004), and lower hemoglobin concentrations (11.79 vs. 12.45 g/dL, p = 0.004). Cardiovascular disease was more frequent among women than men (72.0% vs. 52.2%, p = 0.003), although this difference was attenuated and no longer significant after adjustment for age. A documented urinary source of infection was more frequent among women (51.0% vs. 34.5%, p = 0.015) and remained significantly associated with female sex after age adjustment (OR 2.14, 95% CI 1.20–3.81, p = 0.010; Benjamini–Hochberg-adjusted p = 0.039). No significant difference was detected in Emergency Department treatment: supplemental oxygen, vasopressors and broad-spectrum antibiotics were given with similar frequency to women and men (all p ≥ 0.139). Direct intensive care unit (ICU) admission from the ED occurred in 14 of 100 women (14.0%) and 21 of 113 men (18.6%; OR 0.71, 95% CI 0.34–1.49), and in-hospital mortality in 7 women (7.0%) and 9 men (8.0%; OR 0.87, 95% CI 0.31–2.43). After adjustment, female sex was not independently associated with direct ICU admission (OR 0.64, 95% CI 0.29–1.39; p = 0.257) or in-hospital mortality (OR 0.80, 95% CI 0.27–2.35; p = 0.690). Conclusions: In this single-center retrospective cohort of adults clinically managed for suspected bacterial infection in the emergency department, women were older and more frequently had a documented urinary source of infection. After adjustment for age, female sex remained associated with a documented urinary source of infection. The study did not provide precise evidence that sex was independently associated with direct ICU admission or in-hospital mortality; however, the confidence intervals were wide and clinically relevant differences cannot be excluded. Larger prospective multicenter studies with standardized diagnostic criteria, microbiological confirmation, and adequate outcome-event numbers are needed.