Bacterial infections can be life-threatening conditions that constitute a frequent reason for admission to the Emergency Department (ED). Although early and accurate recognition is crucial to improve the prognosis [1], diagnosis frequently remains challenging due to highly variable clinical presentations.

Body temperature is a vital parameter routinely measured upon admission, which is used as a diagnostic and prognostic marker of infection. The Systemic Inflammatory Response Syndrome (SIRS) and National Early Warning Score (NEWS) use body temperature to help identify potentially infected patients and to stratify their risk of deterioration in the ED [2]. However, body temperature is influenced by environmental parameters and varies widely during the pathogenic evolution of infection [3,4].

Hypothermia is reported in approximately 10% of bacterial infections and can occur regardless of the severity of the inflammatory response [4]. The prevalence of bacterial infections in hypothermic patients presenting to the ED has been scarcely assessed. Although the diagnostic and prognostic value of biomarkers such as C-reactive protein (CRP), leukocyte and lymphocyte counts, or neutrophil to lymphocyte count ratio (NLCR) have been extensively studied in septic patients [5], none of these biomarkers or scores has been evaluated in patients admitted to the ED with hypothermia.

Accordingly, in a representative cohort of patients admitted to the ED with unexplained hypothermia, we assessed the prevalence of bacterial infections and the diagnostic performance of the biomarkers routinely used to predict infection prior to the identification of the infectious source.