Risk factors associated with apyrexia during bacteraemia: a prospective multicenter cohort study

Apyrexia during bacteraemia is not rare and is associated with diagnostic uncertainty. Our aim was to search for risk factors of apyrexia in patients with bacteraemia. This was a prospective bicentric study including all positive blood cultures (PBC) over twenty-seven months. The laboratory gave the PBC results to the infectious disease specialist in real-time. Data was collected from digital medical files. Contaminated blood cultures were not included. Apyrexia was defined by the absence of fever in recent medical history, associated with a body temperature < 38 °C at the initiation of clinical management, confirmed at the time of blood sampling, and constantly observed until PBC. We used logistic regression to figure out the risk factors of apyrexia despite bacteraemia. From January 2023 to March 2025, 423 PBCs were communicated to ID specialists, from which we excluded 71 contaminated ones (17%). Among 352 bacteraemia mainly due to Enterobacterales (n = 165, 47%) and Staphylococcus spp. (n = 83, 24%), apyrexia was observed in 72 cases (20%). The latter were without antibiotic prescription before PBC compared to patients with fever: 35 vs. 13% respectively (p < 0.001). In a multivariate analysis, apyrexia was associated with three risk factors: admission in oncology: adjusted odds ratio (aOR) [95% CI]: 2.03 [1.10-3.73], an enterococcal bacteraemia: 4.01 [1.43-11.36], while urinary infections were protective of apyrexia: 0.16 [0.07-0.39]. Apyrexia during bacteraemia was not rare except in urinary-tract infections and was associated with admission in oncology and Enterococcus spp.