Epidemiology, time course, and risk factors for hospital-acquired bloodstream infections in a cohort of 14,884 patients before and during the COVID-19 pandemic

COVID-19 pandemic has changed in-hospital care and was linked to superimposed infections. Here, we described epidemiology and risk factors for hospital-acquired bloodstream infections (HA-BSIs), before and during COVID-19 pandemic. This retrospective, observational, single-center real-life study included 14,884 patients admitted to hospital wards and intensive care units (ICUs) with at least one blood culture, drawn 48 h after admission, either before (pre-COVID, <i>N</i> = 7382) or during pandemic (<i>N</i> = 7502, 1203 COVID-19+ and 6299 COVID-19–). Two thousand two hundred and forty-five HA-BSI were microbiologically confirmed in 14,884 patients (15.1%), significantly higher among COVID-19+ (22.9%; <i>p</i>_trend &lt; .001). COVID-19+ disclosed a significantly higher mortality rate (33.8%; <i>p</i> &lt; .001) and more ICU admissions (29.7%; <i>p</i> &lt; .001). Independent HAI-BSI predictors were: COVID-19 (OR: 1.43, 95%CI: 1.21–1.69; <i>p</i> &lt; .001), hospitalization length (OR: 1.04, 95%CI: 1.03–1.04; <i>p</i> &lt; .001), ICU admission (OR: 1.38, 95%CI: 1.19–1.60; <i>p</i> &lt; .001), neoplasms (OR:1.48, 95%CI: 1.34–1.65; <i>p</i> &lt; .001) and kidney failure (OR: 1.81, 95%CI: 1.61–2.04; <i>p</i> &lt; .001). Of note, HA-BSI IRs for <i>Acinetobacter spp</i>. (0.16 × 100 patient-days) and <i>Staphylococcus aureus</i> (0.24 × 100 patient-days) peaked during the interval between first and second pandemic waves in our National context. Patients with HA-BSI admitted before and during pandemic substantially differed. COVID-19 represented a risk factor for HA-BSI, though not confirmed in the sole pandemic period. Some etiologies emerged between pandemic waves, suggesting potential COVID-19 long-term effect on HA-BSIs.