Septic source matters: how infection site and microbial etiology affect sepsis prognosis

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Despite advances in critical care, mortality remains high. This study assesses the relationship between septic source, microbial etiology, and in-hospital mortality. This prospective observational study was conducted at the St. Anna University Hospital of Ferrara, Italy, from October 2021 to February 2022. Adult patients with suspected sepsis and a qSOFA score ≥ 2 were included. Data collected included vital signs, laboratory values, septic source classification, microbial etiology, and in-hospital mortality. Statistical analyses were performed using SPSS and jamovi, with an alluvial diagram to visualize relationships. Of 200 screened patients, 187 were included (mean age 85.0±9.6 years). In-hospital mortality was 27.3%. The most common septic sources were urinary (43.3%) and respiratory (28.9%), followed by miscellaneous (11.8%), abdominal (7.0%), and undefined (9.1%). Undefined sources had the highest mortality (58.8%), followed by respiratory (31.5%) and urinary sepsis (22.2%) (p=0.002). Microbial etiology varied by source, with negative cultures (50.3%) being the most common result. No direct association between microbial etiology and mortality was found (p=0.470), but mortality differed when analyzed in conjunction with septic source. The alluvial diagram highlighted complex interactions between infection site, microbial etiology, and survival demonstrating that the septic source significantly impacts in-hospital mortality (p=0.012). Septic source significantly impacts in-hospital mortality, with undefined infections carrying the highest risk. The interplay between microbial etiology and infection site influences outcomes. Early infection source identification and tailored antimicrobial strategies are crucial for improving sepsis management.