Abstract
INTRODUCTION: Sepsis remains a prevalent critical illness encountered in emergency departments and intensive care units (ICU), with culture-negative sepsis constituting 30-60% of cases. The effect of culture type on treatment and outcomes remains unclear, and conflicting evidence exists regarding disparities between Gram-positive and Gram-negative infections. OBJECTIVE: To further describe and compare characteristics and outcomes of culture-positive versus culture-negative sepsis. DESIGN, SETTING AND PARTICIPANTS: This retrospective cohort study included 1375 patients admitted to the ICU of a single tertiary care hospital between 2016 and 2019 with a diagnosis of sepsis or septic shock. Patients who did not meet the screening criteria, lacked drawn or documented cultures, or had documented non-bacterial infections, were excluded. MAIN OUTCOMES AND MEASURES: The primary outcome was disease severity and secondary outcomes included in-hospital mortality and duration of hospital and ICU stay. The principal and secondary exposure variables were blood culture status (positive vs. negative) and Gram staining (positive vs. negative), respectively. RESULTS: Overall, 943 patients (68.5%) were culture-negative and 432 (31.5%) were culture-positive. Gram-positive bacteria were isolated from 178 patients, Gram-negative bacteria from 199 patients, and both from 55 patients. Culture-positive patients demonstrated an almost two-fold higher likelihood of requiring vasopressors (adjusted odds ratio (OR): 1.98), a higher incidence of stress-dose steroid administration (adjusted OR, 1.68), and higher resuscitative fluid administration at six and 72 hours than culture-negative patients. No significant between-group differences emerged in the ICU or hospital length of stay, or mortality. No significant variations were observed when comparing Gram-positive and Gram-negative bacteremia. CONCLUSION: Although significant differences in illness severity existed between blood culture-negative and blood culture-positive patients with sepsis, patient-oriented secondary outcomes did not exhibit significant between-group differences. These results indicate that clinicians should not be reassured by the lack of proven bacteremia in patients with suspected sepsis, given similar outcomes.