Characteristics and clinical outcomes of culture-negative and culture-positive septic shock: a single-center retrospective cohort study

Abstract

Background: We evaluated the characteristics and outcomes of culture-negative versus culture-positive septic shock.Methods: We performed a retrospective observational study of data from a prospective registry from 2014 to 2018. A total of 2,499 adult patients with septic shock were enrolled. The primary outcome was 90-day mortality, and the secondary outcomes were the length of hospital stay, a requirement for mechanical ventilation or renal replacement therapy, and in-hospital mortality.Results: Of 1,718 patients with septic shock, 1,012 (58.9%) patients were culture-positive (blood 803, urine 302, sputum 102, others 204) and the median pathogen detection time was 9.5 hours (aerobic 10.2 hours and anaerobic 9.0 hours). The most common site of culture-positive infection was the hepatobiliary tract (39.5%), while for the culture-negative it was the lower respiratory tract (38.2%). The culture-negative group had a lower mean body temperature (37.3 vs 37.7 ℃), lactate (2.5 vs. 3.2 mmol/L), C-reactive protein (11.1 vs 11.9 mg/dL), and sequential organ failure assessment score (7.0 vs. 8.0) than that of the culture-positive group. However, 90-day mortality between the groups was not significantly different (32.7 vs 32.2%, p=0.83), and the other clinical outcomes also did not differ significantly. Moreover, a shorter culture detection time was correlated with a higher sequential organ failure assessment score but not with mortality.Conclusion: Patients with septic shock are frequently culture-negative, especially in cases where the infection focus is in the lower respiratory tract. Although culture-negative was associated with a degree of organ dysfunction, it was not an independent predictor of death.