Late Phase of Sepsis Characterized by Increased Microbiological Burden, Death Rate

Recent models capturing the pathophysiology of sepsis and ex-vivo data from patients are speculating about immunosuppression in the so-called late phase of sepsis. Clinical data regarding survival and microbiological burden are missing. Gordon P. Otto, of the Clinic for Anesthesiology and Intensive Care at Jena University Hospital inJena, Germany, and colleagues, sought to determine the clinical significance of the 'late phase' of sepsis with respect to overall survival and occurrence of microbiological findings.

In a retrospective trial, 16,041 patient charts from a university intensive care unit were screened, and 999 patients with severe sepsis or septic shock were identified. Three phases were established according to the mortality peaks which were separated by two distinct nadirs: phase I (days 1-5), phase II (days 6-15) and phase III (days 16-150). Patients were analyzed for outcome, SOFA Scores, procalcitonin levels, antimicrobial treatment, dialysis, mechanical ventilation and results of blood cultures during their hospital stay.

Out of 999 enrolled patients, 308 died during the course of sepsis presenting a characteristic mortality rate (30.8 percent) with three distinct mortality peaks (at the days 2,7 and 17). Overall 36.7 percent of all deaths occurred in the early phase (phase I) and 63.3 percent during the later phases (phase II+III). In total, 2,117 blood cultures were drawn. In phase I, 882 blood cultures were drawn, representing a sampling rate of 88 percent with a positive rate of 14.9 percent. In phase II, 461 samples were taken, indicating a sampling rate of 52 percent and a positive rate of 11.3 percent. Within phase III, 524 samples were obtained representing a sampling rate of 66 percent with a positive rate of 15.3 percent, which was significantly higher compared to the positive rate of phase II and similar to phase I. In particular, the rate of typically opportunistic bacteria increased significantly from 9 percent in phase I up to 18 percent in phase III. The same is true for Candida spp. (phase I 13 percent, phase III 30 percent).

The researchers conclude that the later phase of sepsis is associated with a significant re-increase of positive blood culture results, especially regarding opportunistic bacteria and fungi. They add that these observations warrant further studies focusing on the underlying mechanisms resulting in this outcome burden in the later phase of sepsis. Their research was published in Critical CAre 2011.

Reference: Otto GP, Sossdorf M and Claus RA, et al. The late phase of sepsis is characterized by an increased microbiological burden and death rate. Critical Care 2011, 15:R183doi:10.1186/cc10332