Host response signature trends in persistent bacteraemia and metastatic infection due to and Gram-negative bacilli: a prospective multicentre observational study.

BACKGROUND

A prompt diagnosis of bacteraemia and sepsis is essential. Markers to predict the risk of persistent bacteraemia and metastatic infection are lacking. SeptiCyte RAPID is a host response assay stratifying patients according to the risk of infectious vs sterile inflammation through a scoring system (SeptiScore). In this study we explore the association between SeptiScore and persistent bacteraemia as well as metastatic and persistent infection in the context of a proven bacteraemia episode.

METHODS

This is a prospective multicentre observational 14-month study on patients with proven bacteraemia caused by or Gram-negative bacilli. Samples for assessment by SeptiCyte were collected with paired blood cultures for 4 consecutive days after the index blood culture.

RESULTS

We included 86 patients in the study, 40 with and 46 with Gram-negative bacilli bacteraemia. SeptiScores over the follow-up were higher in patients with Gram-negative compared to bacteraemia (median 6.4, IQR 5.5-7.4 vs 5.6 IQR 5.1-6.2,  = 0.002). Higher SeptiScores were found to be associated with positive blood cultures at follow-up (AUC = 0.86, 95%CI 0.68-1.00) and with a diagnosis of metastatic infection at day 1 and 2 of follow-up (AUC = 0.79, 95%CI 0.57-1.00 and AUC = 0.82, 95%CI 0.63-1.00 respectively) in the context of Gram-negative bacteraemia while no association between SeptiScore and the outcomes of interest was observed in bacteraemia. Mixed models confirmed the association of SeptiScore with positive blood cultures at follow-up ( = 0.04) and metastatic infection ( = 0.03) in the context of Gram-negative bacteraemia but not bacteraemia after adjusting for confounders.

CONCLUSIONS

SeptiScores differ in the follow-up of and Gram-negative bacteraemia. In the setting of Gram-negative bacteraemia SeptiScore demonstrated a good negative predictive value for the outcomes of interest and might help rule out the persistence of infection defined as metastatic spread, lack of source control or persistent bacteraemia.