Background: Prior studies have suggested that surveillance blood cultures (SBCs) may not be indicated in the setting of Gram-negative bacteremia (GNB). However, it is unclear how particular microbial species influence the need for SBCs in GNB.
Methods: We conducted a prospective cohort study of inpatients at Duke with Staphylococcus aureus bacteremia (SAB) and GNB from 2002-2015. Patients who died <24 hours from the first positive blood culture were excluded. Patients provided written informed consent. SBCs were defined as a blood culture drawn from 24 hours to 7 days from initial positive blood culture. Persistent bacteremia was defined as a positive SBC with the same organism. Statistical testing included Fishers exact and chi-square tests.
Results: There were 2856 episodes of bacteremia over the study period (SAB: 1147 [40%]; GNB: 1709 [60%]). SBCs were drawn in 87% (1003/1147) of SAB patients and 64% (1097/1709) of GNB patients. SBC rates varied by GNB species (p<0.001), being more commonly drawn for those patients with Pseudomonas bacteremia (128/159 [80%]) than those with Escherichia bacteremia (377/592 [62%]). In GNB, acquisition of SBCs, regardless of positivity, was associated with decreased in-hospital mortality (177/1173 [15%] versus 109/536 [20%]; p=0.008). The in-hospital mortality benefit associated with SBCs varied with GNB species, including Pseudomonas (30/128 [23%] versus 14/31 [45%]; p=0.02) and Escherichia (33/377 [9%] versus 37/215 [17%]; p=0.003). In-hospital mortality in those with SAB was also lower when SBCs were drawn (143/1003 [14%] versus 46/144 [32%]; p=0.0001) (Figure). In GNB, positive SBCs, relative to negative SBCs, was associated with increased in-hospital mortality (44/217 [20%] versus 133/956 [14%]; p=0.02). Persistent bacteremia occurred in 49% (494/1003) of SAB patients and 20% (217/1097) of GNB patients with SBCs. Persistent bacteremia risk differed by GNB species (p=0.004), and was highest among those with Stenotrophomonas maltophilia (9/19 [47%]) or Serratia (24/76 [31%]).
Conclusion: Acquisition of SBCs in patients with GNB was associated with decreased mortality, and this was driven in part by species-specific differences.
S. A. Maskarinec,
F. Ruffin, None
V. G. Fowler Jr., Merck, Cerexa/Actavis, Pfizer, Advanced Liquid Logis, NIH, MedImmune, Basilea, Karius, Contrafect, Regneron, Genentech, Affinergy, Locus, Medical Surface, Inc, Achaogen, Astellas, Arsanis, Bayer, Cubist, Debiopharm, Durata, Grifols, Medicines Co, Novartis: Collaborator , Consultant and Scientific Advisor , Consulting fee , Research grant and Research support .
J. T. Thaden, None