1039. Surveillance Blood Cultures Associated With Decreased Mortality in Gram Negative Bacteremia
Session: Poster Abstract Session: Bacteremia and Endocarditis
Friday, October 5, 2018
Room: S Poster Hall

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.

Stacey A. Maskarinec, MD, PhD1, David Van Duin, MD, PhD2, Felicia Ruffin, MSN, RN3, Vance G. Fowler Jr., MD4,5 and Joshua T. Thaden, MD, PhD1, (1)Infectious Diseases, Duke University Medical Center, Durham, NC, (2)Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, (3)Division of Infectious Diseases, Duke University Medical Center, Durham, NC, (4)Duke Clinical Research Institute, Durham, NC, (5)Duke University, Durham, NC

Disclosures:

S. A. Maskarinec, None

D. Van Duin, achaogen: Scientific Advisor , Consulting fee . shionogi: Scientific Advisor , Consulting fee . Allergan: Scientific Advisor , Consulting fee . Astellas: Scientific Advisor , Consulting fee . Neumedicine: Scientific Advisor , Consulting fee . Roche: Scientific Advisor , Consulting fee . T2 Biosystems: Scientific Advisor , Consulting fee .

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

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