118. Factors Associated with Positive Follow-up Blood Cultures in Gram-Negative Septicemia

BACKGROUND: Bloodstream infections remain a significant cause of morbidity and mortality. No guidelines for the management of noncatheter-associated Gram-negative septicemia exist. There is considerable debate regarding the role of follow-up blood cultures. Studies have shown inadequate antibiotic therapy increases mortality in Gram-negative sepsis. We evaluated factors associated with a higher likelihood of positive follow-up blood cultures (FUBC). METHODS: A retrospective cohort study was conducted to look at factors associated with an increased likelihood of positive FUBC. Data were obtained via Epic chart review. Empiric antimicrobial regimens were reviewed in all patients with MDRO infections. RESULTS: We identified 1,527 patients ≥18 years admitted with gram-negative septicemia from January 1, 2013 through January 1, 2018. A total of 8.4% had positive FUBC. Patients with positive FUBC had a younger median age than the no-growth group (64.7 vs. 69.4, P <0.001). Admission systolic blood pressure was lower in the group with positive FUBC than the no-growth group (107 vs. 116, P = 0.008). The odds ratio for positive FUBC for cardiac device was 2.08 (95% CI = [0.97, 4.35], P = 0.061); central line infection (vs. urinary tract infection) adjusted odds ratio was 2.08 (95% CI = [1.10, 3.95], P = 0.025). The positive FUBC group had a larger proportion of multidrug-resistant organisms (MDRO) (21.9% vs. 10.4%, P < 0.001) with an odds ratio of 2.40 (95% CI = [1.53, 3.78]). In this group, those who received inadequate empiric antibiotics had a significantly higher percentage of repeat positive results (78.6% vs. 57.1%, P = 0.033). In summary, patients with either an MDRO, a central line infection (vs. urinary tract infection), or the presence of a cardiac device (vs. no cardiac device present) had over twice the odds of positive FUBC than those without. CONCLUSION: Though the role of FUBC for Gram-negative septicemia has been brought into question, our results show that the presence of central lines, cardiac devices, infections with MDRO organisms, or inadequate empiric antibiotics on admission were factors strongly correlated with subsequent positive FUBC. Therefore, we believe that repeating blood cultures in this subset of patients require further study and consideration. DISCLOSURES: All authors: No reported disclosures.