235. Investigation of the relationship between the number of positive blood cultures and patient prognosis

Abstract

Abstract Background The relationship between the number of positive blood cultures (NPBCs) and clinical outcomes has not been well-studied. The purpose of this study was to assess the impact of NPBCs (one set or two) on clinical outcomes. Methods We conducted a retrospective study comparing the clinical features of two sets of positive blood cultures (NPBCs=2) and one set of positive blood culture (NPBCs=1) in adult patients with bacteremia and fungemia from 2004 to 2021 at a tertiary hospital in Tokyo, Japan. We focused on four pathogens commonly encountered in clinical practice, including Staphylococcus aureus (S. aureus), Streptococci, gram-negative rods (GNR) (Enterobacterales and Pseudomonas aeruginosa), and Candida species, as the true causative pathogens in bacteremia and fungemia. The primary outcome was in-hospital mortality, and secondary outcomes were ICU admission and use of vasopressor drugs. Results In univariate analysis, NPBCs=2 for S. aureus was associated with vasopressor use, and NPBCs=2 for Streptococci was linked to a higher rate of ICU admission. However, these differences were not significant in multivariate analysis. Interestingly, NPBCs=2 for S. aureus had a positive impact on in-hospital mortality compared with NPBCs=1 (OR 0.574, 95%CI 0.376–0.877, p < 0.05). NPBCs for Candida species did not affect clinical outcomes. Furthermore, NPBCs=2 for GNR was associated with vasopressor use (OR 1.62, 95%CI 1.27–2.07, p < 0.05) in both univariate and multivariate analysis. We performed logistic regression analysis using the five items with the highest clinical significance: NPBCs=2, serum Cr > 1.2 mg/dL, Hb < 12 g/dL, heart rate > 90 beats/min, and platelet count < 150,000/μL. Based on the β coefficient, we assigned scores to each item and created a STAT-2 (S: Serum Cr, T: Thrombocytopenia, A: Anemia, T: Tachycardia, 2: NPBCs=2) score for the use of hypertensive drugs for GNR. The receiver operating characteristic (ROC) curve for the STAT-2 score with a cutoff of 6 points or higher had an area under the curve (AUC) of 0.763. The specificity was 90.8%, with a positive likelihood ratio of 4.13 (95% CI 3.40-5.02). Conclusion Our study suggests that NPBCs can predict clinical outcomes in patients with certain pathogenic infections. Disclosures All Authors: No reported disclosures