1000. Antimicrobial Susceptibility of Gram-Positive Bacteria Isolated From Patients Hospitalized With Bacteremia in United States and European Medical Centers: Results From the International Dalbavancin Evaluation of Activity (IDEA) Program

BACKGROUND: Gram-positive bacteria (GP), mainly S. aureus (SA), coagulase-negative staphylococci (CoNS), and Enterococcus spp., represent major causes of bacteremia in hospitalized patients. We evaluated the activity of dalbavancin (DALBA) and comparator agents against contemporary GP from patients with bacteremia. METHODS: A total of 8,296 GP unique isolates were consecutively collected from 33 United States (n = 4,409) and 39 European (EUR; n = 3,887) medical centers in 2015–2017 and susceptibility tested by reference broth microdilution methods. RESULTS: The most common organisms were SA (48.3% in United States, 44.3% in EUR), CoNS (14.3% in United States, 15.6% in EUR), and E. faecalis (EF; 11.5% in United States, 13.1% in EUR). All SA isolates were susceptible (S) to DALBA (MIC(50/90), 0.03/0.03 mg/L), linezolid (LZD; MIC(50/90), 1/2 mg/L), vancomycin (VAN; MIC(50/90), 1/1 mg/L), and teicoplanin (TEI; MIC(50/90), ≤0.5/≤0.5 mg/L); >99.9% were S to daptomycin (DAPTO; MIC(50/90), 0.25/0.5 mg/L). Based on MIC(50), DALBA was 8-fold more active than DAPTO and 32-fold more active than VAN against SA, and DALBA activity was not adversely affected by oxacillin (OXA) resistance (R). Among CoNS, 99.9% of isolates were inhibited at a DALBA MIC of ≤0.25 mg/L (MIC(50/90), 0.03/0.06 mg/L); S to DAPTO (MIC(50/90), 0.5/0.5 mg/L), LZD (MIC(50/90), 0.5/1 mg/L), VAN (MIC(50/90), 1/2 mg/L), and TEI (MIC(50/90), 2/4 mg/L) were 99.9%, 97.6%, 100.0%, and 98.5%, respectively. Among EF, 97.7% were DALBA-S (96.4% in USA, 99.0% in EUR; MIC(50/90), 0.03/0.06 mg/L), 97.5% were VAN-S (96.1% in United States, 99.0% in EUR; MIC(50/90), 1/2 mg/L), and all isolates were S to ampicillin (MIC(50/90), 1/1 mg/L), DAPTO (MIC(50/90), 0.5/1 mg/L) and LZD (MIC(50/90),1/2 mg/L). Among E. faecium isolates (n = 656; 7.9% overall), 63.9% were inhibited at ≤0.25 mg/L of DALBA (33.4% in United States, 87.5% in EUR) and 61.6% were VAN-S (32.8% in United States, 84.0% in EUR). DALBA was highly active against β-hemolytic streptococci (BHS; n = 686 [8.3%]; MIC(50/90), 0.015/0.03 mg/L) and viridans group streptococci (VGS; n = 432 [5.2%]; MIC(50/90), 0.015/0.03 mg/L). CONCLUSION: DALBA was very active against SA, CoNS, VAN-S enterococci, BHS, and VGS isolated from patients with bacteremia. Based on MIC(50), DALBA was generally 8- to 32-fold more active than DAPTO and VAN against these organisms. DISCLOSURES: H. S. Sader, Allergan: Research Contractor, Research support. R. K. Flamm, Allergan: Research Contractor, Research support. U. Rappo, Allergan: Employee, Salary. D. Debabov, Allergan: Employee, Salary. M. Castanheira, Allergan: Research Contractor, Research support. R. E. Mendes, Allergan: Research Contractor, Research support.