1547. Activity of Tedizolid and Comparator Agents against Gram-Positive Bacterial Isolates Causing Skin and Skin Structure Infections in Pediatric Patients during 2015-2019 in the US

BACKGROUND: New strategies to treat acute bacterial skin and skin structure infections (ABSSSI) are needed due to the spread of methicillin-resistant Staphylococcus aureus (MRSA), a common multidrug resistant pathogen of ABSSSIs. Tedizolid (TZD) was approved by the US FDA for treating ABSSSI in adults and is under evaluation for treating pediatric patients. Accordingly, the activity of TZD and comparators was evaluated against clinical surveillance isolates collected from pediatric patients with SSSI in the US. METHODS: A total of 2,758 Gram-positive isolates were collected from pediatric patients with SSSIs in 33 sites in the US between 2015 and 2019 as part of the Surveillance of Tedizolid Activity and Resistance (STAR) Program. Bacterial identification was confirmed by MALDI-TOF MS and susceptibility (S) testing performed by the CLSI reference broth microdilution method. Current CLSI interpretative criteria was applied. RESULTS: S. aureus (SA; n=2,163; 78.4%) was the most frequent pathogen recovered from all age groups (≤ 1y; 2-5y; 6-12y; 13-17y), followed by β-hemolytic streptococci (BHS; n=460; 16.7%), and coagulase-negative staphylococci (CoNS; n=70; 2.5%). TZD was active against all SA (MIC(50/90), 0.12/0.25 mg/L; 100% S). Equivalent TZD MIC(50/90) values (0.12/0.25 mg/L) were observed against MRSA (n=886; 41.0%; MIC(50/90), 0.12/0.25 mg/L) and methicillin susceptible (MSSA; MIC(50/90), 0.12/0.25 mg/L) isolates, regardless the age group. TZD also was very active against BHS (MIC(50/90), 0.12/0.25 mg/L; 100% S, regardless of species). TZD, linezolid, and daptomycin had 100.0% S rates against the main Gram-positive species and organism groups (Figure). Ceftaroline and clindamycin showed S rates of >90% against MRSA, MSSA, S. pyogenes and S. dysgalactiae. Lower S rates were observed for clindamycin against VGS (88.2%) and S. agalactiae (64.1%). TZD was the most potent agent (MIC(90), 0.25 mg/L) against Enterococcus faecalis (n=30, 1.1%), and a vancomycin-resistance phenotype was observed in 1 (3.3%) isolate. CONCLUSION: TZD was highly active against Gram-positive clinical isolates responsible for SSSI in pediatric patients across US hospitals from a 5-year period. TZD was equipotent or more potent than comparators against MSSA and MRSA isolates. Table 1 [Image: see text] DISCLOSURES: Cecilia G. Carvalhaes, MD, PhD, A. Menarini Industrie Farmaceutiche Riunite S.R.L. (Research Grant or Support)Allergan (Research Grant or Support)Cidara Therapeutics (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Fox Chase Chemical Diversity Center (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Merck (Research Grant or Support)Merck (Research Grant or Support)Merck & Co, Inc. (Research Grant or Support)Pfizer (Research Grant or Support) Helio S. Sader, MD, PhD, A. Menarini Industrie Farmaceutiche Riunite S.R.L. (Research Grant or Support)Allergan (Research Grant or Support)Allergan (Research Grant or Support)Allergan (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Melinta (Research Grant or Support)Merck (Research Grant or Support)Merck (Research Grant or Support)Paratek Pharma, LLC (Research Grant or Support)Pfizer (Research Grant or Support) Paul R. Rhomberg, n/a, Cidara Therapeutics (Research Grant or Support)Fox Chase Chemical Diversity Center (Research Grant or Support)Merck (Research Grant or Support) Mariana Castanheira, PhD, 1928 Diagnostics (Research Grant or Support)A. Menarini Industrie Farmaceutiche Riunite S.R.L. (Research Grant or Support)Allergan (Research Grant or Support)Allergan (Research Grant or Support)Amplyx Pharmaceuticals (Research Grant or Support)Cidara Therapeutics (Research Grant or Support)Cidara Therapeutics (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Fox Chase Chemical Diversity Center (Research Grant or Support)GlaxoSmithKline (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Merck (Research Grant or Support)Merck (Research Grant or Support)Merck & Co, Inc. (Research Grant or Support)Merck & Co, Inc. (Research Grant or Support)Paratek Pharma, LLC (Research Grant or Support)Pfizer (Research Grant or Support)Qpex Biopharma (Research Grant or Support) Rodrigo E. Mendes, PhD, A. Menarini Industrie Farmaceutiche Riunite S.R.L. (Research Grant or Support)Allergan (Research Grant or Support)Allergan (Research Grant or Support)Basilea Pharmaceutica International, Ltd (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Department of Health and Human Services (Research Grant or Support)GlaxoSmithKline (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Merck (Research Grant or Support)Merck (Research Grant or Support)Pfizer (Research Grant or Support)