1449. Frequency and Antimicrobial Susceptibility of Coagulase-Negative Staphylococcal (CoNS) Species Isolated from Clinical Specimens in United States and European Hospitals

Abstract

BackgroundCoNS represent an important cause of bloodstream infections, osteoarticular infections, foreign-body-associated infections and endocarditis. We evaluated the frequency of CoNS species and the activity of dalbavancin (DALB) in comparison to vancomycin (VAN), daptomycin (DAP) and other agents against a large collection of CoNS isolates.Methods5,088 CoNS isolates causing clinically significant infection were consecutively collected from 122 medical centers located in the United States (79 centers) and Europe (43 centers in 21 nations) over 6 years (2014-2019) and susceptibility tested by CLSI broth microdilution methods against DALB and comparators. Species identification was confirmed by MALDI-TOF.ResultsMost isolates were from bloodstream (BSI; 53.5%) or skin/skin structure infections (28.5%). S. epidermidis was the most common species overall (54.6%; Table) and for BSI (61.3%). The second most common species were S. lugdunensis overall (12.3%) and S. hominis for BSI (14.7%). DALB (MIC50/90, 0.03/0.06 mg/L) inhibited > 99.9% of CoNS isolates at the susceptible (S) breakpoint established by CLSI for S. aureus (≤ 0.25 mg/L) and was 8-fold more active than DAP (MIC50/90, 0.25/0.5 mg/L; 99.9% S) and 32-fold more active than VAN (MIC50/90, 1/2 mg/L; > 99.9% S). Linezolid was active against 98.7% of isolates (MIC50/90, 0.5/1 mg/L). All species were inhibited at ≤0.25 mg/L of DALB, except S. epidermidis (> 99.9%) and S. warneri (98.9%; Table). The most DALB-S species were S. capitis and S. simulans (MIC50/90, 0.015/0.03 mg/L for both species), whereas the highest DALB MIC50/90 values were observed with S. haemolyticus and S. saprophyticus (MIC50/90, 0.06/0.12 mg/L and highest MIC of 0.25 mg/L for both species). In contrast, 47.8% of S. epidermidis and 34.7% S. haemolyticus exhibited decreased susceptibility to VAN (MIC ≥ 2 mg/L), and 23.2% of S. capitis and 28.4% of S. warneri showed decreased susceptibility to DAP (MIC ≥ 1 mg/L). Overall oxacillin-S rate was 39.3%, varying from 3.0% for S. saprophyticus to 95.4% for S. lugdunensis. In general, BSI isolates were slightly less S than non-BSI isolates.ConclusionAntimicrobial susceptibility varied widely among CoNS species. DALB exhibited potent in vitro activity against all CoNS species.Table 1 Disclosures 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) 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) Jennifer M. Streit, BS, A. Menarini Industrie Farmaceutiche Riunite S.R.L. (Research Grant or Support)A. Menarini Industrie Farmaceutiche Riunite S.R.L. (Research Grant or Support)Allergan (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)Paratek Pharma, LLC (Research Grant or Support) S. J. Ryan Arends, PhD, Allergan (Research Grant or Support)Cipla Ltd. (Research Grant or Support)GlaxoSmithKline (Research Grant or Support)Melinta Therapeutics, Inc. (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)