Antimicrobial activity of dalbavancin tested against Gram-positive organisms isolated from patients with infective endocarditis in US and European medical centres.

Background: The management of endocarditis requires aggressive and prolonged antimicrobial treatment. We evaluated the in vitro activity of dalbavancin against bacteria from patients with infective endocarditis.
Methods: A total of 626 Gram-positive organisms were collected from patients with a diagnosis of bacterial endocarditis in the USA (n = 222) and Europe (n = 404) from 2007 to 2017 via the SENTRY Antimicrobial Surveillance Program and were tested for susceptibility to dalbavancin and comparators by broth microdilution.
Results: The most common organisms were Staphylococcus aureus (48.4%), Enterococcus faecalis (19.6%) and viridans group streptococci (VGS; 12.5%). Dalbavancin and daptomycin showed complete activity (100.0% susceptibility per CLSI criteria) against S. aureus, but dalbavancin MIC values were 4- to 8-fold lower. Vancomycin, linezolid and teicoplanin were also active against all S. aureus when CLSI criteria were applied. Ceftaroline was active against all MSSA (MIC90 0.25 mg/L) and 78.4% of MRSA isolates at ≤1 mg/L. All E. faecalis isolates were susceptible to ampicillin, daptomycin and linezolid, whereas 97.6% of isolates were susceptible to dalbavancin (MIC90 0.06 mg/L) and 96.7% were susceptible to vancomycin (MIC90 2 mg/L). All VGS and CoNS isolates were susceptible to dalbavancin, daptomycin, vancomycin and linezolid. Against Enterococcus faecium, 65.7% of isolates were inhibited by ≤0.25 mg/L dalbavancin and 62.9% were vancomycin susceptible.
Conclusions: Dalbavancin exhibited potent in vitro activity against a large collection of Gram-positive isolates recovered from patients with endocarditis in US and European medical centres. These results support further investigations to determine the role of dalbavancin in the treatment of infective endocarditis.
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