Fosfomycin plus Beta-lactams: Synergistic Bactericidal Combinations in Methicillin-resistant (MRSA) and Glycopeptide-Intermediate Resistant (GISA) Staphylococcus aureus Experimental Endocarditis

The urgent need of effective therapies for methicillin-resistant Staphylococcus aureus (MRSA) infective endocarditis (IE) is a cause of concern. We aimed to ascertain the in vitro and in vivo activity of the older antibiotic fosfomycin combined with different beta-lactams against MRSA and glycopepti...

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Authors: Rio Fernández, Antonio del, García de la Mària, Cristina, Entenza, José Manuel, Gasch, Oriol, Armero, Yolanda, Soy Muner, Dolors, Mestres Lucio, Carlos-Alberto, Pericàs, Juan M., Falces Salvador, Carles, Ninot, Salvador, Almela, M. (Manel), Cervera, Carlos, Gatell, José M., Moreno Camacho, Ma. Asunción, Moreillon, Philippe, Marco Reverté, Francesc, Miró Meda, José M. (José María), 1956-, Hospital Clínic Experimental Endocarditis Study Group
Format: article
Status:Versión aceptada para publicación
Publication Date:2016
Country:España
Institution:Universidad de Barcelona
Repository:Dipòsit Digital de la UB
OAI Identifier:oai:diposit.ub.edu:2445/184262
Online Access:https://hdl.handle.net/2445/184262
Access Level:Open access
Keyword:Endocarditis
Antibiòtics
Antibiotics
Description
Summary:The urgent need of effective therapies for methicillin-resistant Staphylococcus aureus (MRSA) infective endocarditis (IE) is a cause of concern. We aimed to ascertain the in vitro and in vivo activity of the older antibiotic fosfomycin combined with different beta-lactams against MRSA and glycopeptide-intermediate-resistant S. aureus (GISA) strains. Time-kill tests with 10 isolates showed that fosfomycin plus imipenem (FOF+IPM) was the most active evaluated combination. In an aortic valve IE model with two strains (MRSA-277H and GISA-ATCC 700788), the following intravenous regimens were compared: fosfomycin (2 g every 8 h [q8h]) plus imipenem (1 g q6h) or ceftriaxone (2 g q12h) (FOF+CRO) and vancomycin at a standard dose (VAN-SD) (1 g q12h) and a high dose (VAN-HD) (1 g q6h). Whereas a significant reduction of MRSA-227H load in the vegetations (veg) was observed with FOF+IPM compared with VAN-SD (0 [interquartile range [IQR], 0 to 1] versus 2 [IQR, 0 to 5.1] log CFU/g veg; P = 0.01), no statistical differences were found with VAN-HD. In addition, FOF+IPM sterilized more vegetations than VAN-SD (11/15 [73%] versus 5/16 [31%]; P = 0.02). The GISA-ATCC 700788 load in the vegetations was significantly lower after FOF+IPM or FOF+CRO treatment than with VAN-SD (2 [IQR, 0 to 2] and 0 [IQR, 0 to 2] versus 6.5 [IQR, 2 to 6.9] log CFU/g veg; P < 0.01). The number of sterilized vegetations after treatment with FOF+CRO was higher than after treatment with VAN-SD or VAN-HD (8/15 [53%] versus 4/20 [20%] or 4/20 [20%]; P = 0.03). To assess the effect of FOF+IPM on penicillin binding protein (PBP) synthesis, molecular studies were performed, with results showing that FOF+IPM treatment significantly decreased PBP1, PBP2 (but not PBP2a), and PBP3 synthesis. These results allow clinicians to consider the use of FOF+IPM or FOF+CRO to treat MRSA or GISA IE.Copyright © 2015, American Society for Microbiology. All Rights Reserved.

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