Distinct Subpopulations of Intravalvular Methicillin-Resistant Staphylococcus aureus With Variable Susceptibility to Daptomycin in Tricuspid Valve Endocarditis.

We present a case of endocarditis wherein organisms cultured from different valve leaflets yielded different daptomycin susceptibility from each other, and from organisms obtained from peripheral blood culture. Genomic analyses showed mutations in mprF, purR and agrA. Pharmacokinetic simulations showed consistent activity of daptomycin+beta-lactam against all subpopulations. This represents an opportunity to understand S. aureus evolution and fitness in vivo on daptomycin therapy, and the role of beta-lactams to prevent selection of daptomycin resistant subpopulations. PMID: 31932377 [PubMed - as supplied by publisher]
Source: Antimicrobial Agents and Chemotherapy - Category: Microbiology Authors: Tags: Antimicrob Agents Chemother Source Type: research

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Ability of Bicarbonate Supplementation to Sensitize Selected Methicillin-Resistant Staphylococcus aureus (MRSA) Strains to β-Lactam Antibiotics in an Ex Vivo Simulated Endocardial Vegetation Model. Antimicrob Agents Chemother. 2019 Dec 16;: Authors: Rose WE, Bienvenida AM, Xiong YQ, Chambers HF, Bayer AS, Ersoy SC Abstract Supplementation of standard growth media (cation-adjusted Mueller-Hinton Broth [CAMHB]) with bicarbonate (NaHCO3 ) increases β-lactam susceptibility of selected MRSA strains ("NaHCO3-responsive"). This "sensitization" phenomenon translated to enhanced &...
Source: Antimicrobial Agents and Chemotherapy - Category: Microbiology Authors: Tags: Antimicrob Agents Chemother Source Type: research
Abstract The purpose of this study was to describe and compare the duration of Staphylococcus aureus bacteremia (SAB) according to methicillin resistance and primary foci of infection. We also aimed to newly define persistent SAB considering these results. Non-duplicated episodes of SAB in patients aged ≥15 years from 14 hospitals between January 2009 and February 2018 in Korea were analyzed. The duration of SAB was defined as the number of days from the administration of a susceptible antibiotic after the onset of SAB to the last day of positive blood culture for S. aureus SAB durations were described and comp...
Source: Antimicrobial Agents and Chemotherapy - Category: Microbiology Authors: Tags: Antimicrob Agents Chemother Source Type: research
ConclusionsThese results confirmed a synergistic effect between daptomycin plus ceftaroline and increased bactericidal activity against MRSA, suggesting that this combination may be effective for the treatment of invasive MRSA infection. Our experience highlights the potential clinical use of synergy testing to guide difficult treatment decisions in patients with MDR MRSA infection.
Source: Journal of Antimicrobial Chemotherapy - Category: Microbiology Source Type: research
Bicarbonate Resensitization of Methicillin-Resistant Staphylococcus aureus to β-Lactam Antibiotics. Antimicrob Agents Chemother. 2019 Apr 22;: Authors: Ersoy SC, Abdelhady W, Li L, Chambers HF, Xiong YQ, Bayer AS Abstract Endovascular infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a major healthcare concern, especially infective endocarditis (IE). Standard antimicrobial susceptibility testing (AST) defines most MRSA strains as 'resistant' to β-lactams, often leading to use of costly and/or toxic treatment regimens. In this investigation, five prototype MRSA strai...
Source: Antimicrobial Agents and Chemotherapy - Category: Microbiology Authors: Tags: Antimicrob Agents Chemother Source Type: research
Abstract Bacteriophage-derived lysins are cell wall hydrolytic enzymes which represent a potential new class of antibacterial therapeutics in development to address burgeoning antimicrobial resistance. CF-301, the lead compound in this class, is in clinical development as an adjunctive treatment to potentially improve clinical cure rates of Staphylococcus aureus bacteremia and infective endocarditis (IE) when used in addition to antibiotics. In order to profile CF-301's activity in a clinically relevant milieu, we assessed its in vitro activity in human blood vs. in a conventional testing medium (cation-adjusted M...
Source: Antimicrobial Agents and Chemotherapy - Category: Microbiology Authors: Tags: Antimicrob Agents Chemother Source Type: research
In conclusion, for the treatment of MRSA experimental endocarditis, the combination of daptomycin plus fosfomycin showed synergistic and bactericidal activity. PMID: 29610194 [PubMed - as supplied by publisher]
Source: Antimicrobial Agents and Chemotherapy - Category: Microbiology Authors: Tags: Antimicrob Agents Chemother Source Type: research
Authors: Concia E, Viscoli C, Del Bono V, Giannella M, Bassetti M, De Rosa GF, Durante Mangoni E, Esposito S, Giusti M, Grossi P, Menichetti F, Pea F, Petrosillo N, Tumbarello M, Stefani S, Venditti M, Viale P, group of Italian Experts Abstract Staphylococcus aureus is still an important problem in clinical and therapeutic area, worldwide. In Italy, in recent years, methicillin resistance remained stable, yet considerably high, the percentage of strains of MRSA being around 40%. It was deemed interesting and timely to carry out a consensus conference using the RAND/UCLA method to collect the opinion of a group of e...
Source: Journal of Chemotherapy - Category: Cancer & Oncology Tags: J Chemother Source Type: research
ar LM Abstract Many serious bacterial infections are antibiotic-refractory due to biofilm formation. A key structural component of biofilm is extracellular DNA which is stabilized by bacterial proteins, including those from the DNABII family. TRL1068 is a high affinity human monoclonal antibody against a DNABII epitope conserved across both gram-positive and gram-negative bacterial species. In the current study, the efficacy of TRL1068 for disruption of biofilm was demonstrated in vitro in the absence of antibiotics by scanning electron microscopy. In vivo efficacy of this antibody was investigated in a well-chara...
Source: Antimicrobial Agents and Chemotherapy - Category: Microbiology Authors: Tags: Antimicrob Agents Chemother Source Type: research
This study aimed to assess whether traditional initial loading and maintenance doses of teicoplanin were appropriate in endocarditis and renal failure patients with methicillin-resistant Staphylococcus aureus (MRSA) infections and to recommend optimal dosage regimens. Pharmacokinetic parameters and physicochemical properties of teicoplanin were performed to develop pharmacokinetic models using GastroPlus(TM). Concentration-time curves of teicoplanin in endocarditis and renal failure patients with MRSA infections were simulated by changing clearance (CL) and volume of distribution of the central compartment (Vc). ...
Source: Journal of Chemotherapy - Category: Cancer & Oncology Tags: J Chemother Source Type: research
Abstract Background/Aims: The aim of our study was to compare the characteristics of nosocomial infective endocarditis (NIE) with community-acquired infective endocarditis (CIE) and to determine independent risk factors for in-hospital death. Methods: We retrospectively reviewed the medical records of 560 patients diagnosed with infective endocarditis. NIE was defined by a diagnosis made> 72 hours after hospital admission or within 2 months of hospital discharge. Results: Among the 560 cases reviewed, 121 were classified as NIE. Compared with patients with CIE, patients with NIE were older (mean &plus...
Source: The Korean Journal of Internal Medicine - Category: Internal Medicine Authors: Tags: Korean J Intern Med Source Type: research
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