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High prevalence of isolates with reduced glycopeptide susceptibility in persistent or recurrent bloodstream infections due to methicillin-resistant Staphylococcus aureus.

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Uçkay Ilker, Bernard Louis, Buzzi Marta, Harbarth Stephan, François Patrice, Huggler Elzbieta, Ferry Tristan, Schrenzel Jacques, Renzoni Adriana, Vaudaux Pierre, Lew Daniel P,
Project Mécanismes moléculaires de la resistance intermédiaire aux glycopeptides chez les staphyloques dorés
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Original article (peer-reviewed)

Journal Antimicrobial agents and chemotherapy
Volume (Issue) 56(3)
Page(s) 1258 - 64
Title of proceedings Antimicrobial agents and chemotherapy
DOI 10.1128/AAC.05808-11

Abstract

Reduced susceptibility to glycopeptides in methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates is considered a risk factor for failure of glycopeptide therapy. We compared the prevalences of MRSA isolates with reduced glycopeptide susceptibility in patients with versus without persistent or recurrent MRSA bloodstream infections. A retrospective cohort study at the University Hospital of Geneva identified 27 patients with persistent or recurrent clonally related MRSA bacteremic episodes over an 8-year period, which included 208 consecutive nosocomial MRSA bacteremic episodes. Vancomycin and teicoplanin MICs were determined by a modified macrodilution assay allowing improved detection of glycopeptide-intermediate MRSA isolates (GISA), characterized by elevated teicoplanin or/and vancomycin MICs (≥ 4 μg/ml). For 16 patients (59%), their pretherapy and/or posttherapy MRSA isolates showed elevated teicoplanin MICs, among which 10 (37%) concomitantly displayed elevated vancomycin MICs. In contrast, 11 other patients (41%) were persistently or recurrently infected with non-GISA isolates. In comparison, only 39 (22%) of 181 single isolates from patients with no microbiological evidence of persistent or recurrent infections showed elevated teicoplanin MICs, among which 14 (8%) concomitantly displayed elevated vancomycin MICs. Clinical, microbiological, and pharmacokinetic variables for patients persistently or recurrently infected with GISA or non-GISA isolates were similar. Bacteremic patients with a poor response to glycopeptide therapy had a 2.8-fold- and 4.8-fold-higher rates of MRSA isolates displaying elevated teicoplanin and vancomycin MICs, respectively, than patients with single isolates (P < 0.0001). Detection of elevated teicoplanin MICs may help to predict a poor response to glycopeptide therapy in MRSA bacteremic patients.
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