High MICs for Vancomycin and Daptomycin and Complicated Catheter-Related Bloodstream Infections with Methicillin-Sensitive Staphylococcus aureus.

Rafael San-Juan,Isabel Morales,Fernando Chaves,Francisco López-Medrano,Marina De Cueto,Elena Resino-Foz,María Ángeles Orellana,Elena Loza,Mario Fernández-Ruiz,Miquel Pujol,Antonio Lalueza,Alicia Rico,María P Romero,Jesús Fortún,Carmen Ardanuy,Esther Viedma,Alejandra Morales-Cartagena,José María Aguado

doi:10.3201/eid2206.151709

Abstract

We investigated the prognostic role of high MICs for antistaphylococcal agents in patients with methicillin-sensitive Staphylococcus aureus catheter-related bloodstream infection (MSSA CRBSI). We prospectively reviewed 83 episodes from 5 centers in Spain during April 2011-June 2014 that had optimized clinical management and analyzed the relationship between E-test MICs for vancomycin, daptomycin, oxacillin, and linezolid and development of complicated bacteremia by using multivariate analysis. Complicated MSSA CRBSI occurred in 26 (31.3%) patients; MICs for vancomycin and daptomycin were higher in these patients (optimal cutoff values for predictive accuracy = 1.5 μg/mL and 0.5 μg/mL). High MICs for vancomycin (hazard ratio 2.4, 95% CI 1.2-5.5) and daptomycin (hazard ratio 2.4, 95% CI 1.1-5.9) were independent risk factors for development of complicated MSSA CRBSI. Our data suggest that patients with MSSA CRBSI caused by strains that have high MICs for vancomycin or daptomycin are at increased risk for complications.

Highlights

We investigated the prognostic role of high MICs for antistaphylococcal agents in patients with methicillin-sensitive Staphylococcus aureus catheter-related bloodstream infection (MSSA CRBSI)
In a previous retrospective study, we observed that high MICs for vancomycin were associated with development of complicated methicillin-sensitive S. aureus (MSSA) CRBSI, regardless of the initial antimicrobial drug therapy used, which suggested that intrinsic characteristics of these strains might explain their pathogenic role in development of complicated bacteremia [13]
We designed this multicenter prospective study to confirm the prognostic role of high MICs for vancomycin and to explore if increased MICs for other antistaphylococcal agents could influence the risk for developing complicated MSSA CRBSI

Summary

Introduction

We investigated the prognostic role of high MICs for antistaphylococcal agents in patients with methicillin-sensitive Staphylococcus aureus catheter-related bloodstream infection (MSSA CRBSI). Some studies have identified high MICs for vancomycin (defined as an MIC >1.5 μg/mL by E-test) as a simple laboratory-based marker, which has been shown To avoid these confounding factors, we focused on a more homogeneous population of patients with MSSA catheter-related bloodstream infection (MSSA CRBSI) for whom specific efforts were devoted to optimize clinical management. In a previous retrospective study, we observed that high MICs for vancomycin were associated with development of complicated MSSA CRBSI, regardless of the initial antimicrobial drug therapy used (vancomycin or β-lactams), which suggested that intrinsic characteristics of these strains might explain their pathogenic role in development of complicated bacteremia [13]

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