Microarray Optimizes Enterococcal Bacteremia Therapy

Molecular technologies have significantly shortened the time to enterococci isolate identification versus conventional methods.

Enterococci are a major cause of bloodstream infection in hospitalized patients and have limited antimicrobial treatment options due to many resistance mechanisms, requiring rapid bacterial identification and antibiotic resistance determination.


Scientists at the University of Florida Health (Jacksonville, FL, USA) evaluated the clinical and economic impact of a rapid bacterial microarray identification system for patients with enterococcal bacteremia, which can lead to sepsis. All patients with documented enterococcal bacteremia from February 1, 2012 to September 09, 2012 (pre-microarray period) and September 10, 2012 to February 28, 2013 (post-microarray period) were included in this study.

The Verigene Gram-Positive Blood Culture Nucleic Acid Test (BC-GP, Nanosphere, Inc.; Northbrook, IL, USA) was evaluated by the investigators. The BC-GP test is a qualitative in vitro diagnostic test that utilizes microarray technology to detect specific bacterial DNA from positive patient blood cultures. Within two and a half hours, the BC-GP test can rapidly recognize the presence of the following organisms: Staphylococcus aureus, S. epidermidis, S. lugdunensis, Streptococcus anginosus group, S. agalactiae, S. pneumoniae, S. pyogenes, Enterococcus faecalis, E. faecium, and Listeria spp. Additionally, the BC-GP test identifies three resistance markers, that confer resistance to methicillin and vancomycin in Enterococcus sp.

Following implementation of Verigene BC-GP for the detection of bloodstream infections caused by Enterococcus, there was an average per patient reduction in hospital length of stay of 21.7 days, and an average savings of USD 60,729 in hospital costs. Verigene results enabled clinicians to immediately select appropriate therapy for 100% of patients with vancomycin-susceptible Enterococcus (VSE) bacteremia, potentially resulting in further cost savings. There was a significant decrease in the average time it took for patients to receive appropriate treatment (23.4 hours), and there was complete agreement between BC-GP test results and those derived from conventional culture and susceptibility methods, along with a significant reduction in time to reporting of test results.

Yvette McCarter, PhD, D(ABMM), a senior author of the study said, “Minimizing time to appropriate antimicrobial therapy permits more effective targeting of the causative pathogens, decreases antimicrobial exposure, and can result in cost avoidance. Utilization of assays such as the BC-GP test, supported by collaboration between microbiology and pharmacy, can optimize antimicrobial use, decrease unnecessary length of stay and costs, and improve time to appropriate therapy." The study was published on September 25, 2013, in the Journal of Clinical Microbiology .

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University of Florida Health
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