284. Evaluation of Empiric and Targeted Antibiotic-Usage for Enterococcal Bloodstream Infections at Boston Medical Center
Session: Poster Abstract Session: Antimicrobial Therapy: Clinical Studies
Friday, October 21, 2011
Room: Poster Hall B1

Enterococcus faecalis (EFL) blood isolates are susceptible to ampicillin more often than to vancomycin at our hospital while Enterococcus faecium (EFM) blood isolates are typically resistant to both agents. We sought to characterize antimicrobial treatment of enterococcal bloodstream infections (EBSI) to identify opportunities to reduce vancomycin use and improve clinical practice.


We performed a retrospective chart review on 100 adult patients hospitalized with EBSI in 2008-2009. Empiric antimicrobial therapy was defined as the antimicrobial treatment prescribed when blood culture gram stain results demonstrated gram positive cocci in pairs and short chains. Peptide nucleic acid in situ fluorescence hybridization (PNA FISH) was performed on those blood cultures.  Targeted treatment for EFL was defined as the antimicrobial prescribed when PNA-fish results indicated EFL; targeted treatment for EFM was the antimicrobial prescribed when final susceptibility data were available. Use of a penicillin-class antimicrobial for EFL was deemed appropriate targeted therapy.  Appropriate targeted therapy for EFM was determined by susceptibility testing.  Targeted vancomycin therapy was only deemed appropriate for isolates that were ampicillin-resistant and vancomycin-sensitive. 


Data were analyzed on 68 evaluable patients. Of those 68 patients, 40 blood cultures were positive for EFL and 25 were positive for EFM; 3 were positive for other enterococcal species.  Forty-five of 68 patients (66.2%) received vancomycin as empiric therapy.  Only 8 of 25 patients (32%) with EFM bacteremia received empiric therapy that was active against the isolate.  The proportion of appropriate targeted antimicrobial therapy was 65.2% for EFL and 60% for EFM.  Even after PNA-FISH results and susceptibility testing were available, 8 of 40 patients (20%) with EFL bacteremia and 5 of 25 (20%) patients with EFM bacteremia remained on vancomycin inappropriately.  


Vancomycin use was excessive for EBSI treatment.  Over one-third of blood isolates were EFM and not susceptible to prescribed empiric therapy. One-third of targeted therapy remained inappropriate. Our study identifies many opportunities for improving therapy of EBSI.

Subject Category: A. Antimicrobial agents and Resistance

Sarah Taimur, MD, Department of Medicine, Section of Infectious Diseases, Boston Medical Center, Boston University School of Medicine, Boston, MA and Tamar Barlam, MD, MSc, Department of Medicine, Section of Infectious Diseases , Boston Medical Center, Boston University School of Medicine, Boston, MA


S. Taimur, None

T. Barlam, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.