210. Vancomycin- and Daptomycin-Resistant Enterococcus faecium Bacteremia and Colonization in Leukemic Patients with Prolonged Neutropenia
Session: Poster Abstract Session: Antimicrobial Resistance: Clinical Studies
Friday, October 21, 2011
Room: Poster Hall B1
Background: 

Vancomycin-resistant Enterococcus faecium (VREF) bacteremia has been reported to be increasing in frequency and associated with significant morbidity and mortality in acute leukemics with prolonged neutropenia and VRE colonization.  We report on our experience with the empiric use of varying doses of daptomycin and other antibiotics active against VREF in these patients, as well as the development of a cluster of daptomycin-resistant E. faecium (DREF) bacteremia and colonization.

Methods: 

A retrospective chart review was conducted of patients with acute leukemia and prolonged neutropenia with positive culture(s) for VREF bacteremia and/or colonization from July 2009 to June 2010.  We collected susceptibility data of the VREF, dosage of empiric anti-VREF antibacterial therapy, and the incidence of breakthrough VREF bacteremia in colonized patients.

Results: 

The incidence of breakthrough VREF bacteremia varied by agent selected for empiric therapy: daptomycin (9/72, 12.5%), tigecycline (2/9, 22%), linezolid (0/13, 0%), dalfopristin-quinopristin (0/3, 0%).  Incidence of breakthrough VREF bacteremia varied with daptomycin dose: 9/55 (16%) with dose < 7.5 mg actual body weight/kg/day (median dose 6 mg/kg/day) versus 1 case (with MIC=8) out of 17 (5.9%) with higher doses.  Lower doses of daptomycin were utilized prior to the initiation of weekly VREF screening with associated susceptibility testing.   Despite daptomycin’s low volume of distribution, dosing based on ideal body weight did not correlate as well with the incidence of breakthrough bacteremia as actual body weight.  DREF bacteremia and colonization was first detected in 2009 with daptomycin MIC ranging from 8 to greater than 256.  Daptomycin therapy was avoided in these patients.

Conclusion: 

Breakthrough VREF bacteremia and the appearance of DREF occurred despite the use of daptomycin 6 mg/kg/day in neutropenic VREF colonized patients.  We recommend close monitoring for VREF colonization in these patients including susceptibility data to select appropriate empiric antibacterial therapy directed against VREF/DREF in these patients.  Daptomycin 8 mg/kg/day appears promising to prevent or treat VREF infections if MIC < 4.  Linezolid is an alternative especially in cases of DREF.


Subject Category: A. Antimicrobial agents and Resistance

Niraj Jani1, Rod Quilitz, PharmD2, Ana Velez, MD1, Ramon Sandin, MD3, Dawn Ruge, BS4 and John Greene, MD5, (1)University of South Florida College of Medicine, Tampa, FL, (2)Pharmacy, Moffitt Cancer Center, Tampa, FL, (3)Hematopathology and Laboratory Medicine, Moffitt Cancer Center, Tampa, FL, (4)Moffitt Cancer Center, Tampa, FL, (5)H. Lee Moffitt Cancer Center, Tampa, FL

Disclosures:

N. Jani, None

R. Quilitz, None

A. Velez, None

R. Sandin, None

D. Ruge, None

J. Greene, None

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