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606 Case Series Of Daptomycin Non-Susceptible Enterococcus Infections In A Tertiary Center

Sunday, April 3, 2011
Trinity Ballroom (Hilton Anatole)
Theodoros Kelesidis, MD , Ronald Reagan UCLA Medical Center, Los Angeles, CA
Daniel Uslan, MD , Ronald Reagan UCLA Medical Center, Los Angeles, CA
David Pegues, MD , Ronald Reagan UCLA Medical Center, Los Angeles, CA
Background: There are limited clinical data regarding risk factors associated with development of daptomycin-non-susceptible Enterococcus (DNSE) infections and outcome of these infections.

Objective: To describe clinical experience with a series of DNSE isolates in a tertiary center.

Methods: We retrospectively reviewed 19 cases of infections associated with DNSE (defined as daptomycin minimal inhibitory concentration [MIC] >4 mcg/ml by the Clinical Laboratory Standards Institute [CLSI], 2003) identified at a tertiary center from January 2007-January 2010. Comorbidities, hospital course, and antibiotic exposure history were reviewed. The most prevalent conditions and risk factors that were encountered in these cases that may be associated with isolation of DNSE were determined.

Results: Of the 19 cases, there were 10 bloodstream (52.6%), 5 urinary tract (26.3%), 2 soft tissue (10.5%) and 2 intraabdominal (10.5%) infections. Ten patients (52.6%) were male. Median age was 59 years (range, 26 to 80). Recent surgery (<3 months), hospitalization for >30 days, diabetes, end stage renal disease, gastrointestinal disease were observed in 16 (84.2%), 13 (68.4%), 9 (47.4%), and 9 (47.4%) cases, respectively. Recent antimicrobial exposure (within 3 months) is summarized in Table. In 8 cases (42.1%) there was no previous exposure to daptomycin. Twelve (63.2%) of the cases were treated with linezolid. Six patients (31.6%) died.

Table: Antibiotic exposure (within 3 months) of isolation of DNSE.

Agent                                           No. (%)         Days of therapy (+SD)

Anti-anaerobic                               6 (84.2%)      38.4 (25.6)

Vancomycin                                  14 (73.7%)     24 (18.3)

Daptomycin                                  11 (57.9%)     45.5 (25.1)

Third-generation cephalosporin       7 (26.8%)       28.6 (28.4)

Conclusions: In our series of 19 cases of DNSE, 40% of isolates had de novo resistance to daptomycin with no prior exposure. Patients tended to be ill with numerous comorbidities and recent surgery. Since daptomycin is one of a limited number of antimicrobials active against vancomycin-resistant Enterococcus, case-control studies are needed to determine risk factors associated with development of DNSE infections. To our knowledge, this is the largest described series of DNSE isolates.