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Daptomycin exposure precedes infection and/or colonization with daptomycin non-susceptible enterococcus

Jeremy C Storm125*, Daniel J Diekema125, Jennifer S Kroeger23, Sarah J Johnson14 and Birgir Johannsson125*

Author Affiliations

1 University of Iowa Hospital and Clinics, Iowa City, IA, USA

2 Carver College of Medicine, University of Iowa, Iowa City, IA, USA

3 College of Public Health, University of Iowa, Iowa City, IA, USA

4 College of Pharmacy, University of Iowa, Iowa City, IA, USA

5 Department of Internal Medicine, Division of Infectious Diseases, SW 54–11, General Hospital, 200 Hawkins Drive, Iowa City, IA, 52242, USA

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Antimicrobial Resistance and Infection Control 2012, 1:19  doi:10.1186/2047-2994-1-19

Published: 29 May 2012

Abstract

Background

Daptomycin non-susceptible enterococci (DNSE) are emerging as an important cause of healthcare-associated infection, however little is known about the epidemiology of DNSE. At the University of Iowa Hospitals and Clinics (UIHC) an increase in the frequency of patients infected and/or colonized with DNSE has occurred. The goals of this study were to evaluate potential factors associated with the development of DNSE colonization and/or infection and to compare the characteristics of patients with prior daptomycin exposure to those without prior daptomycin exposure.

Methods

The study is a retrospective case-series involving all patients with DNSE infection and/or colonization at UIHC, a 734-bed academic referral center, from June 1, 2005 to June 1, 2011.

Results

The majority of patients with DNSE colonization and/or infection had prior daptomycin exposure (15 of 25; 60%), a concomitant gastrointestinal process (19 of 25; 76%), or were immunosuppressed (21 of 25; 84%). DNSE infection was confirmed in 17 of 25 (68%) patients, including 9 patients with bacteremia. Twelve of 17 (71%) patients with DNSE infection had prior daptomycin exposure, including 7 of 9 (78%) patients with bacteremia. Compared to patients without prior daptomycin exposure, patients with prior daptomycin exposure were less likely to harbor E. faecalis (0% vs. 33%; p = 0.019). A high proportion of patients (10 of 25; 40%) died during their hospitalizations. Most enterococcal isolates were E. faecium (86%), and were vancomycin-resistant (72%). Molecular typing revealed a diverse population of DNSE.

Conclusions

Prior daptomycin exposure, immunosuppression, and/or a concomitant gastrointestinal process, may be associated with the development of DNSE. PFGE revealed a diverse population of DNSE, which along with both increasing numbers of DNSE detected yearly and increasing annual rates of daptomycin usage, suggests the emergence of DNSE under antimicrobial pressure.

Keywords:
Enterococcus; Daptomycin; Resistance; Non-Susceptible; DNSE