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Author Notes:

Correspondence: J.E. McGowan Jr; Tel.: +1 404 727 9365; Email: jmcgowa@sph.emory.edu

Acknowledgments: The authors thank Judy Rothberg for technical assistance.

Disclosures: No competing interests declared.

No ethical approval required.

Subject:

Research Funding:

Phase 5 of Project ICARE was supported in part by unrestricted research grants to the Rollins School of Public Health of Emory University by: Astra-Zeneca Pharmaceuticals, Wilmington, DE; Elan Pharmaceuticals, San Diego, CA; Johnson & Johnson Pharmaceutical Research & Development, LLC, Raritan, NJ; Pfizer Incorporated, New York, NY; and 3M Health Care Products, St Paul, MN.

Keywords:

  • Staphylococci
  • Vancomycin
  • Teicoplanin
  • Heteroresistance

Characterisation of a Staphylococcus aureus strain with progressive loss of susceptibility to vancomycin and daptomycin during therapy

Tools:

Journal Title:

International Journal of Antimicrobial Agents

Volume:

Volume 33, Number 6

Publisher:

, Pages 564-568

Type of Work:

Article | Post-print: After Peer Review

Abstract:

Following an initial response to vancomycin therapy, a patient with meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia developed endocarditis, failed a second course of vancomycin and then failed daptomycin therapy. An increase in the vancomycin minimum inhibitory concentrations of four consecutive MRSA blood isolates from 2 μg/mL to 8 μg/mL was shown by Etest. Population analysis of four successive blood culture isolates recovered over the 10-week period showed that the MRSA strain became progressively less susceptible to both vancomycin and daptomycin. Retrospectively, the macro Etest method using teicoplanin indicated a decrease in vancomycin susceptibility in the second blood isolate. The patient improved after treatment with various courses of trimethoprim/sulphamethoxazole, quinupristin/dalfopristin and linezolid. Early detection of vancomycin-heteroresistant S. aureus isolates, which appeared to have clinical significance in this case, continues to be a challenge for the clinical laboratory. Development of suitable practical methods for this should be given priority. Concurrent development of resistance to vancomycin and daptomycin, whilst rare, must be considered in a patient who is unresponsive to daptomycin following vancomycin therapy.

Copyright information:

© 2009 Elsevier B.V. and the International Society of Chemotherapy. Published by Elsevier B.V. All rights reserved.

This is an Open Access work distributed under the terms of the Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported License (http://creativecommons.org/licenses/by-nc-nd/3.0/).

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