This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Weinstein, M. P.
Right arrow Articles by Reller, L. B.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Weinstein, M. P.
Right arrow Articles by Reller, L. B.

 Previous Article  |  Next Article 

Journal of Clinical Microbiology, August 2004, p. 3747-3751, Vol. 42, No. 8
0095-1137/04/$08.00+0     DOI: 10.1128/JCM.42.8.3747-3751.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Multicenter Evaluation of Use of Penicillin and Ampicillin as Surrogates for In Vitro Testing of Susceptibility of Enterococci to Imipenem

Melvin P. Weinstein,1,2,3* Stanley Mirrett,4,5 Saman Kannangara,1 Jan Monahan,6 Lizzie J. Harrell,4,5 Alan C. Wilson,1 and L. Barth Reller4,5,7

Departments of Medicine,1 Pathology, Robert Wood Johnson Medical School,2 Microbiology Laboratory, Robert Wood Johnson University Hospital, New Brunswick, New Jersey 08901-0019,3 Departments of Pathology,4 Medicine,5 Clinical Microbiology Laboratory, Duke University Medical Center, Durham, North Carolina 27710,6 Microbiology Laboratory, University of Colorado Hospital, Denver, Colorado 802207

Received 10 February 2004/ Returned for modification 17 March 2004/ Accepted 20 April 2004

Imipenem is approved by the U.S. Food and Drug Administration (FDA) for treatment of infections caused by Enterococcus faecalis. However, there are no NCCLS guidelines for testing susceptibility of enterococci against imipenem. To assess whether or not ampicillin or penicillin could be used as a surrogate for broth microdilution (BMD) testing of imipenem versus Enterococcus species, 633 strains of E. faecalis, E. faecium, and other enterococci isolated from blood cultures of patients at three geographically distinct university hospitals were tested by the NCCLS BMD and disk diffusion (DD) methods. Using FDA susceptibility breakpoints for imipenem and NCCLS breakpoints for penicillin and ampicillin, categorical agreement (CA) for penicillin-imipenem and ampicillin-imipenem tested with E. faecalis and E. faecium by BMD was ≥94% but was ≤90% for other enterococci. Using the DD method, CA for ampicillin-imipenem tested with E. faecalis and E. faecium was ≥98% and was 92% for other enterococci; CA for penicillin-imipenem was 91% for E. faecalis, 98% for E. faecium, and 87% for other enterococci. Further analysis showed that testing E. faecalis with ampicillin resulted in no false-susceptible (FS) or false-resistant (FR) results by BMD, no FS results by DD, and a single FR result by DD (0.2%), whereas testing with penicillin resulted in no FS results by BMD or DD and two FR results by BMD (0.4%). For E. faecium and other enterococci, the combination of FS and FR results was such that surrogate testing with penicillin or ampicillin appears not to be sufficiently reliable to be used clinically. We conclude that ampicillin is an accurate predictor of the in vitro activity of imipenem against E. faecalis.

* Corresponding author. Mailing address: Departments of Medicine and Pathology, UMDNJ-Robert Wood Johnson Medical School, 1 Robert Wood Johnson Place, New Brunswick, NJ 08901-0019. Phone: (732) 235-7713. Fax: (732) 235-7951. E-mail: weinstei{at}umdnj.edu.

Journal of Clinical Microbiology, August 2004, p. 3747-3751, Vol. 42, No. 8
0095-1137/04/$08.00+0     DOI: 10.1128/JCM.42.8.3747-3751.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Metzidie, E., Manolis, E. N., Pournaras, S., Sofianou, D., Tsakris, A. (2006). Spread of an unusual penicillin- and imipenem-resistant but ampicillin-susceptible phenotype among Enterococcus faecalis clinical isolates. J Antimicrob Chemother 57: 158-160 [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»