Paradoxical Effect of Caspofungin against Candida Bloodstream ...

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Jul 21, 2010 - caspofungin paradoxical effect was also eliminated by chitin synthase inhibitor ... vitro paradoxical effect, in which certain Candida isolates ex-.
ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, June 2011, p. 2641–2647 0066-4804/11/$12.00 doi:10.1128/AAC.00999-10 Copyright © 2011, American Society for Microbiology. All Rights Reserved.

Vol. 55, No. 6

Paradoxical Effect of Caspofungin against Candida Bloodstream Isolates Is Mediated by Multiple Pathways but Eliminated in Human Serum䌤 Ryan K. Shields,1 M. Hong Nguyen,1* Chen Du,1 Ellen Press,1 Shaoji Cheng,1 and Cornelius J. Clancy1,2 Department of Medicine, University of Pittsburgh,1 and VA Health care System,2 Pittsburgh, Pennsylvania 15261 Received 21 July 2010/Returned for modification 21 October 2010/Accepted 10 March 2011

Paradoxical growth of Candida in vitro at echinocandin concentrations exceeding the MIC is well described, but the clinical relevance is unknown. We assessed echinocandin paradoxical effects against Candida bloodstream isolates (BSI) in the presence or absence of human serum and investigated regulatory mechanisms. As determined by broth microdilution, a paradoxical effect was evident for 60% (18/30), 23% (7/30), and 13% (4/30) of Candida albicans BSI exposed to caspofungin, anidulafungin, and micafungin, respectively, at achievable human serum concentrations (