Journal of Clinical Microbiology, Mar 1996, 489-495, Vol 34, No. 3
MA Ghannoum, JH Rex and JN Galgiani
In summary, it is clear that in vitro susceptibility testing can predict
outcome in selected clinical situations. The clearest data are from the
fluconazole-treated AIDS patients with oropharyngeal candidiasis. In this
setting, the homogeneity of the underlying immune defect, combined with the
ease of identification and monitoring of the infection, creates a
near-perfect test situation. In more complex scenarios, such as the
heterogeneous population of patients enrolled in a recent study of
candidemia, no such clear-cut correlation was present. The importance of
host factors in the correlation of the MIC with outcome cannot be
overemphasized. Examples of these parameters include patient status
(underlying disease, the presence of intravascular catheters, and CD4+
T-cell number), drug pharmacokinetics (absorption and distribution),
patient compliance, and drug-drug interactions. Identification of relevant
factors can substantially improve the degree of the MIC-outcome correlation
and thus improve the clinical utility of in vitro testing. An important
feature in this entire process is the role of standardized susceptibility
testing procedures. While not without flaws, the proposed NCCLS reference
method has been invaluable in allowing multiple investigators to contribute
data that can be used to clarify the correlation between the fluconazole
MIC and outcome. While the development of simplified second- generation
methods is eagerly anticipated, the role of the reference method as a
common touchstone is critical. Only by use of either the reference method
itself or methods with a known relationship to the reference method can
this broad collaborative process really proceed. Current work is focusing
on defining interpretive breakpoints for fluconazole and Candida species,
refinement of the in vitro procedures used to measure susceptibility to
amphotericin B, ketoconazole, and itraconazole, and the acquisition of a
broad base of data on the relationship between the MIC and outcome for
these three drugs. Although considerable work remains to be done, the
available data suggest that solutions to each of these problems are
possible and that routine susceptibility testing of fungi will become
meaningful for clinical decision making in the foreseeable future.
Copyright © 1996 by the American Society for Microbiology. All rights reserved.
Susceptibility testing of fungi: current status of correlation of in vitro data with clinical outcome
Division of Infectious Diseases, Department of Internal Medicine, Harbor-University of California, Los Angeles, USA. ghannoum@humc.edu
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