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Journal of Clinical Microbiology, June 2000, p. 2369-2373, Vol. 38, No. 6
Immunocompromised Host Section, Pediatric
Oncology Branch, National Cancer Institute,1
Pharmacy Department, National Institutes of Health Warren Grant
Magnuson Clinical Center,2 and
Veterinary Resources Program, Nation Center for Research
Resources, National Institutes of Health,3
Bethesda, Maryland 20892
Received 18 November 1999/Returned for modification 23 December
1999/Accepted 1 February 2000
Oropharyngeal and esophageal candidiasis (OPEC) is a frequent
opportunistic mycosis in immunocompromised patients. Azole-resistant OPEC is a refractory form of this infection occurring particularly in
human immunodeficiency virus (HIV)-infected patients. The procedures developed by the Antifungal Subcommittee of the National Committee for
Clinical Laboratory Standards (NCCLS) are an important
advance in standardization of in vitro antifungal susceptibility
methodology. In order to further understand the relationship between
NCCLS methodology and antifungal therapeutic response, we
studied the potential correlation between in vitro susceptibility to
fluconazole and in vivo response in a rabbit model of
fluconazole-resistant OPEC. MICs of fluconazole were determined by
NCCLS methods. Three fluconazole-susceptible (FS) (MIC,
0095-1137/00/$04.00+0
Correlation between In Vitro and In Vivo Antifungal Activities in
Experimental Fluconazole-Resistant Oropharyngeal and
Esophageal Candidiasis
0.125 µg/ml) and three fluconazole-resistant (FR) (MIC,
64
µg/ml) isolates of Candida albicans from prospectively monitored HIV-infected children with OPEC were studied. FR isolates were recovered from children with severe OPEC refractory to
fluconazole, and FS isolates were recovered from those with mucosal
candidiasis responsive to fluconazole. Fluconazole at 2 mg/kg of body
weight/day was administered to infected animals for 7 days. The
concentrations of fluconazole in plasma were maintained above the MICs
for FS isolates throughout the dosing interval. Fluconazole
concentrations in the esophagus were greater than or equal to those in
plasma. Rabbits infected with FS isolates and treated with fluconazole had significant reductions in oral mucosal quantitative cultures (P < 0.001) and tissue burden of C. albicans in tongue, soft palate, and esophagus
(P < 0.001). In comparison, rabbits infected with FR
isolates were unresponsive to fluconazole and had no reduction in oral
mucosal quantitative cultures or tissue burden of C. albicans versus untreated controls. We conclude that there is a
strong correlation between in vitro fluconazole susceptibility by
NCCLS methods and in vivo response to fluconazole therapy of
OPEC due to C. albicans.
*
Corresponding author. Mailing address: Bldg. 10, Rm.
13N-240, Immunocompromised Host Section, Pediatric Oncology Branch,
National Cancer Institute, Bethesda, MD 20892. Phone: (301) 496-7103. Fax: (301) 402-0575. E-mail: walsht{at}mail.nih.gov.
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