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Journal of Clinical Microbiology, June 2000, p. 2254-2260, Vol. 38, No. 6
Mycotic Diseases Branch, Division of
Bacterial and Mycotic Diseases, National Center for Infectious
Diseases, Centers for Disease Control and Prevention, Atlanta,
Georgia 30333,1 and Morehouse School
of Medicine, Atlanta, Georgia 303102
Received 3 November 1999/Returned for modification 11 February
2000/Accepted 27 March 2000
The PASCO antifungal susceptibility test system, developed in
collaboration with a commercial company, is a broth microdilution assay
which is faster and easier to use than the reference broth microdilution test performed according to the National Committee for
Clinical Laboratory Standards (NCCLS) document M27-A guidelines. Advantages of the PASCO system include the system's inclusion of
quality-controlled, premade antifungal panels containing 10, twofold
serial dilutions of drugs and a one-step inoculation system whereby all
wells are simultaneously inoculated in a single step. For the prototype
panel, we chose eight antifungal agents for in vitro testing
(amphotericin B, flucytosine, fluconazole, ketoconazole, itraconazole,
clotrimazole, miconazole, and terconazole) and compared the results
with those of the NCCLS method for testing 74 yeast isolates (14 Candida albicans, 10 Candida glabrata, 10 Candida tropicalis, 10 Candida krusei, 10 Candida dubliniensis, 10 Candida parapsilosis,
and 10 Cryptococcus neoformans isolates). The overall agreements between the methods were 91% for fluconazole, 89% for amphotericin B and ketoconazole, 85% for itraconazole, 80% for flucytosine, 77% for terconazole, 66% for miconazole, and 53% for
clotrimazole. In contrast to the M27-A reference method, the PASCO
method classified as resistant seven itraconazole-susceptible isolates
(9%), two fluconazole-susceptible isolates (3%), and three
flucytosine-susceptible isolates (4%), representing 12 major errors.
In addition, it classified two fluconazole-resistant isolates (3%) and
one flucytosine-resistant isolate (1%) as susceptible, representing
three very major errors. Overall, the agreement between the methods was
greater than or equal to 80% for four of the seven species tested
(C. dubliniensis, C. glabrata, C. krusei, and C. neoformans). The lowest agreement
between methods was observed for miconazole and clotrimazole and for
C. krusei isolates tested against terconazole. When the
data for miconazole and clotrimazole were removed from the analysis,
agreement was
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Comparative Evaluation of PASCO and National Committee for
Clinical Laboratory Standards M27-A Broth Microdilution Methods for
Antifungal Drug Susceptibility Testing of Yeasts
80% for all seven species tested. Therefore, the PASCO
method is a suitable alternative procedure for the testing of the
antifungal susceptibilities of the medically important
Candida spp. and C. neoformans against a range
of antifungal agents with the exceptions only of miconazole and
clotrimazole and of terconazole against C. krusei isolates.
*
Corresponding author. Mailing address: Centers for
Disease Control and Prevention, 1600 Clifton Rd. NE, Mailstop G-11,
Atlanta, GA 30333. Phone: (404) 639-3098. Fax: (404) 639-3546. E-mail: cjm3{at}cdc.gov.
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