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Journal of Clinical Microbiology, Sep 1997, 2266-2269, Vol 35, No. 9
R Ignatius, S Henschel, O Liesenfeld, U Mansmann, W Schmidt, S Koppe, T Schneider, W Heise, U Futh, EO Riecken, H Hahn and R Ullrich
At present, the laboratory diagnosis of intestinal infections caused by
microsporidia depends on the detection of the typical spores either with a
modified trichrome stain (MTS) or by staining with fluorochromes. The
purpose of the present study was (i) to compare staining with MTS (MTS
method) and the staining with the fluorochrome Uvitex 2B (U2B method) with
respect to their sensitivities and specificities, particularly in the
presence of low numbers of spores, and (ii) to evaluate their reliabilities
under routine laboratory conditions. First, 30 negative human stool
specimens as well as 30 specimens enriched with a low concentration of
microsporidial spores were examined. The U2B and MTS methods detected 27
and 30, of the positive samples, respectively (95% confidence intervals for
sensitivity, 0.73 to 0.98 for the U2B method and 0.88 to 1.00 for the MTS
method) without yielding false-positive results (95% confidence intervals
for specificity, 0.88 to 1.00 for the MTS and U2B methods). In addition,
analysis of serial dilutions of 17 stool specimens from AIDS patients
containing microsporidia revealed comparable detection thresholds (P =
0.52) for both methods. Finally, 40 slides prepared from one stool specimen
containing very few microsporidia and 40 negative slides were included in
the routine diagnostic program during 1 month in order to monitor
laboratory handling and run-to-run variations. Again, both methods
exhibited comparable sensitivities (95% confidence intervals, 0.83 to 0.99
for the MTS method and 0.91 to 1.00 for the U2B method) and specificities
(95% confidence intervals, 0.91 to 1.00 for the MTS and U2B methods). In
conclusion, MTS and U2B methods are equally useful in the diagnosis of
microsporidiosis. However, since detection thresholds for both methods
differed considerably in all diluted stool specimens, performance of a
combination of both methods may be more sensitive than the performance of
only one procedure in the event of very low numbers of microsporidial
spores.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Comparative evaluation of modified trichrome and Uvitex 2B stains for detection of low numbers of microsporidial spores in stool specimens
Institut fur Medizinische Mikrobiologie und Infektionsimmunologie, Auguste-Viktoria-Krankenhaus, Berlin, Germany.
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