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Journal of Clinical Microbiology, Sep 1997, 2243-2251, Vol 35, No. 9
SP Franzot, JS Hamdan, BP Currie and A Casadevall
Little is known about the global molecular epidemiology of the human
pathogenic fungus Cryptococcus neoformans. We studied 51 clinical and
environmental (pigeon excreta) isolates from two cities in Brazil (Belo
Horizonte and Rio de Janeiro) by analyzing their carbon assimilation
patterns, electrophoretic karyotypes, restriction fragment length
polymorphisms (RFLPs) with the C. neoformans repetitive element-1 (CNRE-
1), and URA5 sequences. Results were compared to those previously obtained
for isolates from New York City by the same DNA typing methods.
Computer-assisted analysis of RFLPs and contour-clamped homogeneous
electrophoresis (CHEF) patterns and URA5 sequences was performed to
generate dendrograms. Some environmental and clinical isolates were found
to be indistinguishable by CHEF, CNRE-1 RFLP, and URA5 sequence analyses.
Similarly, some isolates from Rio de Janeiro and Belo Horizonte were
indistinguishable by the three DNA typing techniques. Overall, Brazilian
isolates appeared to be less heterogeneous by DNA analysis than isolates
from other regions. Several Brazilian isolates were highly related to New
York City isolates. Phylogenetic analysis of the sequences obtained for the
Brazilian isolates and those obtained for New York City isolates was
congruent with the dendrogram generated from the CNRE-1 RFLP data. In
summary our results indicate (i) that the discriminatory power of the DNA
typing method differs for Brazilian and New York City strains, with the
order being CNRE-1 RFLP analysis > URA5 sequence analysis > CHEF
analysis and CHEF analysis > URA5 sequence analysis > CNRE-1 RFLP
analysis, respectively; (ii) that there are differences in local genetic
diversity for Brazilian and New York City isolates; (iii) that there is
additional evidence linking clinical isolates to those in pigeon excreta;
and (iv) that some isolates from Brazil and New York City are closely
related, consistent with the global dispersal of certain pathogenic
strains.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Molecular epidemiology of Cryptococcus neoformans in Brazil and the United States: evidence for both local genetic differences and a global clonal population structure
Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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