Candidemia surveillance in Brazil: evidence for a geographical boundary defining an area exhibiting an abatement of infections by Candida albicans group 2 strains

Abstract

Prospective population surveillance has been conducted for candidemia in Brazil (A. L. Colombo, M. Nucci, B. J. Park, et al., J. Clin. Microbiol. 44:2816-2823, 2006). In the present study, a total of 63 isolates from 61 patients, representing 11 medical centers from nine geographic regions, were characterized by multilocus sequence typing (MLST). A total of 48 unique profiles or diploid sequence types (DSTs) were observed, with nine new sequence types (STs) and 32 new DSTs. There were no apparent correlations between center/region and DST patterns. Subtypes were compared to those in a known characterized reference set, including a large database of strains obtained worldwide. Significantly, only one C. albicans group 2 isolate was found in our collection, although isolates from this particular group are commonly found worldwide. These data, combined with information from other previously reported studies, establish a statistically significant diminishment of group 2 strains in Central and South America, including Mexico and portions of the Southwestern United States.

FIG. 1.

UPGMA dendrogram showing uncorrected p distances for 63 Candida albicans strains typed by MLST. The dashed line shows the cutoff at a P value of 0.1, used to delineate clades. Bootstrap values are shown at the nodes (n = 1,000). Clade (group) assignments are given at the right.

FIG. 2.

eBURST analysis of group 1 strains from this study and previously observed DSTs unique to Brazil. The blue circle (DST69) represents the predicted progenitor of the clonal cluster, and yellow circles represent secondary progenitors. Sizes are proportional to the frequency in the population. Green numbers represent DSTs reported in a previous study (17).