Abstract
BackgroundEpidemiological studies worldwide have shown that A. fumigatus exhibits important phenotypic and genotypic diversity, and these findings have been of great importance in improving the diagnosis and treatment of diseases caused by this fungus. However, few studies have been carried out related to the epidemiology of this fungus in Latin America. This study´s aim is to report on the epidemiology of the fungus by analyzing the phenotypic variability of Aspergillus section Fumigati isolates from different Latin American countries and the relationship between this variability, the geographical origin and genotypic characteristics.MethodsWe analyzed the phenotypic characteristics (macro- and micromorphology, conidial size, vesicles size, antifungal susceptibility and thermotolerance at 28, 37 and 48°C) of A. section Fumigati isolates from Mexico (MX), Argentina (AR), Peru (PE) and France (FR). The results were analyzed using analysis of variance (ANOVA) and Tukey's multiple comparison test to detect significant differences. Two dendrograms among isolates were obtained with UPGMA using the Euclidean distance index. One was drawn for phenotypic data, and the other for phenotypic and genotypic data. A PCoA was done for shown isolates in a space of reduced dimensionality. In order to determine the degree of association between the phenotypic and genotypic characteristics AFLP, we calculated the correlation between parwise Euclidean distance matrices of both data sets with the nonparametric Mantel test.ResultsNo variability was found in the macromorphology of the studied isolates; however, the micromorphology and growth rate showed that the PE isolates grew at a faster rate and exhibited the widest vesicles in comparison to the isolates from MX, AR and FR. The dendrogram constructed with phenotypic data showed three distinct groups. The group I and II were formed with isolates from PE and FR, respectively, while group III was formed with isolates from MX and AR. The dendrogram with phenotypic and genotypic data showed the same cluster, except for an isolate from FR that formed a separate cluster. This cluster was confirmed using PCoA. The correlation between the phenotypic and genotypic data of the isolates revealed a statistically significant association between these characteristics.ConclusionsThe PE isolates showed specific phenotypic characteristics that clearly differentiate them from the rest of the isolates, which matches the genotypic data. The correlation between the phenotypic and genotypic characteristics showed a statistically significant association. In conclusion, phenotypic and genotypic methods together increase the power of correlation between isolates.
Highlights
Epidemiological studies worldwide have shown that A. fumigatus exhibits important phenotypic and genotypic diversity, and these findings have been of great importance in improving the diagnosis and treatment of diseases caused by this fungus
The PE isolates showed the widest vesicles (23.35 ± 0.75 μm), followed by FR (20.73 ± 0.83 μm), MX (17.97 ± 0.84 μm) and AR (17.62 ± 0.78 μm). These sizes are within the range that is described for A. fumigatus
To provide more information regarding this fungus, we studied the phenotypic characteristics of clinical and environmental isolates of A. fumigatus from MX, AR, PE and FR, and we assessed the relationship between the phenotypic and the genotypic characteristics reported in the literature for these isolates [21], to determine whether the variability of the phenotypic characteristics correlated with the genotypic characteristics
Summary
Epidemiological studies worldwide have shown that A. fumigatus exhibits important phenotypic and genotypic diversity, and these findings have been of great importance in improving the diagnosis and treatment of diseases caused by this fungus. Aspergillus fumigatus Fresenius is a filamentous, saprophytic fungus of great biological importance, as it is one of the major opportunistic pathogens causing invasive aspergillosis (IA) in immunosuppressed patients [1,2]. Its association with this type of patients depends on the host characteristics and on some typical phenotypic features that contribute to its pathogenicity such as its nutritional versatility, growth rate and efficient sporulation at a temperature of 37°C or higher [3,4]. The most relevant have reported variability in the pigment and texture of the colonies, growth rate at different temperatures, size and shape of the conidia, atypical phialides and differences in the size and shape of the conidial heads [9,10,11,12,13]
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