Clinical spectrum of aspergillus infections in Hong Kong

Abstract

Aspergillus species are responsible for a variety of human diseases, ranging from allergic bronchopulmonary aspergillosis to invasive aspergillosis. Identification of Aspergillus species could facilitate the selection of antifungal regimens and epidemiological studies. Most of the clinical microbiology laboratories identify Aspergillus species by traditional phenotypic and/or antigen detection methods, which are laborious, time-consuming and inaccurate. In recent years, sequence analysis of β-tubulin and calmodulin genes becomes widely used for the identification of fungal species due to their relatively high resolving power, universality of usage, and high availability in the public databases. It can also be used for the taxonomic classification and the identification of rare and even novel fungal species. In this study, we aim to evaluate the effectiveness of analyzing the β-tubulin and calmodulin gene sequences for the identification of Aspergillus species and subsequently to determine the clinical spectrum of Aspergillus infections in Hong Kong during 2012-2014.

In this study, 48 Aspergillus strains isolated from patients over a 3-year period were characterised to the species level using sequencing of β-tubulin and calmodulin genes and the clinical spectrum of the 48 patients was described. Sequencing of β-tubulin and calmodulin genes showed that all 48 strains were known Aspergillus species. Ten different Aspergillus species were identified, including A. fumigatus (n=16), Aspergillus species of the A. flavus clade (n=7), A. awamori (n=7), A. terreus (n=6), A. tubingensis (n=4), A. sydowii (n=3), A. pseudocaelatus (n=2), A. uniguis (n=1), Aspergillus species of the A. tamarii clade (n=1), and A. austroafricanus (n=1). These Aspergillus species were shown to be associated with respiratory infections, infections of nail, ear canal infections, invasive infections, and eye infection. This study also described the first reported cases of ear infection associated with A. pseudocaelatus. To conclude, sequence analysis of β-tubulin and calmodulin genes enables accurate and rapid Aspergillus species differentiation.