Molecular identification and in vitro antifungal susceptibility ofScedosporiumcomplex isolates from high-human-activity sites in Mexico

Abstract

The genus Scedosporium is a complex of ubiquitous moulds associated with a wide spectrum of clinical entities, with high mortality principally in immunocompromised hosts. Ecology of these microorganisms has been studied performing isolations from environmental sources, showing a preference for human-impacted environments. This study aimed to evaluate the presence and antifungal susceptibility of Scedosporium complex species in soil samples collected in high-human-activity sites of Mexico. A total of 97 soil samples from 25 Mexican states were collected. Identifications were performed by microscopic morphology and confirmed by sequencing of the rDNA (internal transcribed spacer [ITS], D1/D2) and β-tubulin partial loci. Antifungal susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) protocols. Soil samples of urban gardens and industrial parks constituted the best sources for isolation of Scedosporium complex species. S. apiospermum sensu stricto was the most prevalent species (69%), followed by S. boydii (16%). Voriconazole (minimal inhibitory concentration [MIC] geometric mean ≤2.08 µg/mL), followed by posaconazole (MIC geometric mean ≤2.64 µg/mL), exhibited excellent in vitro activity for most species. Amphotericin B and fluconazole demonstrated limited antifungal activity, and all of the strains were resistant to echinocandins. This is the first report in Mexico of environmental distribution and antifungal in vitro susceptibility of these emergent pathogens.

Scedosporium spp. from Clinical Setting in Argentina, with the Proposal of the New Pathogenic Species Scedosporium americanum

“…In the present study, MIC values of antifungals tested against S. boydii, S. apiospermum and S. angustum are in agreement with those reported by other authors [21,37,40,41]. In addition, we have confirmed VOR and POS show the highest activity in vitro against these species (MIC values ≤ 1 mg/L against 48/50 strains) and that the in vitro behaviour of antifungal drugs against the fungi is intra-and interspecies-dependent.…”

“…Both cases of infection by S. aurantiacum represent the first report in the Americas. Furthermore, we report for the first time an autochthonous case of infection by S. dehoogii, although this fungus has been isolated from environment in Chile and Mexico [37,38]. Surprisingly, our strain DMic 165285 was found to represent a novel species, Scedosporium americanum (clade D).…”

Scedosporium species in soils from various biomes in Northwestern Morocco

“…Most of the culture-positive samples exhibited a neutral pH within a range of 7-7.6. The same pH range was also found for Scedosporium-positive samples in Western France [18] and Austria [12], as well as in Thailand [20,22]. The influence of pH was also illustrated by comparison of the radial growth of these fungi in agar-based media with a neutral (7.4) or acid (5.4) pH.…”

“…They showed great variations in the relative abundance of Scedosporium species from one country to another. Scedosporium apiospermum was the most abundant species in Bangkok [23], Mexico [22] and in Austria and The Netherlands [12], whereas S. dehoogii predominated in Western France [8] and S. aurantiacum in Australia [19]. However, such studies have never been performed in Africa, and to the best of our knowledge, only sporadic isolations of Scedosporium sp.…”

“…Several large scale studies dealing with the ecology of these pathogens and the distribution of the different Scedosporium species have been conducted, mainly in Europe, including France [18], Austria and the Netherlands [12], but also in Australia [19], Thailand [20] and South America [21,22]. They showed great variations in the relative abundance of Scedosporium species from one country to another.…”