Browsing by Author "Clemons, Karl V."
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- Antifungal susceptibility of 175 Aspergillus isolates from various clinical and environmental sourcesPublication . Sabino, Raquel; Carolino, Elisabete; Veríssimo, Cristina; Martinez, Marife; Clemons, Karl V.; Stevens, David A.Some environmental Aspergillus spp. isolates have been described as resistant to antifungals, potentially causing an emerging medical problem. In the present work, the antifungal susceptibility profile of 41 clinical and 134 environmental isolates of Aspergillus was determined using the CLSI microdilution method. The aim of this study was to compare environmental and clinical isolates with respect to their susceptibility, and assess the potential implications for therapy of isolates encountered in different environments. To our knowledge, this is the first report comparing antifungal susceptibility profiles of Aspergillus collected from different environmental sources (poultries, swineries, beach sand, and hospital environment). Significant differences were found in the distribution of the different species sections for the different sources. Significant differences were also found in the susceptibility profile of the different Aspergillus sections recovered from the various sources. Clear differences were found between the susceptibility of clinical and environmental isolates for caspofungin, amphotericin B and posaconazole, with clinical isolates showing overall greater susceptibility, except for caspofungin. In comparison to clinical isolates, hospital environmental isolates showed significantly less susceptibility to amphotericin B and posaconazole. These data indicate that species section identity and the site from which the isolate was recovered influence the antifungal susceptibility profile, which may affect initial antifungal choices.
- Aspergillus em ambiente hospitalar: um risco para o desenvolvimento de infeções nosocomiais?Publication . Raquel, Sabino; Veríssimo, Cristina; Viegas, Carla; Brandão, João; Parada, Helena; Martins, Carlos; Furtado, Cristina; Clemons, Karl V.; Stevens, David A.
- Molecular identification of clinical and environmental avian Aspergillus isolatesPublication . Sabino, Raquel; Burco, Julia; Valente, Joana; Veríssimo, Cristina; Clemons, Karl V.; Stevens, David A.; Tell, Lisa A.Aspergillosis causes high morbidity and mortality in avian species. The main goal of this study was to use molecular techniques to identify Aspergillus species collected from different avian species with aspergillosis. A subsample of those isolates was also screened for resistance to itraconazole. Over a 2-year period, clinical samples were recovered from 44 birds with clinical signs of the disease, clinical pathology results suspicious of aspergillosis, or from birds that died from Aspergillus spp. infection. Environmental sampling was also performed in seabird rehabilitation centers and natural seabird environments. Seventy-seven isolates (43 clinical and 34 environmental) were identified as Aspergillus fumigatus sensu stricto. No cryptic species from the Fumigati section were detected. Two environmental isolates were identified as Aspergillus nidulans var. dentatus and Aspergillus spinulosporus. None of the Aspergillus isolates tested were resistant to itraconazole. Our study emphasizes the dominant association of Aspergillus fumigatus sensu stricto in avian mycoses and shows the lack of itraconazole resistance in the studied isolates.
- New polymorphic microsatellite markers able to distinguish among Candida parapsilosis sensu stricto isolatesPublication . Sabino, Raquel; Sampaio, Paula; Rosado, Laura; Stevens, David A.; Clemons, Karl V.; Pais, CéliaAmong the Candida species causing bloodstream infections, Candida parapsilosis is one of the most frequently isolated. The objective of the present work was the identification of new microsatellite loci able to distinguish among C. parapsilosis isolates. DNA sequences with trinucleotide repeats were selected from the C. parapsilosis genome database. PCR primer sets flanking the microsatellite repeats were designed and tested with 20 independent isolates. On the basis of the amplification efficiency, specificity, and observed polymorphism, four of the sequences were selected for strain typing. Two hundred thirty-three independent C. parapsilosis sensu stricto isolates were genotyped by using these markers. The polymorphic loci exhibited from 20 to 42 alleles and 39 to 92 genotypes. In a multiplex analysis, 192 genotypes were obtained and the combined discriminatory power of the four microsatellites was 0.99. Reproducibility was demonstrated by submission of subcultures of 4 isolates each, in triplicate, interspersed with unique numbers among a group of 30 isolates for blind testing. Comparison of the genotypes obtained by microsatellite analysis and those obtained by randomly amplified polymorphic DNA analysis, restriction fragment length polymorphism analysis, and internal transcribed sequence grouping was performed and showed that the microsatellite method could distinguish individual isolates; none of the other methods could do that. Related species, C. orthopsilosis and C. metapsilosis, were not confused with C. parapsilosis sensu stricto. These new microsatellites are a valuable tool for use for the differentiation of C. parapsilosis sensu stricto strains, vital in epidemiology to answer questions of strain relatedness and determine pathways of transmission.
- The role of occupational Aspergillus exposure in the development of diseasesPublication . Sabino, Raquel; Veríssimo, Cristina; Viegas, Carla; Viegas, Susana; Brandão, João; Alves-Correia, Magna; Borrego, Luís-Miguel; Clemons, Karl V.; Stevens, David A.; Richardson, MalcolmAspergillus spp. have a high nutritional versatility and good growth on a large variety of construction materials. They also colonize soil or food, but decaying vegetation is their primary ecological niche. Therefore, exposure to fungi may occur at home, during hospitalization, during specific leisure activities, or at the workplace. The development of Aspergillus infections depends on the interplay between host susceptibility and the organism. Environments with high counts of fungal elements (conidia, hyphal fragments and others), high levels of bioarerosols, and elevated concentrations of mycotoxins or other volatile organic compounds should be considered as potential hazards, since they may present a risk to the exposed person. Rural tasks as well as work related to wood and food industries, poultries, swineries, waste handling plants, and other occupational environments involving contaminated organic material are among the ones posing higher respiratory risks to the workers. This paper presents a review of several studies related to occupational and indoor exposure to Aspergillus, potential health effects related to that exposure, and associated exposure assessment procedures.