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Yeast are among the most frequent pathogens in humans. The dominant yeast causing human infections belong to the genus Candida and Candida albicans is the most frequently isolated species. However, several non- C. albicans species are becoming increasingly common in patients worldwide. The relationships between yeast in humans and the natural environments remain poorly understood. Furthermore, it is often difficult to identify or exclude the origins of disease-causing yeast from specific environmental reservoirs. In this study, we compared the yeast isolates from tree hollows and from clinics in Hamilton, Ontario, Canada. Our surveys and analyses showed significant differences in yeast species composition, in their temporal dynamics, and in yeast genotypes between isolates from tree hollows and hospitals. Our results are inconsistent with the hypothesis that yeast from trees constitute a significant source of pathogenic yeast in humans in this region. Similarly, the yeast in humans and clinics do not appear to contribute to yeast in tree hollows. [ABSTRACT FROM AUTHOR]

This study seeks to determine the distribution and diversity of yeasts in and around the Hamilton area in Canada. In light of the increasing number of fungal infections along with rising morbidity and mortality rates, especially among the immunocompromised, understanding the diversity and distribution of yeasts in natural environments close to human habitations has become an increasingly relevant topic. In this study, we analyzed 1110 samples obtained from the hollows of trees, shrubs, and avian droppings at eight geographical sites in and around Hamilton, Ontario, Canada. A total of 88 positive yeast strains were isolated and identified belonging to 20 yeast species. Despite the relative proximity of the sampling sites, our DNA fingerprinting results showed that the yeast populations were highly heterogenous. Among the 14 tree species sampled, cedar, cottonwood, and basswood hollows had relatively high yeast colonization rates. Interestingly, C andida parapsilosis was isolated almost exclusively from pine trees only. Our results are consistent with microgeographic and ecological differentiation of yeast species in and around an urban environment. [ABSTRACT FROM AUTHOR]

The 53rd annual conference of the Genetics Society of Canada was held at McMaster University in Hamilton, Ontario, from 17 to 20 June 2010. About 100 geneticists from across Canada and the US attended the meeting, with a total of 27 posters and 55 oral presentations. The presentations highlighted the power of genetics for understanding a variety of biological issues from sex and recombination to alcoholism and cancer, from DNA replication to antimicrobial resistance, horizontal gene transfer, foraging, and courtship. Large-scale genomic and transcriptomic comparisons were included in many presentations to demonstrate the impact of genomics in biomedical research. The combined molecular, developmental, and evolutionary genetic investigations presented at the meeting, especially those on model organisms, highlighted that genes and genetic systems can evolve very rapidly. La 53ième conférence annuelle de la Société de génétique du Canada a eu lieu à l'Université McMaster à Hamilton en Ontario du 17 au 20 juin 2010. Environ 100 généticiens de partout au Canada et des Etats-Unis ont participé à cette conférence où ont été présentées 27 affiches et 55 communications. Les présentations ont mis en lumière la puissance de la génétique pour contribuer à la compréhension d'une gamme de processus biologiques allant du sexe et de la recombinaison à l'alcoolisme et au cancer, de la réplication de l'ADN à la résistance antimicrobienne, au transfert horizontal de gènes, aux comportements alimentaires et sexuels. Des comparaisons génomiques et transcriptomiques à grande échelle faisaient partie de nombreuses présentations et démontrent l'impact de la génomique en recherche biomédicale. Les investigations combinant la génétique moléculaire, du développement et de l'évolution présentées lors de cette conférence, particulièrement chez les espèces modèles, ont fait ressortir que les gènes et les systèmes génétiques peuvent évoluer très rapidement. [ABSTRACT FROM AUTHOR]

Plant-growth promoting rhizobacteria benefit crop health and growth through various mechanisms including phosphate and potassium solubilisation, and antimicrobial activity. Previously, we sequenced the genome of bacterial strain Burkholderia cenocepacia CR318, which was isolated from the roots of the starch corn (Zea mays L.) in London, Ontario, Canada. In this work, the species identity of this isolate is confirmed by recA phylogeny and in silico DNA-DNA hybridization (isDDH), and its plant-growth promoting characteristics are described. B. cenocepacia CR318 exhibited strong activity of inorganic phosphate and potassium solubilization. It significantly promoted the growth of corn plants and roots by solubilizing inorganic tricalcium phosphate under greenhouse conditions. Functional analysis of the complete B. cenocepacia CR318 genome revealed genes associated with phosphate metabolism such as pstSCAB encoding a high affinity inorganic phosphate-specific transporter, and the pqqABCDE gene cluster involved in the biosynthesis of pyrroloquinoline quinone (PQQ), which is a required cofactor for quinoprotein glucose dehydrogenase (Gdh). However, it appears that B. cenocepacia CR318 lacks the quinoprotein Gdh which can produce gluconic acid to solubilize inorganic phosphate. Overall, these findings provide an important step in understanding the molecular mechanisms underlying the plant growth promotion trait of B. cenocepacia CR318., Competing Interests: Declaration of Competing Interest No conflict of interest declared., (Crown Copyright © 2019. Published by Elsevier GmbH. All rights reserved.)

Aspergillus fumigatus is a ubiquitous opportunistic fungal pathogen that can cause aspergillosis in humans. Over the last decade there have been increasing global reports of treatment failure due to triazole resistance. An emerging hypothesis states that agricultural triazole fungicide use causes clinical triazole resistance. Here we test this hypothesis in Hamilton, Ontario, Canada, by examining a total of 195 agricultural, urban, and clinical isolates using 9 highly polymorphic microsatellite markers. For each isolate, the in vitro susceptibilities to itraconazole and voriconazole, 2 triazole drugs commonly used in the management of patients, were also determined. Our analyses suggested frequent gene flow among the agricultural, urban environmental, and clinical populations of A. fumigatus and found evidence for widespread sexual recombination within and among the different populations. Interestingly, all 195 isolates analyzed in this study were susceptible to both triazoles tested. However, compared with the urban population, agricultural and clinical populations showed significantly reduced susceptibility to itraconazole and voriconazole, consistent with ecological niche-specific selective pressures on A. fumigatus populations in Hamilton. Frequent gene flow and genetic recombination among these populations suggest greater attention should be paid to monitor A. fumigatus populations in Hamilton and other similar jurisdictions.

In Canada, the incidence of candidemia, the bloodstream infection caused by Candida species, varied from 1.2-5.1 cases/100,000, representing the third most common type of bloodstream infections in intensive care unit patients. However, the relative contributions of nosocomial transmission in candidemia remain poorly understood. In this study, we investigated the prevalence of nosocomial clusters among the causative agents for candidemia in Hamilton, Ontario, Canada, during a period from January 2005 to February 2009. We genotyped 134 isolates from 125 unrelated patients with candidemia, among which were 87 C. albicans, 20 C. parapsilosis, 11 C. glabrata, 15 C. tropicalis, and one C. krusei. Our PCR fingerprinting analyses using three highly polymorphic primers identified a total of 99 genotypes, with 18 of them shared by 44 independent isolates. Nine pairs of isolates were obtained from the same patients at the same time and each pair had identical fingerprints. Interestingly, all 44 independent strains belonging to each of the shared genotypes were isolated from patients within 3-months stay in the Hamilton hospitals. Both inter- and intra-ward clusters were found, including one that contained strains from intensive care units in two hospitals. Our results indicated that 33% of the patients with candidemia were infected by nosocomial clusters and suggested that measures should be taken in hospitals to prevent nosocomial acquisition of Candida infections.