Les abcès cérébraux sont des infections potentiellement mortelles, entraînant souvent des séquelles graves. La prise en charge médicale en reste empirique en raison d’un manque de connaissance approfondie des microorganismes responsables de cette condition. Dans la plupart des laboratoires microbiologiques, le diagnostic d’abcès cérébral est basé sur la culture du pus recueilli chirurgicalement. Malheureusement, cette procédure a de nombreuses limites et ne permet l’identification que d’une petite partie de la population microbienne en cause. L’amplification par PCR et le séquençage du gène codant la fraction 16S de l’ADN ribosomal ont récemment été utilisées pour surmonter les limites de la culture, et ont été démontré leur efficacité dans la documentation des infections bactériennes. Malheureusement, cette procédure présente un degré de discrimination limité en cas d’infection polymicrobienne. Des études métagénomiques de flores complexes de l’homme, basées sur une combinaison de PCR, clonage et séquençage des produits de PCR se sont avérées utiles pour évaluer la diversité bactérienne des flores dentaires, vaginales et intestinales. Nous avons appliqué cette technique à des échantillons d’abcès cérébral pour étudier la flore associée à cette maladie. Dans une première étape, nous avons réalisé une enquête en utilisant la culture et les techniques moléculaires. Le but de cette étude était d’analyser et d’évaluer les bactéries de la flore responsable des abcès cérébraux, en comparant la culture à trois techniques moléculaires basées sur le gène 16S rDNA, incluant le séquençage direct, le clonage suivi de séquençage par méthode de Sanger, et le séquençage direct des produits de PCR par pyroséquençage. Cette enquête a déterminé que la variété des espèces bactériennes associée aux abcès cérébraux est beaucoup plus grande que précédemment décrite, et inclut de nombreuses bactéries anaérobies et des bactéries incultivables de la flore buccale. Cette étude préliminaire a identifié 49 agents bactériens différents, et a permis l’identification de 27 bactéries jamais détectées auparavant dans des abcès du cérébraux, dont 15 n’avaient jamais été cultivées. Un tel nombre d’espèces bactériennes impliquées dans les abcès cérébraux a motivé l’étude de 51 nouveaux spécimens dans le but de décrire plus en détail la flore associée aux abcès cérébraux en fonction de leurs étiologies. Ainsi, nous avons effectué une analyse métagénomique, basé sur le gène 16S rDNA, de 51 patients ayant développé un abcès cérébral. Notre stratégie a été beaucoup plus discriminatoire et a permis à l’identification d’un plus grand nombre de bactéries que la culture et l’amplification et le séquençage direct de l’ANRr 16S. La combinaison des données de 71 patients (20 de la première étude et 51 de la deuxième étude) a permis l’identification de plusieurs associations à l’aide de la méthode de data mining.En outre, notre étude a permis l’identification de deux nouvelles bactéries, la première étant une nouvelle espèce de genre Staphylococcus (Staphylococcus massiliensis) et la seconde étant une bactérie anaérobie qui représente une nouvelle espèce dans un nouveau genre au sein du phylum des Bacteroidetes (Phocaeicola abscesses). En outre, nous avons décrit deux cas inhabituels d’abcès du cerveau, à Mycoplasma hominis après curetage utérin, et à Nocardia carnea chez un greffé rénal. Malgré les limites inhérentes à la procédure de clonage, nos résultats suggèrent que le clonage et le séquençage de gène DNAr 16S est une méthode très performante pour identifier les agents bactériens associés aux abcès cérébraux. / Brain abscess is a life-threatening infection with frequent serious sequelae. The medical management remains empirical due to a lack of comprehensive knowledge of the microorganisms responsible for this condition. In most microbiology laboratories the diagnosis of brain abscess is based on culture from pus collected surgically. Unfortunately, this procedure has many limitations and reveals only a small portion of the true microbial population. PCR-amplified 16S rDNA sequencing has recently been used to overcome the limitations of culture-based bacterial detection in brain abscess pus, and it was demonstrated to be effective in the documentation of monomicrobial infections. Unfortunately, this procedure failed to discriminate among polymicrobial floras.Metagenomic studies of complex human floras using a combination of 16S rDNA PCR and cloning-sequencing of PCR products proved useful to evaluate the bacterial diversity of dental, vaginal and intestinal floras. Thus, we applied this technique to brain abscess samples to study the flora associated with this condition. In a first step, we performed an investigation using culture and molecular techniques. The purpose of this investigation was to analyze and evaluate the bacterial flora responsible for brain abscess by comparing standard culture technique to three techniques using 16S rDNA amplification, that is, direct sequencing, multiple sequencing following cloning, and multiple sequencing via high throughput pyrosequencing. This investigation has determined that the variety of brain abscess-associated bacterial species is much larger than previously reported, and it includes many anaerobes and uncultured bacteria from the oral cavity flora. This preliminary study identified 49 distinct brain abscess bacterial agents, and enabled the identification of 27 bacteria never detected before in brain abscess, 15 of which were uncultured.Such a high number of bacterial species involved in brain abscess prompted the study of 51 new specimens in an effort to describe further the flora associated with brain abscesses and their etiologies. Thus, we performed a 16S rDNA-based metagenomic analysis of cerebral abscesses from 51 patients. Our strategy was significantly more discriminatory and enabled the identification of greater number of bacterial taxa, than culture and conventional 16S rDNA PCR/sequencing, respectively. The combination of data from 71 patients (20 from the first study and 51 from the second study) enabled the identification of several associations using the data mining analysis. Also, these studies permitted the identification of two novel bacteria, the first being a novel Staphylococcus species (Staphylococcus massiliensis) and the second being a novel anaerobic bacterium that represents a novel species in a new genus within the phylum Bacteroidetes (Phocaeicola abscesses). In addition, we reported tow unusual cases of brain abscess, the first case was a Mycoplasma hominis brain abscess following uterus curettage and the second case was a Nocardia carnea infection in a kidney transplant recipient patient.Despite limitations inherent to the cloning procedure, our results suggest that cloning and sequencing of PCR-amplified 16S rDNA is a highly valuable method to identify bacterial agents of brain abscesses.

Soil nematodes play an important role in indication for assessing soil environments and ecosystems. Previous studies of nematode community analyses based on molecular identification have shown to be useful for assessing soil environments. Here we applied PCR-DGGE method for molecular analysis of five soil nematode communities (designed as S1 to S5) collected from four provinces in Southeastern Vietnam (Binh Duong, Ba Ria Vung Tau, Binh Phuoc and Dong Nai) based on SSU gene. By sequencing DNA bands derived from S5 community sample, our data show 15 species containing soil nematode, other nematode and non-nematode (fungi) species. Genus Meloidogyne was found as abundant one. The genetic relationship of soil nematode species in S5 community were determined by Maximum Likelihood tree re-construction based on SSU gene. This molecular approach is applied for the first time in Vietnam for identification of soil nematode communities. / Tuyến trùng đất đóng vai trò chỉ thị quan trọng trong công tác đánh giá môi trường và hệ sinh thái đất. Các nghiên cứu trước đây đã cho thấy lợi ích của việc phân tích cộng đồng tuyến trùng đất bằng định danh sinh học phân tử đối với việc đánh giá môi trường đất. Ở đây, chúng tôi ứng dụng phương pháp PCR-DGGE dựa trên gene SSU để phân tích năm (ký hiệu từ S1 đến S5) cộng đồng tuyến trùng đất thuộc các vùng trồng chuyên canh cây hồ tiêu ở miền nam Việt Nam (Bình Dương, Bà Rịa Vũng Tàu, Bình Phước và Đồng Nai). Bằng cách giải trình tự các vạch của mẫu tuyến trùng S5, kết quả cho thấy cộng đồng tuyến trùng này có 15 loài gồm nhóm tuyến trùng đất, nhóm các loại tuyến trùng khác và nhóm không phải tuyến trùng (nấm) và trong đó Meloidogyne là giống ưu thế. Mối quan hệ di truyền của các các loài tuyến trùng đất thuộc cộng đồng S5 được xác định bằng việc thiết lập cây phát sinh loài Maximum Likelihood dựa trên gene SSU. Đây là nghiên cứu đầu tiên ở Việt Nam sử dụng kỹ thuật PCR-DGGE để phân tích các cộng đồng tuyến trùng đất trồng hồ tiêu.

Orientador: Sandra de Moraes Gimenes Bosco / Resumo: Pythium insidiosum é o agente etiológico da pitiose, uma infecção granulomatosa crônica, com prevalência em regiões de clima tropical e subtropical que acomete mamíferos, principalmente equinos, cães e humanos. Este micro-organismo é um falso fungo que apresenta uma ampla distribuição geográfica, sendo muito prevalente na América do Sul (pitiose equina e canina) e na Tailândia (pitiose humana). Estudos moleculares têm permitido diagnóstico precoce e melhor compreensão das relações filogenéticas, dividindo o patógeno em três clados (I, II e III ou A, B e C). Entretanto essas informações são ainda bastante limitadas e novas regiões gênicas poderiam ajudar a esclarecer a história evolutiva dessa espécie. Assim sendo, este trabalho visou estabelecer as relações filogenéticas entre 52 isolados de P. insidiosum, americanos e asiáticos, por meio do sequenciamento de três novas regiões gênicas: a região do fator de alongamento da tradução (Tef-1α), α e β tubulina, além da padronização da técnica de Pulse Filed Gel Electrophoresis (PFGE) para esta espécie. A região do Tef-1α mostrou-se menos polimórfica em relação a α e β tubulina, entretanto separou as cepas aqui trabalhadas em dois clados distintos, sendo um composto apenas de cepas classificadas previamente como sendo do clado III (asiáticas), e agrupou todas as cepas americanas junto às cepas do clado II. A filogenia baseada no gene da β tubulina separou os isolados nos três clados esperados. Em relação à α tubulina houve diferenc... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Pythium insidiosum is the etiological agent of pythiosis, a chronic granulomatous infection, prevalent in tropical and subtropical regions that affects mammals, especially horses, dogs and humans. This is a fungus-like microorganism that has a wide geographical distribution and is very prevalent in South America (equine and canine pythiosis) and Thailand (human pythiosis). Molecular studies have allowed early diagnosis and better understand of phylogenetic relationships, and the pathogen is currently divided into three clades (I, II and III or A, B and C). However, this information is still quite limited for this pathogen and new gene regions could help understanding the evolutionary history of this species. Therefore, this study aimed to establish the phylogenetic relationships among 52 american and asian P. insidiosum isolates by sequencing three new gene regions: the translation elongation factor (Tef-1α), α and β tubulin, in addition to the standardization of the Pulse Filed Gel Electrophoresis (PFGE) technique for this species. The Tef-1α region showed little polymorphic in relation to α and β tubulin, however it separated the strains here studied into two distinct clades, being composed only of strains previously classified as clade III (Asian), and grouped all the American strains next to the clade II strains. The β tubulin gene-based phylogeny separated the isolates into the three expected clades. Regarding α tubulin there was differentiation of isolates in clades I a... (Complete abstract click electronic access below) / Mestre

<p>  </p> <p>Spotted-wing Drosophila (SWD), <em>Drosophila suzukii</em> (Matsumura), is an economically-important pest of small fruits worldwide. Currently, timing of management is based on morphological identification of adult flies captured in baited monitoring traps; however, distinguishing SWD from other native drosophilids in traps is a time-consuming process that requires magnification. And a degree-day model that could help small fruit growers understand and predict the seasonal activity of this pest has not been developed for Indiana. Due to the low tolerance for maggots in fruit market, most small fruit growers rely on intensive, insecticide applications on a calendar-based schedule without guidance on the activity levels of SWD. </p> <p>A total of 6,051 SWD adults were monitored weekly using commercial Scentry traps at three highbush blueberry orchards during May to August. I applied the published SWD developmental thresholds of 7.2 °C (lower) and 31.5 °C (upper) and the single-sine method to calculate accumulated degree days in the year of 2021 and 2022. A predictive model from two years of data at three locations exhibited an S-shaped curve, with 5%, 25%, and 50% of adults detected at ~907, 1,293, and 1,523 CDD, respectively. By examining infestations in three varieties, ‘Bluecrop’, ‘Blueray’, and ‘Elliot’, I found that blueberry infestation rate increased as the trap captures increased. The use of early-ripening highbush blueberry varieties can reduce infestation and regardless of variety, as berries became softer, the number of SWD egg scars in berries increased.</p> <p>DNA-based diagnostic methods, like loop-mediated isothermal amplification (LAMP), have the potential to improve SWD detection by replacing morphological identification with DNA-based identification. Positive results of the LAMP assay are based on a visible color change from pink to yellow when focal DNA is present. I tested the reliability of LAMP results using SWD DNA and then evaluated the sensitivity of LAMP in discriminating between SWD and two native drosophilids common captured in monitoring traps in Indiana, <em>Drosophila affinis</em> and <em>D. simulans</em>. I found the LAMP assay can quickly and accurately identify SWD with as little as 0.1 ng/μl of DNA. Following optimization, the assay also suggested success in discriminating between SWD and these two native species: it only requires an individual fly, DNA extraction is not necessary. </p> <p>By better predicting seasonal SWD activity and optimizing DNA-based diagnostics for this pest, this study can help improve the timely detection of SWD and the management in small fruit systems. </p>

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

O complexo Sporothrix schenckii reúne espécies etiologicamente relacionadas à esporotricose, uma micose que pode acometer seres humanos e animais. Foi realizada a identificação fenotípica e molecular de 85 isolados provenientes de quatro estados brasileiros (Minas Gerais, Rio de Janeiro, Rio Grande do Sul e São Paulo). Foram pesquisadas a produção de enzimas, o perfil de inibição por leveduras killer, a suscetibilidade aos antifúngicos comerciais e aos extratos de plantas. Os isolados foram identificados como S. schenckii, S. brasiliensis e S. globosa, com predomínio de S. schenckii. Houve discordância de 37,7% entre a identificação das espécies do complexo S. schenckii utilizando metodologias fenotípicas e genotípicas. Entre os antifúngicos testados, a terbinafina foi o fármaco mais ativo; seguido por cetoconazol e itraconazol, enquanto fluconazol e voriconazol foram os menos ativos. Cinco isolados fúngicos foram detectados como resistentes ao itraconazol, sendo um S. globosa e quatro S. schenckii. Não houve diferença nos perfis de suscetibilidade aos antifúngicos entre as espécies do complexo Sporothrix schenckii. Entre os extratos de origem vegetal, o mais ativo foi o proveniente de Pterocaulon polystachyum, mostrando que o uso popular das plantas reforça a importância de pesquisas etnofarmacológicas, abrindo a possibilidade de encontrar novos agentes antifúngicos clinicamente eficazes. Doze das 18 leveduras killer avaliadas apresentaram atividade frente a todos os isolados do complexo S. schenckii estudados. No entanto, não houve diferença na suscetibilidade as toxinas entre as espécies de Sporothrix. Todos os isolados produziram desoxiribonuclease, urease e proteinase. Atividade fosfolipase e esterase foi detectada em 83 (97,6%) e 80 (94,1%), respectivamente, dos isolados testados. Todas as amostras do complexo S. schenckii produziram, pelo menos, quatro das enzimas avaliadas, e 78 (91,8%) dos isolados produziram todas as enzimas analisadas no estudo. No entanto, não foi possível diferenciar as espécies de Sporothrix baseado no perfil enzimático. Entre as enzimas extracelulares avaliadas nos isolados do complexo S. schenckii, desoxiribonuclease e esterase foram produzidas em maior quantidade, podendo vir a ser um fator de virulência. Além disso, o caldo Sabouraud dextrose mostrou potencial para ser usado na avaliação in vitro da atividade antifúngica frente ao complexo S. schenckii. / The Sporothrix schenckii complex combines species etiologically related to sporotrichosis, a mycosis which can affect humans and animals. The phenotypic and genotypic identification of 85 strains from four Brazilian States (Minas Gerais, Rio de Janeiro, Rio Grande do Sul and São Paulo) was performed. The enzymatic production, profile of inhibition by killer yeasts, susceptibility to marketed antifungal and to plant extracts were surveyed. The isolates were identified as S. schenckii, S. brasiliensis and S. globosa, with the predominance of S. schenckii. There was 37.7% disagreement regarding the species classification using phenotypic and genotypic methodologies. Among the tested antifungals, terbinafine was the most active drug, followed by ketoconazole and itraconazole, while fluconazole and voriconazole were the least active ones. Five isolates - one S. globosa and four S. schenckii - were resistent to itraconazole. There was no difference as to the profiles of the susceptibility to the antifungal agents among the Sporothrix species. The most active vegetal extract was from Pterocaulon polystachyum, showing that the popular use of these plants reinforces the importance of ethnopharmacological researches, with the possibility of finding new clinically effective antifungal agents. Twelve out of the 18 evaluated killer yeasts showed activity against all the tested strains of the S. schenckii complex. However, there was no difference in susceptibility to the toxins among the Sporothrix species complex. All the isolates were desoxiribonuclease, urease and proteinase positive. Phospholipase and esterase activities were detected in 83 (97.6%) and 80 (94.1%), respectively, among the isolates evaluated. All the S. schenckii complex strains produced at least four of the evaluated enzymes, and 78 (91.8%) of the isolates produced all the enzymes analyzed in the study. However, it is not possible to differentiate the Sporothrix species based on their enzymatic profile. Among the extracellular enzymes evaluated in the S. schenckii complex isolates, desoxiribonuclease and esterase were the most prominent ones, and their production may be a virulence factor. Furthermore, the Sabouraud dextrose broth showed potential to be used in the in vitro evaluation of the antifungal activity against the S. schenckii complex.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

O complexo Sporothrix schenckii reúne espécies etiologicamente relacionadas à esporotricose, uma micose que pode acometer seres humanos e animais. Foi realizada a identificação fenotípica e molecular de 85 isolados provenientes de quatro estados brasileiros (Minas Gerais, Rio de Janeiro, Rio Grande do Sul e São Paulo). Foram pesquisadas a produção de enzimas, o perfil de inibição por leveduras killer, a suscetibilidade aos antifúngicos comerciais e aos extratos de plantas. Os isolados foram identificados como S. schenckii, S. brasiliensis e S. globosa, com predomínio de S. schenckii. Houve discordância de 37,7% entre a identificação das espécies do complexo S. schenckii utilizando metodologias fenotípicas e genotípicas. Entre os antifúngicos testados, a terbinafina foi o fármaco mais ativo; seguido por cetoconazol e itraconazol, enquanto fluconazol e voriconazol foram os menos ativos. Cinco isolados fúngicos foram detectados como resistentes ao itraconazol, sendo um S. globosa e quatro S. schenckii. Não houve diferença nos perfis de suscetibilidade aos antifúngicos entre as espécies do complexo Sporothrix schenckii. Entre os extratos de origem vegetal, o mais ativo foi o proveniente de Pterocaulon polystachyum, mostrando que o uso popular das plantas reforça a importância de pesquisas etnofarmacológicas, abrindo a possibilidade de encontrar novos agentes antifúngicos clinicamente eficazes. Doze das 18 leveduras killer avaliadas apresentaram atividade frente a todos os isolados do complexo S. schenckii estudados. No entanto, não houve diferença na suscetibilidade as toxinas entre as espécies de Sporothrix. Todos os isolados produziram desoxiribonuclease, urease e proteinase. Atividade fosfolipase e esterase foi detectada em 83 (97,6%) e 80 (94,1%), respectivamente, dos isolados testados. Todas as amostras do complexo S. schenckii produziram, pelo menos, quatro das enzimas avaliadas, e 78 (91,8%) dos isolados produziram todas as enzimas analisadas no estudo. No entanto, não foi possível diferenciar as espécies de Sporothrix baseado no perfil enzimático. Entre as enzimas extracelulares avaliadas nos isolados do complexo S. schenckii, desoxiribonuclease e esterase foram produzidas em maior quantidade, podendo vir a ser um fator de virulência. Além disso, o caldo Sabouraud dextrose mostrou potencial para ser usado na avaliação in vitro da atividade antifúngica frente ao complexo S. schenckii. / The Sporothrix schenckii complex combines species etiologically related to sporotrichosis, a mycosis which can affect humans and animals. The phenotypic and genotypic identification of 85 strains from four Brazilian States (Minas Gerais, Rio de Janeiro, Rio Grande do Sul and São Paulo) was performed. The enzymatic production, profile of inhibition by killer yeasts, susceptibility to marketed antifungal and to plant extracts were surveyed. The isolates were identified as S. schenckii, S. brasiliensis and S. globosa, with the predominance of S. schenckii. There was 37.7% disagreement regarding the species classification using phenotypic and genotypic methodologies. Among the tested antifungals, terbinafine was the most active drug, followed by ketoconazole and itraconazole, while fluconazole and voriconazole were the least active ones. Five isolates - one S. globosa and four S. schenckii - were resistent to itraconazole. There was no difference as to the profiles of the susceptibility to the antifungal agents among the Sporothrix species. The most active vegetal extract was from Pterocaulon polystachyum, showing that the popular use of these plants reinforces the importance of ethnopharmacological researches, with the possibility of finding new clinically effective antifungal agents. Twelve out of the 18 evaluated killer yeasts showed activity against all the tested strains of the S. schenckii complex. However, there was no difference in susceptibility to the toxins among the Sporothrix species complex. All the isolates were desoxiribonuclease, urease and proteinase positive. Phospholipase and esterase activities were detected in 83 (97.6%) and 80 (94.1%), respectively, among the isolates evaluated. All the S. schenckii complex strains produced at least four of the evaluated enzymes, and 78 (91.8%) of the isolates produced all the enzymes analyzed in the study. However, it is not possible to differentiate the Sporothrix species based on their enzymatic profile. Among the extracellular enzymes evaluated in the S. schenckii complex isolates, desoxiribonuclease and esterase were the most prominent ones, and their production may be a virulence factor. Furthermore, the Sabouraud dextrose broth showed potential to be used in the in vitro evaluation of the antifungal activity against the S. schenckii complex.

O complexo Sporothrix schenckii reúne espécies etiologicamente relacionadas à esporotricose, uma micose que pode acometer seres humanos e animais. Foi realizada a identificação fenotípica e molecular de 85 isolados provenientes de quatro estados brasileiros (Minas Gerais, Rio de Janeiro, Rio Grande do Sul e São Paulo). Foram pesquisadas a produção de enzimas, o perfil de inibição por leveduras killer, a suscetibilidade aos antifúngicos comerciais e aos extratos de plantas. Os isolados foram identificados como S. schenckii, S. brasiliensis e S. globosa, com predomínio de S. schenckii. Houve discordância de 37,7% entre a identificação das espécies do complexo S. schenckii utilizando metodologias fenotípicas e genotípicas. Entre os antifúngicos testados, a terbinafina foi o fármaco mais ativo; seguido por cetoconazol e itraconazol, enquanto fluconazol e voriconazol foram os menos ativos. Cinco isolados fúngicos foram detectados como resistentes ao itraconazol, sendo um S. globosa e quatro S. schenckii. Não houve diferença nos perfis de suscetibilidade aos antifúngicos entre as espécies do complexo Sporothrix schenckii. Entre os extratos de origem vegetal, o mais ativo foi o proveniente de Pterocaulon polystachyum, mostrando que o uso popular das plantas reforça a importância de pesquisas etnofarmacológicas, abrindo a possibilidade de encontrar novos agentes antifúngicos clinicamente eficazes. Doze das 18 leveduras killer avaliadas apresentaram atividade frente a todos os isolados do complexo S. schenckii estudados. No entanto, não houve diferença na suscetibilidade as toxinas entre as espécies de Sporothrix. Todos os isolados produziram desoxiribonuclease, urease e proteinase. Atividade fosfolipase e esterase foi detectada em 83 (97,6%) e 80 (94,1%), respectivamente, dos isolados testados. Todas as amostras do complexo S. schenckii produziram, pelo menos, quatro das enzimas avaliadas, e 78 (91,8%) dos isolados produziram todas as enzimas analisadas no estudo. No entanto, não foi possível diferenciar as espécies de Sporothrix baseado no perfil enzimático. Entre as enzimas extracelulares avaliadas nos isolados do complexo S. schenckii, desoxiribonuclease e esterase foram produzidas em maior quantidade, podendo vir a ser um fator de virulência. Além disso, o caldo Sabouraud dextrose mostrou potencial para ser usado na avaliação in vitro da atividade antifúngica frente ao complexo S. schenckii. / The Sporothrix schenckii complex combines species etiologically related to sporotrichosis, a mycosis which can affect humans and animals. The phenotypic and genotypic identification of 85 strains from four Brazilian States (Minas Gerais, Rio de Janeiro, Rio Grande do Sul and São Paulo) was performed. The enzymatic production, profile of inhibition by killer yeasts, susceptibility to marketed antifungal and to plant extracts were surveyed. The isolates were identified as S. schenckii, S. brasiliensis and S. globosa, with the predominance of S. schenckii. There was 37.7% disagreement regarding the species classification using phenotypic and genotypic methodologies. Among the tested antifungals, terbinafine was the most active drug, followed by ketoconazole and itraconazole, while fluconazole and voriconazole were the least active ones. Five isolates - one S. globosa and four S. schenckii - were resistent to itraconazole. There was no difference as to the profiles of the susceptibility to the antifungal agents among the Sporothrix species. The most active vegetal extract was from Pterocaulon polystachyum, showing that the popular use of these plants reinforces the importance of ethnopharmacological researches, with the possibility of finding new clinically effective antifungal agents. Twelve out of the 18 evaluated killer yeasts showed activity against all the tested strains of the S. schenckii complex. However, there was no difference in susceptibility to the toxins among the Sporothrix species complex. All the isolates were desoxiribonuclease, urease and proteinase positive. Phospholipase and esterase activities were detected in 83 (97.6%) and 80 (94.1%), respectively, among the isolates evaluated. All the S. schenckii complex strains produced at least four of the evaluated enzymes, and 78 (91.8%) of the isolates produced all the enzymes analyzed in the study. However, it is not possible to differentiate the Sporothrix species based on their enzymatic profile. Among the extracellular enzymes evaluated in the S. schenckii complex isolates, desoxiribonuclease and esterase were the most prominent ones, and their production may be a virulence factor. Furthermore, the Sabouraud dextrose broth showed potential to be used in the in vitro evaluation of the antifungal activity against the S. schenckii complex.

Soil nematodes play an important role in indication for assessing soil environments and ecosystems. Previous studies of nematode community analyses based on molecular identification have shown to be useful for assessing soil environments. Here we applied PCR-DGGE method for molecular analysis of five soil nematode communities (designed as S1 to S5) collected from four provinces in Southeastern Vietnam (Binh Duong, Ba Ria Vung Tau, Binh Phuoc and Dong Nai) based on SSU gene. By sequencing DNA bands derived from S5 community sample, our data show 15 species containing soil nematode, other nematode and non-nematode (fungi) species. Genus Meloidogyne was found as abundant one. The genetic relationship of soil nematode species in S5 community were determined by Maximum Likelihood tree re-construction based on SSU gene. This molecular approach is applied for the first time in Vietnam for identification of soil nematode communities. / Tuyến trùng đất đóng vai trò chỉ thị quan trọng trong công tác đánh giá môi trường và hệ sinh thái đất. Các nghiên cứu trước đây đã cho thấy lợi ích của việc phân tích cộng đồng tuyến trùng đất bằng định danh sinh học phân tử đối với việc đánh giá môi trường đất. Ở đây, chúng tôi ứng dụng phương pháp PCR-DGGE dựa trên gene SSU để phân tích năm (ký hiệu từ S1 đến S5) cộng đồng tuyến trùng đất thuộc các vùng trồng chuyên canh cây hồ tiêu ở miền nam Việt Nam (Bình Dương, Bà Rịa Vũng Tàu, Bình Phước và Đồng Nai). Bằng cách giải trình tự các vạch của mẫu tuyến trùng S5, kết quả cho thấy cộng đồng tuyến trùng này có 15 loài gồm nhóm tuyến trùng đất, nhóm các loại tuyến trùng khác và nhóm không phải tuyến trùng (nấm) và trong đó Meloidogyne là giống ưu thế. Mối quan hệ di truyền của các các loài tuyến trùng đất thuộc cộng đồng S5 được xác định bằng việc thiết lập cây phát sinh loài Maximum Likelihood dựa trên gene SSU. Đây là nghiên cứu đầu tiên ở Việt Nam sử dụng kỹ thuật PCR-DGGE để phân tích các cộng đồng tuyến trùng đất trồng hồ tiêu.