Serological investigation and PCR in detection of pathogenic leptospires in snakes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Isolation of extraintestinal pathogenic Escherichia coli from diarrheic dogs and their antimicrobial resistance profile

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Protection levels of vaccinated pigeons (Columba livia) against a highly pathogenic newcastle disease virus strain

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The adaptive potential of a plant pathogenic fungus, Rhizoctonia solani AG-3, under heat and fungicide stress

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of pathogenic fungi occurrence in traumatogenic structures of freshwater fish

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Clues to the presence of pathogenic fungi in certain environments

The presence of various pathogenic fungi in rather unsuspected hosts and environments has always attracted the attention of the scientific community. Reports on the putative role of animals in fungal infections of humans bear important consequences on public health as well as on the understanding of fungal ecology. Fungi are ubiquitous in nature and their great capacity for adaptation allows them to survive and indeed, to thrive, in plants, trees and other natural substrata. Nonetheless, we are just beginning to learn the significance that these diverse fungal habitats have on the increasing number of immunosuppressed individuals. The accidental or permanent presence of fungi in animals, plants, soils and watercourses should not be taken too lightly because they constitute the source where potential pathogens will be contracted. If those fungal habitats that carry the largest risks of exposure could be defined, if seasonal variations in the production of infectious propagules could be determined, and if their mode of transmission were to be assessed, it would be possible to develop protective measures in order to avoid human infection. Additionally, unsuspected avenues for the exploration of fungal survival strategies would be opened, thus enhancing our capacity to react properly to their advancing limits. This paper explores several ecological connections between human pathogenic fungi and certain animals, trees, waterways and degraded organic materials. The occurrence of such connections in highly endemic areas will hopefully furnish more precise clues to fungal habitats and allow the design of control programs aimed at avoiding human infection.

Inteins in pathogenic fungi: a phylogenetic tool and perspectives for therapeutic applications

Inteins or internal proteins are coding sequences that are transcribed and translated with flanking sequences (exteins). After translation, the inteins are excised by an autocatalytic process and the host protein assumes its normal conformation and develops its expected function. These parasitic genetic elements have been found in important, conserved proteins in all three domains of life. Most of the eukaryotic inteins are present in the fungi kingdom and the PRP8 intein is one of the most widespread inteins, occurring in important pathogens such as Cryptococcus neoformans (varieties grubii and neoformans), Cryptococcus gattii, Histoplasma capsulatum and Paracoccidioides brasiliensis. The knowledge of conserved and non-conserved domains in inteins have opened up new opportunities for the study of population variability in pathogenic fungi, including their phylogenetic relationships and recognition or diagnoses of species. Furthermore, inteins in pathogenic fungi should also be considered a promising therapeutic drug target, since once the autocatalytic splicing is inhibited, the host protein, which is typically vital, will not be able to perform its normal function and the fungal cell will not survive or reproduce.

Surfactin reduces the adhesion of food-borne pathogenic bacteria to solid surfaces

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Seasonality of pathogenic fungi in mites of rubber tree plantations adjacent to fragments of Cerrado

Fungos são os patógenos mais freqüentemente observados em populações de ácaros, auxiliando o controle destes em diferentes culturas. Vinte e cinco amostras de folhas foram coletadas de cultivos de seringueiras vizinhas a dois fragmentos de vegetação de Cerrado. em cada seringal, 25 plantas foram selecionadas para coletas e sete folhas ao redor da copa foram coletadas até a altura de sete a oito metros do solo. Aproximadamente 250 indivíduos de Calacarus heveae Feres, Phyllocoptruta seringueirae Feres e Tenuipalpus heveae Baker, coletados aleatoriamente, foram montados. Hirsutella thompsonii Fisher foi observado nas três espécies de ácaros e T. heveae foi a espécie mais infectada. Os maiores níveis de infecção ocorreram de novembro a fevereiro (estação chuvosa). Na estação seca, os níveis de infecção ficaram abaixo dos 5%. H. thompsonii tem potencial para ser usado como micoacaricida na estação chuvosa.

Potential of non-pathogenic Fusarium oxysporum isolates for control of Fusarium wilt of tomato

O trabalho avaliou a eficiência dos isolados (141/3, 233, 233/1, 245, 245/1, 251, 251/2, 251/5 e 257) de Fusarium oxysporum não patogênico ao tomateiro (Lycopersicon esculentum), no controle da murcha vascular causada por Fusarium oxysporum f. sp. lycopersici, raça 2 em plântulas de tomateiro cv. Viradoro. Para verificar o efeito dos isolados de F. oxysporum não patogênicos, o sistema radicular de plântulas de tomateiro, com 30 dias de idade, foi imerso na suspensão de conídios (10(6) ml-1) e as mudas transplantadas para substrato de cultivo. Após 35 dias do transplante foi verificado que esses isolados não foram patogênicos às plantas de tomateiro, nem afetaram o desenvolvimento das mudas. A eficiência dos isolados de Fusarium oxysporum não patogênicos no controle da murcha foi determinada imergindo-se as raízes de mudas de tomateiro em suspensão de conídios (10(6) conídios ml-1) e transplantando-as em substratos previamente infestados com os isolados de F. oxysporum f.sp. lycopersici, raça 2 (10(5) conídios ml-1 de substrato). Transcorridos 35 dias do transplante, foram realizadas as avaliações da severidade na escala de 1=planta sadia a 6=planta morta ou com vasos coloridos e folhas murchas até o ponteiro e altura das mudas. Os isolados de F. oxysporum não patogênicos foram eficientes em reduzir a severidade da doença e em manter normal o seu desenvolvimento. Esses resultados evidenciam a atividade antagônica dos isolados de F. oxysporum não patogênico no controle da murcha vascular do tomateiro, causada por Fusarium oxysporum f. sp. lycopersici raça 2.

Pathogenic variation in Colletotrichum gloeosporioides infecting Stylosanthes spp. in a center of diversity in Brazil

Pathogenic variation in Colletotrichum gloeosporioides infecting species of the tropical pasture legume Stylosanthes at its center of diversity was determined from 296 isolates collected from wild host population and selected germ plasm of S. capitata, S. guianensis, S. scabra, and S. macrocephala in Brazil. A putative host differential set comprising 11 accessions was selected from a bioassay of 18 isolates on 19 host accessions using principal component analysis. A similar analysis of anthracnose severity data for a subset of 195 isolates on the 11 differentials indicated that an adequate summary of pathogenic variation could be obtained using only five of these differentials. of the five differentials, S. seabrana 'Primar' was resistant and S. scabra 'Fitzroy' was susceptible to most isolates. A cluster analysis was used to determine eight natural race clusters using the 195 isolates. Linear discriminant functions were developed for eight race clusters using the 195 isolates as the training data set, and these were applied to classify a test data set of the remaining 101 isolates. All except 11 isolates of the test data set were classified into one of the eight race clusters. Over 10% of the 296 isolates were weakly pathogenic to all five differentials and another 40% were virulent on just one differential. The unclassified isolates represent six new races with unique virulence combinations, of which one isolate is virulent on all five differentials. The majority of isolates came from six field sites, and Shannon's index of diversity indicated considerable variation between sites. Pathogenic diversity was extensive at three sites where selected germ plasm were under evaluation, and complex race clusters and unclassified isolates representing new races were more prevalent at these sites compared with sites containing wild Stylosanthes populations.

Interaction of pathogenic fungi with host cells: Molecular and cellular approaches

This review provides an overview of several molecular and cellular approaches that are likely to supply insights into the host-fungus interaction. Fungi present intra- and/or extracellular host-parasite interfaces, the parasitism phenomenon being dependent on complementary surface molecules. The entry of the pathogen into the host cell is initiated by the fungus adhering to the cell surface, which generates an uptake signal that may induce its cytoplasmatic internalization. Furthermore, microbial pathogens use a variety of their surface molecules to bind to host extracellular matrix (ECM) components to establish an effective infection. on the other hand, integrins mediate the tight adhesion of cells to the ECM at sites referred to as focal adhesions and also play a role in cell signaling. The phosphorylation process is an important mechanism of cell signaling and regulation; it has been implicated recently in defense strategies against a variety of pathogens that alter host-signaling pathways in order to facilitate their invasion and survival within host cells. The study of signal transduction pathways in virulent fungi is especially important in view of their putative role in the regulation of pathogenicity. This review discusses fungal adherence, changes in cytoskeletal organization and signal transduction in relation to host-fungus interaction. (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

EVALUATION OF DIFFERENT TECHNIQUES FOR THE DIFFERENTIATION OF PATHOGENIC AND NON PATHOGENIC STRAINS OF YERSINIA-ENTEROCOLITICA

Different methods and tests have been used to evaluate the pathogenic potential of distinct Y. enterocolitica serotypes and biotypes. We tested a total of 60 Y. enterocolitica strains, being 25 of human origin (serotype O3 biotype 4 and serotype O5 biotype 1); 6 of animal origin (serotype O3 biotype 4); 19 isolated from the environment (serotype O5.27 biotypes 1 and 2); and 8 isolated from food (serotype O5 biotype 1 and serotype 05.27 biotype 1). The methods used were based on plasmid gene expression (autoagglutination, calcium-dependence at 37 degrees C and Congo Red absorption tests), chromosomal gene expression (assays for pyrazinamidase activity, salicin fermentation and esculin hydrolysis), and invasion of HEp-2 cells. All but one of the Y. enterocolitica O3 strains, were found to be potentially pathogenic when submitted to the pyrazinamidase-salicin-esculin tests. In contrast, the results obtained with the assays related to plasmidial gene expression were not so uniform, probably due to plasmid loss. The least homogeneous results were obtained with the HEp-2 cell invasion test. Y. enterocolitica O5 behaved in a uniform manner when tested with the first two groups of tests (based on chromosomal and plasmidial gene expression), but not when tested with the HEp-2 invasion assay. The strains of serotype O5.27 biotype 1 presented a uniform behavior hen submitted to the chromosomic-related tests, showing no pathogenicity. However, they did not provide conclusive results with the tests related to plasmidial gene expression or HEp-2 cell invasion. We conclude that the tests related to chromosomal gene expression (esculin-salicin-pyrazinamidase) are simple and highly effective for the detection of potentially pathogenic Y. enterocolitica isolated from clinical cases.

PATHOGENIC OR POTENTIALLY PATHOGENIC BACTERIA AS CONTAMINANTS OF FRESH-WATER FROM DIFFERENT SOURCES IN ARARAQUARA, BRAZIL

The microbiological quality of various fresh waters in the Araraquara region, state of São Paulo, Brazil was investigated. Ninety-nine water samples were taken from rivers, reservoirs, artesian and non-artesian wells, springs and tap waters, and these waters were analysed using: plate counts of heterotrophic microorganisms (per 1 ml); Most Probable Number (MPN) of fecal coliforms and E. coli (per 100 ml); tests for presence of Salmonella, Shigella, Yersinia, the E. coli pathogens of classes EPEC, ETEC and EIEC and Mycobacterium, Shigella, Yersinia and enteroinvasive E. coli (EIEC) were not isolated. The other types of microorganisms were isolated in varying proportions. We conclude that the waters investigated represent a potential microbiological health risk.