Microbiological quality of recreational waters in Araraquara, SP, Brazil

The microbiological flora of 108 water samples was explored to evaluate the role of recreational waters as a possible source of human diseases in Araraquara, S.P., Brazil. These waters included six swimming pools and three lakes with beaches. The number of total and fecal coliforms, Escherichia coli, fecal streptococci, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and heterotrophic organisms was determined. As was the occurrence of Salmonella, Shigella, Yersinia, enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), Mycobacteria, yeasts in general and dermatophytes. Shigella, Yersinia, EIEC and dermatophytes were not isolated. Other organisms or groups of microorganisms were found in variable proportions. From this study it is concluded that recreational waters used by the population of Araraquara, may be contaminated with potentially pathogenic microorganism and this may serve as a source of human diseases.

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.

Sensitivity of ant (Cephalotes) colonies and individuals to antibiotics implies feeding symbiosis with gut microorganisms

Ants in the tribe Cephalotini are exceptional in that they maintain microorganisms in their digestive tract. To understand what these microorganisms mean to the ants, we observed the feeding habits of Cephalotes pusillus and Cephalotes atratus, finding that in nature they feed on extrafloral nectars, homopteran secretions, and bird droppings. Feeding the antibiotic kanamycin to colonies of C. pusillus in the laboratory kills them. Ants desiccate or starve rather than feed on liquids to which the antibiotics gentamycin and netilmycin have been added, but feed and survive on liquids containing nystatin, penicillin, and ampicillin. We identified over 10 microorganisms from the intestine of C. pusillus with different antibiotic-resistance patterns. The bacteria are from the genera Corynebacterium, Brevibacterium, Sphingobacterium, Ochrobactrum, Myroides, Brevundimonas, Alcaligenes, Stenotrophomonas, Moraxella, and Pseudomonas. We hypothesize that the microorganisms provide nutrients to the ants by synthesizing amino acids from carbohydrates and nitrates. We do not know whether the ants collect the bacteria from the environment, but they transmit them to their young. They culture them in their digestive tract, eventually feeding on them.

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.

Bioleaching of metals from anaerobic sewage sludge: Effects of total solids, leaching microorganisms, and energy source

The effects of municipal sewage sludge solids concentration, leaching microorganisms (Thiobacillus thiooxidans or Thiobacillus ferrooxidans) and the addition of energy source (SO or Fe(II)) on the bioleaching of metals from sewage sludge has been investigated under laboratory conditions using shake flasks. The results show that metal solubilization was better accomplished if additional energy source is supplemented to the microorganisms and that T. thiooxidans furnishes, in general, more adequate conditions for the bioleaching than T. ferrooxidans. At a total solids concentration of 70 g L-1 (originally present in the sludge) pH drop and ORP increase are attenuated, so metal solubilization is negatively affected. Tt was also demonstrated that if lead (Pb) solubilization is to be achieved, than a special combination of microorganism/energy source must be applied.

Transcriptional activation of MMP-13 by periodontal pathogenic LPS requires p38 MAP kinase

Matrix metal loprotease-13 (MMP-13) is induced by pro-inflammatory cytokines and increased expression is associated with a number of pathological conditions such as tumor metastasis, osteoarthritis, rheumatoid arthritis and periodontal diseases. MMP-13 gene regulation and the signal transduction pathways activated in response to bacterial LPS are largely unknown. In these studies, the role of the mitogen-activated protein kinase (MAPK) pathways in the regulation of MMP-13 induced by lipopolysaccharide was investigated. Lipopolysaccharide from Escherichia coli and Actinobacillus actinomycetemcomitans significantly (P < 0.05) increased MMP-13 steady-state mRNA (average of 27% and 46% increase, respectively) in murine periodontal ligament fibroblasts. MMP-13 mRNA induction was significantly reduced by inhibition of p38 MAP kinase. Immunoblot analysis indicated that p38 signaling was required for LPS-induced MMP-13 expression. Lipopolysaccharide induced proximal promoter reporter (-660/+32 mMMP-13) gene activity required p38 signaling. Collectively, these results indicate that lipopolysaccharide-induced murine MMP-13 is regulated by p38 signaling through a transcriptional mechanism.