Bioprotective potential of lactic acid bacteria and their metabolites against enterotoxigenic Escherichia coli.

Escherichia coli is one of the main pathogens that impacts swine production. Given the need for methods for its control, the in vitro effect of lactic acid bacteria (LAB) and their metabolites against E. coli F4 was evaluated through cell culture and microbiological analysis. The strains Limosilactobacillus fermentum 5.2, Lactiplantibacillus plantarum 6.2, and L. plantarum 7.1 were selected. To evaluate the action of their metabolites, lyophilized cell-free supernatants (CFS) were used. The effect of CFS was evaluated in HT-29 intestinal lineage cells; in inhibiting the growth of the pathogen in agar; and in inhibiting the formation of biofilms. The bioprotective activity of LAB was evaluated via their potential for autoaggregation and coaggregation with E. coli. The CFS did not show cytotoxicity at lower concentrations, except for L. fermentum 5.2 CFS, which is responsible for cell proliferation at doses lower than 10 mg ml-1. The CFS were also not able to inhibit the growth of E. coli F4 in agar; however, the CFS of L. plantarum 7.1 resulted in a significant decrease in biofilm formation at a dose of 40 mg ml-1. Regarding LAB, their direct use showed great potential for autoaggregation and coaggregation in vitro, thus suggesting possible effectiveness in animal organisms, preventing E. coli fixation and proliferation. New in vitro tests are needed to evaluate lower doses of CFS to control biofilms and confirm the bioprotective potential of LAB, and in vivo tests to assess the effect of LAB and their metabolites interacting with animal physiology.

Contaminação microbiológica de resinas compostas utilizadas em uma clínica-escola de Odontologia / Microbiological contamination of composite resins used in a Dental school clinic

O objetivo desse estudofoi verificar a contaminação microbiológica deresinas compostas utilizadas em uma clínica-escola de Odontologia. Trata-se de uma pesquisa experimental/laboratorial, na qual foramcoletadas amostras de 10 bisnagas de resina composta, sendo uma delas o controle negativo. Porções de resina composta contidas no interior das bisnagas foram coletadas e mergulhadas em tubos de ensaio contendo caldo nutriente eposterior semeadura em placas e coloraçãopara caracterizar as colônias e observar bactérias e fungos. Todas as amostras apresentaram contaminação, inclusive o tubo contendo meio de cultura utilizado como controle de manuseio do experimento. Essas contaminações podem ter relação com as falhas dos meios de biossegurança empregados na clínica-escola e com os métodos de transporte e armazenamento das bisnagas de resina composta. Portanto, existe a necessidade de conscientização dos estudantese docentespara a adoção de medidas de biossegurança específicas para o manuseio das resinas compostas (AU).

The aim of this study was to verify the microbiological contamination in composite resins used at one Dental school clinic. This is an experimental/laboratory study, in which samples of 10 tubes of composite resin were collected, one of which was the negative control. Portions of composite resin inside the tubes were collected and dipped in test tubes containing nutrient broth for subsequent seeding on to plates and staining for the characterization of bacterial and fungal colonies. All samples revealed contamination, including the tube containing culture medium used as control for handling the experiment. These contaminations may be related to failures in biosafety measures employed in theDental school clinic and to the transport and storage methods for the tubes of composite resin. Therefore, it is necessary to raise awareness among students and teachers to adopt specific biosafety measures for the handling of composite resins (AU).

Differentially expressed proteins in the interaction of Paracoccidioides lutzii with human monocytes.

BACKGROUND: Fungi of the genus Paracoccidioides are the etiological agents of paracoccidioidomycosis, a highly prevalent mycosis in Latin America. Infection in humans occurs by the inhalation of conidia, which later revert to the form of yeast. In this context, macrophages are positioned as an important line of defense, assisting in the recognition and presentation of antigens, as well as producing reactive oxygen species that inhibit fungal spreading. AIMS: The objective of this study was to identify differentially expressed proteins during the interaction between Paracoccidioides lutzii Pb01 strain and human U937 monocytes. METHODS: Two-dimensional electrophoresis, combined with mass spectrometry, was used to evaluate the differential proteomic profiles of the fungus P. lutzii (Pb01) interacting with U937 monocytes. RESULTS: It was possible to identify 25 proteins differentially expressed by Pb01 alone and after interacting with U937 monocytes. Most of these proteins are directly associated with fungal metabolism for energy generation, such as glyceraldehyde-3-phosphate dehydrogenase, and intracellular adaptation to monocytes. Antioxidant proteins involved in the response to oxidative stress, such as peroxiredoxin, cytochrome, and peroxidase, were expressed in greater quantity in the interaction with monocytes, suggesting their association with survival mechanisms inside phagocytic cells. We also identified 12 proteins differentially expressed in monocytes before and after the interaction with the fungus; proteins involved in the reorganization of the cytoskeleton, such as vimentin, and proteins involved in the response to oxidative stress, such as glioxalase 1, were identified. CONCLUSIONS: The results of this proteomic study of a P. lutzii isolate are novel, mimicking in vitro what occurs in human infections. In addition, the proteins identified may aid to understand fungal-monocyte interactions and the pathogenesis of paracoccidioidomycosis.