Wladimir Padilha da Silva

Essential oil of the leaves of Eugenia uniflora L.: Antioxidant and antimicrobial properties

Essential oil (EO) of the leaves of Eugenia uniflora L. (Brazilian cherry tree) was evaluated for its antioxidant, antibacterial and antifungal properties. The acute toxicity of the EO administered by oral route was also evaluated in mice. The EO exhibited antioxidant activity in the DPPH, ABTS and FRAP assays and reduced lipid peroxidation in the kidney of mice. The EO also showed antimicrobial activity against two important pathogenic bacteria, Staphylococcus aureus and Listeria monocytogenes, and against two fungi of the Candida species, C. lipolytica and C. guilliermondii. Acute administration of the EO by the oral route did not cause lethality or toxicological effects in mice. These findings suggest that the EO of the leaves of E. uniflora may have the potential for use in the pharmaceutical industry.

Hazards in non-pasteurized milk on retail sale in Brazil: prevalence of Salmonella spp, Listeria monocytogenes and chemical residues

A instabilidade do mercado de leite no Brasil forca pequenos produtores de leite a procurar alternativas de comercio de sua producao, o que inclui a venda de leite cru para individuos que dao preferencia a esse tipo de leite. Considerando a importância desse mercado e os conhecidos riscos a saude que o consumo de leite cru pode representar, este estudo avaliou a qualidade microbiologica e a presenca de Listeria monocytogenes, Salmonella spp., residuos de cloretos, antimicrobianos e inseticidas (organofosforados e carbamatos) em leite cru produzido em 210 propriedades leiteiras localizadas em quatro importantes estados produtores de leite no Brasil (Parana, Sao Paulo, Minas Gerais e Rio Grande do Sul). Em 66% das propriedades selecionadas, a ordenha era manual. Em 33% a ordenha era semi-automatica (ordenha mecânica balde ao pe) e em apenas 1% o sistema de ordenha e armazenamento era totalmente mecânico (sistema fechado). Todas as amostras de leite cru foram negativas para L. monocytogenes, Salmonella spp e residuos de cloretos. As contagens de aerobios mesofilos foram superiores a 105 UFC/mL em 75,7% das amostras. Em 80,4%, as contagens de coliformes foram superiores a 102 UFC/mL. Escherichia coli foi detectada em 36,8% das amostras. Inseticidas e residuos de antibioticos foram observados em 74,4% e 11,5% das amostras, respectivamente. Niveis inaceitaveis de microrganismos indicadores de higiene, inseticidas e residuos de antibioticos foram considerados fatores de risco mais importantes que os dois patogenos estudados.

Highly specific fiber optic immunosensor coupled with immunomagnetic separation for detection of low levels of Listeria monocytogenes and L. ivanovii

BackgroundImmunomagnetic separation (IMS) and immunoassays are widely used for pathogen detection. However, novel technology platforms with highly selective antibodies are essential to improve detection sensitivity, specificity and performance. In this study, monoclonal antibodies (MAbs) against Internalin A (InlA) and p30 were generated and used on paramagnetic beads of varying diameters for concentration, as well as on fiber-optic sensor for detection.ResultsAnti-InlA MAb-2D12 (IgG2a subclass) was specific for Listeria monocytogenes and L. ivanovii, and p30-specific MAb-3F8 (IgM) was specific for the genus Listeria. At all bacterial concentrations (103–108 CFU/mL) tested in the IMS assay; the 1-μm diameter MyOne beads had significantly higher capture efficiency (P < 0.05) than the 2.8-μm diameter M-280 beads with both antibodies. The highest capture efficiency for MyOne-2D12 (49.2% for 105 CFU/mL) was significantly higher (P < 0.05) than that of MyOne-3F8 (16.6 %) and Dynabeads anti-Listeria antibody (9 %). Furthermore, capture efficiency for MyOne-2D12 was highly specific for L. monocytogenes and L. ivanovii. Subsequently, we captured L. monocytogenes by MyOne-2D12 and MyOne-3F8 from hotdogs inoculated with mono- or co-cultures of L. monocytogenes and L. innocua (10–40 CFU/g), enriched for 18 h and detected by fiber-optic sensor and confirmed by plating, light-scattering, and qPCR assays. The detection limit for L. monocytogenes and L. ivanovii by the fiber-optic immunosensor was 3 × 102 CFU/mL using MAb-2D12 as capture and reporter antibody. Selective media plating, light-scattering, and qPCR assays confirmed the IMS and fiber-optic results.ConclusionsIMS coupled with a fiber-optic sensor using anti-InlA MAb is highly specific for L. monocytogenes and L. ivanovii and enabled detection of these pathogens at low levels from buffer or food.

Leite cru de quatro regiões leiteiras brasileiras: perspectivas de atendimento dos requisitos microbiológicos estabelecidos pela Instrução Normativa 51

Evidencias que o leite produzido e consumido no Brasil nem sempre apresenta a qualidade desejada tem gerado a discussao e desenvolvimento de novas politicas de incentivo a producao leiteira, resultando no desenvolvimento do Programa Nacional de Melhoria da Qualidade do Leite. Em complementacao, em 2002 o Ministerio da Agricultura publicou a Instrucao Normativa 51 (IN51), com importantes inovacoes em relacao a conservacao e transporte do leite cru, alem de estabelecimento de um padrao de qualidade para esse tipo de leite (106 UFC/mL), a ser implantado em diferentes prazos nas diferentes regioes do pais, a partir de 2005. O presente trabalho teve como objetivo verificar se o leite cru produzido em quatro areas de quatro estados produtores de leite no Brasil estaria, nesse momento, em condicoes de cumprir o estabelecido na IN 51, especialmente quanto ao atendimento dos padroes microbiologicos previstos. Amostras de leite cru, coletadas em 210 diferentes propriedades nas regioes de Vicosa, MG (47), Pelotas, RS (50), Londrina, PR (63) e Botucatu, SP (50), foram analisadas quanto aos niveis de contaminacao por aerobios mesofilos, utilizando o PetrifilmTM AC. Parcela significativa das amostras (48,6%) apresentaram contagens acima do determinado pela IN51, sendo 21,3% na regiao de Vicosa (MG), 56,0% na regiao de Pelotas (RS), 47,6% na regiao de Londrina (PR) e 68,0% na regiao de Botucatu (SP). Considerando as diferencas de cada regiao, foi possivel observar a importância da refrigeracao na conservacao e transporte da producao, bem como da implantacao de boas praticas e assistencia tecnica nas propriedades. Os resultados obtidos permitem concluir que a adequacao as normas estabelecidas pela IN51 pode ser mais dificil em algumas regioes do que em outras, sendo fundamental a adocao da refrigeracao na conservacao e no transporte da producao, e de programas regionais de assistencia a produtores leiteiros.

Identification of Staphylococcus aureus, S. intermedius and S. hyicus by PCR amplification of coa and nuc genes

Sixty-five strains of coagulase positive staphylococci (Staphylococcus aureus, S. intermedius and S. hyicus) were identified at species level by PCR amplification of the coa gene, specific for S. aureus, and of the nuc gene, specific for S. intermedius and for S. hyicus.

Characterization of Listeria monocytogenes isolated from a fresh mixed sausage processing line in Pelotas-RS by PFGE

Listeria monocytogenes is a bacterium capable to adhere to the surfaces of equipment and utensils and subsequently form biofilms. It can to persist in the food processing environmental for extended periods of time being able to contaminate the final product. The aim of this study was to trace the contamination route of L. monocytogenes on a fresh mixed sausage processing line, from raw material to the final product. The isolates obtained were characterized by serotyping and molecular typing by pulsed-field gel electrophoresis (PFGE) using the restriction enzymes ApaI and AscI. L. monocytogenes was detected in 25% of the samples. The samples of raw material were not contaminated, however, the microorganism was detected in 21% of the environmental samples (food contact and non-food contact), 20.8% of the equipments, 20% of the food workers hands, 40% of the mass ready to packaging and in all the final products samples, demonstrating that the contamination of final product occurred during the processing and the importance of cross contamination. PFGE yielded 22 pulsotypes wich formed 7 clusters, and serotyping yielded 3 serotypes and 1 serogroup, however, the presence of serotypes 4b and 1/2b in the final product is of great concern for public health. The tracing of contamination showed that some strains are adapted and persisted in the processing environment in this industry.

Prevalence of Listeria spp. in feces and carcasses at a lamb packing plant in Brazil

The objective of this work was to study the occurrence of Listeria species in feces and on dressed and cooled carcasses of lambs at a packing plant in Brazil. Listeria spp. were recovered on Oxford and Palcam agars. The 35 fecal samples yielded Listeria welshimeri (20%) and Listeria innocua (8.6%). The 69 carcass samples yielded L. innocua (34.8%), Listeria monocytogenes (4.3%), and Listeria ivanovii (1.5%). More Listeria spp. were recovered with two selective agars than with either agar alone.

Listeria spp. no processamento de lingüiça frescal em frigoríficos de Pelotas, RS, Brasil

Food that is highly manipulated, such as fresh sausages, is frequently responsible for spreading food borne diseases. Due to the threat that the bacterium Listeria monocytogenes represents to public health, the aim of this work was to study the presence of Listeria spp., especially Listeria monocytogenes, during processing of fresh sausages, in three slaughterhouses with state food inspection, in the city of Pelotas, Brazil. The raw material used for the sausage elaboration, the equipment used in the processing and the end products were analyzed. The results showed Listeria spp. in 100% of the 41 samples analyzed. Among the different species, L. innocua was the most frequent, isolated from 97.6% of the samples, followed by the L. monocytogenes and L. welshimeri that were isolated from 29.3% and 24.4% of the samples, respectively. The presence of these microorganisms in the samples analyzed, especially in the end product, shows the need for adequateness of the cleaning and sanitation practices of the food processing plants analyzed. It also shows a potential risk of listeriosis to the consumer.

Insights into the genome of the xanthan-producing phytopathogen Xanthomonas arboricola pv. pruni 109 by comparative genomic hybridization

The phytopathogenic bacterium Xanthomonas arboricola pv. pruni is the causal agent of Prunus Bacterial Spot disease that infects cultivated Prunus species and their hybrids. Furthermore, X. arboricola pv. pruni (Xap) plays a role in biotechnology since it produces xanthan gum, an important biopolymer used mainly in the food, oil, and cosmetics industry. To gain first insights into the genome composition of this pathovar, genomic DNA of X. arboricola pv. pruni strains was compared to the genomes of reference strains X. campestris pv. campestris B100 (Xcc B100) and X. campestris pv. vesicatoria 85-10 (Xcv 85-10) applying microarray-based comparative genomic hybridizations (CGH). The results implied that X. arboricola pv. pruni 109 lacks 6.67% and 5.21% of the genes present in the reference strains Xcc B100 and Xcv 85-10, respectively. Most of the missing genes were found to be organized in clusters and do not belong to the core genome of the two reference strains. Often they encode mobile genetic elements. Furthermore, the absence of gene clusters coding for the lipopolysaccharide (LPS) O-antigens of Xcc B100 and Xcv 85-10 indicates that the structure of the O-antigen of X. arboricola pv. pruni 109 differs from that of Xcc B100 and Xcv 85-10.

Listeria monocytogenes: monitoramento desse perigo biológico na cadeia produtiva de frangos do sul do Rio Grande do Sul

Listeria monocytogenes is a pathogenic bacterium which has become a huge challenge to the food industries, including the poultry industry, and to the health surveillance agencies. Although poultry production is in expansion in southern of Rio Grande do Sul, Brazil, there are not reports about this pathogen thus this study aimed at assessing the prevalence of L monocytogenes and its serotypes in the several segments of this productive chain. In the broilers flocks L. monocytogenes were isolated in 2.9% (1/35) from cloacal swabs samples. This microorganism was not isolated from broiler houses samples. In the abattoir, 11% of the samples presented L. monocytogenes contamination, and in the chilled chicken from retailers its prevalence was 33.3% (15/45). It was observed that 51.6% (16/31) from L. monocytogenes strains belonged to serotype 1/2b, 22.5% (7/31) to serotype 4e, 16,1% (5/31) to serotype 1/2a, 6,4% (2/31) to serotype 4b, and 3,2% (1/31) to serotype 1/2c. The spread of L. monocytogenes in the poultry production chain in southern Rio Grande do Sul and the presence of poultry serotypes in cases/outbreaks of listeriosis cause concern to public health.