Luís Augusto Nero

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.

Microbiological Quality and Safety of Raw Milk and Soft Cheese and Detection of Autochthonous Lactic Acid Bacteria with Antagonistic Activity Against Listeria monocytogenes, Salmonella Spp., and Staphylococcus aureus

This study aimed to characterize the microbiological quality and safety of raw milk and soft cheese, verifying possible associations between microbial populations, and the detection of lactic acid bacteria (LAB) with antagonistic activity against foodborne pathogens. Raw milk (n = 36) and soft cheese (n = 18) samples were collected and submitted for the analysis of mesophilic aerobes, total coliforms, Escherichia coli, LAB, coagulase-positive Staphylococcus (CPS), Listeria monocytogenes, and Salmonella spp. In all, 389 LAB isolates were randomly selected and submitted for antagonistic tests against L. monocytogenes, St. aureus, Salmonella Typhimurium, and Lactobacillus sakei. The samples presented high counts of mesophilic aerobes, total coliforms, and LAB, and also high and significant correlation indices between these populations. Low levels of CPS and E. coli were observed, as well as an absence of Salmonella spp. and L. monocytogenes. A substantial portion of the analyzed samples presented LAB cultures with antagonistic activity, but not against Salmonella Typhimurium. The obtained results indicate the antimicrobial potential of the autochthonous microbiota of raw milk and soft cheese. Despite the spoilage potential, the LAB present in the studied food products can be isolated and properly characterized as antagonistic cultures, to be used in bioconservation studies for pathogen control in foods.

Listeria monocytogenes and Salmonella spp. in Raw Milk Produced in Brazil: Occurrence and Interference of Indigenous Microbiota in their Isolation and Development

This study aimed to verify the occurrence of Listeria monocytogenes and Salmonella spp. in raw milk produced in Brazil. On account of the poor microbiological quality of this product, possible interference from the indigenous microbiota in these pathogens was also evaluated. Two‐hundred and ten raw milk samples were collected in four important milk‐producing areas in Brazil, tested for L. monocytogenes and Salmonella spp. presence, and for enumeration of indicator microorganisms: mesophilic aerobes, total coliforms and Escherichia coli. The interference of the indigenous microbiota in the isolation procedures was also tested, as well the frequency of naturally occurring raw milk strains with antagonistic activity against both pathogens. The pathogens were not isolated in any raw milk sample, but poor microbiological quality was confirmed by the high levels of indicator microorganisms. When present at high levels, the indigenous microbiota generated an evident interference in the methodologies of L. monocytogenes and Salmonella spp. isolation, mainly when the pathogens appeared at low levels. Three‐hundred and sixty raw milk strains were tested for antagonistic activity against both pathogens, and 91 (25.3%) showed inhibitory activity against L. monocytogenes and 33 (9.2%) against Salmonella spp. The majority of the antagonistic strains were identified as Lactic Acid Bacteria species, mainly Lactococcus lactis subsp. lactis and Enterococcus faecium, known by antimicrobial substance production.

Foodborne Pathogens and Microbiological Characteristics of Raw Milk Soft Cheese Produced and on Retail Sale in Brazil

The consumption of raw milk soft cheeses (RMSC), which are typically manufactured in small dairy farms under unsatisfactory hygiene conditions, is common in Brazil. Due to these production characteristics, this type of cheese is a potential carrier of pathogenic microorganisms, such as Listeria monocytogenes, Salmonella, and enterotoxin-producing Staphylococcus spp. Considering these characteristics, in this work, we aimed to detect the presence of these pathogenic microorganisms in RMC and to evaluate their microbiological quality. Fifty-five samples of this product were collected from different noninspected commercial establishments and submitted to the enumeration of mesophilic aerobes (MA), total coliforms (TC), Escherichia coli, and coagulase-positive staphylococci (CPS), and detection of L. monocytogenes and Salmonella spp. All analyzed samples were negative for Salmonella spp. and L. monocytogenes. All samples presented counts of MA higher than 10(6) colony forming units/g (CFU/g; range, 3.0x10(6) to 4.0x10(9)). TC were present at levels between 1.0x10(3) and 1.8x10(8) CFU/g, and E. coli between 1.0x10(2) and 3.5x10(6) CFU/g. CPS were detected in 17 (30.9%) samples at levels higher than 10(4) CFU/g. These results confirm the poor microbiological quality of raw milk used in the manufacturing of RMC samples, and also the inadequate production conditions. Therefore, the evaluation of microbiological safety and quality of these products must be constantly reported to alert the official agencies about the significance of proper inspection.

Resíduos de antibióticos em leite cru de quatro regiões leiteiras no Brasil

Antimicrobial residues present in milk can have many adverse effects for public health and for the dairy industry. The aim of this study is to evaluate the presence of antibiotics using the Charm-test™ kit (b-lactams and sulfonamides, mainly) in 210 raw milk samples collected in four different milk-producing areas in Brazil: 47 in Vicosa - MG, 50 in Pelotas - RS, 63 in Londrina - PR and 50 in Botucatu - SP. Antibiotic residues were detected in 24 samples (11.4%). Among them, 13 (20.6%) were from Londrina - PR, 4 (8.0%) from Botucatu - SP, 4 (8.5%) from Vicosa - MG, and 3 (6.0%) from Pelotas - RS. Despite being qualitative results only, it is evident that antibiotics may be an important chemical hazard in milk produced in Brazil.

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.

Evaluation of Petrifilm EC and HS for total coliforms and Escherichia coli enumeration in water

Petrifilmx99 EC e HS foram comparados ao metodo do Numero Mais Provavel (NMP) para determinar sua eficiencia na enumeracao de coliformes totais e E. coli em 145 amostras de agua (76 de agua in natura e 69 de agua de abastecimento). Em agua in natura, Petrifilmx99 HS e EC mostraram boa correlacao com o metodo de NMP. Em agua clorada (< 20 col/100 mL e negativas) a concordância foi baixa. Para enumeracao de E. coli, Petrifilmx99 EC mostrou boa correlacao com o metodo de NMP. Os resultados indicaram que Petrifilmx99 EC e HS podem ser usados com seguranca para enumeracao de coliformes totais e E. coli em agua, desde que as contagens esperadas sejam maiores que 20/100 mL.

Organofosforados e carbamatos no leite produzido em quatro regiões leiteiras no Brasil: ocorrência e ação sobre Listeria monocytogenes e Salmonella spp.

Chemical residues may be present in foods due to contamination in early stages of production, posing a potential risk to consumers. Organophosphates and carbamates are used in the control of parasites in animals and may generate residues in foods derived from these animals, like milk. This study aimed to survey the presence of these two pesticides in raw milk samples collected in four important milk-producing regions in Brazil and observe any possible relationship between presence of these compounds and the previously reported absence of Listeria monocytogenes e Salmonella spp. in the same milk samples. Organophosphates and/or carbamates were detected in 196 (93.8%) out of 209 samples. For evaluation of the interference of these products on detection of L. monocytogenes and Salmonella spp., 28 milk samples containing these pesticides were boiled for 10 minutes, added of the pathogens, and their multiplication was monitored during storage at 4 °C and 25 °C. No significant differences (p < 0.05) were observed in the growth of these pathogens in the milk samples when compared to negative controls, indicating absence of interference of the compounds on the detection of L. monocytogenes or Salmonella spp. However, the high frequency of raw milk samples containing organophosphates and/or carbamates poses a potential health problem to the consumers, even after heat treatment of the milk.

Salmonella spp. and hygiene indicator microorganisms in chicken carcasses obtained at different processing stages in two slaughterhouses.

Chicken meat is considered an important vehicle of foodborne pathogens such as Salmonella spp., demanding an effective control of its contamination during industrial processing. This study aimed to investigate the presence of Salmonella spp. and microbiological indicators at different stages of processing in two slaughterhouses (Sh1, high-capacity; Sh2, low-capacity). Surface samples of chicken carcasses were collected in the following sequential stages: (A) immediately before evisceration, (B) after evisceration, (C) after showering, and (D) after chiller. All samples were submitted for detection of Salmonella spp. and enumeration of mesophilic aerobes, total coliforms, thermotolerant coliforms, and Escherichia coli. The obtained means and frequencies were compared by analysis of variance and chi-square tests (p < 0.05), considering different slaughterhouses and stages of processing. No significant differences were observed between the frequencies of Salmonella spp. obtained at different steps in Sh1 and Sh2 (p > 0.05). Sh2 showed higher levels of microbiological contamination when compared with Sh1 for mesophilic aerobes (in stages B and D), total coliforms and thermotolerant coliforms (stage D), and E. coli (all stages) (p < 0.05). The variation in the levels of contamination by microbiological indicators over the processing indicated the significance of different control procedures adopted by slaughterhouses for the microbiological quality of chicken carcasses.

Serotypes and Pulsotypes Diversity of Listeria monocytogenes in a Beef-Processing Environment

Utensils and equipment from meat-processing facilities are considered relevant cross-contamination points of Listeria monocytogenes to foods, demanding tracking studies to identify their specific origins, and predict proper control. The present study aimed to detect L. monocytogenes in a beef-processing facility, investigating the diversity of serotypes and pulsotypes in order to identify the possible contamination routes. Surface samples from knives (n=26), tables (n=78), and employees hands (n=74) were collected before and during the procedures from a beef-processing facility, in addition to surface samples of end cuts: round (n=32), loin (n=30), and chuck (n=32). All samples were subjected to L. monocytogenes screening according ISO 11.290-1, and the obtained isolates were subjected to serotyping and pulsed-field gel electrophoresis. Listeria spp. were identified in all processing steps, in 61 samples, and L. monocytogenes was detected in 17 samples, not being found only in knives. Eighty-five isolates were identified as L. monocytogenes, from serotypes 1/2c (n=65), 4b (n=13), and 1/2b (n=7), being grouped in 19 pulsotypes. Considering these results, cross-contamination among hands, tables, and beef cuts could be identified. The obtained data indicated the relevance of cross-contamination in the beef-processing facility, and the occurrence of serotypes 1/2b and 4b in beef cuts distributed for retail sale is a public health concern.