Abstract Although the consumption of fresh and minimally processed vegetables is considered healthy, outbreaks related to the contamination of these products are frequently reported. Among the food-borne pathogens that contaminate vegetables is Listeria monocytogenes, a ubiquitous organism that exhibits the ability to survive and multiply at refrigerated temperatures. This study aimed to evaluate the occurrence of L. monocytogenes in vegetables as well as the antimicrobial resistance of isolates. The results showed that 3.03% of samples were contaminated with L. monocytogenes, comprising 2.22% of raw vegetables and 5.56% of ready-to-eat vegetables. Multiplex PCR confirmed the virulence potential of the isolates. Antimicrobial resistance profiling showed that 50% of the isolates were susceptible to the antibiotics used. The resistance of one isolate to penicillin G, a commonly employed therapeutic agent, and the presence of serotype 4b, a serotype commonly associated with food-borne outbreaks, could be potential health hazards for consumers.

The purpose of this study was to determine the effect of bacteriophage P100 on strains of Listeria monocytogenes in artificially inoculated soft cheeses. A mix of L. monocytogenes 1/2a and Scott A was inoculated in Minas Frescal and Coalho cheeses (approximately 10(5) cfu/g) with the bacteriophage added thereafter (8.3 x 10(7) PFU/g). Samples were analyzed immediately, and then stored at 10 ºC for seven days. At time zero, 30 min post-infection, the bacteriophage P100 reduced L. monocytogenes counts by 2.3 log units in Minas Frescal cheese and by 2.1 log units in Coalho cheese, compared to controls without bacteriophage. However, in samples stored under refrigeration for seven days, the bacteriophage P100 was only weakly antilisterial, with the lowest decimal reduction (DR) for the cheeses: 1.0 log unit for Minas Frescal and 0.8 log units for Coalho cheese. The treatment produced a statistically significant decrease in the counts of viable cells (p < 0.05) and in all assays performed, we observed an increase of approximately one log cycle in the number of viable cells of L. monocytogenes in the samples under refrigeration for seven days. Moreover, a smaller effect of phages was observed. These results, along with other published data, indicate that the effectiveness of the phage treatment depends on the initial concentration of L. monocytogenes, and that a high concentration of phages per unit area is required to ensure sustained inactivation of target pathogens on food surfaces.

O objetivo desse estudo foi avaliar a qualidade higiênico-sanitária de hortaliças e água de irrigação e a eficácia do uso de suco de limão e vinagre na redução de cepas de E. coli inoculadas em alface. Cento e quarenta amostras de hortaliças e 45 amostras da água de irrigação foram coletadas e investigadas para a presença de coliformes termotolerantes e Salmonella spp. Para verificar a eficácia de sanitizantes naturais de uso doméstico na redução de E. coli na alface inoculada, quatro tratamentos foram testados: suco de limão fresco, vinagre de álcool, mistura suco de limão-vinagre e mistura suco de limão-vinagre-água. A análise microbiológica revelou altas taxas de contaminação por coliformes termotolerantes e identificou a presença de E. coli em 32% das amostras das hortaliças investigadas e em 56% das amostras de água. Embora nenhuma diferença estatística significativa (p < 0, 05) tenha sido identificada entre as soluções testadas, o tratamento com a combinação de suco de limão e vinagre forneceu a mais alta Redução Decimal (RD) para E. coli O157: H7, enquanto o uso de vinagre apenas foi o tratamento mais efetivo contra a cepa E. coli indígena

The purpose of this study is to evaluate the hygienic-sanitary quality of vegetables and irrigation water and assess the effectiveness of lemon juice and vinegar in reducing E. coli strains inoculated on lettuce. One hundred and forty samples of vegetables and 45 samples of irrigation water were investigated for thermotolerant coliforms and Salmonella spp. In order to verify the effectiveness of natural household sanitizers in reducing E. coli in inoculated lettuce, four treatment solutions were tested: fresh lemon juice, alcohol vinegar, lemon juice-vinegar mixture, and lemon juice-vinegar-water mixture. The microbiological analysis revealed high rates of contamination by thermotolerant coliforms and identified the presence of E. coli in 32% of the tested vegetable samples and 56% of the water samples. While no significant statistical difference (p < 0, 05) was identified in the tested solutions, the treatment with a combination of lemon juice and vinegar resulted in the highest Decimal Reductions (DR) of E. coli O157: H7 while the treatment with vinegar alone was the most effective against the indigenous E. coli strain

Foi conduzido monitoramento microbiológico das mãos de manipuladores de alimentos como parte de um estudo para implantação do Sistema de Análise de Perigos e Pontos Críticos de Controle em um restaurante institucional, através da contagem padrão de aeróbios mesófilos e anaeróbios facultativos, S. aureus, C. perfringens e presença de Salmonella spp. Foram observadas contagens de microrganismos aerobios mesófilos e anaeróbios facultativos em níveis de até 10(7) UFC/mão, contaminações por S. aureus e C. perfringens e oportunidades de contaminação cruzada por essas mãos principalmente no fatiamento da carne assada. Salmonella spp. não foram isoladas. Foram adotadas medidas corretivas para este ponto crítico de controle, constatando de lavagem das mãos dos manipuladores com água corrente e sabonete líquido neutro seguida de antissepsia com iodóforo. Foram observadas reduções da contagem de aeróbios mesófilos em até 2,6 ciclos log e, apesar desta redução não ser a ideal, ela demonstra a contribuição que esta prática pode trazer aos serviços de alimentação, além do que não foram mais detectados microrganismos patogênicos como S. aureus e C. perfringens.

Microbiological analyses of workers' hands were made for the common indicators, including aerobic mesophilic plate counts (APC), as well as the common food pathogens. Opportunities were observed for cross-contamination of roast beef by workers' hands during slicing operations. Workers' hands showed APC counts of up to 10(7)CFU/hand and the presence of S. aureus and C. perfringens. Salmonella spp were not isolated from hands. These results show that handling of these foods by such workers would be a risk in transmitting pathogenic microrganisms to the foods and is apparent that it is necessary for these workers to take care of personal hygiene. Decimal reductions obtained in the microbiological counts after washing and antisepis of workers' hands were at 2,6 logs cycles and still demonstrated the importance of this practice in food services by the fact that pathogens such as S. aureus and C. perfringens were inhibited or killed.

Foi conduzido monitoramento microbiológico das mãos de manipuladores de alimentos como parte de um estudo para implantação do Sistema de Análise de Perigos e Pontos Críticos de Controle em um restaurante institucional, através da contagem padrão de aeróbios mesófilos e anaeróbios facultativos, S. aureus, C. perfringens e presença de Salmonella spp. Foram observadas contagens de microrganismos aerobios mesófilos e anaeróbios facultativos em níveis de até 10(7) UFC/mão, contaminações por S. aureus e C. perfringens e oportunidades de contaminação cruzada por essas mãos principalmente no fatiamento da carne assada. Salmonella spp. não foram isoladas. Foram adotadas medidas corretivas para este ponto crítico de controle, constatando de lavagem das mãos dos manipuladores com água corrente e sabonete líquido neutro seguida de antissepsia com iodóforo. Foram observadas reduções da contagem de aeróbios mesófilos em até 2,6 ciclos log e, apesar desta redução não ser a ideal, ela demonstra a contribuição que esta prática pode trazer aos serviços de alimentação, além do que não foram mais detectados microrganismos patogênicos como S. aureus e C. perfringens.

Microbiological analyses of workers' hands were made for the common indicators, including aerobic mesophilic plate counts (APC), as well as the common food pathogens. Opportunities were observed for cross-contamination of roast beef by workers' hands during slicing operations. Workers' hands showed APC counts of up to 10(7)CFU/hand and the presence of S. aureus and C. perfringens. Salmonella spp were not isolated from hands. These results show that handling of these foods by such workers would be a risk in transmitting pathogenic microrganisms to the foods and is apparent that it is necessary for these workers to take care of personal hygiene. Decimal reductions obtained in the microbiological counts after washing and antisepis of workers' hands were at 2,6 logs cycles and still demonstrated the importance of this practice in food services by the fact that pathogens such as S. aureus and C. perfringens were inhibited or killed.