Rogeria Comastri de Castro Almeida

Occurrence of Listeria spp. in critical control points and the environment of Minas Frescal cheese processing

Critical control points (CCPs) associated with Minas Frescal cheese (a Brazilian soft white cheese, eaten fresh) processing in two dairy factories were determined using flow diagrams and microbiological tests for detection of Listeria monocytogenes and other species of Listeria. A total of 218 samples were collected along the production line and environment. The CCPs identified were reception of raw milk, pasteurization, coagulation and storage. Thirteen samples were positive for Listeria; 9 samples were Listeria innocua, 2 were Listeria grayi and 2 were L. monocytogenes. In factory A, Listeria was found in 50% of raw milk samples, 33.3% of curd samples, 16.7% of pasteurized milk samples, 16.7% of cheese samples and 25% of rubber pipes used to transport the whey. The microorganism was not obtained from environmental samples in this plant. In factory B, Listeria was found in one sample of raw milk (16.7%) and in three samples of environment (17.6%) and L. monocytogenes was obtained from raw milk (16.7%) and the floor of the cheese refrigeration room (14.3%). Two serotypes, 4b and 1/2a, were observed among the strains of L. monocytogenes isolated, both which are frequently involved in outbreaks of food-borne listeriosis and sporadic cases of the disease all over the world.

Avaliação e controle da qualidade microbiológica de mãos de manipuladores de alimentos

Foi conduzido monitoramento microbiologico das maos de manipuladores de alimentos como parte de um estudo para implantacao do Sistema de Analise de Perigos e Pontos Criticos de Controle em um restaurante institucional, atraves da contagem padrao de aerobios mesofilos e anaerobios facultativos, S. aureus, C. perfringens e presenca de Salmonella spp. Foram observadas contagens de microrganismos aerobios mesofilos e anaerobios facultativos em niveis de ate 10(7) UFC/mao, contaminacoes por S. aureus e C. perfringens e oportunidades de contaminacao cruzada por essas maos principalmente no fatiamento da carne assada. Salmonella spp. nao foram isoladas. Foram adotadas medidas corretivas para este ponto critico de controle, constatando de lavagem das maos dos manipuladores com agua corrente e sabonete liquido neutro seguida de antissepsia com iodoforo. Foram observadas reducoes da contagem de aerobios mesofilos em ate 2,6 ciclos log e, apesar desta reducao nao ser a ideal, ela demonstra a contribuicao que esta pratica pode trazer aos servicos de alimentacao, alem do que nao foram mais detectados microrganismos patogenicos como S. aureus e C. perfringens.

A PCR protocol using inl gene as a target for specific detection of Listeria monocytogenes

Polymerase chain reaction is a powerful technique for detection of pathogens in foods. It is a rapid procedure with both sensitivity and specificity for quick detection and identification of specific pathogenic bacteria from diAerent sources. Listeria monocytogenes detection methods based on PCR amplification of the iap, prfA and hly gene sequences have been reported. The present study undertakes the development of an alternative PCR method using the inl gene sequences as a target to detect pathogenic L. monocytogenes. The presence of a unique and specific DNA amplification fragment of 760 bp for the intragenic repeats B of the inlA gene in all strains of L. monocytogenes as compared to none in other Listeria and unrelated Gram positive and Gram negative species confirms that this procedure is an alternative PCR protocol for detection of L. monocytogenes. ” 2000 Elsevier Science Ltd. All rights reserved.

Programa nacional de alimentação escolar: há segurança na produção de alimentos em escolas de Salvador (Bahia)?

Objetivo Avaliar a seguranca da producao de alimentos em escolas atendidas pelo Programa Nacional de Alimentacao Escolar, em Salvador (BA). Metodos Realizou-se um estudo transversal, com aplicacao de formularios elaborados com base na Resolucao de Diretoria Colegiada no 216/04 da Agencia Nacional de Vigilância Sanitaria/Ministerio da Saude, em amostra estratificada formada por 235 escolas atendidas pelo Programa Nacional de Alimentacao Escolar, contemplando a rede estadual e municipal de ensino da cidade de Salvador. No formulario, os itens avaliados apresentavam pontuacao diferenciada em funcao do grau de risco associado a seguranca dos alimentos. De acordo com a pontuacao obtida, as escolas foram classificadas em cinco grupos em relacao a condicao higienico-sanitaria: critico; insatis-fatorio; regular; bom e excelente. Resultados Na avaliacao global de adequacao, 57,0% (134) das unidades apresentaram condicoes insatisfatorias, 42,6% (100) regulares e 0,4% (1) boa. Os itens que mais contribuiram para o baixo desempenho estao relacionados aos seguintes blocos: edificacao, instalacoes, equipamentos, moveis e utensilios; higienizacao; abastecimento de agua; manipuladores de alimentos; preparo dos alimentos e exposicao do alimento preparado para consumo. Em condicao intermediaria de atendimento ficaram os blocos controle integrado de vetores e pragas urbanas, manejo de residuos e materias-primas, ingredientes e embalagens. Conclusao Verificou-se elevado nivel de nao conformidade quanto ao atendimento dos requisitos sanitarios vigentes, o que evidencia falhas na seguranca da producao da alimentacao escolar. Os resultados indicam a necessidade de adocao de medidas corretivas com vistas a reduzir riscos a saude das criancas assistidas e aumentar a eficiencia do Programa Nacional de Alimentacao Escolar, no municipio de Salvador (BA).

Control of Listeria monocytogenes growth in soft cheeses by bacteriophage P100

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 105 cfu/g) with the bacteriophage added thereafter (8.3 × 107 PFU/g). Samples were analyzed immediately, and then stored at 10 °C 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.

Occurrence and antimicrobial resistance patterns of Listeria monocytogenes isolated from vegetables

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.

Methicillin-Resistant Staphylococcus aureus in Raw Meats and Prepared Foods in Public Hospitals in Salvador, Bahia, Brazil

This study investigated the presence of methicillin-resistant Staphylococcus aureus (MRSA) in raw meat and fish and foods prepared from them for patient consumption in public hospitals in Salvador, Bahia, in northeastern Brazil. A total of 114 samples of raw meat and fish (chicken, n = 30; beef, n = 30; pork, n = 24; and fish, n = 30) and 63 samples of prepared foods (made with chicken, n = 15; beef, n = 15; pork, n = 15; and fish, n = 18) were collected from the kitchens of 10 different hospitals. Of the 114 investigated raw meat and fish samples, 28.1% were positive for MRSA, which comprised 23.3% beef, 23.3% chicken, 37.5% pork, and 30% fish samples. Of the prepared foods, 9.5% were positive for MRSA, which comprised 5.6% chicken products, 6.7% pork products, and 22.2% fish products. MRSA contamination was not detected in prepared beef dishes. A statistical analysis showed no association between the presence of MRSA and the type of raw food (P > 0.05). The high prevalence of MRSA among the raw foods tested and the presence of the microorganism in prepared foods emphasizes the necessity of enforcing hygienic practices within hospital kitchens.

Hygienic-sanitary quality of vegetables and evaluation of treatments for the elimination of indigenous E. coli and E. coli O157:H7 from the surface of leaves of lettuce (Lactuca sativa L.)

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

Implementation of a HACCP system for on-site hospital preparation of infant formula

Abstract Hazard Analysis and Critical Control Point (HACCP) system was introduced to infant formula preparation rooms in four hospitals in Salvador, Bahia, Brazil. The homogenization of powdered milk and ingredients, refrigeration and holding steps before service were identified as critical control points (CCPs). Utensils and workers’ hands were identified as sources of cross contamination. Educational training courses emphasizing food safety and good preparation practices were introduced to the personnel of the rooms. Corrective actions were adopted at the CCPs that were found to be out-of-control. Implementation of HACCP system improved infant formula quality by reducing total aerobic microbial counts in the formula, and on utensils and workers’ hands of approximately 4.0, 3.0 and 4.0 log cycles, respectively. S. aureus and fecal coliforms were no longer found.

Antibacterial efficacy of nisin, bacteriophage P100 and sodium lactate against Listeria monocytogenes in ready-to-eat sliced pork ham

The effectiveness of bacteriophage P100, nisin and sodium lactate, individually and in combination, in inhibiting Listeria monocytogenes in ready-to-eat pork ham slices was assessed. The antimicrobials were applied to the surfaces of ready-to-eat pork ham slices, which were inoculated with a mixture of L. monocytogenes. Among the individual antimicrobial treatments, bacteriophage P100 was the most effective, decreasing L. monocytogenes to undetectable levels at zero and 72 h post-infection. Sodium lactate was the least effective treatment. Treatment with nisin at zero h significantly reduced initial cell density (p < 0.05). However, this pattern was not observed at 72 h of storage. A significant difference (p < 0.05) existed between the results of separate bacteriophage and nisin treatments after refrigerated storage, but not immediately upon inoculation of the bacteria. The results showed that the use of bacteriophage P100 is the method of choice for the control of bacteria.