Contamination of common food-borne pathogens in foods sold in Changzhou / 公共卫生与预防医学

Objective To understand the contamination status of common food-borne pathogens in foods sold in Changzhou, and to provide evidence for food safety risk assessment and prevention of food-borne diseases. Methods From 2010 to 2020 , 2 513 samples of 17 types of foods were collected in Changzhou area. The detection of pathogenic bacteria was carried out in accordance with the standard operation procedure specified in the “Workbook for Surveillance on Food Microorganisms and Pathogenic Factors in Jiangsu Province”. Results A total of 260 positive samples of common food-borne pathogens were detected in all 2 513 samples with an overall detection rate of 10.30%. Single factor analysis showed that the detection rate of pathogenic bacteria in non-ready-to-eat samples was higher than that in ready-to-eat samples (χ2=148.875，P =0.000). The detection rate of pathogenic bacteria in bulk samples was higher than that in prepackaged ones (χ2=70.956，P=0.000). There is a difference in the detection rate of food-borne pathogens from different types of sampling sites (χ2=65.017，P=0.000). Logistic regression analysis showed that ready-to-eat food, packaging type, and sampling season were significantly correlated with the detection rate of food-borne pathogens. The detection rate of pathogenic bacteria in samples collected in the third or fourth quarters was higher than that in the first quarter. Conclusion The commercial foods sold in Changzhou have a relatively high level of contamination of food-borne pathogenic bacteria, and they should be fully heated and sterilized before consumption. The relevant departments should strengthen supervision and health education in summer and autumn.

Analysis of food-borne pathogens in Nantong City in 2017-2020 / 公共卫生与预防医学

Objective In order to understand the contamination status of food-borne pathogens in food in Nantong City, and to provide a scientific basis for food safety risk assessment and supervision. Methods The monitoring was performed according to the plan of food safety risk surveillance in Nantong City and the manual on monitoring microbes and its pathogenic factors in foodstuffs of Jiangsu Province. A total of 1025 food samples of 11 kinds were monitored from 2017 to 2020 for detecting of pathogenic bacteria such as Listeria monocytogenes, Salmonella, Vibrio parahaemolyticus, Bacillus cereus and Staphylococcus aureus, and the test results were summarized, analyzed and evaluated. Results A total of 142 pathogenic bacteria were detected, with a total positive rate of 13.85%. The detection rate was the highest in 2018 (25.65%), and the lowest in 2017 (4.98%). The highest detection rate was found in meat and meat products(25.38%), followed by aquatic products and animal products (17.92%), cooked rice and flour products around the school (14.29%), the detection rate of barreled drinking water was the lowest (2.86%). 170 strains of pathogenic bacteria were detected from 1025 samples. The higher positive rate was Bacillus cereus in the cooked rice flour products around the school, and 5 strains of Bacillus cereus were detected, with the detection rate was 14.29%. 18 strains of Staphylococcus aureus were detected in meat and meat products, and the detection rate was 13.85%; 70 Vibrio parahaemolyticus were detected in aquatic products, and the detection rate was 13.49%; 16 Listeria monocytogenes were detected in meat and meat products, and the detection rate was 12.31%. The positive rate of catering links is higher than that of circulation links, and the positive rate of urban areas is higher than that of rural areas. Conclusions Pathogenic bacteria were detected in different kinds of food, and the overall situation of food safety is stable. In the future, the monitoring scope will be expanded continuously, the monitoring continuity will be strengthened, the sampling quantity will be increased, the monitoring quality will be improved, the trend of food pollution change in the city shall be mastered in time, food safety warning shall be well done, and food safety education shall be strengthened for food practitioners, food pollution risk shall be reduced and food safety shall be effectively guaranteed.

Reducing Salmonella enterica serovar Enteritidis contamination in food: lytic bacteriophages in a homemade mayonnaise-like matrix / Reducción de la contaminación por Salmonella enterica serovar Enteritidis en alimentos: bacteriófagos líticos en una matriz similar a la mayonesa casera / Redução da contaminação por Salmonella enterica serovar Enteritidis em alimentos: bacteriófagos líticos em uma matriz caseira semelhante à maionese

Abstract Background: Salmonella enterica serovar Enteritidis (SE) is one of the major causes of food-borne disease worldwide, mainly associated with the consumption of poultry products, such as eggs. Several control methods have been implemented in the egg production process, but they have not effectively reduced the outbreaks. Therefore, the use of bacteriophages for the biocontrol of food-borne pathogens is gaining increasing acceptance. Objective: To evaluate a bacteriophage cocktail's effectiveness in reducing SE counts in an experimentally contaminated mayonnaise-like matrix. Methods: Homemade mayonnaise was contaminated with SE (103 CFU/ml) with equal volume to a matrix (1:1) treated with a bacteriophage cocktail (five phages, MOI 105), and stored at 21 °C for 24 and 72 h. Bacterial counts were performed to evaluate the bio-controlling activity of the cocktail and compared with a contaminated but not treated group. Results: Significant reductions (up to 3.75 log10 CFU/ml) were observed in the bacteriophage-treated groups (p<0.0001). Conclusions: These results demonstrate the effectiveness of bacteriophages as biocontrol agents for Salmonella Enteritidis in a raw-egg-derivative foodstuff. Further studies are needed to prove the reduction in an undiluted homemade mayonnaise.

Resumen Antecedentes: La Salmonella enterica, serovar Enteritidis (SE), es una de las principales causas de enfermedades transmitidas por alimentos en todo el mundo, asociadas principalmente al consumo de productos avícolas tales como los huevos. Diferentes métodos de control se han ensayado en el proceso de producción de huevos, pero no han sido capaces de reducir eficazmente los brotes de salmonelosis en las personas. Por esta razón, el uso de bacteriófagos para el control biológico de patógenos transmitidos por los alimentos está ganando cada vez más aceptación. Objetivo: Evaluar la eficacia de un cóctel de bacteriófagos para reducir los recuentos de SE en una matriz similar a la de mayonesa contaminada experimentalmente. Método: La mayonesa casera fue contaminada con SE (103 UFC/ml) en igual volumen que la matriz (1:1), tratada con una mezcla de bacteriófagos (cinco fagos, MOI 105), y almacenada a 21 °C por 24 y 72 h. Se realizaron recuentos bacterianos para evaluar la actividad biocontroladora de la mezcla y compararlos con un grupo contaminado, pero no tratado. Resultados: Se observaron reducciones significativas (hasta 3,75 log10 CFU/ml) en los grupos tratados con bacteriófagos (p<0,0001). Conclusiones: Estos resultados demuestran la efectividad del uso de bacteriófagos como agentes de biocontrol de Salmonella Enteritidis en un alimento crudo derivado del huevo. Sin embargo, se necesita realizar más estudios para comprobar la reducción en mayonesa casera no diluida.

Resumo Antecedentes: Salmonella enterica serovar Enteritidis (SE) é uma das principais causas de doenças transmitidas por alimentos em todo o mundo, principalmente associada ao consumo de produtos derivados de aves, como ovos. Diferentes métodos de controle foram implementados no processo de produção de ovos, mas não foram capazes de reduzir efetivamente os surtos nas pessoas. Por esse motivo, o uso de bacteriófagos para o controle biológico de patógenos de origem alimentar está ganhando crescente aceitação. Objetivo: Avaliar a eficácia de um coquetel de bacteriófagos na redução da contagem de SE em uma matriz experimentalmente semelhante a maionese contaminada. Método: A maionese caseira foi contaminada com SE (103 UFC/ml) no mesmo volume da matriz (1:1), tratada com uma mistura de bacteriófagos (cinco fagos, MOI 105) e armazenada a 21 °C por 24 e 72 h. As contagens bacterianas foram realizadas para avaliar a atividade de biocontrole da mistura e comparadas com um grupo contaminado, mas não tratado. Resultados: Reduções significativas (até 3,75 log10 UFC/ ml) foram observadas nos grupos tratados com bacteriófagos (p<0,0001). Conclusões: Esses resultados demonstram a eficácia do uso de bacteriófagos como agentes de biocontrole de Salmonella Enteritidis em alimentos crus derivados de ovos, mas são necessários mais estudos para verificar a redução da maionese caseira não diluída.

Application of CRISPR in evolution analysis, detecting and typing, virulence and antibiotic resistance regulation in food-borne pathogens / 生物工程学报

Clustered regularly interspaced short palindromic repeats (CRISPR) and its associated protein gene system can limit the horizontal gene transfer, thereby effectively preventing the invasion of foreign gene elements such as bacteriophages. CRISPR arrays of different bacteria are diverse. Based on the differences in the CRISPR system, this review summarizes the application of CRISPR in food-borne pathogen evolution analysis, detection and typing, virulence and antibiotic resistance in recent years. We also address bacterial detection typing method developed based on the characteristics of CRISPR arrays and the association of CRISPR with virulence and drug resistance of food-borne pathogens. The shortcomings of CRISPR in evolution, detection and typing, virulence and resistance applications are analyzed. In addition, we suggest standardizing CRISPR typing methods, improving and expanding the CRISPR database of pathogenic bacteria, and further exploring the co-evolution relationship between phages and bacteria, to provide references for further exploration of CRISPR functions.

Contamination status of food-borne pathogens in foods sold in Guangzhou City, 2013-2018 / 公共卫生与预防医学

Objective To investigate the contamination status of food-borne pathogens in foods sold in Guangzhou, and find the potential food safety hazards, and to provide a scientific basis for formulating food safety measures. Methods From 2013 to 2018, a total of 5 021 food samples from 15 common diets of residents were collected for monitoring Vibrio parahaemolyticus, Staphylococcus aureus, Diarrheagenic Escherichia coli, Vibrio vulnificus, Salmonella, Bacillus cereus, Listeria monocytogenes and Vibrio cholerae. Results Among 5 021 samples, a total of 424 samples were found to carry foodborne pathogens, with a total detection rate of 8.44%. Vibrio parahaemolyticus had the highest detection rate among food-borne pathogens (11.20%), followed by Vibrio vulnificus (9.20%), Bacillus cereus (7.26%), and Staphylococcus aureus (1.72 %), Listeria monocytogenes (1.08%), Escherichia coli (0.86%), and Salmonella (0.48%). Vibrio cholerae was not detected. Among different food categories, the detection rate of aquatic products was the highest, reaching 43.52%, followed by raw aquatic animal food products (16.24%), imported raw livestock and poultry meat (11.11%), foods sold in vendors (10.62%), and baked foods (10.56%). The difference in the detection rate of food-borne pathogens among different foods was statistically significant. Analysis of the detection rate of foods from different sampling locations showed that the highest detection rate was in online shops (22.92%), followed by caterings (12.49%), vendors (11.21%), supermarket (8.995), farmers’ markets (8.59%), and the lowest was retail stores (5.63%). The highest detection rate was found in the third quarter (10.04%), followed by the second quarter (9.81%), and the lowest was in the first quarter (6.43%). Conclusion There was contamination with food-borne pathogens at different degrees in foods sold in Guanghzou. The food safety risk monitoring should be carried out continuously. The prevention and control should be focused on foods with a higher risk of contamination of food-borne pathogens including aquatic animal products, frozen livestock and poultry meat, foods sold in vendors and baked foods.

Establishment and application of multiplex direct PCR for rapid detection of common food borne pathogens in swine products / 中国人兽共患病学报

We established a multiplex direct PCR for rapid detection of E.coli,Salmonella,Staphylococcus aureus,Listeria and Yersinia enterocolitica bacteria.Multiplex direct PCR primers were designed according to gene sequences of phoA (E.coli),inv A (Salmonella),nuc (S.aureus),hl y (Listeria),and ail (Y.enterocolitica).After the multiplex direct PCR were established,the specificity and sensitivity of primers were detected.Then,multiplex direct PCR was applied to examine 60 swine product samples,the detection specificity,accuracy and positive predictive value were calculated compared with the gold standard culture method.Results showed that multiplex direct PCR primers could be used for specific detection of E.coli,Salmonella,S.aureus,Listeria and Y.enterocolitica,with the minimal detectable limit of 10,1,100,1 and 1 CFU,respectively.For the examination of 60 swine product samples using multiplex direct PCR,15 were positive for E.coli,6 positive for Salmonella,21 positive for S.aureus,20 positive for Listeria,and 35 positive for Y.enterocolitica,with all positive detection rates higher than that of culture.The total detection sensitivity was 100％,accuracy was 94％,and positive predictive value was 81.44％.Multiplex direct PCR could be used for specific and sensitive detection of common food-borne pathogens,and the testing time was shorten to be 3 hours because of saving time for template extraction.Multiplex direct PCR might serve the detection of food-borne pathogens in food safety risk monitoring much better.

Evaluación de las propiedades bioactivas in vitro de bacterias ácido lácticas aisladas de nichos ecológicos nativos del Ecuador / Assessment of the in vitro bioactive properties of lactic acid bacteria isolated from native ecological niches of Ecuador

Lactic acid bacteria are known for their biotechnological potential. In various regions of Ecuador numerous indigenous biological resources are largely undocumented. In this study, we evaluated the potential probiotic characteristics and antagonistic in vitro properties of some lactic acid bacteria from native niches of the subtropical rain forests of Ecuador. These isolates were identified according to their morphological properties, standard API50CH fermentation profile and RAPD-DNA polymorphism pattern. The selected isolates were further evaluated for their probiotic potential. The isolates grew at 15 °C and 45 °C, survived at a pH ranging from 2.5 to 4.5 in the presence of 0.3% bile (>90%) and grew under sodium chloride conditions. All selected isolates were sensitive to ampicillin, amoxicillin and cefuroxime and some showed resistance to gentamicin, kanamycin and tetracycline. Moreover, the agar well diffusion assay showed that the supernatant of each strain at pH 3.0 and pH 4.0, but not at pH 7.0 exhibited increased antimicrobial activity (inhibition zone >15 mm) against two foodborne pathogens, Escherichia coli and Salmonella spp. To our knowledge, this is the first report describing the antagonistic activity against two foodborne pathogens and the probiotic in vitro potential of lactic acid bacteria isolated from native biota of Ecuador.

Las bacterias ácido lácticas (BAL) son conocidas por su potencial biotecnológico. En diversas regiones del Ecuador existen recursos biológicos nativos, que en su mayoría no han sido documentados. En este estudio se evaluaron in vitro las posibles características probióticas y antagónicas de algunas BAL aisladas de nichos nativos de la selva subtropical. Estas cepas se clasificaron en función de sus propiedades morfológicas, el perfil estándar de fermentación API50CH y los patrones de polimorfismo RAPD-ADN. Diez microorganismos fueron seleccionados y se probó su potencial probiótico. Todas las bacterias crecieron a 15 °C y 45 °C, sobrevivieron en el rango de pH ácido de 2,5 a 4,5 en presencia de 0,3% de bilis (> 90%), mostraron tolerancia a los tratamientos en cloruro de sodio y diferentes perfiles de sensibilidad a antibióticos. Todas las cepas fueron sensibles a ampicilina, amoxicilina y cefuroxima, y algunas fueron resistentes a gentamicina, kanamicina y tetraciclina. Por otra parte, el ensayo de pruebas de difusión en agar mostró que el sobrenadande de cada cepa cultivada a pH 3,0 y pH 4,0, pero no a pH 7,0, presentó elevada actividad antimicrobiana (zona de inhibición > 15 mm) frente a 2 agentes patógenos alimentarios, Escherichia coli y Salmonella spp. Este estudio describe por primera vez la actividad antagonista frente a patógenos de origen alimentario y el potencial probiótico in vitro de BAL aisladas de nichos ecológicos nativos del Ecuador.

Multidrug resistance and ESBL-producing Salmonella spp. isolated from broiler processing plants

Abstract The aim of this study was to investigate the occurrence of multidrug-resistant, extended spectrum beta-lactamase (ESBL) producing Salmonella spp. isolated from conveyor belts of broiler cutting rooms in Brazilian broiler processing plants. Ninety-eight strains of Salmonella spp. were analyzed. Multidrug resistance was determined by the disk diffusion test and the susceptibility of the isolated bacteria was evaluated against 18 antimicrobials from seven different classes. The double disk diffusion test was used to evaluate ESBL production. Of the 98 strains tested, 84 were multidrug resistant. The highest rates of resistance were against nalidixic acid (95%), tetracycline (91%), and the beta-lactams: ampicillin and cefachlor (45%), followed by streptomycin and gentamicin with 19% and 15% of strain resistance, respectively. By contrast, 97% of the strains were sensitive to chloramphenicol. 45% of the strains were positive for the presence of ESBL activity. In this study, high rates of multidrug resistance and ESBL production were observed in Salmonella spp.

Antibacterial Activity of Phenolic Compounds Derived from Ginkgo biloba Sarcotestas against Food-Borne Pathogens.

Aims: We investigated the antibacterial activity of three groups of phenolic compounds obtained from the chloroform (CHCl3) extract of the fleshy seed coat (sarcotestas) of Ginkgo biloba. Study Design: An experimental study. Methodology: Inhibition of microbial growth was measured by an agar diffusion method and susceptibility tests were performed by the broth microdilution method. Bactericidal effect of Ginkgo biloba compound 5-7 against Salmonella enterica serovar Typhimurium was assessed by time-kill assay. Results: Ginkgo biloba compounds 5-7 and 8-10 showed high antimicrobial activity against Gram-positive and Gram-negative bacteria, including several food-borne pathogens. In particular, compounds 5-7 and 8-10, containing phenolic acids and bilobols, respectively, were highly effective against Salmonella enteric serovar Typhimurium, Listeria monocytogenes, Listeria innocua, Streptococcus pyogenes, Escherichia coli, and Shigella dysenteriae. On the opposite, compounds 1-4, containing cardanols, showed little antibacterial activity. Compounds 5-7 exerted a bactericidal and bacteriolytic effect on Salmonella enteric serovar Typhimurium with a Minimal Inhibitory Concentration (MIC) and a Minimal Bactericidal Concentration (MBC) of 8.3 μg ml–1. Conclusion: The results of this study indicate that phenolic compounds derived from Ginkgo biloba sarcotestas, because of their strong inhibitory characteristics towards food pathogens, can be considered ideal candidates for possible application in food microbiology due to their natural origins.

In vitro antibacterial activities of Broccoli (Brassica oleracea L.var italica) against food borne bacteria.

Foodborne diseases remain substantial and safety of food is an important health, social and economical issue. Food borne illnesses caused by microbial contamination raises concerns to find alternate sources which are safe to human and environmental health. This study was investigated to determine the antibacterial activity of broccoli (Brassica oleracea L. var. italica). Various solvent extracts of broccoli were prepared and analyzed for their phytoconstituents. A total of six food borne bacteria viz., Bacillus cereus ATCC 10876, Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, Salmonella typhimurium MTCC 3224 and Shigella flexneri ATCC 12022 were tested against the broccoli extracts. Minimum inhibitory concentration (MIC) values of 10 - 320 μg ml-1 were recorded against most of the pathogens with acetone and methanol as the potential extracts. B. subtilis ATCC 6633 (15.4 mm) and Bacillus cereus ATCC 10876 (16.3 mm) were found to be the most sensitive organisms among the pathogens tested.

Effect of Agrimonia Pilosa Ledeb. Extract on the Growth of Food-Borne Pathogens

This study was performed to investigate the antimicrobial effect of the Agrimonia pilosa Ledeb. extracts against food-borne pathogens. First, the Agrimonia pilosa Ledeb. was extracted with methanol at room temperatures, and fractionation of the methanol extracts from Agrimonia pilosa Ledeb. was carried out by using petroleum ether, chloroform, and ethyl acetate, and methanol respectively. The antimicrobial activity of the Agrimonia pilosa Ledeb. extracts was determined using a paper disc method against food-borne pathogens and food spoilage bacteria. The petroleum ether extracts of Agrimonia pilosa Ledeb. showed the highest antimicrobial activity against Pseudomonas aeruginosa. The synergistic effect has been found in combined extracts of Agrimonia pilosa Ledeb. and Perillae folium as compared to each extracts alone. Finally, the growth inhibition curve was determined using ethyl acetate extracts of Agrimonia pilosa Ledeb. against Bacillus Cereus and Salmonella Enteritidis. The petroleum ether extract of Agrimonia pilosa Ledeb. showed strong antimicrobial activity against Bacillus Cereus at the concentration of 4,000 ppm. The 4,000 ppm of petroleum ether extract from Agrimonia pilosa Ledeb. retarded the growth of Bacillus Cereus more than 24 hours and Salmonella Enteritidis up to 36 hours. The petroleum ether extracts of Agrimonia pilosa Ledeb. has been shown the antimicrobial effect against Bacillus Cereus and Salmonella Enteritidis.

Antimicrobial Effect of Pulsatilla Koreana Extracts on Food-Borne Pathogens

This study was performed to investigate the antimicrobial effect of the Pulsatilla koreana extracts against food-borne pathogens. First, the Pulsatilla koreana was extracted with methanol at room temperatures, and fractionation of the methanol extracts from Pulsatilla koreana was carried out by using petroleum ether, chloroform, and ethyl acetate, and methanol respectively. The antimicrobial activity of the Pulsatilla koreana extracts was determined using a paper disc method against food-borne pathogens and food spoilage bacteria. The ethyl acetate extracts of Pulsatilla koreana showed the highest antimicrobial activity against Staphylococcus aureus, Salmonella enteritidis and Shigella dysenteriae. The Staphylococcus aureus and Shigella dysenteriae were inhibited by petroleum ether and chloroform extracts of Pulsatilla koreana as well as ethyl acetate extracts of Pulsatilla koreana. The synergistic effect has been found in combined extracts of Pulsatilla koreana and Portulaca oleracea as compared to each extracts alone. Finally, the growth inhibition curve was determined using ethyl acetate extracts of Pulsatilla koreana against Staphylococcus aureus and Shigella dysenteriae. The ethyl acetate extract of Pulsatilla koreana showed strong antimicrobial activity against Staphylococcus aureus at the concentration of 2,000 ppm. The 2,000 ppm of ethyl acetate extract from Pulsatilla koreana retarded the growth of S. aureus more than 12 hours and Shigella dysenteriae up to 9 hours.

Effect of Artemisia Capillaris Extract on the Growth of Food-Borne Pathogens

In this study, Artemisia capillaries, which has been used as a folk remedy, was investigated for its antimicrobial activity. First, the Aremisia capillaris was extracted with methanol at room temperature, and fractionation of the methanol extracts from Artemisia capillaris was carried out using petroleum ether, chloroform, and ethyl acetate. Second, the antimicrobial activity of the Artemisia capillaris extracts was determined using a paper disc method and minimum inhibitory concentration of ethyl acetate extracts from Artemisia capillaris against food-borne pathogens and food spoilage bacteria was measured. Finally, the growth inhibition curve was determined using ethyl acetate extracts of Artemisia capillaris against Staphylococcus aureus and Salmonella typhimurium. The ethyl acetate extract of Artemisia capillaris showed strong antimicrobial activity against S. typhimurium at a concentration of 1,000 ppm. The 3,000 ppm of ethyl acetate extract from Artemisia capillaris retarded the growth of S. aureus and S. typhimurium for up to 6 hours.