AIM: To prepare a kind of magnetic iron-dextran nanopartides that was coated with anti-E.coli O157:H7 IgG, analyze its application conditions, and try to use it to isolate E.coli O157:H7 from foods. METHODS: Magnetic ...AIM: To prepare a kind of magnetic iron-dextran nanopartides that was coated with anti-E.coli O157:H7 IgG, analyze its application conditions, and try to use it to isolate E.coli O157:H7 from foods. METHODS: Magnetic iron-dextran nanopartides were prepared by the reaction of a mixture of ferric and ferrous ions with dextran polymers under alkaline conditions. The particles were coated with antiserum against E.coli O157: H7 by the periodate oxidation-borohydride reduction procedure. The oxidation time, amount of antibody coating the particles, amount of nanoparticles, incubation time and isolation time were varied to determine their effects on recovery of the organisms. Finally, the optimum conditions for isolating E.coli O157:H7 from food samples were established. RESULTS: E.coli O157:H7 can be isolated from samples within 15 min with the sensitivity of 101 CFU/mL or even less. In the presence of 108 CFU/mL of other organisms, the sensitivity is 101-102 CFU/mL. Nonspecific binding of other bacteria to the particles was not observed. Two and a half hours of enrichment is enough for the particles to detect the target from the food samples inoculated with 1 CFU/g. CONCLUSION: Isolation of target bacteria by immuno magnetic nanoparticles is an efficient method with high sensitivity and specificity. The technique is so simple that it can be operated in lab and field even by untrained personnel.展开更多
The genome of the enterohemorrhagic Escherichia coli O157∶H7 EDL933 contains 177 “O”-islands (OIs). To study their potential contribution to the O157-specific pathogenicity, we surveyed the distribution of 22 OIs b...The genome of the enterohemorrhagic Escherichia coli O157∶H7 EDL933 contains 177 “O”-islands (OIs). To study their potential contribution to the O157-specific pathogenicity, we surveyed the distribution of 22 OIs by PCR and DNA hybridization in 17 isolates of Shiga toxin producing (Stx-positive) E.coli O157∶H7, and compared with their distribution in 21 isolates of Stx-negative E.coli O157 and 21 isolates of non-O157 enteric pathogens. Fourteen of 22 OIs were present in non-O157 entericpathogens analyzed. Eight of 22 OIs were found only in the 17 Shiga toxin- (Stx) positive E.coli O157∶H7 isolates, but they were absent from the 21 Stx-negative E.coli O157∶NM and O157︰Hund isolates tested. Among the 8 OIs, only OI43 or OI48 were exclusively detected in Stx-positive E.coli O157∶H7, absent from neither of Stx-negative E.coli O157 and non-O157 enteric pathogens, such as Salmonella, Shigella, Citrobacter, Vibrio cholera, enteropathogenic E.coli (EPEC), enteroadherent E.coli (EAEC), enteroinvasive E.coli (EIEC) and enterotoxingenic E.coli (ETEC). The OI43 and OI48 are 83 kb in size and identical in DNA sequences, which encode genes for urease, tellurite resistance and adherence. By analyzing their junction genes with PCR and DNA hybridization, we found that 21 Chinese isolates have OI48 only. However, for 7 Japanese patient isolates, 4 have OI43 and 3 have OI48; for American isolates, 2 have both of OI43 and OI48, 2 have OI48 only. These data confirmed the highly plasticity of the pathogenic E.coli genome. The unique presence of OI43/OI48 in Stx-positive E.coli O157∶H7 denotes its critical role in the pathogenicity specific to this pathogen.展开更多
Escherichia coli O157 : H7 is a foodborne pathogen that poses a major threat to public health. Epidemiologic investigations have identified dairy cows, especially calves, are the principal reservoir of E. coli O157 : ...Escherichia coli O157 : H7 is a foodborne pathogen that poses a major threat to public health. Epidemiologic investigations have identified dairy cows, especially calves, are the principal reservoir of E. coli O157 : H7. In this study, based on the results, E. coli O157 : H7 was the main cause of E. coli disease outbreak in late October, 2015, and more than 90% of newborn calves died of serious diarrhea. Through further experiments, the drug sensitivity and resistance of the strain, the expression of the virulence gene and virulence pathogenicity were studied. E. coli O157 : H7 isolates were resistant to 12 antibiotics including penicillin, tetracycline and ampicillin, and were sensitive to eight antibiotics including cefoperazone, ceftazidime and amikacin. Resistance genes included tetB, strB, aadB, aphA, floR, TEM and virulence genes included stx1, eaeA and hlyA. Using specific pathogen free mice, the result showed that the isolate was pathogenic with a median lethal dose of 7.9×107 CFU · mL-1. This study described the pathogenesis and clinical manifestations of E. coli O157 : H7 infection. These results guided the use of antibiotics in prevent and control of bacterial infections in the future.展开更多
This study examined the survival of acid-adapted E. coli O157 in kombucha during fermentation and refrigerated kombucha mixed with fruit juices. Acidic and non-acidic kombucha mixes were fermented at 25°C usin...This study examined the survival of acid-adapted E. coli O157 in kombucha during fermentation and refrigerated kombucha mixed with fruit juices. Acidic and non-acidic kombucha mixes were fermented at 25°C using a commercially available starter culture and inoculated with a 5-strain mixture of acid-adapted E. coli O157. There was >5-log reduction in the pathogen count for both starter mixes within 7 days of fermentation. For the kombucha-juice blends at refrigerated temperature, 14 ml of lemon, apple, orange, and mango juices were mixed with 186 ml kombucha separately. The treatments were inoculated with a 5-strain mixture of acid-adapted E. coli O157 and incubated at 5°C for 14 days. >5-log reduction in the pathogen count was observed in lemon, control, and mango juice blend after 1, 3, and 14 days, respectively. The total reduction in pathogen count in the apple and orange juice blend after 14 days was 4.43 and 4.12 log CFU/ml, respectively. The inability of the kombucha fruit blend to cause a 5-log reduction of E. coli O157 suggests the need for following strict hygienic and good sanitation practices during blending and bottling for home fermenters and an approved HACCP plan for foodservice operators to ensure product safety.展开更多
The strains ofLactobacillus delbrueckii subsp, lactis widely used in food preservation due to ability produce high amount of hydrogen peroxide at refrigerator temperatures to inhibit food-borne pathogens and psychroph...The strains ofLactobacillus delbrueckii subsp, lactis widely used in food preservation due to ability produce high amount of hydrogen peroxide at refrigerator temperatures to inhibit food-borne pathogens and psychrophilic spoilage microorganisms. In order to improve of bio-preservation efficacy ofL. delbrueckii MH 10 mutations causing resistance to streptomycin （str） were used. Among UV-mutagenized population of L. delbruecla＇i three str mutants producing high amounts of H2O2 were selected. Sir mutants produced significant amounts of hydrogen peroxide 50-60 μg/ml in sodium phosphate buffer （0.2 M, pH 6.5） and in beef broth （BB） at 5 ℃ for 5 days submerged cultivation without of growth. Evaluation mutants antibacterialactivity at refrigeration temperatures against food-borne pathogen Escherichia coli O157：H7 revealed elimination of pathogen total number up to practically undetectable amount for 3 days. In case of solid-state cultivation on agar-based medium, disks soaked by mutant cells suspensions formed larger inhibitory zones on E. coli O157：H7 lawn for one-day cold exposition. The size of inhibition zone depends on concentration of LAB cells. Str mutants L. delbrueckii reduced initial amount 2 - 105 of E. coil O 157：H7 in ground beef up to 3 log for 3 days of solid-state cocultivation when the wild strain reduced only 2 log. The application ofL. delbrueckii mutants did not cause any changes in sensory characteristics of ground beef, moreover promotes expanding of shelf-life due to inhibition of psychrophilic spoilage microorganisms.展开更多
This study was conducted to isolate and identify antibiotic resistant bacteria in fresh tomato sold in three different local markets of Dhaka city. On an average 〉 5.0 log CFU/g of natural microbial populations and c...This study was conducted to isolate and identify antibiotic resistant bacteria in fresh tomato sold in three different local markets of Dhaka city. On an average 〉 5.0 log CFU/g of natural microbial populations and coliform bacteria was present in the samples. Prevalence of Salmonella spp., E. coli, Listeria spp., and Yersinia spp., were recorded through cultivation dependent assay of tomato samples of different markets. Almost all of the isolates were uniformly resistant to rifampicin, erythromycin, clindamycin and oxacillin （100%）, vancomycin （93%）, amoxicillin （87%）, whereas 60% of the isolates were found to be resistant to ampicillin and cephalexin. Antibiotic sensitivity test of the presumptive E. coli and Salmonella spp. and corresponding plasmid profiling indicated a correlation of plasmid mediated multidrug resistance （MDR） of these environmental bacteria. Washing with sanitizing agents such as acidified sodium chlorite （ASC） and 200 ppm chlorinated water was able to reduce _〈 2.0 log CFU/g of natural microflora and coliform bacteria. In contrast, ASC was able to reduce 〈 2.0 log CFU/g of other food borne pathogens and, chlorinated water was able to reduce up to undetectable level. Therefore, washing of tomato with 200 ppm chlorinated water could be useful in reducing the pathogen populations on tomatoes.展开更多
Microbial quality (MQ) of meat contact surfaces (MCS) of six major abattoirs was evaluated with a subsequent further isolation and identification of E. coli O157. Two hundred and forty 240 swab samples (SS) from MCS t...Microbial quality (MQ) of meat contact surfaces (MCS) of six major abattoirs was evaluated with a subsequent further isolation and identification of E. coli O157. Two hundred and forty 240 swab samples (SS) from MCS that include cutting equipment, floor, tables and transport media were collected for total aerobic plate count and isolation of E. coli O157. Results of the SS indicated a mean value 7.1 ± 0.3 log<sub>10</sub> cfu/cm<sup>2</sup>. A minimum value of 6.4 ± 0.6 log<sub>10</sub> cfu/cm<sup>2</sup> was recorded oncutting instrument from Ningi abattoir, while a maximum value of 7.8 ± 0.3 log<sub>10</sub> cfu/cm<sup>2</sup> was obtained from tables at Darazo abattoir. Only 3 (1.2%) of the 240 SS of the MCS were positive for E. coli O157 using the latex agglutination kit (Difco, Michigan, USA).展开更多
between enteric pathogens and plant hosts have been shown to be multifaceted.This series of studies sought to expand our knowledge in this area and evaluate whether spinach cultivar selection may be used to curtail pa...between enteric pathogens and plant hosts have been shown to be multifaceted.This series of studies sought to expand our knowledge in this area and evaluate whether spinach cultivar selection may be used to curtail pathogen contamination and ultimately reduce microbiological risk associated with this crop.As a component to that assessment,potential antimicrobials that were constituents within spinach leaves were first analysed and found to be spatially non-uniform,being more concentrated on the outer edges of the leaves than in the centre of the leaves.Consequently,the entire foliage of a plant was sampled in subsequent studies examining the fate of Salmonella and Escherichia coli O157:H7 on seven cultivars of spinach.Cultivar did not affect the degree of Salmonella internalized into spinach tissue(P>0.05);however,it appeared that those Salmonella that were internalized were transient residents as the percentage of plants containing this internalized pathogen dropped within 24 h.No relationship existed between antimicrobial levels(total phenols or antioxidant capacity)of the spinach cultivars and the prevalence of plants exhibiting Salmonella internalization or the persistence of Salmonella or E.coli O157:H7 after the plants had been sprayed with the pathogen.In both growth chamber and field studies,Salmonella was more resistant than E.coli O157:H7 to inactivation.Cultivar affected the persistence of both E.coli O157:H7 and Salmonella but the ranking for each pathogen’s survival on three of those cultivars differed suggesting the difficulty in finding one cultivar that would be inhospitable to multiple pathogens.展开更多
The recent Escherichia coli epidemic in Germany gave a lesson at an international level.There is no time to solve food security problems when an epidemic is on the way.The epidemic in Germany exposed the fissures in t...The recent Escherichia coli epidemic in Germany gave a lesson at an international level.There is no time to solve food security problems when an epidemic is on the way.The epidemic in Germany exposed the fissures in the control systems of the Federal Risk Evaluation Institute of this country,as well as showing the incompetency of health authorities,who had great difficulty in resolving the situation.To summarize,the possibility of prevention was confused with the utopian idea of non-occurrence.It was not less important the public’s recognition and the“awakening”of health ministers in the European Union as regards the proven fact that pathogenic and even lethal microorganisms may be present in the food we eat.Argentina has the highest incidence of hemolytic uremic syndrome in the world,and the next epidemic is likely not to occur in Germany,but in any other country,such as Argentina.In order to avoid complicity,we do not wish to remain silent about the situation in Argentina.Therefore,this is the writer’s motive for writing this article,which describes the scientific advances and the ethical pitfalls related to a disease transmitted by food,particularly hemolytic uremic syndrome,in Argentina.展开更多
Objectives:A study to determine food safety hazard status of fish products from Lake Chivero was conducted in selected high density suburbs of Harare.Lake water and fish were tested for E.coli O157:H7,total bacterial,...Objectives:A study to determine food safety hazard status of fish products from Lake Chivero was conducted in selected high density suburbs of Harare.Lake water and fish were tested for E.coli O157:H7,total bacterial,fungal counts,mercury(Hg)and aflatoxin B1(AFB1)to determine contamination levels and assessing human health hazard exposure.Materials and Methods:Membrane filtration method was used to determine E.coli O157:H7 viable counts using CHROM agar.Plate count and Potato dextrose agar were used for determination of total viable bacterial and fungal counts.Concentrations of Hg and AFB1 in fish and water were determined by Atomic Absorption Spectrophotometer and High Performance Liquid Chromatography-Mass Spectrometry.A questionnaire survey was conducted on 136 adult fish consumers to determine the fish consumption patterns to assess hazard exposure against international standards.Results:Significant levels of microbial contamination above international standards in both fish and water were recorded.Mean E.coli O157:H7 counts were 106±10(cfu/cm^(2))in fish and 52±14(cfu/100ml)in water.Mean Log10 TBC were 8.98±0.26(cfu/cm^(2))in fish and 9.05±0.05(cfu/ml)in water.Mean Log10 TFC were 4.83±0.02(cfu/cm^(2))in fish and 4.56±0.03(cfu/ml)in water.Hg and AFB1 were 0.018(μg/kg)and 0.025(μg/kg)in fish and 0.008(μg/kg)and 0.005(μg/kg)in water,both with a hazard quotient(HQ)<1 using CODEX STAN 193-1995 of 2015.Conclusion:Fish and water are contaminated with E.coli O157:H7,contain bacterial and fungal loads above international food safety guidance levels.Fish were caught already contaminated with pathogens together with toxigenic Hg and carcinogenic AFB1 although their concentration levels are within international food safety toxicological levels.Levels of Hg and AFB1 in water were almost double that of fish,implying bio-accumulation occurred in fish.Thus,fish consumers are exposed to food safety hazards and are at risk of contracting foodborne illnesses from consuming contaminated fish.展开更多
基金Supported by the National High-technology Research and Development Program of China (863 Program), No. 2003AA302260
文摘AIM: To prepare a kind of magnetic iron-dextran nanopartides that was coated with anti-E.coli O157:H7 IgG, analyze its application conditions, and try to use it to isolate E.coli O157:H7 from foods. METHODS: Magnetic iron-dextran nanopartides were prepared by the reaction of a mixture of ferric and ferrous ions with dextran polymers under alkaline conditions. The particles were coated with antiserum against E.coli O157: H7 by the periodate oxidation-borohydride reduction procedure. The oxidation time, amount of antibody coating the particles, amount of nanoparticles, incubation time and isolation time were varied to determine their effects on recovery of the organisms. Finally, the optimum conditions for isolating E.coli O157:H7 from food samples were established. RESULTS: E.coli O157:H7 can be isolated from samples within 15 min with the sensitivity of 101 CFU/mL or even less. In the presence of 108 CFU/mL of other organisms, the sensitivity is 101-102 CFU/mL. Nonspecific binding of other bacteria to the particles was not observed. Two and a half hours of enrichment is enough for the particles to detect the target from the food samples inoculated with 1 CFU/g. CONCLUSION: Isolation of target bacteria by immuno magnetic nanoparticles is an efficient method with high sensitivity and specificity. The technique is so simple that it can be operated in lab and field even by untrained personnel.
基金This work was supported by the Basic Research Program from Ministry of Science and Technology,China (G1999054101 to J.Xu.) and PRA program from AFCRST (B99 03) to LFW
文摘The genome of the enterohemorrhagic Escherichia coli O157∶H7 EDL933 contains 177 “O”-islands (OIs). To study their potential contribution to the O157-specific pathogenicity, we surveyed the distribution of 22 OIs by PCR and DNA hybridization in 17 isolates of Shiga toxin producing (Stx-positive) E.coli O157∶H7, and compared with their distribution in 21 isolates of Stx-negative E.coli O157 and 21 isolates of non-O157 enteric pathogens. Fourteen of 22 OIs were present in non-O157 entericpathogens analyzed. Eight of 22 OIs were found only in the 17 Shiga toxin- (Stx) positive E.coli O157∶H7 isolates, but they were absent from the 21 Stx-negative E.coli O157∶NM and O157︰Hund isolates tested. Among the 8 OIs, only OI43 or OI48 were exclusively detected in Stx-positive E.coli O157∶H7, absent from neither of Stx-negative E.coli O157 and non-O157 enteric pathogens, such as Salmonella, Shigella, Citrobacter, Vibrio cholera, enteropathogenic E.coli (EPEC), enteroadherent E.coli (EAEC), enteroinvasive E.coli (EIEC) and enterotoxingenic E.coli (ETEC). The OI43 and OI48 are 83 kb in size and identical in DNA sequences, which encode genes for urease, tellurite resistance and adherence. By analyzing their junction genes with PCR and DNA hybridization, we found that 21 Chinese isolates have OI48 only. However, for 7 Japanese patient isolates, 4 have OI43 and 3 have OI48; for American isolates, 2 have both of OI43 and OI48, 2 have OI48 only. These data confirmed the highly plasticity of the pathogenic E.coli genome. The unique presence of OI43/OI48 in Stx-positive E.coli O157∶H7 denotes its critical role in the pathogenicity specific to this pathogen.
文摘Escherichia coli O157 : H7 is a foodborne pathogen that poses a major threat to public health. Epidemiologic investigations have identified dairy cows, especially calves, are the principal reservoir of E. coli O157 : H7. In this study, based on the results, E. coli O157 : H7 was the main cause of E. coli disease outbreak in late October, 2015, and more than 90% of newborn calves died of serious diarrhea. Through further experiments, the drug sensitivity and resistance of the strain, the expression of the virulence gene and virulence pathogenicity were studied. E. coli O157 : H7 isolates were resistant to 12 antibiotics including penicillin, tetracycline and ampicillin, and were sensitive to eight antibiotics including cefoperazone, ceftazidime and amikacin. Resistance genes included tetB, strB, aadB, aphA, floR, TEM and virulence genes included stx1, eaeA and hlyA. Using specific pathogen free mice, the result showed that the isolate was pathogenic with a median lethal dose of 7.9×107 CFU · mL-1. This study described the pathogenesis and clinical manifestations of E. coli O157 : H7 infection. These results guided the use of antibiotics in prevent and control of bacterial infections in the future.
文摘This study examined the survival of acid-adapted E. coli O157 in kombucha during fermentation and refrigerated kombucha mixed with fruit juices. Acidic and non-acidic kombucha mixes were fermented at 25°C using a commercially available starter culture and inoculated with a 5-strain mixture of acid-adapted E. coli O157. There was >5-log reduction in the pathogen count for both starter mixes within 7 days of fermentation. For the kombucha-juice blends at refrigerated temperature, 14 ml of lemon, apple, orange, and mango juices were mixed with 186 ml kombucha separately. The treatments were inoculated with a 5-strain mixture of acid-adapted E. coli O157 and incubated at 5°C for 14 days. >5-log reduction in the pathogen count was observed in lemon, control, and mango juice blend after 1, 3, and 14 days, respectively. The total reduction in pathogen count in the apple and orange juice blend after 14 days was 4.43 and 4.12 log CFU/ml, respectively. The inability of the kombucha fruit blend to cause a 5-log reduction of E. coli O157 suggests the need for following strict hygienic and good sanitation practices during blending and bottling for home fermenters and an approved HACCP plan for foodservice operators to ensure product safety.
文摘The strains ofLactobacillus delbrueckii subsp, lactis widely used in food preservation due to ability produce high amount of hydrogen peroxide at refrigerator temperatures to inhibit food-borne pathogens and psychrophilic spoilage microorganisms. In order to improve of bio-preservation efficacy ofL. delbrueckii MH 10 mutations causing resistance to streptomycin （str） were used. Among UV-mutagenized population of L. delbruecla＇i three str mutants producing high amounts of H2O2 were selected. Sir mutants produced significant amounts of hydrogen peroxide 50-60 μg/ml in sodium phosphate buffer （0.2 M, pH 6.5） and in beef broth （BB） at 5 ℃ for 5 days submerged cultivation without of growth. Evaluation mutants antibacterialactivity at refrigeration temperatures against food-borne pathogen Escherichia coli O157：H7 revealed elimination of pathogen total number up to practically undetectable amount for 3 days. In case of solid-state cultivation on agar-based medium, disks soaked by mutant cells suspensions formed larger inhibitory zones on E. coli O157：H7 lawn for one-day cold exposition. The size of inhibition zone depends on concentration of LAB cells. Str mutants L. delbrueckii reduced initial amount 2 - 105 of E. coil O 157：H7 in ground beef up to 3 log for 3 days of solid-state cocultivation when the wild strain reduced only 2 log. The application ofL. delbrueckii mutants did not cause any changes in sensory characteristics of ground beef, moreover promotes expanding of shelf-life due to inhibition of psychrophilic spoilage microorganisms.
文摘This study was conducted to isolate and identify antibiotic resistant bacteria in fresh tomato sold in three different local markets of Dhaka city. On an average 〉 5.0 log CFU/g of natural microbial populations and coliform bacteria was present in the samples. Prevalence of Salmonella spp., E. coli, Listeria spp., and Yersinia spp., were recorded through cultivation dependent assay of tomato samples of different markets. Almost all of the isolates were uniformly resistant to rifampicin, erythromycin, clindamycin and oxacillin （100%）, vancomycin （93%）, amoxicillin （87%）, whereas 60% of the isolates were found to be resistant to ampicillin and cephalexin. Antibiotic sensitivity test of the presumptive E. coli and Salmonella spp. and corresponding plasmid profiling indicated a correlation of plasmid mediated multidrug resistance （MDR） of these environmental bacteria. Washing with sanitizing agents such as acidified sodium chlorite （ASC） and 200 ppm chlorinated water was able to reduce _〈 2.0 log CFU/g of natural microflora and coliform bacteria. In contrast, ASC was able to reduce 〈 2.0 log CFU/g of other food borne pathogens and, chlorinated water was able to reduce up to undetectable level. Therefore, washing of tomato with 200 ppm chlorinated water could be useful in reducing the pathogen populations on tomatoes.
文摘Microbial quality (MQ) of meat contact surfaces (MCS) of six major abattoirs was evaluated with a subsequent further isolation and identification of E. coli O157. Two hundred and forty 240 swab samples (SS) from MCS that include cutting equipment, floor, tables and transport media were collected for total aerobic plate count and isolation of E. coli O157. Results of the SS indicated a mean value 7.1 ± 0.3 log<sub>10</sub> cfu/cm<sup>2</sup>. A minimum value of 6.4 ± 0.6 log<sub>10</sub> cfu/cm<sup>2</sup> was recorded oncutting instrument from Ningi abattoir, while a maximum value of 7.8 ± 0.3 log<sub>10</sub> cfu/cm<sup>2</sup> was obtained from tables at Darazo abattoir. Only 3 (1.2%) of the 240 SS of the MCS were positive for E. coli O157 using the latex agglutination kit (Difco, Michigan, USA).
文摘between enteric pathogens and plant hosts have been shown to be multifaceted.This series of studies sought to expand our knowledge in this area and evaluate whether spinach cultivar selection may be used to curtail pathogen contamination and ultimately reduce microbiological risk associated with this crop.As a component to that assessment,potential antimicrobials that were constituents within spinach leaves were first analysed and found to be spatially non-uniform,being more concentrated on the outer edges of the leaves than in the centre of the leaves.Consequently,the entire foliage of a plant was sampled in subsequent studies examining the fate of Salmonella and Escherichia coli O157:H7 on seven cultivars of spinach.Cultivar did not affect the degree of Salmonella internalized into spinach tissue(P>0.05);however,it appeared that those Salmonella that were internalized were transient residents as the percentage of plants containing this internalized pathogen dropped within 24 h.No relationship existed between antimicrobial levels(total phenols or antioxidant capacity)of the spinach cultivars and the prevalence of plants exhibiting Salmonella internalization or the persistence of Salmonella or E.coli O157:H7 after the plants had been sprayed with the pathogen.In both growth chamber and field studies,Salmonella was more resistant than E.coli O157:H7 to inactivation.Cultivar affected the persistence of both E.coli O157:H7 and Salmonella but the ranking for each pathogen’s survival on three of those cultivars differed suggesting the difficulty in finding one cultivar that would be inhospitable to multiple pathogens.
基金Supported by research grant from the Louis Albert Foundation,Tolosa,Argentina(Grant No.185001).
文摘The recent Escherichia coli epidemic in Germany gave a lesson at an international level.There is no time to solve food security problems when an epidemic is on the way.The epidemic in Germany exposed the fissures in the control systems of the Federal Risk Evaluation Institute of this country,as well as showing the incompetency of health authorities,who had great difficulty in resolving the situation.To summarize,the possibility of prevention was confused with the utopian idea of non-occurrence.It was not less important the public’s recognition and the“awakening”of health ministers in the European Union as regards the proven fact that pathogenic and even lethal microorganisms may be present in the food we eat.Argentina has the highest incidence of hemolytic uremic syndrome in the world,and the next epidemic is likely not to occur in Germany,but in any other country,such as Argentina.In order to avoid complicity,we do not wish to remain silent about the situation in Argentina.Therefore,this is the writer’s motive for writing this article,which describes the scientific advances and the ethical pitfalls related to a disease transmitted by food,particularly hemolytic uremic syndrome,in Argentina.
文摘Objectives:A study to determine food safety hazard status of fish products from Lake Chivero was conducted in selected high density suburbs of Harare.Lake water and fish were tested for E.coli O157:H7,total bacterial,fungal counts,mercury(Hg)and aflatoxin B1(AFB1)to determine contamination levels and assessing human health hazard exposure.Materials and Methods:Membrane filtration method was used to determine E.coli O157:H7 viable counts using CHROM agar.Plate count and Potato dextrose agar were used for determination of total viable bacterial and fungal counts.Concentrations of Hg and AFB1 in fish and water were determined by Atomic Absorption Spectrophotometer and High Performance Liquid Chromatography-Mass Spectrometry.A questionnaire survey was conducted on 136 adult fish consumers to determine the fish consumption patterns to assess hazard exposure against international standards.Results:Significant levels of microbial contamination above international standards in both fish and water were recorded.Mean E.coli O157:H7 counts were 106±10(cfu/cm^(2))in fish and 52±14(cfu/100ml)in water.Mean Log10 TBC were 8.98±0.26(cfu/cm^(2))in fish and 9.05±0.05(cfu/ml)in water.Mean Log10 TFC were 4.83±0.02(cfu/cm^(2))in fish and 4.56±0.03(cfu/ml)in water.Hg and AFB1 were 0.018(μg/kg)and 0.025(μg/kg)in fish and 0.008(μg/kg)and 0.005(μg/kg)in water,both with a hazard quotient(HQ)<1 using CODEX STAN 193-1995 of 2015.Conclusion:Fish and water are contaminated with E.coli O157:H7,contain bacterial and fungal loads above international food safety guidance levels.Fish were caught already contaminated with pathogens together with toxigenic Hg and carcinogenic AFB1 although their concentration levels are within international food safety toxicological levels.Levels of Hg and AFB1 in water were almost double that of fish,implying bio-accumulation occurred in fish.Thus,fish consumers are exposed to food safety hazards and are at risk of contracting foodborne illnesses from consuming contaminated fish.
