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1.
Lett Appl Microbiol ; 73(1): 81-87, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33797068

ABSTRACT

We present estimations for the amounts of Arcobacter (A. butzleri, A. cryaerophilus and A. skirrowii) and Campylobacter (C. jejuni, C. coli and C. fetus) species in retail chicken, pork and beef meat using PCR-MPN. Arcobacter butzleri, A. cryaerophilus and C. jejuni were found in 100, 60 and 55% of chicken samples, respectively. No other Arcobacter or Campylobacter species were found in chicken. The MPNs of A. butzleri, A. cryaerophilus and C. jejuni were greater than 103 per 100 g in 50, 0 and 5% of samples, respectively. The MPN of A. butzleri was higher than that of C. jejuni in 95% of samples. In pork, A. butzleri and A. cryaerophilus were detected in 10 and 11 (50 and 55%) of 20 samples, respectively. No other Arcobacter or Campylobacter species were found in pork. Only one pork sample had more than 103 MPN per 100 g of A. cryaerophilus. For beef, only two samples tested positive for A. cryaerophilus, at 4600 and 92 MPN per 100 g. Overall, we found that the presence and MPNs of Arcobacter species are very high in chicken. In contrast, the positive ratios of Arcobacter in pork were high as chicken samples, but MPNs were lower than in chicken.


Subject(s)
Arcobacter/physiology , Campylobacter/physiology , Food Microbiology , Meat/microbiology , Animals , Arcobacter/genetics , Arcobacter/isolation & purification , Campylobacter/genetics , Campylobacter/isolation & purification , Cattle , Chickens , Japan , Polymerase Chain Reaction , Pork Meat/microbiology , Red Meat/microbiology
2.
J Appl Microbiol ; 122(1): 268-278, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27718315

ABSTRACT

AIM: This study assessed whether multilocus variable-number tandem repeat analysis (MLVA) and antimicrobial susceptibility testing discriminated diarrhoeagenic atypical enteropathogenic Escherichia coli (aEPEC) from aEPEC indigenous to domestic animals or healthy people. METHODS AND RESULTS: MLVA genotyping of 142 aEPEC strains isolated from foods and faecal samples of domestic animals and humans revealed 126 distinct MLVA profiles that distributed to four clusters, yielding a Simpson's index of diversity (D) of 99·8%. Cluster 2 included 87% of cattle isolates and 67% of patient isolates. The plurality (15/34, 44%) of strains from healthy humans mapped to Cluster 1, while half (18/41, 44%) of the swine strains belonged to Cluster 4. Testing for antimicrobial susceptibility revealed that 52 strains (37%) of aEPEC were resistant to one or more agents; only 10 strains (7%) exhibited resistance to more than three agents. Strains isolated from swine or food exhibited a wider variety of resistance phenotypes than bovine or human strains. CONCLUSIONS: MLVA assigned the aEPEC isolates from cattle and patients to Cluster 2, distinct from aEPEC from other sources. Hog yards may be a larger source of drug-resistant strains than are cattle ranches. SIGNIFICANCE AND IMPACT OF THE STUDY: MLVA suggests that human diarrhoeagenic aEPEC are derived from cattle and are distinct from strains carried by healthy people and other animals. Cattle appear to be reservoirs of human diarrhoeagenic aEPEC.


Subject(s)
Anti-Bacterial Agents/pharmacology , Enteropathogenic Escherichia coli/drug effects , Enteropathogenic Escherichia coli/isolation & purification , Escherichia coli Infections/microbiology , Escherichia coli Infections/veterinary , Feces/microbiology , Food Microbiology , Animals , Cattle , Drug Resistance, Bacterial , Enteropathogenic Escherichia coli/classification , Enteropathogenic Escherichia coli/genetics , Escherichia coli Proteins/genetics , Escherichia coli Proteins/metabolism , Genotype , Humans , Minisatellite Repeats , Swine
3.
Epidemiol Infect ; 142(11): 2237-47, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25078437

ABSTRACT

Consumption of seafood contaminated with Vibrio parahaemolyticus causes foodborne infections, which are on the rise owing to increased consumption of raw seafood in Asia, Europe, North America, and other regions. V. parahaemolyticus infections have been common in Japan since the 1960s. Following an epidemic in 1997, the Japanese Ministry of Health, Labour, and Welfare instituted regulations for seafood in 1999, which appear to be reducing V. parahaemolyticus infections. In this review, we describe the scientific findings for these regulations. Analyses of the V. parahaemolyticus serotypes and isolate characteristics in samples from infected patients and contaminated seafood are discussed. In addition, based on the results of a survey, we show that new food safety regulations have led to improvements in food hygiene at many seafood retail shops, food service facilities, and restaurants. This example from Japan could be of immense help to control foodborne infections in other countries.


Subject(s)
Food Contamination/legislation & jurisprudence , Food Safety , Vibrio Infections/prevention & control , Vibrio parahaemolyticus/pathogenicity , Female , Food Contamination/prevention & control , Humans , Japan , Male , Seafood/adverse effects , Seafood/analysis , Vibrio Infections/epidemiology
4.
Article in English | MEDLINE | ID: mdl-23199079

ABSTRACT

The National Food Surveillance System in Japan was formed in 1998 to monitor the contamination of retail foods with bacterial pathogens. Approximately 2000-3000 samples were tested annually, and the data from food categories that had more than 400 samples collected during 1998-2008 were analysed. With regard to meat, the frequency of positive samples for Salmonella in chicken for raw consumption and ground chicken was 12.7% and 33.5%, respectively. Moreover, Shiga toxin-producing Escherichia coli (STEC) O157 was found in ground meat, organ meat and processed meat, although at a low frequency (0.1%). The prevalence of Campylobacter jejuni/coli was 13.3% and 20.9% in chicken for raw consumption and ground chicken, respectively. In vegetables and fruit, Salmonella was detected in cucumber, lettuce, sprout and tomato samples at a frequency of around 0.1-0.2%. With regard to seafood, Salmonella was found in 0.5% of oysters for raw consumption. Seafood was not contaminated with STEC O157 or Shigella. Serotype Infantis was the most frequently detected serotype of Salmonella in seafood, followed by the serotypes Typhimurium, Schwarzengrund and Manhattan. In ground chicken, 72.2% of the strains were identified as the serotype Infantis. E. coli, as an indicator of food hygiene, was detected in all food categories. The results show the prevalence of the above-mentioned pathogens in the retail food supplied in Japan; further, they indicate that consumption of raw food carries the risk of contracting food-borne infections.


Subject(s)
Commerce , Food Microbiology/statistics & numerical data , Foodborne Diseases/epidemiology , Foodborne Diseases/microbiology , Animals , Bacteria/classification , Bacteria/isolation & purification , Food Microbiology/standards , Fruit/microbiology , Humans , Japan/epidemiology , Meat/microbiology , Time Factors , Vegetables/microbiology
5.
Epidemiol Infect ; 139(10): 1505-10, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21205441

ABSTRACT

Intake of a small dose of foodborne pathogens can cause infection. In this study, an estimation of the infectious dose of the pathogens was obtained by conducting microbiological risk assessments. The contamination levels of foodborne pathogens were analysed in 17 outbreaks of Salmonella, Escherichia coli O157, enterotoxigenic E. coli, Vibrio parahaemolyticus, and Campylobacter jejuni occurring in Japan between 2004 and 2006. The infectious dose was estimated in 14 of the 17 outbreaks utilizing existing data. In three outbreaks of Salmonella infection in which the infection rate was 89-100%, the dose of the ingested pathogens was estimated to be 259,000-14,000,000,000 c.f.u. In other outbreaks of Salmonella infection, the infection rate and dose of the ingested pathogens were 10-66·4% and 81-1560 c.f.u. or most probable number (MPN), respectively. The ingested Salmonella dose is likely to be related to the infection rate; however, storage conditions should be taken into account when making this determination. In an outbreak of E. coli O157 infection, the infection rate and ingestion dose were 100% and 2 to <9 c.f.u., respectively, while in an outbreak of enterotoxigenic E. coli infection, they were 93% and 25-1000 c.f.u., respectively. Finally, in an outbreak of C. jejuni infection, the infection rate and ingestion dose were 37·5% and 360 MPN, respectively. These results will be particularly valuable for risk assessment.


Subject(s)
Bacteria/pathogenicity , Bacterial Infections/microbiology , Disease Outbreaks , Foodborne Diseases/microbiology , Gastroenteritis/microbiology , Bacterial Load , Eating , Humans , Japan
6.
J Food Prot ; 73(8): 1537-42, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20819369

ABSTRACT

In recent years, bottled mineral water has undergone inactivation by methods other than the traditional heat treatment during the production process; there are fewer reports of the effectiveness of these inactivation methods on yeasts and molds in mineral water than on bacteria and protozoan oocysts. In this study, we evaluated the effects of UV irradiation and ozone treatment compared with heat treatment at 85 degrees C on yeast cells and mold spores inoculated into mineral water. A 5-log reduction occurred at a UV radiation dose of 31,433 microJ/cm2 for Saccharomyces cerevisiae and at 588,285 microJ/cm2 for Penicillium pinophilum. The treatment time for 5-log reduction estimated for UV irradiation was about 0.6 min for S. cerevisiae and about 10.7 min for P. pinophilum; at an ozone concentration of 0.1 ppm, it was 1.75 min for S. cerevisiae and 2.70 min for P. pinophilum, and at a concentration of 0.6 ppm, it was 0.32 min for S. cerevisiae and 0.57 min for P. pinophilum. Comparison of the inactivation effects among the three methods showed that UV irradiation and ozone treatment were less effective than heat treatment at 85 degrees C. Thus, when UV irradiation and ozone treatment are used for inactivation of mineral water, it seems that they need to be combined with heat treatment to achieve a definite effect. Yeast cells are more sensitive to all three inactivation methods than are mold spores, and the sensitivity of yeast cells and mold spores to these inactivation methods may vary among genera.


Subject(s)
Food Irradiation , Fungi/radiation effects , Oxidants, Photochemical/pharmacology , Ozone/pharmacology , Water Microbiology , Yeasts/radiation effects , Colony Count, Microbial , Consumer Product Safety , Dose-Response Relationship, Drug , Dose-Response Relationship, Radiation , Fungi/drug effects , Fungi/growth & development , Hot Temperature , Humans , Time Factors , Ultraviolet Rays , Yeasts/drug effects , Yeasts/growth & development
7.
J Food Prot ; 73(6): 1077-84, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20537263

ABSTRACT

To identify a rapid method for extracting a large amount of DNA from fungi associated with food hygiene, extraction methods were compared using fungal pellets formed rapidly in liquid media. Combinations of physical and chemical methods or commercial kits were evaluated with 3 species of yeast, 10 species of ascomycetous molds, and 4 species of zygomycetous molds. Bead grinding was the physical method, followed by chemical methods involving sodium dodecyl sulfate (SDS), cetyl trimethyl ammonium bromide (CTAB), and benzyl chloride and two commercial kits. Quantity was calculated by UV absorbance at 260 nm, quality was determined by the ratio of UV absorbance at 260 and 280 nm, and gene amplifications and electrophoresis profiles of whole genomes were analyzed. Bead grinding with the SDS method was the most effective for DNA extraction for yeasts and ascomycetous molds, and bead grinding with the CTAB method was most effective with zygomycetous molds. For both groups of molds, bead grinding with the CTAB method was the best approach for DNA extraction. Because this combination also is relatively effective for yeasts, it can be used to extract a large amount of DNA from a wide range of fungi. The DNA extraction methods are useful for developing gene indexes to identify fungi with molecular techniques, such as DNA fingerprinting.


Subject(s)
Colony Count, Microbial/methods , DNA, Fungal/isolation & purification , Food Microbiology , Fungi/isolation & purification , Yeasts/isolation & purification , Consumer Product Safety , DNA, Fungal/analysis , Food Contamination/analysis , Fungi/genetics , Gene Amplification , Humans , Time Factors , Yeasts/genetics
8.
J Appl Microbiol ; 106(2): 410-20, 2009 Feb.
Article in English | MEDLINE | ID: mdl-19200309

ABSTRACT

AIMS: The source and routes of diarrhoeagenic Escherichia coli (DEC) have not been clarified because it is difficult to detect these organisms in samples with numerous coliform bacteria. We have developed multiplex real-time PCR assays for exhaustive detection of DEC. METHODS AND RESULTS: Primers and TaqMan probes were designed to amplify and quantify one gene (eae, stx1, stx2, elt, est, virB, aggR, astA, and afaB) from each of seven pathotypes of DEC, in duplex or triplex reactions under the same PCR cycling conditions. Specificity was confirmed using 860 strains including 88 DEC strains. The fluorescence threshold cycle and DNA concentrations correlated with decision coefficients of more than 0.99. Subsequently, meat samples and enrichment broths were spiked with DEC and the assays used to detect the genes. The detection limits varied from 7.1 x 10(2) to 1.1 x 10(4) CFU ml(-1), depending on the target genes. All meat samples spiked with a variety of DEC (more than 10 CFU 10 g(-1)) were found to be positive by the method. CONCLUSIONS: The present system allows for the efficient and simultaneous determination of various DEC pathotypes. SIGNIFICANCE AND IMPACT OF THE STUDY: This system makes epidemiological investigations for DEC sensitive and quick, and is a useful tool to clarify the source and routes of DEC.


Subject(s)
Bacteriological Techniques/methods , Escherichia coli/isolation & purification , Food Microbiology , Polymerase Chain Reaction/methods , Culture Media , DNA Primers , DNA, Bacterial/analysis , Escherichia coli/genetics , Food Contamination , Limit of Detection , Meat/microbiology , Sensitivity and Specificity , Water Microbiology
9.
J Food Prot ; 71(7): 1460-4, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18680947

ABSTRACT

A total of 353 samples of 29 types of seafood were tested for Salmonella prevalence and total microbial population. Salmonella enterica serotype Weltevreden was isolated from 2 of 47 black tiger prawn samples. The contamination levels of Salmonella were in a range of <30 to 40 most probable number per 100 g. In addition, one sample of black tiger prawns and two samples of white shrimp were positive for Salmonella invA gene on PCR assay. Although the mean aerobic bacterial count was greater than 4 log CFU/g in most of the sample types, those in the two Salmonella-isolated samples of black tiger prawn were 7.48 and 5.18 log CFU/g, respectively. These results indicate the possibility that shrimp and prawns contribute to foodborne infections. The improvement of seafood quality is an important issue, and the information on contamination by pathogens should be provided as feedback to the originating country, with the aim of increasing safety.


Subject(s)
Food Contamination/analysis , Salmonella/isolation & purification , Seafood/microbiology , Shellfish/microbiology , Animals , Colony Count, Microbial/methods , Consumer Product Safety , Food Microbiology , Humans , Japan , Prevalence , Salmonella/growth & development , Salmonella enterica/growth & development , Salmonella enterica/isolation & purification
10.
Avian Dis ; 51(2): 578-83, 2007 Jun.
Article in English | MEDLINE | ID: mdl-17626487

ABSTRACT

About 16,000 spent hens from 23 farms in the northern area of Japan were purchased in 1996, 1997, 1998, and 1999 to isolate Salmonella in two poultry processing plants. Salmonella was detected in 12 of 23 farms (52.2%). In particular, the serotypes Enteritidis and Infantis were detected in four and three farms, respectively. The prevalence rates in the hens' ceca, immature eggs, and the yolk of mature eggs in oviducts were 14%, 7.2%, and 6.8%, respectively. A total of 23 serotypes were detected. The major serotypes of the strains were Enteritidis, Corvallis, Typhimurium, and Infantis, but most of the strains were untypable. In the same area during 1992 to 1996, Salmonella was detected in eggs associated with four outbreaks of Salmonella Enteritidis infection and one outbreak of Salmonella Infantis infection. The ratio of contamination was approximately 1%, and the level was estimated to be 93 MPN(most probable number)/100 g in one outbreak. In farms that produced the eggs associated with all of the five outbreaks of Salmonella, the serotype Enteritidis or Infantis was isolated from hens. Farms where Salmonella was not detected were not related to any of the outbreaks.


Subject(s)
Chickens/microbiology , Food Microbiology , Ovum/microbiology , Salmonella Infections/epidemiology , Salmonella/isolation & purification , Animals , Disease Outbreaks , Female , Humans , Poultry Diseases/epidemiology , Poultry Diseases/microbiology , Prevalence , Salmonella Infections/microbiology
11.
Lett Appl Microbiol ; 45(1): 100-7, 2007 Jul.
Article in English | MEDLINE | ID: mdl-17594468

ABSTRACT

AIM: The aim of this study was to develop a loop-mediated isothermal amplification (LAMP) assay targeting the genes for the four classical enterotoxins, SEA, SEB, SEC and SED, in Staphylococcus aureus. METHODS AND RESULTS: Specific primers were designed which target each specific sequence of the enterotoxin genes. With 30 strains of Staph. aureus, the results of the LAMP assay to each enterotoxin, SEA, SEB, SEC and SED, completely accorded with the results of polymerase chain reaction (PCR) assay. Enterotoxin production, determined by a reverse passive latex agglutination assay, strongly correlated with the presence of the corresponding genes. Amplification was not observed when 14 strains of nonenterotoxigenic Staph. aureus and 20 strains consisting of 19 bacterial species other than Staph. aureus were tested. In addition, the sensitivity of the LAMP assay was generally higher than that of conventional PCR assay and it rapidly detected enterotoxigenic Staph. aureus strains within 60 min. CONCLUSIONS: The LAMP assay developed in this study is rapid, specific and sensitive for the detection of enterotoxigenic Staph. aureus. SIGNIFICANCE AND IMPACT OF THE STUDY: The method is suitable for clinical diagnosis and food safety applications.


Subject(s)
Bacterial Toxins/genetics , Enterotoxins/genetics , Nucleic Acid Amplification Techniques/methods , Staphylococcus aureus/genetics , Superantigens/genetics , Bacterial Toxins/metabolism , DNA Primers , Enterotoxins/metabolism , Humans , Polymerase Chain Reaction , Sensitivity and Specificity , Staphylococcus aureus/metabolism , Superantigens/metabolism , Time Factors
12.
J Food Prot ; 70(2): 373-7, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17340871

ABSTRACT

We studied the effects of autoclaved (121 degrees C, 15 min) sugar solutions on the survival and growth of Vibrio parahaemolyticus and other bacteria. The growth and survival of V. parahaemolyticus in Luria-Bertani media and phosphate buffer, respectively, were inhibited by the addition of D-glucose autoclaved in pH 8.0 phosphate buffer. The bactericidal effect of autoclaved D-glucose was very small when autoclaved in pH 7.0 phosphate buffer, but larger effects were observed when autoclaved in the buffer at an alkaline pH. The autoclaving of D-glucose in CH3COONa, NaHCO3, and Na2HPO4 solutions at pH 7.6 to 8.5 also generated bactericidal effects, but it was not the case when D-glucose was autoclaved in Na2SO4, (NH4)2SO4, or NH4Cl solution at pH 8.0. The same effects as autoclaved D-glucose were observed in autoclaved lactose, D-fructose, and D-ribose. The bactericidal effects of autoclaved D-glucose were also noted in Salmonella Enteritidis, Listeria monocytogenes, and E. coli strains, but the effects were smaller than those seen in V. parahaemolyticus and V. vulnificus. The growth of V. parahaemolyticus in clam extracts was also inhibited by the addition of autoclaved D-glucose, indicating that heat-treated reduced sugars can exert bactericidal effects in foods.


Subject(s)
Food Microbiology , Food Preservation/methods , Glucose/metabolism , Hot Temperature , Vibrio parahaemolyticus/growth & development , Colony Count, Microbial , Consumer Product Safety , Culture Media/chemistry , Hydrogen-Ion Concentration , Time Factors , Vibrio parahaemolyticus/metabolism , Vibrio parahaemolyticus/physiology
13.
J Food Prot ; 70(1): 90-6, 2007 Jan.
Article in English | MEDLINE | ID: mdl-17265865

ABSTRACT

A reproducible real-time PCR method that targets the putative transcriptional regulator gene of Staphylococcus aureus was developed to quantify this microorganism in milk samples. On the basis of partial sequences of this gene determined from S. aureus strains, we designed the specific primers and probe for use in a quantitative PCR assay. These specificities were confirmed with 25 strains of S. aureus and 35 strains of other bacteria. A real-time PCR assay with serial 10-fold dilutions of purified DNA and pure culture was conducted. It was possible to construct standard curves with a high correlation coefficient (r2 = 0.99) in the range of 50 ng to 50 fg for purified DNA and 10(7) to 10(1) CFU/ml for a pure culture. The constructed standard curve for milk samples was similar to that for the pure culture, and the quantification of S. aureus in the range of 10(7) to 10(1) CFU/ml was possible. Moreover, to determine how our real-time PCR method would perform under actual analytical conditions, we quantified the DNA from S. aureus after two types of heat treatments were used for the pasteurization of milk. The amount of DNA found was affected after heat treatment at 63 degrees C for 30 min (low-temperature long-time method) but not at 72 degrees C for 15 s (high-temperature short-time method). The results indicate that the real-time PCR method developed in this study is effective for monitoring S. aureus contamination in milk because of its high specificity and sensitivity.


Subject(s)
DNA, Bacterial/analysis , Food Contamination/analysis , Hot Temperature , Milk/microbiology , Polymerase Chain Reaction/methods , Staphylococcus aureus/isolation & purification , Animals , Base Sequence , Cattle , Colony Count, Microbial , Consumer Product Safety , Humans , Sensitivity and Specificity , Species Specificity , Time Factors
14.
J Food Prot ; 69(10): 2519-23, 2006 Oct.
Article in English | MEDLINE | ID: mdl-17066938

ABSTRACT

A total of 259 samples of 40 types of spices were tested for Salmonella prevalence and total microbial and spore populations. Salmonella enterica serotypes Weltevreden and Senftenberg were isolated from a black- and red-pepper sample, respectively. Because Salmonella was not detected by the most-probable-number method, it indicated that at least one cell of the microorganism was present in 25 g of sample. The mean aerobic bacterial count was greater than 5.39 log CFU/g in turmeric, garam masala, curry powder, and paprika. The mean bacterial spore counts were greater than 4.33 log CFU/g in turmeric and curry powder. The mean aerobic bacterial count in the two Salmonella-isolated samples was 6.93 log CFU/g. These results indicate that spices can be a source of contamination in the products where they are used as ingredients, and methods to reduce the microbial load in spices should be used.


Subject(s)
Consumer Product Safety , Food Contamination/analysis , Salmonella/isolation & purification , Spices/microbiology , Bacteria, Aerobic/classification , Bacteria, Aerobic/isolation & purification , Colony Count, Microbial , Humans , Japan , Phylogeny , Salmonella/classification , Spores, Bacterial/isolation & purification
15.
Food Addit Contam ; 23(2): 212-8, 2006 Feb.
Article in English | MEDLINE | ID: mdl-16449065

ABSTRACT

The levels of formaldehyde (FA) and acetaldehyde (AA) in polyethylene terephthalate (PET) bottles and in commercial mineral water are reported. All the water samples bottled in Japan contained detectable levels of FA (10.1-27.9 microg l(-1)) and AA (44.3-107.8 microg l(-1)). Of 11 European bottled water samples, eight did not contain either FA or AA, while the remaining three had detectable levels of FA (7.4-13.7 microg l(-1)) and AA (35.9-46.9 microg l(-1)). In three North American bottled water samples, two contained FA (13.6 and 19.5 microg l(-1)) and AA (41.4 and 44.8 microg l(-1)), and one did not. Regardless of the region of origin, all the sterilized water samples contained FA and AA, whilst in contrast, none of the unsterilized water without carbonate contained FA or AA. Of the carbonated water samples, three contained FA and AA, and one did not. When fortified with FA and AA, the commercial water sample without otherwise detectable FA and AA was able to reduce levels, although the commercial water sample containing FA and AA could not. The presence of bacteria in the commercial water samples was investigated using an ATP-based bioluminescent assay and heterotrophic plate count method. The commercial water without FA and AA contained heterotrophic bacteria, whilst the commercial water with FA and AA did not contain detectable bacteria. It is suggested that in this case both FA and AA migrated from PET materials, but were subsequently decomposed by the heterotrophic bacteria in the unsterilized water.


Subject(s)
Acetaldehyde/analysis , Food Packaging , Formaldehyde/analysis , Mineral Waters/analysis , Polyethylene Terephthalates , Colony Count, Microbial/methods , Food Contamination , Mineral Waters/microbiology , Sterilization
16.
Epidemiol Infect ; 134(4): 780-5, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16371182

ABSTRACT

Vibrio parahaemolyticus and Vibrio vulnificus were isolated from faecal samples of wild aquatic birds in winter. Although V. parahaemolyticus and V. vulnificus were present in low numbers in seawater in the area where the faecal samples of the birds were collected, the pathogens were isolated from the faeces of the birds. This study demonstrates that wild aquatic birds are a vehicle for V. parahaemolyticus and V. vulnificus to survive in winter.


Subject(s)
Birds/microbiology , Vibrio parahaemolyticus/isolation & purification , Vibrio vulnificus/isolation & purification , Animals , Feces/microbiology , Japan , Seawater/microbiology , Serotyping
17.
Epidemiol Infect ; 133(6): 1043-8, 2005 Dec.
Article in English | MEDLINE | ID: mdl-16274500

ABSTRACT

Two elementary schools were served lunches that were cooked in the same kitchen. An outbreak of Escherichia coli O157:H7 occurred at one school where the dishes that were prepared for the school were lukewarm and kept for 33 min at an average temperature of 45 degrees C before serving. However, no outbreak occurred at the other school where dishes were hot and were kept for 60 min at an average temperature of 50 degrees C before serving. In a series of experiments on the survival of E. coli O157:H7 in the liquid portion of similarly prepared food, the population of E. coli O157:H7 was reduced by 10-3 by heating at 50 degrees C for 60 min and by only 10-1 by heating at 45 degrees C for 40 min. Further, E. coli O157:H7 survived at 45 degrees C for 40 min but not at 50 degrees C for 60 min at pH 4.0 with a 4.0% salt concentration that was similar to that of the liquid part of the food. These results indicate that pH and salt concentration of cooked food markedly affect the survival of E. coli O157:H7 and help to explain the occurrence of the disease outbreak at only one of the schools.


Subject(s)
Diarrhea/epidemiology , Disease Outbreaks/statistics & numerical data , Escherichia coli O157/growth & development , Food Handling/methods , Hot Temperature , Sodium Chloride/pharmacology , Escherichia coli O157/drug effects , Food Contamination/analysis , Food Contamination/prevention & control , Food Handling/statistics & numerical data , Food Microbiology , Humans , Hydrogen-Ion Concentration , Meat Products/microbiology , Temperature , Time Factors
18.
J Food Prot ; 68(5): 1081-2, 2005 May.
Article in English | MEDLINE | ID: mdl-15895746

ABSTRACT

To gain a better understanding about the effect of growth temperature on heat resistance of Yersinia enterocolitica, we determined decimal reduction times at 60 degrees C (D60-values) for O:3; O:5,27; O:8; and O:9 strains harboring virulence plasmid coding for Yersinia outer membrane protein and experimentally virulence plasmid-deleted strains after they were grown to stationary phase at 7, 25, or 37 degrees C. Bacteria were inoculated into Trypticase soy broth and were incubated at several temperatures. D60-values of O:3; O:5,27; and O:8 strains were larger when they were grown at 37 degrees C than at 7 or 25 degrees C, despite the presence or absence of virulence plasmids. However, similar D60-values were observed in O:9 strains, despite growth at 7, 25, or 37 degrees C. The results indicate two types of Y. enterocolitica strains, growth temperature-dependent and -independent, and a Yersinia outer membrane protein that is not directly involved in growth temperature-dependent heat resistance.


Subject(s)
Bacterial Outer Membrane Proteins/drug effects , Food Microbiology , Hot Temperature/adverse effects , Yersinia enterocolitica/growth & development , Bacterial Outer Membrane Proteins/metabolism , Plasmids , Serotyping , Temperature , Time Factors , Virulence , Yersinia enterocolitica/genetics , Yersinia enterocolitica/pathogenicity
19.
J Food Prot ; 67(12): 2820-4, 2004 Dec.
Article in English | MEDLINE | ID: mdl-15633695

ABSTRACT

Thirty-three plants used in cooking for aroma and taste were examined for antibacterial activity against pathogens causing foodborne infections. Vibrio parahaemolyticus and Staphylococcus aureus were sensitive to many kinds of plant extracts, whereas Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Enteritidis populations decreased in only six, one, and three plant extracts, respectively. The polyphenol content in the plants was significantly different between the antibacterial plants and nonantibacterial plants, indicating that the polyphenols were related to the antibacterial action of these plants. Antibacterial activity of various concentrations of leaf extracts from Japanese persimmon, white cedar, and grape were investigated. Japanese persimmon and white cedar leaf extracts at low concentrations affected L. monocytogenes and V. parahaemolyticus rapidly. With grape leaf extract at low concentrations, the population of L. monocytogenes decreased similarly to Japanese persimmon and white cedar leaves. This study demonstrates that many plants used in cooking for aroma and taste contain polyphenols and exhibit antibacterial activity against foodborne pathogens.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Cooking/methods , Flavonoids/pharmacology , Phenols/pharmacology , Plant Extracts/pharmacology , Bacteria/growth & development , Colony Count, Microbial , Food Microbiology , Microbial Sensitivity Tests , Odorants , Plant Extracts/chemistry , Polyphenols , Taste
20.
J Food Prot ; 66(9): 1675-80, 2003 Sep.
Article in English | MEDLINE | ID: mdl-14503724

ABSTRACT

PCR is an important method for the detection of thermostable direct hemolysin gene (tdh)-positive (pathogenic hemolysin-producing) strains of Vibrio parahaemolyticus in seafood because tdh-negative (nonpathogenic) V. parahaemolyticus strains often contaminate seafood and interfere with the direct isolation of tdh-positive V. parahaemolyticus. In this study, the use of PCR to detect the tdh gene of V. parahaemolyticus in various seafoods artificially contaminated with tdh-positive V. parahaemolyticus was examined. PCR was inhibited by substances in oysters, squid, mackerel, and yellowtail but not by cod, sea bream, scallop, short-necked clam, and shrimp. To improve detection, DNA was purified by either the silica membrane method, the glass fiber method, or the magnetic separation method, and the purified DNA was used as the PCR primer template. For all samples, the use of the silica membrane method and the glass fiber method increased detection sensitivity. The results of this study demonstrate that the use of properly purified template DNA for PCR markedly increases the effectiveness of the method in detecting pathogenic tdh-positive V. parahaemolyticus in contaminated seafood.


Subject(s)
Hemolysin Proteins/isolation & purification , Polymerase Chain Reaction/methods , Seafood/microbiology , Vibrio parahaemolyticus/isolation & purification , Animals , Bacterial Proteins , DNA, Bacterial/analysis , Food Contamination/analysis , Food Microbiology , Gene Amplification , Genes, Bacterial , Hemolysin Proteins/genetics , Humans , Sensitivity and Specificity , Vibrio parahaemolyticus/genetics , Vibrio parahaemolyticus/pathogenicity
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