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ABSTRACT: Influence of selective media on successful detection of Shiga toxin–producing Escherichia coli in food, fecal, and environmental samples
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
Hussein S. Hussein, Laurie M. Bollinger
www.liebertonline.com/doi/abs/10.1089/fpd.2008.0081
Shiga toxin–producing Escherichia coli (STEC) strains have caused a large number of human illness outbreaks worldwide. In most cases, the infection was traced to consumption of meats or vegetables contaminated with cattle feces. To combat this public health problem, pre- and post-harvest control strategies are continuously implemented to assure food safety. Thus, rapid, reliable, and sensitive methods for STEC detection must be available to provide confidence not only in the meats or vegetables entering the food chain but also in testing humans with illnesses. As a result, enrichment for STEC has been a critical step in any successful protocol for their detection. The base media commonly used for STEC enrichment include sorbitol MacConkey agar, tryptic soy broth (TSB), E. coli broth, enterohemorrhagic E. coli broth, buffered peptone water (BPW), and brain heart infusion broth. In addition to bile salts, antibiotics (e.g., tellurite, cefixime, novobiocin, vancomycin, cefsulodin, and acriflavin) are used at different concentrations to enrich for STEC. In most published reports, however, the reasons for choosing the selective medium were not provided. Thus, this review was intended to evaluate the base media and antibiotics commonly used for STEC detection. The efficacy of a detection method will certainly depend on the choice of the base medium, selective agents, and their concentrations. The interactions among these factors are also expected to affect sensitivity of the detection method, especially when the test sample contains a small number of STEC cells. Because sensitivity of detection is expected to decline when testing for stressed or injured STEC cells, as is the case in environmental samples, a pre-enrichment step in TSB or BPW without antibiotics may be necessary. Future research should focus on identifying possible antibiotic combinations that effectively inhibit most background bacteria without affecting pathogenic STEC strains in the test sample.
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ABSTRACT: Antimicrobial resistance of Listeria monocytogenes isolated from a poultry further processing plant
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
Steven A. Lyon, Mark E. Berrang, Paula J. Fedorka-Cray, Daniel L. Fletcher, Richard J. Meinersmann
www.liebertonline.com/doi/abs/10.1089/fpd.2007.0070
The aim of this study was to compare antimicrobial resistance profiles of distinct types of Listeria monocytogenes isolated from a commercial poultry cooking plant. One hundred fifty-seven L. monocytogenes isolates representing 14 different actA types were tested for susceptibility to 19 antimicrobial drugs using the broth microdilution method. All isolates were susceptible to antimicrobials except for ceftriaxone (153 isolates [97%] intermediate or resistant), oxacillin with 2% NaCl (142 isolates [90%] resistant), ciprofloxacin (59 isolates [37%] intermediate or resistant), tetracycline (5 isolates [3%] resistant), clindamycin (43 isolates [27%] intermediate), linezolid (3 isolates [2%] intermediate), and trimethoprim/sulfamethoxazole (1 isolate [
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ABSTRACT: Impact of persistent bovine viral diarrhea viral infection on the duration and level of shedding of Escherichia coli O157 in calves
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
Sruti Sreerama, Michael W. Sanderson, Melinda Wilkerson, T.G. Nagaraja
www.liebertonline.com/doi/abs/10.1089/fpd.2007.0064
Objectives:
The goal of this study was to determine whether calves persistently infected with bovine viral diarrhea virus (BVDV) and inoculated with Escherichia coli O157 will shed the organism at a higher concentration and for a longer duration than calves not infected with BVDV.
Materials:
Nine calves, 6–8 weeks old, persistently infected with noncytopathic BVDV and eight calves not infected with BVDV obtained from separate cow-calf operations were used in this study. BVDV status, positive or negative, of all calves was confirmed by repeated testing throughout the study. Both groups were orally inoculated with 109 colony-forming units (CFU) of five nalidixic acid–resistant strains of E. coli O157. All calves were examined daily, and fecal samples were collected three times a week for 55 days for detection and enumeration of the nalidixic acid–resistant E. coli O157. Calves were then necropsied, and samples from the gastrointestinal tract were taken for the detection of the nalidixic acid–resistant E. coli O157.
Results:
Data analysis indicated no statistical difference in the concentration of E. coli O157 shed or the duration of shedding between the persistently infected BVDV calves and the control calves throughout the length of the study.
Conclusions:
Our data indicate that persistent infection with noncytopathic BVDV does not play a role in the level or duration of shedding of E. coli O157 in cattle.
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ABSTRACT: An investigation into the efficacy of washing trucks following the transportation of pigs—A Salmonella perspective
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
Celine Mannion, John Egan, Brendan P. Lynch, Seamus Fanning, Nola Leonard
www.liebertonline.com/doi/abs/10.1089/fpd.2007.0069
Washing of trucks before leaving the abattoir is mandatory in the Republic of Ireland; however, little is known about the efficacy of the cleaning methods in use on trucks following the transportation of live pigs in Ireland. A National Salmonella Control Programme is in place in the Republic of Ireland, which requires the categorization of all pigs according to their Salmonella status. Herds in categories 1, 2, and 3 have a serological prevalence of infection with Salmonella serotypes of =10%, >10% to =50%, and >50% to =100%, respectively. Healthy pigs can carry Salmonella serotypes in their intestine, and the stress of transport may induce these carriers to shed the bacterium at a higher rate. Salmonella-contaminated trucks may infect other farms, abattoirs, and other animals if the trucks are not cleaned between trips. The main objective of this study was to determine the efficacy of washing trucks transporting pigs from category 1 and category 3 herds. In total, six category 3 and three category 1 herds were followed to three separate abattoirs. Salmonella organisms in samples collected from farm pens and from trucks preload, postload, and after washing were quantified and compared using serotyping, phage typing, and pulsed-field gel electrophoresis (PFGE). Enterobacteriaceae counts were also evaluated to indicate the level of contamination of the environment with enteric bacteria. Results suggest that although trucks are visually clean after cold-water power hosing, such washing is not effective at reducing levels of Enterobacteriaceae regardless of category. Of the 108 samples taken from trucks transporting category 3 herds, 6% were positive for Salmonella spp. preload, 17% postload, and 18% after washing. In contrast, of the 54 samples taken from trucks transporting the three category 1 herds, 11% were positive for Salmonella spp. preload, 11% postload, and 6% after washing. Salmonella isolates from the trucks postload and after washing were indistinguishable, based on PFGE patterns, from salmonellae isolated on farm, indicating the probable shedding by carrier pigs during transit. These results demonstrate the need for better cleaning of trucks after each load, particularly when transporting pigs from high-risk herds.
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ABSTRACT: Evaluation of a loop-mediated isothermal amplification assay for detecting Vibrio vulnificus in raw oysters
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
Feifei Han, Beilei Ge
www.liebertonline.com/doi/abs/10.1089/fpd.2008.0084
Human consumption of raw or undercooked seafood, particularly oysters, may lead to severe infections due to the presence of Vibrio vulnificus. In this study, a sensitive and specific loop-mediated isothermal amplification (LAMP) assay was developed to detect this pathogen in raw oysters. Two outer and two inner primers were designed to specifically recognize the V. vulnificus cytolysin/hemolysin gene (vvhA), and the reaction could be completed in 1 hour at 63°C. Direct visual observation of the LAMP amplicons was achieved with the aid of SYBR Green I fluorescent dye. The assay specificity was determined using 50 bacterial strains, including multiple Vibrio spp. and bacteria of other genera. No false-positive or false-negative results were observed. The detection limit of the LAMP assay was approximately 20 colony-forming units (CFU) in pure cultures, 10-fold more sensitive than a conventional polymerase chain reaction (PCR). When directly applied in oyster homogenate, the LAMP assay had a detection limit of approximately 107 CFU/g. After 5-hour enrichment, LAMP was capable of detecting 7 CFU of V. vulnificus per gram of oyster tissue without lengthy DNA extraction steps. This level of detection was 1000-fold more sensitive than PCRs included for comparison. Because of its isothermal format and unique amplicon detection technique, this rapid and sensitive LAMP assay holds potential for future field applications.
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ABSTRACT: Epidemiological data on Pathogenic Yersinia enterocolitica in Southern GERMANY during 2000–2006
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
Michael Bucher, Cornelia Meyer, Britta Grotzbach, Silke Wacheck, Andreas Stolle, Maria Fredriksson-Ahomaa
www.liebertonline.com/doi/abs/10.1089/fpd.2007.0076
Yersinia enterocolitica is the most common species causing enteric yersiniosis, which is still the third most frequently reported foodborne gastroenteritis in Europe. Y. enterocolitica generally causes sporadic human infections, and outbreaks are rare. The most important infection source of yersiniosis is believed to be contaminated pork and pork products. Data on the prevalence of pathogenic Y. enterocolitica in animals and foodstuffs are very limited and old; thus, more information on the extent and range of the prevalence of this enteropathogen in nonhuman sources is needed. In this work, prevalence of pathogenic Y. enterocolitica in different sources in Bavaria is presented. Further, the antimicrobial resistance of human and nonhuman strains is reported. The highest isolation rate of pathogenic Y. enterocolitica (67%) was found in tonsils of slaughter pigs. No pathogenic strains were isolated from cattle, sheep, turkey, and horses. ail-Positive Y. enterocolitica was detected in dogs (5%), cats (3%), and rodents (3%) by real-time PCR. Pathogenic Y. enterocolitica was isolated only from raw pork, especially from edible offal (51%). Surprisingly, 38% of game was contaminated with this pathogen when the samples were studied with PCR. Additionally, some raw pork sausages and one poultry sample were PCR positive. All pathogenic Y. enterocolitica isolates from nonhuman sources were belonging to bioserotype 4/O:3. Antimicrobial resistance of 60 human and 140 porcine strains of bioserotype 4/O:3 was tested by the agar disc diffusion method to 15 different antimicrobial agents. All Y. enterocolitica 4/O:3 strains were susceptible to most of the tested antibacterial agents.
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ABSTRACT: Outbreak of Escherichia coli O157:H7 associated with raw milk consumption in the Pacific Northwest
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
Justin Denny, Maya Bhat, K. Eckmann
www.liebertonline.com/doi/abs/10.1089/fpd.2007.0072
In late 2005, health officials in Clark County, Washington noted a higher than expected number of Escherichia coli cases among residents and sought to identify a possible common source for infection. In order to identify risk factors, health officials conducted a retrospective cohort study and an environmental site investigation using pulsed-field gel electrophoresis (PFGE) to identify and prevent future cases from occurring. Several lines of evidence supported raw milk as the cause of infections: 1) all ill persons drank raw milk from the same cow share; 2) illness was associated with an increasing amount of milk consumed; 3) E. coli O157:H7 was isolated from raw milk samples and environmental samples collected from the floor of the milking parlour; and 4) PFGE patterns were indistinguishable between case-patients, raw milk samples, and environmental samples. Together, these findings made clear the health risks associated with the consumption of raw milk. The high amount of media interest in this investigation empowered public health officials to work with state legislators to pass State Senate Bill 6377 in Washington State which clarified that state licensing requirements apply to all milk production facilities including cow-share programs.
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ABSTRACT: Evaluation and control of the risk of foodborne pathogens and spoilage bacteria present in awa-uirou, a sticky rice cake containing sweet red bean paste
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
Naoki Okahisa, Yasuhiro Inatsu, Vijay K. Juneja, Shinichi Kawamoto
www.liebertonline.com/doi/abs/10.1089/fpd.2007.0073
The risk of food poisoning and growth of spoilage bacteria in Awa-Uirou, a sticky rice cake containing sweet red bean paste, was evaluated. Toxin-producing bacteria such as Staphylococcus aureus and Bacillus cereus are the main causes of food poisoning linked to this kind of food. The water activity in this product is in the range suitable for growth of S. aureus, B. cereus, and B. subtilis. The viable count of S. aureus or B. cereus spore cocktail was significantly reduced to 2.3 log colony-forming units (CFU)/g after 70 minutes steaming treatment at 100°C. However, the heat-resistant endospores of B. subtilis germinated during storage at 30°C to cause appreciable syneresis of the starch gel matrix in 4 days. The addition of 0.5% glycine before steaming treatment was found to effectively suppress the growth of B. cereus but was not effective in controlling S. aureus throughout the 7 days incubation period at 30°C. On the other hand, S. aureus and B. cereus could grow > 5.0 log CFU/g in an inoculated sample without glycine within 3 days when stored at 30°C. Moreover, addition of 0.5% glycine before the steaming process did not have any significant effect on color, texture, or taste of sticky rice cake. Therefore, results of this study demonstrated that the addition of 0.5% glycine before the steaming process could inhibit B. cereus and B. subtilis multiplication in the steamed rice confection which in turn may help reduce the risk of food poisoning or quality loss.
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ABSTRACT: Continued decline in the incidence of Campylobacter infections, FoodNet 1996–2006
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
Elizabeth Ailes, Linda Demma, Sharon Hurd, Julie Hatch, Timothy F. Jones, Duc Vugia, Alicia Cronquist, Melissa Tobin-D'Angelo, K
www.liebertonline.com/doi/abs/10.1089/fpd.2008.0090
Campylobacter is a leading cause of foodborne illness worldwide. In the United States, changes in the incidence of culture-confirmed Campylobacter infections have been monitored by the Foodborne Diseases Active Surveillance Network (FoodNet) since 1996. In 2006, the incidence of culture-confirmed Campylobacter infection in the FoodNet sites was 12.7 per 100,000 persons. This represents a 30% decline (95% confidence = 35% to 24% decrease) compared to the 1996–1998 illness baseline; however, most of the decline occurred between 1996 and 1999 and the incidence still remains above the national health objective. Important declines were observed in four FoodNet sites (California, Connecticut, Georgia, and Maryland), all age groups, and both sexes. To promote continued progress towards achieving the national health objective, the epidemiology of Campylobacter infections in the United States, including geographic variation and higher incidence among the very young, warrants further study.
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ABSTRACT: A large Escherichia coli O157 outbreak in SWEDEN associated with locally produced lettuce
6/20/2008
Foodborne Pathogens and Disease Volume: 5, Number: 3 Jun 2008
A. Soderstrom, P. Osterberg, A. Lindqvist, B. Jonsson, A. Lindberg, S. Blide Ulander, C. Welinder-Olsson, S. Lofdahl, B. Kaijser
www.liebertonline.com/doi/abs/10.1089/fpd.2007.0065
In 2005 a large outbreak of verotoxin-producing Escherichia coli (VTEC) occurred in Sweden. Cases were interviewed and cohort and case–control studies were conducted. Microbiological investigations were performed using polymerase chain reaction (PCR) to detect the Shiga-like toxin (Stx) genes followed by cultivation and pulsed-field gel electrophoresis. A total of 135 cases were recorded, including 11 cases of hemolytic uremic syndrome. The epidemiological investigations implicated lettuce as the most likely source of the outbreak, with an OR of 13.0 (CI 2.94–57.5) in the case–control study. The lettuce was irrigated by water from a small stream, and water samples were positive for Stx 2 by PCR. The identical VTEC O157 Stx 2 positive strain was isolated from the cases and in cattle at a farm upstream from the irrigation point. An active surveillance and reporting system was crucial and cooperation between all involved parties was essential for quickly identifying the cause of this outbreak. Handling of fresh greens from farm to table must be improved to minimize the risk of contamination.
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Food safety news is compiled from a number of sources and is provided only
for informational purposes. Many of the news stories have been compiled,
selected, and edited by the Food
Safety Network at the University of Guelph with permission. News stories
from other sources are added as appropriate. Accuracy and completeness cannot
be guaranteed by Iowa State University. Headlines are sometimes rewritten
for clarity or to fit space. Original sources are indicated whenever possible
and full stories may not be posted to honor the original author copyright.
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