PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Foodborne pathogen”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

Acquisition of microbiological data to enhance food safety.

The routine acquisition and archiving of microbiological data is undertaken for two reasons. The first is the development of historical microbiological profiles of foods, ingredients, or processes in order to determine or verify that microorganisms of concern are being controlled to the level desired. The second reason is data concerning the pathogenicity or virulence of foodborne pathogens and their behavior in foods in order to develop strategies and criteria for assuring microbiological safety. Both types of microbiological data are essential to effective food safety programs. A firm understanding of the uses and limitations of both is essential to correct acquisition, interpretation, and use of such data.

Databases, Factual↗

Altering the thermal resistance of foodborne bacterial pathogens with an eggshell membrane waste by-product.

Eggshells from egg-breaking operations are a significant waste disposal problem. Thus, the development of value-added by-products from this waste would be welcomed by the industry. The ability of extracted eggshell membranes containing, several bacteriolytic enzymes (i.e., lysozyme and beta-N-acetylglucosaminidase) or other membrane components to alter the thermal resistance of gram-positive and gram-negative bacterial pathogens was evaluated. Mid-log phase cells of Salmonella Enteritidis (SE), Salmonella Typhimurium (ST), Escherichia coli O157:H7 (EC), Listeria monocytogenes Scott A (LM), and Staphylococcus aureus (SA) were suspended in 100 ml of 0.1% peptone water (pH 6.9, 10(7-8) CFU/ml) containing either 0 (control) or 10 g of an eggshell membrane extract and incubated at 37 degrees C for 45 min. Following exposure, membrane-free samples (1.5 ml) were heated in a 56 degrees C (LM, SA), 54 degrees C (SE, ST), or 52 degrees C (EC) water bath from 0 to 14 min in sealed glass reaction vials (12 by 32 mm), and the survivors were recovered on brain heart infusion agar. Population reductions ranging from 27.6% (SA) to 99.8% (LM) (ST, 43.8%; SE, 47.5%; EC, 71.8%) were observed for cells treated for 45 min with extracted membrane, as compared to controls. D-value reductions ranging from 0 (LM) to 87.2% (SE) (SA, 36.7%; EC, 83.3%; ST, 86.3%) were observed when membrane-treated cells were subsequently heat inactivated. The effects of exposure pH, time, temperature, and organic load on membrane activity were also evaluated with Salmonella Typhimurium. Exposure pH (5.0 versus 6.9), time (15 versus 45 min), and temperature (4 degrees C versus 37 degrees C) did not significantly reduce the impact of eggshell membranes on D-values. However, the presence of organic matter (0.1% peptone water versus skim milk) significantly reduced the thermal resistance-reducing capacity of the membranes. These preliminary findings provide information on the potential use of extracted eggshell membranes to alter bacterial heat resistance.

Acetylglucosaminidase↗

[Effects of "host factor" bile on adaptability and virulence of Vibrios, foodborne potential pathogenic agents].

In order to improve the knowledge of host/pathogenic agent interaction and to obtain a more careful estimation of risk related to ingestion of food contaminated by Vibrio spp., the effects of bile extracts have been studied. The growth of one V. fluvialis, two V. alginolyticus, and three V. parahaemolyticus strains, isolated from mollusks and crustaceans, has been determined to evaluate their adaptability to intestinal environment. Moreover, the expression of virulence factors responsible for the colonization, as bacterial "swarming mobility", biofilm production, adherence on epithelial cells and hydrophobicity, has been evaluated. Using a bile concentration of 1.5%, all examined strains showed a constant inhibitory effect, quite moderate in the first growth phases. Bile increased the "swarming mobility" and biofilm production; also the adherence was favored, but only after adaptation and during the early logarithmic phase. The decreased hydrophobicity could explain the reduction of adherence during the stationary phase. Studying the phenotypic expression of virulence factors in "minor vibrios" in the presence of bile, it was possible to extend the knowledge about their pathogenetic mechanisms owing to the ingestion of contaminated food. That permits a more careful estimation of risk related to the contamination, considering the high frequency of isolation of these species in some seafood.

Adaptation, Physiological↗

Microbiological safety of mayonnaise, salad dressings, and sauces produced in the United States: a review.

The literature on the death and survival of foodborne pathogens in commercial mayonnaise, dressing, and sauces was reviewed and statistically analyzed with emphasis on Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes. The absence of reports of foodborne illness associated directly with the consumption of commercially prepared acidic dressings and sauces is evidence of their safety. Salmonella, E. coli O157:H7, E. coli, L. monocytogenes, Staphylococcus aureus, and Yersinia enterocolitica die when inoculated into mayonnaise and dressings. Historically, mayonnaise and dressings have been exempt from the acidified food regulations and have justly deserved this status due primarily to the toxic effect of acetic and to a lesser extent lactic and citric acids. These organic acids are inimical to pathogenic bacteria and are effective natural preservatives with acetic being the most effective in killing pathogenic bacteria at the pH values encountered in these products. Statistical analysis on data reported in the literature shows that the most important and significant factor in destroying pathogenic bacteria is pH as adjusted with acetic acid followed by the concentration of acetic acid in the water phase. The reported highest manufacturing target pH for dressings and sauces is 4.4, which is below the 4.75 pKa of acetic acid and below the reported inhibitory pH of 4.5 for foodborne pathogens in the presence of acetic acid. The overall conclusion is that these products are very safe. They should remain exempt from the acidified food regulations providing adequate research has been done to validate their safety, and the predominant acid is acetic and reasonable manufacturing precautions are taken.

Animals↗

Comparison of enzyme-linked immunomagnetic chemiluminescence with U.S. Food and Drug Administration's Bacteriological Analytical Manual method for the detection of Escherichia coli O157:H7.

Escherichia coli O157:H7, a major foodborne pathogen, has been associated with numerous cases of foodborne illnesses. Rapid methods have been developed for the screening of this pathogen in foods in order to circumvent timely plate culture techniques. Unfortunately, many rapid methods are presumptive and do not claim to confirm the presence of E. coli O157:H7. The previously developed method, enzyme-linked immunomagnetic chemiluminescence (ELIMCL), has been improved upon to allow for fewer incidences of false positives when used to detect E. coli O157:H7 in the presence of mixed cultures. The key feature of this assay is that it combines the highly selective synergism of both anti-O157 and anti-H7 antibodies in the sandwich immunoassay format. This work presents application of a newly semi-automated version of ELIMCL to the detection of E. coli O157:H7 in pristine buffered saline yielding detection limits of approximately 1 x 10(5) to 1 x 10(6) of live cells/mL. ELIMCL was further demonstrated to detect E. coli O157:H7 inoculated into artificially contaminated ground beef at ca. 400 CFU/g after a 5 h enrichment and about 1.5 h assay time for a total detection time of about 6.5 h. Finally, ELIMCL was compared with USFDA's Bacteriological Analytical Manual method for E. coli O157:H7 in a double-blind study. Using McNemar's treatment, the two methods were determined to be statistically similar for the detection of E. coli O157:H7 in ground beef inoculated with mixed cultures of select bacteria.

Bacteriological Techniques↗

Zoonotic bacterial populations, gut fermentation characteristics and methane production in feedlot steers during oral nitroethane treatment and after the feeding of an experimental chlorate product.

Nitroethane inhibits the growth of certain zoonotic pathogens such as Campylobacter and Salmonella spp., foodborne pathogens estimated to cause millions of human infections each year, and enhances the Salmonella- and Escherichia coli-killing effect of an experimental chlorate product being developed as a feed additive to kill these bacteria immediately pre-harvest. Limited studies have shown that nitroethane inhibits ruminal methane production, which represents a loss of 2-12% of the host's gross energy intake and contributes to global warming and destruction of the ozone layer. The present study was conducted to assess the effects of 14-day oral nitroethane administration, 0 (0X), 80 (1X) or 160 (2X)mg nitroethane/kg body weight per day on ruminal and fecal E. coli and Campylobacter, ruminal and fecal methane-producing and nitroethane-reducing activity, whole animal methane emissions, and ruminal and fecal fermentation balance in Holstein steers (n=6 per treatment) averaging 403+/-26 (SD) kg BW. An experimental chlorate product was fed the day following the last nitroethane administration to determine effects on E. coli and Campylobacter. The experimental chlorate product decreased (P<0.001) fecal, but not ruminal (P>0.05) E. coli concentrations by 1000- and 10-fold by 24 and 48 h, respectively, after chlorate feeding when compared to pre-treatment concentrations (>5.7 log(10) colony forming units/g). No effects (P>0.05) of nitroethane or the experimental chlorate product were observed on fecal Campylobacter concentrations; Campylobacter were not recovered from ruminal contents. Nitroethane treatment decreased (P<0.01) ruminal (8.46, 7.91 and 4.74+/-0.78 micromol/g/h) and fecal (3.90, 1.36 and 1.38+/-0.50 micromol/g/h) methane-producing activity for treatments 0X, 1X and 2X, respectively. Administration of nitroethane increased (P<0.001) nitroethane-reducing activity in ruminal, but not fecal samples. Day of study affected ruminal (P<0.0001) but not fecal (P>0.05) methane-producing and nitroethane-reducing activities (P<0.01); treatment by day interactions were not observed (P>0.05). Ruminal accumulations of acetate decreased (P<0.05) in 2X-treated steers when compared with 0X- and 1X-treated steers, but no effect (P>0.05) of nitroethane was observed on propionate, butyrate or the acetate to propionate ratio. Whole animal methane emissions, expressed as L/day or as a proportion of gross energy intake (%GEI), were unaffected by nitroethane treatment (P>0.05), and were not correlated (P>0.05) with ruminal methane-producing activity. These results demonstrate that oral nitroethane administration reduces ruminal methane-producing activity but suggest that a microbial adaptation, likely due to an in situ enrichment of ruminal nitroethane-reducing bacteria, may cause depletion of nitroethane, at least at the 1X administration dose, to concentrations too low to be effective. Further research is warranted to determine if the optimization of dosage of nitroethane or related nitrocompouds can maintain the enteropathogen control and anti-methanogen effect in fed steers.

Administration, Oral↗

Expression of major cold shock proteins and genes by Yersinia enterocolitica in synthetic medium and foods.

Yersinia enterocolitica is a psychrotrophic foodborne pathogen that has been implicated in outbreaks of foodborne illness involving cold-stored foods, especially milk and pork. A major mechanism bacteria use to adapt to cold is expression of cold shock proteins. The objective of this research was to study the expression of major cold shock proteins of Y. enterocolitica in Luria-Bertani (LB) broth, milk, and pork following a temperature downshift from 30 to 4 degrees C. Y. enterocolitica was inoculated into 10 ml of LB broth, sterile skim milk, or pork, and the samples were stored at 4 degrees C (cold shock) or 30 degrees C (control) for 0, 4, 8, 12, and 24 h. At each sampling time, total protein and total RNA were extracted from Y. enterocolitica harvested from LB broth, milk, and pork and subjected to two-dimensional gel electrophoresis and dot blot analysis. Two major cold shock proteins (CspA1 and CspA2) of approximately 7 kDa and their genes were expressed by Y. enterocolitica following cold shock. However, the CspA1 and CspA2 proteins were not expressed by Y. enterocolitica at 30 degrees C. Y. enterocolitica CspA1 and CspA2 were observed as early as 2 h of cold shock in cultures from LB broth and milk and at 8 h of cold shock in cultures from pork.

Animals↗

Evaluation of universal preenrichment broth for growth of heat-injured pathogens.

Universal preenrichment broth (UPB) was developed to enable enrichment of injured foodborne pathogens of different genera simultaneously in lieu of having to undergo separate simultaneous enrichment cultures for subsequent detection or isolation of each pathogen. Enrichment conditions in UPB for growth of injured pathogens to populations that will enable pathogen detection by rapid immuno-based or polymerase chain reaction (PCR)-based assays have not been defined. Hence, studies were done to determine recovery and growth rates of heat-injured Escherichia coli O157:H7, Salmonella enterica ser. Typhimurium, Salmonella enterica ser. Enteritidis. and Listeria monocytogenes in UPB. Bacterial cells were heat injured in tryptic phosphate broth at 57.2 degrees C and inoculated at populations of ca. 0.17 to 63 injured cells per ml with raw ground beef, fresh chicken, lettuce, and environmental sponge samples. Enrichment cultures were sampled at 1, 2, 3, 4, 5, 6, and 24 h at 37 degrees C postinoculation, and pathogens were enumerated on appropriate selective media. Results revealed that recovery and growth of pathogens during the first 6 h of enrichment were not sufficient to ensure adequate numbers of bacteria (> 10(3) CFU/ ml) for detection by most immunoassays or PCR assays. Cells often required 3 to 4 h for recovery before growth was initiated. Salmonella Typhimurium, Salmonella Enteritidis, E. coli O157:H7, or L. monocytogenes cell populations in enrichment cultures with ground beef or lettuce at 6 h were 0.5 to 2.9 log10 CFU/ml. At 24 h of incubation, cell counts of enrichment samples for the three pathogens from all food and environmental sponge samples ranged from 4.0 to 8.3 log10 CFU/ml. Enrichment in UPB at 37 degrees C of foods or environmental sponge samples containing heat-injured cells of Salmonella Typhimurium, Salmonella Enteritidis, E. coli O157:H7, or L. monocytogenes reliably provides at 24 h of incubation-but not at 6 h-sufficient cell populations for detection by rapid immunoassay or PCR assay procedures that can detect at least 4 log10 CFU/ml. These results raise questions regarding the sensitivity of rapid detection methods that employ an abbreviated enrichment protocol of 6 h or less.

Animals↗

Chloramphenicol and tetracycline synergize with bacteriophage SeKF_13 to inactivate antimicrobial-resistant Salmonella Typhimurium.

UNLABELLED: Non-typhoidal Salmonella is estimated to cause up to 1 billion cases of global foodborne illness per year. Salmonella Typhimurium is a serovar of gravest worldwide concern as it is capable of infecting animal and human hosts and can also acquire antimicrobial resistance (AMR) determinants at a rapid rate. Recent advances in phage research have positioned them as especially useful for inactivation of Salmonella where antibiotics have proven no longer effective. Even more recently, phage-antibiotic synergy (PAS) has been proposed as a solution for AMR Salmonella, where synergistic combinations of phages and antibiotics are more effective than application of phage or antibiotic alone. Utilizing an in-house phage isolate, SeKF_13, we sought to determine the existence of PAS against a strain of Salmonella enterica serovar Typhimurium 14028 2a that is clinically resistant to bacteriostatic antibiotics chloramphenicol and tetracycline. Checkerboard assays revealed the presence of synergy when sub-lethal (sub-MIC) levels of either tetracycline or chloramphenicol were combined with phage SeKF_13 (P < 0.05; two-way ANOVA). Compared to tetracycline or chloramphenicol alone, the addition of phage also decreased the MICs of both antibiotics twofold. We also monitored the development of resistance and found that PAS significantly suppressed emergence of resistance compared to the antibacterial agents alone (P < 0.05; Tukey's HSD). Whole-genome sequencing revealed that SeKF_13 is devoid of genes encoding integrase, antimicrobial resistance, and virulence, ensuring safety in future applications. Together, our results suggest that combined treatment of phage and antibiotic can improve antimicrobial efficacy against antibiotic-resistant Salmonella enterica. IMPORTANCE: Salmonella enterica is a foodborne pathogen that causes one of the highest rates of foodborne illness worldwide. They are also capable of becoming resistant to antimicrobials very rapidly (i.e., antimicrobial resistance; AMR) due to their ability to acquire AMR determinants, undermining the effectiveness of current treatments. Bacteriophages (phages), viral predators of bacteria, have been proven to be effective in some cases, but recently, phage-antibiotic synergy has been proposed as a more effective solution than phages or antibiotics alone. We found this was, indeed, the case; using phage SeKF_13 and tetracycline or chloramphenicol (to which the Salmonella strain was resistant), we found that combination treatment was significantly more effective than either treatment alone. These results demonstrate that combined treatment of phage and antibiotic can bolster treatment efficacy against AMR Salmonella.

Salmonella typhimurium↗

Food poisoning syndromes.

Despite our society's advances in sanitation, food preservation, and hygiene, the prevalence of foodborne disease remains high (12.6 million cases per year in the United States). Although there is a constant need for education of food handlers and consumers, there is also a need for continued vigilant monitoring of coastal waters, meat packing facilities, and imported foods. As long as antibiotics are used in poultry and cattle feeds, one can expect the incidence of antibiotic-resistant foodborne pathogens to rise. There are several promising areas of research in the field of foodborne illnesses. Molecular biologists are actively characterizing the genes that enable invasive enteric pathogens such as Salmonella and Yersinia to enter tissues, and the bacterial toxins associated with secretory diarrheas continue to be the subject of intense scrutiny. Epidemiologists are implementing new techniques such as DNA fingerprinting and multilocus enzyme electrophoresis for tracing pathogens in disease outbreaks. Similarly, the use of computers in the food industry facilitates the tracing of contaminated foods. Although the rates of foodborne illness may not decrease significantly during the next decade, we can expect more rapid identification and tracing of outbreaks as well as an improved understanding of the pathogenesis of the foodborne diseases.

Diarrhea↗

Prevalence and expression of enterotoxins in Bacillus cereus and other Bacillus spp., a literature review.

Members of the Bacillus genus are ubiquitous soil microorganisms and are generally considered harmless contaminants. However, a few species are known toxin producers, including the foodborne pathogen, B. cereus. This species produces two distinct types of foodborne illness, the emetic (vomit-inducing) syndrome, associated with consumption of toxin in cooked rice dishes, and the diarrheal illness seen occasionally following consumption of contaminated meats, sauces, and certain dairy products. In the latter case, illness results from the production of enterotoxins by vegetative cells in the small intestine of the host. In dairy products, the occurrence of Bacillus spp. is inevitable, and the spore-forming ability of this organism allows it to easily survive pasteurization. Many strains have been shown to grow and produce enterotoxin in dairy products at refrigeration temperatures. Evaluation of toxin gene presence and toxin expression in Bacillus spp. other than B. cereus has not been thoroughly investigated. However, the presence of natural isolates of Bacillus spp. harboring one or more enterotoxin gene(s) and subsequent demonstration of conditions which may support toxin expression holds crucial importance in the food safety arena.

Bacillus↗

Genomic characterization and pathogenicity of ruminant Listeria monocytogenes isolates in a murine oral infection model.

Listeria monocytogenes is a major foodborne pathogen; its ruminant isolates display zoonotic characteristics, causing similar clinical signs in humans, including abortion and encephalitis. However, data on whole genome sequencing and pathogenicity of ruminant L. monocytogenes isolates remain sparse. This study aimed to analyze the genotypic characteristics of L. monocytogenes isolates from ruminants with listeriosis. Furthermore, we assessed the in vivo pathogenicity of four ruminant L. monocytogenes isolates, characterized via whole-genome sequencing-based genetic clustering, in orogastrically inoculated mice. The isolate LM18 (serotype 1/2b, ST224, SL6178) had the lowest lethal dose compared to the other three isolates including previous hypervirulence type (serotype 4b, ST1, SL1) and caused secondary bacteremia in lungs, with sustained bacterial loads in the spleen and liver. Genomic (listeria pathogenicity island -1 and -3) and virulence gene (actA and llsX) mutation analyses associated with virulence suggested from well-recognized studies could not elucidate the virulence of the isolates. SSI-1, which only exists in the isolate LM18 (serotype 1/2b, ST224, SL6178), may help L. monocytogenes survive in the gastrointestinal environment, thereby affecting its virulence. Further research should investigate the role of SSI-1 in the pathogenicity of L. monocytogenes. Moreover, additional studies utilizing larger datasets of ruminant isolates are required to validate our genotypic characterization and to obtain a comprehensive picture of further genotypic differences crucial for L. monocytogenes pathogenicity.

Animals↗

Information systems in food safety management.

Information systems are concerned with data capture, storage, analysis and retrieval. In the context of food safety management they are vital to assist decision making in a short time frame, potentially allowing decisions to be made and practices to be actioned in real time. Databases with information on microorganisms pertinent to the identification of foodborne pathogens, response of microbial populations to the environment and characteristics of foods and processing conditions are the cornerstone of food safety management systems. Such databases find application in: Identifying pathogens in food at the genus or species level using applied systematics in automated ways. Identifying pathogens below the species level by molecular subtyping, an approach successfully applied in epidemiological investigations of foodborne disease and the basis for national surveillance programs. Predictive modelling software, such as the Pathogen Modeling Program and Growth Predictor (that took over the main functions of Food Micromodel) the raw data of which were combined as the genesis of an international web based searchable database (ComBase). Expert systems combining databases on microbial characteristics, food composition and processing information with the resulting "pattern match" indicating problems that may arise from changes in product formulation or processing conditions. Computer software packages to aid the practical application of HACCP and risk assessment and decision trees to bring logical sequences to establishing and modifying food safety management practices. In addition there are many other uses of information systems that benefit food safety more globally, including: Rapid dissemination of information on foodborne disease outbreaks via websites or list servers carrying commentary from many sources, including the press and interest groups, on the reasons for and consequences of foodborne disease incidents. Active surveillance networks allowing rapid dissemination of molecular subtyping information between public health agencies to detect foodborne outbreaks and limit the spread of human disease. Traceability of individual animals or crops from (or before) conception or germination to the consumer as an integral part of food supply chain management. Provision of high quality, online educational packages to food industry personnel otherwise precluded from access to such courses.

Consumer Product Safety↗

Effects of sodium chlorate on antibiotic resistance in Escherichia coli O157:H7.

The spread of antibiotic resistance from farm animals to human pathogens has become a matter of great public health significance, and methods to reduce foodborne pathogenic bacteria without utilizing traditional antibiotics have been sought. Chlorate kills Escherichia coli O157:H7 in vitro and in vivo and has been proposed as a feed additive to be included in food animal rations immediately prior to slaughter to reduce E. coli O157:H7 populations in the animal gastrointestinal tract. This study was designed to examine the effect that the development of chlorate resistance in E. coli O157:H7 has on resistance to 32 medically important antibiotics. Chlorate resistance numerically increased antibiotic resistance in E. coli O157:H7 strain 6058 and strain 933 to six and four antibiotics, respectively, but chlorate resistance affected resistance to only two antibiotics (cefoxotin and sulfadimethoxine) in both strains examined. Based on the fact that chlorate resistant mutants do not appear to compete well in vivo and based on the results of the current study, it appears unlikely that chlorate treatment will result in a dissemination of antibiotic resistance. However, further research is needed to confirm these results.

Animals↗

A review of conventional detection and enumeration methods for pathogenic bacteria in food.

With continued development of novel molecular-based technologies for rapid, high-throughput detection of foodborne pathogenic bacteria, the future of conventional microbiological methods such as viable cell enumeration, selective isolation of bacteria on commercial media, and immunoassays seems tenuous. In fact, a number of unique approaches and variations on existing techniques are currently on the market or are being implemented that offer ease of use, reliability, and low cost compared with molecular tools. Approaches that enhance recovery of sublethally injured bacteria, differentiation among species using fluorogenics or chromogenics, dry plate culturing, differentiation among bacteria of interest using biochemical profiling, enumeration using impedence technology, techniques to confirm the presence of target pathogens using immunological methods, and bioluminescence applications for hygiene monitoring are summarized here and discussed in relation to their specific advantages or disadvantages when implemented in a food microbiology setting.

Bacteria↗

Escherichia coli serotype O157:H7: novel vehicles of infection and emergence of phenotypic variants.

Escherichia coli serotype O157:H7 was only recognized as a human pathogen a little more than a decade ago, yet it has become a major foodborne pathogen. In the United States, the severity of serotype O157:H7 infections in the young and the elderly has had a tremendous impact on human health, the food industry, and federal regulations regarding food safety. The implication of acidic foods as vehicles of infection has dispelled the concept that low-pH foods are safe. Further, the association of nonbovine products with outbreaks suggests that other vehicles of transmission may exist for this pathogen. In laboratory diagnosis, most microbiologic assays rely on a single phenotype to selectively isolate this pathogen. However, the increasing evidence that phenotypic variations exist among isolates in this serogroup may eventually necessitate modifications in assay procedures to detect them.

Animals↗

The new American diet and the changing face of foodborne illness.

Pathogens responsible for foodborne illness are changing, owing to changes in the American diet as well as in food production and distribution. Microbial adaptations to heat, acid, cold, and antibiotics have made food safety a challenging task. This article reviews the common pathogens, their sources, and treatment.

Agriculture↗