Foodborne Organisms Research Articles

Contamination of Retail Foods, Particularly Turkey, from Community Markets (Minnesota, 1999–2000) with Antimicrobial-Resistant and Extraintestinal PathogenicEscherichia coli

To assess the food supply as a possible vehicle for antimicrobial-resistant and extraintestinal pathogenic Escherichia coli (ExPEC), we defined the prevalence, density, clonal diversity, virulence characteristics, and antimicrobial resistance profiles of E. coli among diverse retail food items. A microbiological survey was undertaken of 346 food items (vegetables, produce, beef, pork, chicken, and turkey) purchased as a convenience sample from 16 retail markets within the Minneapolis-St. Paul area in 1999-2000, with selective cultures for E. coli and extensive molecular and phenotypic characterization of E. coli isolates. Meats, particularly turkey products, were often extensively contaminated with antimicrobial-resistant E. coli and ExPEC, to a much greater extent than were produce items, even those from farmer's markets. Moreover, meat-source E. coli differed substantially from produce-source E. coli with respect to phylogenetic background (more commonly from virulence-associated phylogenetic groups B2 or D), virulence genotype (more extensive), and antimicrobial resistance profile (more extensive). Molecular typing methods matched four turkey-source isolates to selected human clinical and fecal isolates representing the O7:K1:H-, O83:K1, and O73/O77:K52:H18 ("clonal group A") clonal groups of ExPEC. Meats purchased in grocery stores, particularly turkey products, are frequently contaminated with antimicrobial-resistant E. coli and ExPEC. Further study is needed regarding the origins and health consequences of these foodborne organisms, both to clarify the need for and to guide the possible development of appropriate regulatory and monitoring systems and preventive interventions.

Evaluation of Antimicrobial Spectrum and Cytotoxic Activity of Pleurocidin for Food Applications

ABSTRACT: Pleurocidin, an antimicrobial peptide originally isolated from the winter flounder (Pleuronecetes americanus),was evaluated for potential use in food application. Eighteen microbial species, including yeasts, molds, and foodborne bacterial pathogens, were evaluated. Liquid‐based minimal inhibitory concentration (MIC) technique was used to test antimicrobial activity of the synthetic peptide. Hemolytic and cytotoxic effects on human cells were investigated using colorimetric analysis. Pleurocidin was found to be effective against foodborne organisms including Vibrio parahemolyticus(MIC of 69 μM), Escherichia coliO157:H7 (5.3 μM), Listeria monocytogenes(23 μM), Saccharomyces cerevisiae(5.5 μM), and Penicillium expansum(20.6 μM). Antimicrobial activity occurred without significant hemolytic or cytotoxic effect on human intestinal cells.

Blocking nonspecific adsorption of native food-borne microorganisms by immunomagnetic beads with ι-carrageenan

We present herein the partitioning characteristics of anti- Salmonella and anti- Escherichia coli O157 immunomagnetic beads (IMB) with respect to the nonspecific adsorption of several nontarget food-borne organisms with and without an assortment of well-known blocking agents, such as casein, which have been shown to be useful in other immunochemical applications. We found several common food-borne organisms that strongly interacted with both types of IMB, especially with anti- Salmonella form (av Δ G 0=−20±4 kJ mol −1) even in the presence of casein [1% (w/v): Δ G 0=−18±3 kJ mol −1; ΔΔ G 0∼−2 kJ mol −1]. However, when one of the most problematic organisms (a native K12-like E. coli isolate; Δ G 0=−19±2 kJ mol −1) was tested for nonspecific binding in the presence of ι-carrageenan (0.03–0.05%), there was an average decline of ca. 90% in the equilibrium capture efficiency ξ (Δ G 0=−11±4 kJ mol −1; ΔΔ G 0∼−8 kJ mol −1). Other anionic polysaccharides (0.1% κ-carrageenan and polygalacturonic acid) had no significant effect (av Δ G 0=−19±1 kJ mol −1; ΔΔ G 0∼0 kJ mol −1). Varying ι-carrageenan from 0% to 0.02% resulted in ξ significantly diminishing from 0.69 (e.g., 69% of the cells captured; Δ G 0=−19±3 kJ mol −1) to 0.05 (Δ G 0=−11±2 kJ mol −1; ΔΔ G 0∼−9 kJ mol −1) at about 0.03% ι-carrageenan where ξ leveled off. An optimum blocking ability was achieved with 0.04% ι-carrageenan suspended in 100 mM phosphate buffer. We also demonstrated that the utilization of ι-carrageenan as a blocking agent causes no great loss in the IMBs capture efficiency with respect to the capture of its target organisms, various salmonellae.

Foodborne disease surveillance needs in Australia: Harmonisation of molecular laboratory testing and sharing data from human, animal, and food sources

Foodborne diseases cause significant morbidity and mortality in Australia and throughout the world. Outbreaks of foodborne disease often require investigators to collaborate across jurisdictional boundaries—even at times internationally. Notified cases of foodborne disease are only a small proportion of the total burden of foodborne disease affecting the community. Many pathogens that contaminate food are zoonotic in origin (that is, are transmitted to humans from lower vertebrates), although the pathway from animal to human via foods is complex and difficult to understand. This article describes how our ability to understand and control foodborne diseases in Australia can be enhanced through improving our surveillance datasets by harmonising methods for advanced microbiological testing of foodborne organisms, and sharing data obtained from human, food, and animal sources.

Policy regarding papers concerned with food-borne organisms

Policy regarding papers concerned with food-borne organisms

Efficacy of Chitosan, Carvacrol, and a Hydrogen Peroxide–Based Biocide against Foodborne Microorganisms in Suspension and Adhered to Stainless Steel

The ability of natural compounds to inactivate foodborne organisms adhered to surfaces was investigated with the ultimate aim of replacing synthetic biocides by more environmentally friendly, natural alternatives. The antimicrobial efficacy of 0.5, 1.0, and 2.0% chitosan and Spor-Klenz RTU (a commercial biocide based on hydrogen peroxide and peroxyacetic acid) and 0.5, 1.25, and 2.0mM carvacrol was determined at 20°C against Listeria monocytogenes, Salmonella enterica serovar Typhimurium, Staphylococcus aureus, and Saccharomyces cerevisiae adhered to stainless steel disks. Treatment with up to 2.0% chitosan reduced the viable cell count in the microbial films of the four test organisms by 2.4, 1.8, 2.3, and 0.9 log CFU/test surface (t.s.), respectively. By contrast, planktonic counts of the same organisms were reduced by 0.8 to 1.7 log CFU/ml at 2.0% chitosan. Treatment with 2mM carvacrol reduced the viable counts of adhered listeriae, salmonellae, and yeasts by 2 to 3 log CFU/t.s. but S. aureus counts were reduced by only 0.9 log CFU/t.s. The efficacy of any single compound was species specific. In the case of microbial films prepared using listeriae and salmonellae, Spor-Klenz RTU was most biocidal, followed by carvacrol and then chitosan. However, dried films of S. aureus were most sensitive to chitosan and relatively resistant to carvacrol and Spor-Klenz RTU. By contrast, yeast films were most sensitive to carvacrol and least sensitive to chitosan. It was concluded that carvacrol and chitosan may have potential for use as natural biocides although optimization of conditions would be necessary.

Antimicrobial Activity of a 14-Residue Synthetic Peptide against Foodborne Microorganisms

A chemically synthesized short-chain peptide composed of six leucine and eight lysine (6K8L) residues was demonstrated to be biocidal against several foodborne organisms including Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas fluorescens, and Kluyveromyces marxianus suspended in phosphate buffer at concentrations of 5 to 50 μg/ml. All strains were reduced by 3 log10 CFU/ml within 10 min at peptide concentrations of <10 μg/ml. The peptide reduced by 3 log10 CFU/ml E. coli O157:H7 counts in apple juice and was active over the pH range of 3.5 to 7. Peptide concentrations of 100 μg/ml inhibited the aerobic and anaerobic microorganisms present in meat exudate liquid. However, the peptide was not effective against E. coli O157:H7 in skim milk at concentrations up to 100 μg/ml.

Epidemiology of human listeriosis

During the 1980s, investigation of several large epidemics of listeriosis confirmed that transmission of L. monocytogenes in food causes human disease. Progress in laboratory detection and subtyping of the organism has enhanced our ability to compare human and environmental isolates of L. monocytogenes. Transmission by foodborne organisms is now recognized as causing both epidemic and sporadic listeriosis. Continued study of dietary risk factors associated with listeriosis is needed in order to develop dietary recommendations for the expanding population at increased risk of disease. Current research application of new molecular methods to the study of L. monocytogenes may improve the ability to diagnose pregnancy-associated disease and permit the rapid detection and control of L. monocytogenes in the food supply.

Public health and research perspectives on the microbial contamination of foods.

Scientific advances in methodology and epidemiology have resulted in a renewed awareness of foodborne disease, and increased contact among nations of the world has stimulated rapid global distribution of foods as well as foodborne pathogens. New food vehicles are being identified for old, familiar pathogens, and new pathogens are being discovered. Current research in food microbiology has spurred development of rapid and specific methods to identify these pathogens and to assess their virulence. Organisms of recent interest, such as Bacillus, Yersinia, Campylobacter, Listeria, Sporothrix, Giardia, Cryptosporidium, and Anisakis, are the foci of new investigations, as are the more familiar foodborne pathogens, Salmonella, Shigella, Clostridium, Staphylococcus, Entamoeba and Ascaris. Some foodborne organisms, such as parasitic protozoa, serve as hosts for unique bacterial and viral symbionts but also might become infected with mammalian viruses. The remote possibility of the transmission of human immunodeficiency viruses in foodborne protozoa is discussed.

Comparison of miniaturized multitest systems with conventional methodology for identification of Enterobacteriaceae from foods

Four miniaturized multiple test systems were compared with tube methodology used to identify Enterobacteriaceae encountered in foods. Identification aids supplied with each system were used to assign names to isolates at the species level. For the 129 strains tested, the Minitek system demonstrated a 96.9 percent agreement with reactions in tubed media. The Inolex, Analytab, and PathoTec test systems exhibited 94.3, 93.8, and 92.7 percent agreement, respectively. Analytab identified 96.1 percent of the isolates to the species level, whereas the Minitek, PathoTec, and Inolex systems were able to identify 78.3, 32.6, and 27.1 percent, respectively. The results indicate that the Analytab and Minitek systems are acceptable substitutes for the tube methodology routinely employed in identifying enterics from foods. Although the PathoTec system might be used to screen isolates for their identity, neither the presently available PathoTec nor the Inolex systems should be substituted for current methodology when definitive identification of foodborne organisms is required.