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[Some trends in occurence of emergent foodborne pathogens].

The review of the modern foreign and national publications on a problem of circulation emergent foodborne pathogens in an environment is given; and the most important factors affecting on formation of their ecological niche. The data on frequency of allocation of some bacterial pathogens from animal raw material, water, ground and foodstuff are given. The description of the most investigated trends of occurrence emergent food infections is presented. Possible ways of distribution of new bacterial agents to conditions of anthropogenous transformation of an environment, some features of evolutionary changes of food bacterial pathogens, influencing on their etiological and pathogenetic properties are shown.

Animals↗

Specificity of the BAX polymerase chain reaction system for detection of the foodborne pathogen Listeria monocytogenes.

The polymerase chain reaction (PCR) can be used for rapid and specific detection of foodborne pathogens. One commercial kit, the Qualicon BAX system uses PCR to detect Listeria monocytogenes in enrichment cultures derived from food and environmental samples. The specificity and sensitivity of the BAX system for detecting L. monocytogenes were characterized by using both pure and mixed cell cultures, and optimal conditions for production of cell lysates were determined. The BAX system was highly specific for L. monocytogenes, and no interference was seen in the presence of either other Listeria species or microbes from other genera. The assay detected L. monocytogenes at 10(5)-10(6) colony-forming units/mL. This sensitivity is adequate for detecting viable cells after enrichment but prevents false-positive signals from nonviable cells.

Electrophoresis, Polyacrylamide Gel↗

The polymerase chain reaction: applications for the detection of foodborne pathogens.

Faster methods for the detection of foodborne microbial pathogens are needed. The polymerase chain reaction (PCR) can amplify specific segments of DNA and is used to detect and identify bacterial genes responsible for causing diseases in humans. The major features and requirements for the PCR are described along with a number of important variations. A considerable number of PCR-based assays have been developed, but they have been applied most often to clinical and environmental samples and more rarely for the detection of foodborne microorganisms. Much of the difficulty in implementing PCR for the analysis of food samples lies in the problems encountered during the preparation of template DNAs from food matrices; a variety of approaches and considerations are examined. PCR methods developed for the detection and identification of particular bacteria, viruses, and parasites found in foods are described and discussed, and the major features of these reactions are summarized.

Base Sequence↗

Reflections on a career in public health: evolving foodborne pathogens, environmental health, and food safety programs.

Events affecting environmental health and food safety policy, programs and organization and emerging or identified foodborne diseases are reviewed by decade. The review starts with the impact of the 1940s war years on environmental sanitation, as it was called, and disease control. It continues with the intensifying disease surveillance and improvements in sanitation of the 1950s and the improvements in foodborne-disease surveillance and the reorganization of environmental programs of the 1960s. Many previously unknown foodborne pathogens were identified, and more changes in environmental policy came about in the 1970s. Evaluation of foodborne-disease control measures were initiated. In the 1980s, evaluation of major foodborne-disease problems came to the forefront. In the 1990s, the media and consumer groups became aware of foodborne-disease problems and concerned with the environment. The first decade of the 21st century will be faced with continuing dilemmas posed by emerging diseases and will need to provide solutions through the balancing of science, education, and politics.

Disease Outbreaks↗

Relationship between cross-contamination and the transmission of foodborne pathogens in the home.

Environmental microbiologists have accumulated a substantial amount of information about the relationship between cross-contamination and the transmission of foodborne pathogens in the home. This information can be translated into guidelines for safe, effective hygienic practices in the home. Such guidelines cannot be mandated but should be strongly promoted via health and hygiene agencies to the general public. Establishing consensus-based, effective hygiene guidelines will benefit the community by reducing the risk of home-based infections such as foodborne disease and by lowering the associated healthcare costs.

Environmental Microbiology↗

Prevalence of foodborne pathogens in bulk tank milk.

Bulk tank milk from 131 dairy herds in eastern South Dakota and western Minnesota was examined for the presence of for foodborne pathogens. Campylobacter jejuni, shiga-toxin producing Escherichia coli, Listeria monocytogenes, Salmonella spp., and Yersinia enterocolitica were detected in 9.2, 3.8, 4.6, 6.1, and 6.1% of bulk tank milk samples, respectively. Thirty-five of 131 (26.7%) bulk tank milk samples contained one or more species of pathogenic bacteria. Isolates of Salmonella belonged to group D (n = 4), B (n = 2), C (n = 1), and E (n = 1) "O" serogroups. All six isolates of Listeria monocytogenes were identified as O antigen type 1. Four of five isolates of E. coli encoded for the shiga-toxin 2 gene, while one strain encoded for the shiga-toxin 1 gene. Escherichia coli O157:H7 was not isolated from bulk tank milk samples. Based on autoagglutination testing, it was inferred that all eight isolates of Yersinia enterocolitica were likely to be virulent. Non A-grade (manufacturing grade) raw milk producers were at a higher risk (odd's ratio, 4.98; confidence interval, 1.96 to 12.22) of having one or more pathogens in their bulk tank milk than were Grade A producers. It was observed that 21 of 79 (26.6%) dairy producers who consumed raw milk had one or more pathogenic bacteria in their bulk tank milk. The findings of the study warrant the need for educational programs for dairy producers about the risks associated with consumption of raw milk.

Animals↗

Standardization of diagnostic PCR for the detection of foodborne pathogens.

In vitro amplification of nucleic acids using the polymerase chain reaction (PCR) has become, since its discovery in the 1980s, a powerful diagnostic tool for the analysis of microbial infections as well as for the analysis of microorganisms in food samples. However, despite its potential, PCR has neither gained wide acceptance in routine diagnostics nor been widely incorporated in standardized methods. Lack of validation and standard protocols, as well as variable quality of reagents and equipment, influence the efficient dissemination of PCR methodology from expert research laboratories to end-user laboratories. Moreover, the food industry understandably requires and expects officially approved standards. Recognizing this, in 1999, the European Commission approved the research project, FOOD-PCR (http://www.PCR.dk), which aims to validate and standardize the use of diagnostic PCR for the detection of pathogenic bacteria in foods. The present review focuses on the harmonization procedure and standardization criteria for detection of foodborne pathogens by PCR. The progress of standardization so far and future perspectives of diagnostic PCR are discussed.

Bacteria↗

Electron paramagnetic resonance studies of the membrane fluidity of the foodborne pathogenic psychrotroph Listeria monocytogenes.

Listeria monocytogenes is a foodborne psychrotrophic pathogen that grows at refrigeration temperatures. Previous studies of fatty acid profiles of wild-type and cold-sensitive, branched-chain fatty acid deficient mutants of L. monocytogenes suggest that the fatty acid 12-methyltetradecanoic (anteiso-C(15:0)) plays a critical role in low-temperature growth of L. monocytogenes, presumably by maintaining membrane fluidity. The fluidity of isolated cytoplasmic membranes of wild-type (SLCC53 and 10403S), and a cold-sensitive mutant (cld-1) of L. monocytogenes, grown with and without the supplementation of 2-methylbutyric acid, has been studied using a panel of hydrocarbon-based nitroxides (2N10, 3N10, 4N10, and 5N10) and spectral deconvolution and simulation methods to obtain directly the Lorentzian line widths and hence rotational correlation times (tau(c)) and motional anisotropies of the nitroxides in the fast motional region. tau(c) values over the temperature range of -7 degrees C to 50 degrees C were similar for the membranes of strains SLCC53 and 10403S grown at 10 degrees C and 30 degrees C, and for strain cld-1 grown with 2-methylbutyric acid supplementation (which restores branched-chain fatty acids) at 30 degrees C. However, strain cld-1 exhibited a threefold higher tau(c) when grown without 2-methylbutyric acid supplementation (deficient in branched-chain fatty acids) compared to strains SLCC53, 10403S, and supplemented cld-1. No evidence was seen for a clear lipid phase transition in any sample. We conclude that the fatty acid anteiso-C(15:0) imparts an essential fluidity to the L. monocytogenes membrane that permits growth at refrigeration temperatures.

Anisotropy↗

From farm to table to brain: foodborne pathogen infection and the potential role of the neuro-immune-endocrine system in neurotoxic sequelae.

The American diet is among the safest in the world; however, diseases transmitted by foodborne pathogens (FBPs) still pose a public health hazard. FBPs are the second most frequent cause of all infectious illnesses in the United States. Numerous anecdotal and clinical reports have demonstrated that central nervous system inflammation, infection, and adverse neurological effects occur as complications of foodborne gastroenteritis. Only a few well-controlled clinical or experimental studies, however, have investigated the neuropathogenesis. The full nature and extent of neurological involvement in foodborne illness is therefore unclear. To our knowledge, this review and commentary is the first effort to comprehensively discuss the issue of FBP induced neurotoxicity. We suggest that much of this information supports the role of a theoretical model, the neuro-immune-endocrine system, in organizing and helping to explain the complex pathogenesis of FBP neurotoxicity.

Animals↗

Efficacy of electrolyzed oxidizing (EO) and chemically modified water on different types of foodborne pathogens.

This study was undertaken to evaluate the efficacy of electrolyzed oxidizing (EO) and chemically modified water with properties similar to the EO water for inactivation of different types of foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes and Bacillus cereus). A five-strain cocktail of each microorganism was exposed to deionized water (control), EO water and chemically modified water. To evaluate the effect of individual properties (pH, oxidation-reduction potential (ORP) and residual chlorine) of treatment solutions on microbial inactivation, iron was added to reduce ORP readings and neutralizing buffer was added to neutralize chlorine. Inactivation of E. coli O157:H7 occurred within 30 s after application of JAW EO water with 10 mg/l residual chlorine and chemically modified solutions containing 13 mg/l residual chlorine. Inactivation of Gram-positive and -negative microorganisms occurred within 10 s after application of ROX EO water with 56 mg/l residual chlorine and chemically modified solutions containing 60 mg/l residual chlorine. B. cereus was more resistant to the treatments than E. coli O157:H7 and L. monocytogenes and only 3 log10 reductions were achieved after 10 s of ROX EO water treatment. B. cereus spores were the most resistant pathogen. However, more than 3 log10 reductions were achieved with 120-s EO water treatment.

Bacillus cereus↗

Occurrence of foodborne pathogenic bacteria in retail prepackaged portions of marine fish in Spain.

AIMS: To survey the presence of indigenous and nonindigenous foodborne bacterial pathogens in displayed prepacked portions of fresh marine fish. METHODS AND RESULTS: A survey of 50 different samples of fresh marine fish (conger, swordfish, sole, grouper and whiting) was conducted over a period of 5 months. Trays of fillets and steaks were obtained at retail level and tested for foodborne bacterial pathogens. Vibrio cholerae and Salmonella were not detected. Two samples (4%) yielded Vibrio strains carrying a DNA fragment specific for Vibrio parahaemolyticus, but resulted negative to PCR amplification of the virulence-related tdh gene. Levels of motile Aeromonas ranging from 2.29 to 7.20 log CFU g(-1) were found in 31 (62%) samples. All fish portions were positive for the Aeromonas hlyA gene and 38 for both aerA and hlyA genes, which may contribute to diarrhoea-related virulence. The incidence of Listeria monocytogenes was 10%. Levels of Staphylococcus aureus lower than 2 log CFU g(-1) were found in 15 (30%) samples. Numbers of presumptive Clostridium perfringens ranging from 1.82 +/- 0.22 to 4.26 +/- 1.25 log CFU g(-1) were detected in 42 (84%) samples. Edwardsiella tarda was detected in two samples of grouper fillets. CONCLUSIONS: Displayed portions of raw fish carried bacteria that can cause foodborne disease. The risk posed by fresh fish when properly cooked is low, but high when destined to be consumed raw, undercooked or very lightly processed. SIGNIFICANCE AND IMPACT OF THE STUDY: This study revealed that raw fish sold in Spain could be a source of foodborne bacterial pathogens. Improvements in handling and processing are needed to minimize the prevalence of pathogenic bacteria.

Aeromonas↗

Antimicrobial resistance of foodborne pathogens.

Emergence of bacterial antimicrobial resistance has become a serious problem worldwide. While much of the resistance observed in human medicine is attributed to inappropriate use in humans, there is increasing evidence that antimicrobial use in animals selects for resistant foodborne pathogens that may be transmitted to humans as food contaminants.

Anti-Bacterial Agents↗

Attraction of a free-living nematode, Caenorhabditis elegans, to foodborne pathogenic bacteria and its potential as a vector of Salmonella poona for preharvest contamination of cantaloupe.

Caenorhabditis elegans was studied to determine the potential role of free-living microbivorous nematodes as vectors for preharvest contamination of fruits and vegetables with foodborne pathogens. The propensity of C. elegans to be attracted to seven strains of Escherichia coli O157:H7, eight serotypes of Salmonella, six strains of Listeria monocytogenes, and cantaloupe juice was investigated. Twenty to 30 adult worms were placed on the surface of K agar midway between a 24-h bacterial colony and 10 microl of uninoculated tryptic soy broth (TSB) or cantaloupe juice positioned 1.5 cm apart. The numbers of nematodes that migrated to the colony, to the TSB, and to the cantaloupe juice within 5, 10, 15, and 20 min at 21 degrees C were determined, and then the plates were incubated at 37 degrees C for up to 7 days to determine the ability of C. elegans to survive and reproduce in bacterial colonies. The nematode was attracted to colonies of all test pathogens and survived and reproduced within colonies for up to 7 days. C. elegans was not attracted to cantaloupe juice. The potential of C. elegans to serve as a vector for the transport of Salmonella Poona to cantaloupe rinds was investigated. Adult worms that had been immersed in a suspension of Salmonella Poona were deposited 1 or 3 cm below the surface of soil on which a piece of cantaloupe rind was placed. The rind was analyzed for the presence of Salmonella Poona after 1, 3, 7, and 10 days at 21 degrees C. The presence of Salmonella Poona was evident more quickly on rinds positioned on soil beneath which C. elegans inoculated with Salmonella Poona was initially deposited than on rinds positioned on soil beneath which Salmonella Poona alone was deposited. The time required to detect Salmonella Poona on rinds was longer when the rind was placed 3 cm above the inoculum than when the rind was placed 1 cm above the inoculum. Free-living nematodes may play a role in the preharvest dispersal of incidental human pathogens in soil to the surfaces of raw fruits and vegetables in contact with soil during development and maturation, as evidenced by the behavior of C. elegans as a test model.

Animals↗

Antibacterial activity of pepsin-digested lactoferrin on foodborne pathogens in buffered broth systems and ultra-high temperature milk with EDTA.

AIMS: To evaluate the antimicrobial activity in peptone yeast extract glucose (PYG) broth and ultra-high temperature (UHT) milk of bovine lactoferrin hydrolysate (LFH) with pepsin against the foodborne pathogens Salmonella Stanley, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus. METHODS AND RESULTS: The LFH was suspended in PYG and the minimum inhibitory concentration for each pathogen determined. The LFH was also suspended in UHT milk adjusted to pH 4 or 7, samples incubated at 4 or 35 degrees C and the change in bacterial cell population determined. Experiments in UHT milk were conducted using L. monocytogenes and E. coli O157:H7. At pH 4 LFH reduced the population of E. coli O157:H7 and L. monocytogenes by approx. 2 log; however, only E. coli O157:H7 was inhibited in samples adjusted to pH 7. The addition of EDTA (10 mg ml(-1)) to UHT milk supplemented with LFH did not markedly influence the growth of E. coli O157:H7 or L. monocytogenes. CONCLUSIONS: The results suggest that, under low pH and refrigeration conditions, LFH can limit the growth or reduce the population of pathogenic bacteria in a dairy product. SIGNIFICANCE AND IMPACT OF THE STUDY: Natural preservatives that are active against Gram-negative and Gram-positive bacteria are desirable to the food industry. This study demonstrates that LFH is effective in a complex food system. Moreover, the LFH used was not purified, making its use by industry more attractive.

Animals↗

Isolation, identification, and selection of lactic acid bacteria from alfalfa sprouts for competitive inhibition of foodborne pathogens.

Several studies have investigated the control of pathogens on alfalfa sprouts, and some treatments have been shown to be effective in reducing pathogen populations. However, control methods investigated thus far only provide pathogen control at a given point in the sprouting process and can affect germination. Competitive inhibition of pathogens with lactic acid bacteria might provide pathogen control throughout the sprouting process and up to consumption. The purpose of this study was to isolate and identify lactic acid bacteria from alfalfa sprouts to inhibit the growth of foodborne pathogens. Fifty-eight lactic acid bacteria isolates were obtained from alfalfa seeds and sprouts. These isolates were evaluated for inhibitory action against Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes by agar spot tests. All pathogens were inhibited by 32 (55%) of the isolates, S. enterica by 56 (97%), E. coli O157:H7 by 49 (84%), and L. monocytogenes by 41 (71%). The isolates were identified by the Analytical Profile Index evaluation of carbohydrate utilization. Isolates obtained from a sample of alfalfa seeds and identified as Lactococcus lactis subsp. lactis showed zones of inhibition of 4.0 mm or greater for all pathogens. One of these isolates, Lactococcus lactis subsp. lactis (L7), and an isolate previously obtained, Pediococcus acidilactici (D3), were evaluated for competitive inhibition of S. enterica, E. coli O157:H7, and L. monocytogenes in deMan Rogosa Sharpe agar and broth. Pathogen populations were significantly reduced by day 5. The selected isolates will be further evaluated in future studies for inhibitory action toward S. enterica, E. coli O157:H7, and L. monocytogenes during sprouting.

Antibiosis↗

Growth inhibition of foodborne pathogens and food spoilage organisms by select raw honeys.

Twenty-seven honey samples from different floral sources and geographical locations were evaluated for their ability to inhibit the growth of seven food spoilage organisms (Alcaligenes faecalis, Aspergillus niger, Bacillus stearothermophilus, Geotrichum candidum, Lactobacillus acidophilus, Penicillium expansum, Pseudomonas fluorescens) and five foodborne pathogens (Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica Ser. Typhimurium, and Staphylococcus aureus) using an overlay inhibition assay. They were also tested for specific activity against S. aureus 9144 and B. stearothermophilus using the equivalent percent phenol test--a well diffusion assay corresponding to a dilute phenol standard curve. Honey inhibited bacterial growth due to high sugar concentration (reduced water activity), hydrogen peroxide generation, and proteinaceous compounds present in the honey. Some antibacterial activity was due to other unidentified components. The ability of honey to inhibit the growth of microorganisms varies widely, and could not be attributed to a specific floral source or demographic region produced in this study. Antibacterially active samples in this study included Montana buckwheat, tarweed, manuka, melaleuca, and saw palmetto. Furthermore, the bacteria were not uniformly affected by honey. Varying sensitivities to the antimicrobial properties were observed with four strains of S. aureus thus emphasizing the variability in the antibacterial effect of honey samples. Mold growth was not inhibited by any of the honeys tested. B. stearothermophilus, a heat-resistant spoilage bacteria, was shown to be highly sensitive to honey in both the overlay and well diffusion assays; other sensitive bacteria included A. faecalis and L. acidophilus. Non-peroxide antibacterial activity was observed in both assays; the highest instance was observed in the specific activity assay against B. stearothermophilus. Further research could indicate whether honey has potential as a preservative in minimally processed foods.

Anti-Bacterial Agents↗

Chemical compositions and antibacterial effects of essential oils of Turkish oregano (Origanum minutiflorum), bay laurel (Laurus nobilis), Spanish lavender (Lavandula stoechas L.), and fennel (Foeniculum vulgare) on common foodborne pathogens.

Chemical compositions and inhibitory effects of essential oils of Turkish oregano (Origanum minutiflorum O. Schwarz & P. H. Davis), bay laurel (Laurus nobilis L.), Spanish lavender (Lavandula stoechas subsp. stoechas L.), and fennel (Foeniculum vulgare Mill.) on Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium, and Staphylococcus aureus were determined. After the essential oils were applied on the foodborne pathogens at doses of 0 (control), 5, 10, 20, 30, 40, 50, and 80 microL/mL, the resultant numbers of cells surviving were counted. Results revealed that all essential oils exhibited a very strong antibacterial activity against the tested bacteria (P < 0.05). Gas chromatography-mass spectrophotometry analyses revealed that carvacrol (68.23%), 1,8-cineole (60.72%), fenchone (55.79%), and trans-anethole (85.63%) were the predominant constituents in Turkish oregano, bay laurel, Spanish lavender, and fennel essential oils, respectively.

Anti-Bacterial Agents↗