Shedding of foodborne pathogens by Caenorhabditis elegans in compost-amended and unamended soil

Anderson, Gary L.; Kenney, Stephen J.; Millner, Patricia D.; Beuchat, Larry R.; Williams, Phillip L.

doi:10.1016/j.fm.2005.01.018

Cited by 33 publications

(28 citation statements)

References 40 publications

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“…Thus, 1 g of bird feces (E. coli at 7 log CFU/g) dropped on a few lettuce crops (incoming raw material) would be sufficient to contaminate the water in the washing bath at up to 2 log CFU/100 ml. Another potential pathway for E. coli or enteric pathogens to enter the produce chain is via contaminated soil attached to the fresh produce (4,70). Soil contamination might occur in the field via direct excretion by wildlife.…”

Section: Discussionmentioning

confidence: 99%

Insight into the Prevalence and Distribution of Microbial Contamination To Evaluate Water Management in the Fresh Produce Processing Industry

Holvoet

Jacxsens

Sampers

et al. 2012

Journal of Food Protection

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This study provided insight into the degree of microbial contamination in the processing chain of prepacked (bagged) lettuce in two Belgian fresh-cut produce processing companies. The pathogens Salmonella and Listeria monocytogenes were not detected. Total psychrotrophic aerobic bacterial counts (TPACs) in water samples, fresh produce, and environmental samples suggested that the TPAC is not a good indicator of overall quality and best manufacturing practices during production and processing. Because of the high TPACs in the harvested lettuce crops, the process water becomes quickly contaminated, and subsequent TPACs do not change much throughout the production process of a batch. The hygiene indicator Escherichia coli was used to assess the water management practices in these two companies in relation to food safety. Practices such as insufficient cleaning and disinfection of washing baths, irregular refilling of the produce wash baths with water of good microbial quality, and the use of high product/water ratios resulted in a rapid increase in E. coli in the processing water, with potential transfer to the end product (fresh-cut lettuce). The washing step in the production of fresh-cut lettuce was identified as a potential pathway for dispersion of microorganisms and introduction of E. coli to the end product via cross-contamination. An intervention step to reduce microbial contamination is needed, particularly when no sanitizers are used as is the case in some European Union countries. Thus, from a food safety point of view proper water management (and its validation) is a critical point in the fresh-cut produce processing industry.

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Section: Discussionmentioning

confidence: 99%

Insight into the Prevalence and Distribution of Microbial Contamination To Evaluate Water Management in the Fresh Produce Processing Industry

Holvoet

Jacxsens

Sampers

et al. 2012

Journal of Food Protection

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“…In the environment, ecological differences between E. coli pathogens and nonpathogens have been observed to be small (1,3,14), but concerns have been raised about the utility of nonpathogenic FIB strains in estimating fecal pollution risk, mainly resulting from reports of naturalized E. coli (39). In this context, the strong temporal trend in ECOR B2 genotypes is interesting, because this subpopulation contains the greatest proportion of virulence factors (38).…”

Section: Discussionmentioning

confidence: 99%

Environmental Patterns Are Imposed on the Population Structure of Escherichia coli after Fecal Deposition

Bergholz

Noar

Buckley

2011

Appl Environ Microbiol

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The intestinal microbe Escherichia coli is subject to fecal deposition in secondary habitats, where it persists transiently, allowing for the opportunity to colonize new hosts. Selection in the secondary habitat can be postulated, but its impact on the genomic diversity of E. coli is unknown. Environmental selective pressure on extrahost E. coli can be revealed by landscape genetic analysis, which examines the influences of dispersal processes, landscape features, and the environment on the spatiotemporal distribution of genes in natural populations. We conducted multilocus sequence analysis of 353 E. coli isolates from soil and fecal samples obtained in a recreational meadow to examine the ecological processes controlling their distributions. Soil isolates, as a group, were not genetically distinct from fecal isolates, with only 0.8% of genetic variation and no fixed mutations attributed to the isolate source. Analysis of the landscape genetic structure of E. coli populations showed a patchy spatial structure consistent with patterns of fecal deposition. Controlling for the spatial pattern made it possible to detect environmental gradients of pH, moisture, and organic matter corresponding to the genetic structure of E. coli in soil. Ecological distinctions among E. coli subpopulations (i.e., E. coli reference collection [ECOR] groups) contributed to variation in subpopulation distributions. Therefore, while fecal deposition is the major predictor of E. coli distributions on the field scale, selection imposed by the soil environment has a significant impact on E. coli population structure and potentially amplifies the occasional introduction of stress-tolerant strains to new host individuals by transmission through water or food.

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“…elegans has not been directly associated with food-borne pathogens in natural environments, it has been shown experimentally to be capable of transporting S. enterica from manure to vegetables (15) and also to have the potential to carry food-borne pathogens into vertebrates (41, 42). Our findings further demonstrate that, more than a mere mechanical vector bacterium, C.…”

Section: Discussionmentioning

confidence: 99%

“…While free-living nematodes have long been recognized as major players in soil ecology (10–12), their ability to carry and shed pathogenic bacteria in the vicinity of crops, livestock, and human populations has been causing some concern for food production (13) and public health (14–16). In particular, C.…”

Section: Introductionmentioning

confidence: 99%

Spread and Transmission of Bacterial Pathogens in Experimental Populations of the Nematode Caenorhabditis elegans

Díaz

Restif

2014

Appl Environ Microbiol

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Caenorhabditis elegans is frequently used as a model species for the study of bacterial virulence and innate immunity. In recent years, diverse mechanisms contributing to the nematode's immune response to bacterial infection have been discovered. Yet despite growing interest in the biochemical and molecular basis of nematode-bacterium associations, many questions remain about their ecology. Although recent studies have demonstrated that free-living nematodes could act as vectors of opportunistic pathogens in soil, the extent to which worms may contribute to the persistence and spread of these bacteria has not been quantified. We conducted a series of experiments to test whether colonization of and transmission between C. elegans nematodes could enable two opportunistic pathogens (Salmonella enterica and Pseudomonas aeruginosa) to spread on agar plates occupied by Escherichia coli. We monitored the transmission of S. enterica and P. aeruginosa from single infected nematodes to their progeny and measured bacterial loads both within worms and on the plates. In particular, we analyzed three factors affecting the dynamics of bacteria: (i) initial source of the bacteria, (ii) bacterial species, and (iii) feeding behavior of the host. Results demonstrate that worms increased the spread of bacteria through shedding and transmission. Furthermore, we found that despite P. aeruginosa's relatively high transmission rate among worms, its pathogenic effects reduced the overall number of worms colonized. This study opens new avenues to understand the role of nematodes in the epidemiology and evolution of pathogenic bacteria in the environment.

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Shedding of foodborne pathogens by Caenorhabditis elegans in compost-amended and unamended soil

Cited by 33 publications

References 40 publications

Insight into the Prevalence and Distribution of Microbial Contamination To Evaluate Water Management in the Fresh Produce Processing Industry

Insight into the Prevalence and Distribution of Microbial Contamination To Evaluate Water Management in the Fresh Produce Processing Industry

Environmental Patterns Are Imposed on the Population Structure of Escherichia coli after Fecal Deposition

Spread and Transmission of Bacterial Pathogens in Experimental Populations of the Nematode Caenorhabditis elegans

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