Persistence of <i>Salmonella</i> Enteritidis Phage Type 4 in the environment and arthropod vectors on an empty free‐range chicken farm

Davies, Robert; Breslin, M.

doi:10.1046/j.1462-2920.2003.00387.x

Cited by 90 publications

(57 citation statements)

References 40 publications

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“…A need for coordination of subpopulations with specialized virulence functions provides a framework for understanding how S. enterica serovar Enteritidis can be prevalent in the poultry environment without resulting in egg contamination, why some vector hosts contribute more than others to highincidence egg contamination, and why outbreaks occur sporadically (8,34).…”

Section: Discussionmentioning

confidence: 99%

Subpopulation Characteristics of Egg-Contaminating Salmonella enterica serovar Enteritidis as Defined by the Lipopolysaccharide O Chain

Guard

Gast

Humphrey

et al. 2004

Appl Environ Microbiol

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Characterization of Salmonella enterica serovar Enteritidis was refined by incorporating new data from isolates obtained from avian sources, from the spleens of naturally infected mice, and from the United Kingdom into an existing lipopolysaccharide (LPS) O-chain compositional database. From least to greatest, the probability of avian isolates producing high-molecular-mass LPS O chain ranked as follows: pooled kidney, liver, and spleen; intestine; cecum; ovary and oviduct; albumen; yolk; and whole egg. Mouse isolates were most like avian intestinal samples, whereas United Kingdom isolates were most like those from the avian reproductive tract and egg. Non-reproductive tract organ isolates had significant loss of O chain. Isogenic isolates that varied in ability to make biofilm and to be orally invasive produced different O-chain structures at 25°C but not at 37°C. Hens infected at a 91:9 biofilm-positive/-negative colony phenotype ratio yielded only the negative phenotype from eggs. These results indicate that the environment within the hen applies stringent selection pressure on subpopulations of S. enterica serovar Enteritidis at certain points in the infection pathway that ends in egg contamination. The avian cecum, rather than the intestines, is the early interface between the environment and the host that supports emergence of subpopulation diversity. These results suggest that diet and other factors that alter cecal physiology should be investigated as a means to reduce egg contamination.Salmonella enterica serovar Enteritidis is the leading cause of food-borne salmonellosis worldwide, in part because it is the only one of more than 2,000 serotypes that efficiently contaminates the hen egg and causes human illness (1, 48). S. enterica serovar Enteritidis resembles other pathogenic salmonellae with regard to known virulence mechanisms central to host cell invasion, survival, and growth in the host (7, 9-11, 15, 23, 36, 38, 46, 51, 52). It is important to determine differences between S. enterica serovar Enteritidis and other salmonellae because this information could help reduce egg contamination, specifically, compared to carcass contamination. The egg is produced, marketed, and used by the consumer differently from meat, which suggests that control strategies tailored to the egg industry are needed to realize reductions beyond those already achieved (5). Analysis of strain heterogeneity has established that egg-contaminating S. enterica serovar Enteritidis is predominantly clonal (25,28,31,32,35) but that it nonetheless generates substantial phenotypic variation that alters the incidence of egg contamination in infection models. Chemotyping of the lipopolysaccharide (LPS) O chain is a sensitive method of phenotypic analysis that combines stoichiometry with statistical analysis to produce clusters of data that correlate with LPS O-chain structure (41). Chemotyping has shown that S. enterica serovar Enteritidis efficiently produces high-molecular-mass (HMM) LPS O chain, whereas Salmonella enterica serovar ...

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Section: Discussionmentioning

confidence: 99%

Subpopulation Characteristics of Egg-Contaminating Salmonella enterica serovar Enteritidis as Defined by the Lipopolysaccharide O Chain

Guard

Gast

Humphrey

et al. 2004

Appl Environ Microbiol

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“…There is a correlation between the presence of Salmonella in mice and the contamination of poultry. Moreover, some recent reports have shown that several wildlife species, especially rodents, are involved in the maintenance of S. Enteritidis infection on farms [38,52,86]. It is unlikely, however, that there is a causal link between the use of S. Enteritidis as rodenticide and the human cases reported since 1960 [61,129].…”

Section: Rodent Reservoirmentioning

confidence: 99%

Emergence of Salmonella epidemics: The problems related to Salmonella enterica serotyp Enteritidis and multiple antibiotic resistance in other major serotypes

Cloeckaert²,

2005

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-Two major changes in the epidemiology of salmonellosis occurred in the second half of the 20th century: the emergence of food-borne human infections caused by S. Enteritidis and by multiple-antibiotic resistant strains of Salmonella. This review updates information on the S. Enteritidis pandemic and focuses on the emergence of Salmonella, carrying the SGI1 antibiotic resistance gene cluster, resistant to extended-spectrum cephalosporins, or resistant to fluoroquinolones. The factors responsible for the emergence of these Salmonella strains could be either of human origin or related to bacterial genome evolution. However, our increasing understanding of the molecular fluidity of the genome shows that any attempt to counteract bacteria results in further bacterial evolution or adaptation of other bacteria to take place in the new free ecological niche. In these conditions, we can ask who is faster: humans who want to eliminate bacterial pathogens or bacteria that continuously evolve to gain new niches.

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“…However, the direct application of this waste material to agricultural land can be harmful to the environment due to nutrient and pathogenic microorganisms in runoff (14,29). Salmonella-contaminated litter can be a potential source of produce contamination in the agricultural field due to the prolonged survival of Salmonella in the environment (9,17). Heat treatments are usually recommended to reduce or eliminate potential pathogenic microorganisms in animal wastes.…”

mentioning

confidence: 99%

Validating Thermal Inactivation of Salmonella spp. in Fresh and Aged Chicken Litter

Kim

Diao

Shepherd

et al. 2012

Appl Environ Microbiol

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Our results revealed that a 7-log reduction of Salmonella can be achieved by exposing fresh chicken litter for 80.5 to 100.8, 78.4 to 93.1, and 44.1 to 63 min at 70, 75, and 80°C, respectively, depending on initial moisture contents. However, the aged chicken litter requires more heat treatment.A pproximately 14 million tons of poultry litter, most of which was broiler litter (68%), was produced on U.S. poultry farms in 1990, and over 90% of poultry litter is applied to agricultural land (22). However, the direct application of this waste material to agricultural land can be harmful to the environment due to nutrient and pathogenic microorganisms in runoff (14,29). Salmonella-contaminated litter can be a potential source of produce contamination in the agricultural field due to the prolonged survival of Salmonella in the environment (9, 17). Heat treatments are usually recommended to reduce or eliminate potential pathogenic microorganisms in animal wastes. To produce a heattreated product that tests negative or at less than the detection limit for Salmonella, the temperature range of 65 to 80°C for 30 to 60 min was recommended by different organizations or federal agencies (11,23,33). The California Leafy Green Marketing Agreement (LGMA) has a strict guideline for physically heattreated animal manure. A minimum temperature of 150°C for 60 min, resulting in a moisture content of less than 30%, and a negative result or a result that is less than the detection limit for fecal coliforms, Salmonella, and Escherichia coli O157:H7 are required (3). However, there were no defined heat sources (dry versus moist heat), varying time-temperature requirements, and microbial standards among the guidelines.Most research on heat inactivation of pathogens has shown that dry heat requires a much higher temperature than moist heat to achieve comparable pathogen inactivation in sludge (4,24,37). In contrast, there are few quantitative data on the effects of dry heat on pathogen inactivation. examined thermal inactivation of Salmonella artificially inoculated in sludge using dry heat. Salmonella populations were reduced by ca. 6 logs after 30 min and by more than 8 logs after 90 min at 80°C. Davey (8) calculated that the time required to inactivate clumps of bacteria heated in dry air is about 19 times more than in moist heat.The purpose of this study was to evaluate thermal inactivation of Salmonella spp. in chicken litter under different temperatures, moisture levels, and litter compositions.Preparation of chicken litter. Fresh chicken litter was collected daily from a chicken house of laying hens (single-comb white leghorns), which were raised on the Morgan poultry farm, Clemson, SC. The majority of the litter was feces mixed with a small amount of feathers and wasted feeds. The litter was dried under a hood until the moisture content was reduced to less than 30% and then ground to a particle size of less than 3 mm (sieve pore size, 3 by 3 mm). Aged chicken litter was collected from a local poultry farm (Westminster, SC) where 4...

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Persistence of Salmonella Enteritidis Phage Type 4 in the environment and arthropod vectors on an empty free‐range chicken farm

Cited by 90 publications

References 40 publications

Subpopulation Characteristics of Egg-Contaminating Salmonella enterica serovar Enteritidis as Defined by the Lipopolysaccharide O Chain

Subpopulation Characteristics of Egg-Contaminating Salmonella enterica serovar Enteritidis as Defined by the Lipopolysaccharide O Chain

Emergence of Salmonella epidemics: The problems related to Salmonella enterica serotyp Enteritidis and multiple antibiotic resistance in other major serotypes

Validating Thermal Inactivation of Salmonella spp. in Fresh and Aged Chicken Litter

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