Fate of naturally occurring Escherichia coli O157:H7 and other zoonotic pathogens during minimally managed bovine feedlot manure composting processes.

Reducing Escherichia coli O157:H7 in livestock manures before application to cropland is critical for reducing the risk of foodborne illness associated with produce. Our objective was to determine the fate of naturally occurring E. coli O157:H7 and other pathogens during minimally managed on-farm bovine manure composting processes.

Prevalence rates of Escherichia coli O157:H7 and Salmonella at different sampling sites on cattle hides at a feedlot and processing plant.

The prevalence rates of Escherichia coli O157:H7 and Salmonella at different sampling sites on cattle hides were determined at a feedlot and a processing plant. Sponge samples were collected from six hide surface sites at the feedlot (left and right shoulders, left and right ribs, back, and belly) and four sites at the processing plant (left and right shoulders, back, and belly). The prevalence of E.

Increased detection of Listeria species and Listeria monocytogenes in raw beef, using the Assurance GDS molecular detection system with culture isolation.

Testing for Listeria is challenging because of its slow growth rate. Recently, we described a rapid Listeria culture isolation method. This method can be improved by utilizing a rapid molecular detection test such as the Assurance GDS tests for Listeria and Listeria monocytogenes.

Effectiveness of 1,3-dibromo-5,5 dimethylhydantoin on reduction of Escherichia coli O157:H7- and Salmonella-inoculated fresh meat.

1,3-Dibromo-5,5-dimethylhydantoin (DBDMH; 25 degrees C) and hot water (85 degrees C) spray treatments were evaluated for efficacy in decontamination of pathogenic bacteria attached to beef carcass surfaces represented by cutaneous trunci (CT) muscle sections and beef hearts. Treatments were evaluated using two different systems, a commercial carcass wash cabinet and a model carcass washer. The effects were measured immediately after treatment and again after 48 h of storage at 4 degrees C.

Prevalence and characterization of salmonellae in commercial ground beef in the United States.

Commercially produced ground beef samples (n = 4,136) were collected from seven regions of the United States over a 24-month period (July 2005 to June 2007) and analyzed for the presence of Salmonella enterica by using methods that concurrently provided total prevalence and enumerable levels. The overall prevalence of Salmonella strains was 4.2%.

Prevalence and characterization of Salmonella in bovine lymph nodes potentially destined for use in ground beef.

A potential source of pathogenic bacteria in ground beef is the lymphatic system, specifically the lymph nodes. Bacteria have been isolated from the lymph nodes of cattle at slaughter; however, most studies have dealt with mesenteric lymph nodes, which are not normally incorporated into ground beef. The objective of the current study was to determine the prevalence and multidrug-resistance status of Salmonella in bovine lymph nodes associated with lean and fat trimmings that might be utilized in ground beef production.

Salmonella and Escherichia coli O157:H7 contamination on hides and carcasses of cull cattle presented for slaughter in the United States: an evaluation of prevalence and bacterial loads by immunomagnetic separation and direct plating methods.

The hide and carcass hygiene of cull cattle at slaughter in four geographically distant regions of the United States was examined from July 2005 to April 2006 by measuring the aerobic plate counts (APC) and the prevalences and loads of Salmonella and Escherichia coli O157:H7. The geometric mean log(10) APC CFU/100 cm(2) levels on hides and preevisceration and postintervention carcasses ranged from 6.17 to 8.

Evaluation of various antimicrobial interventions for the reduction of Escherichia coli O157:H7 on bovine heads during processing.

The effectiveness of electrolyzed oxidizing water, FreshFx, hot water, DL-lactic acid, and ozonated water was determined using a model carcass spray-washing cabinet. A total of 140 beef heads obtained from a commercial processing line were inoculated with Escherichia coli O157:H7 on the cheek areas. Each head was exposed to a simulated preevisceration wash and then had antimicrobial wash treatments.

Listeria prevalence and Listeria monocytogenes serovar diversity at cull cow and bull processing plants in the United States.

Listeria monocytogenes, the causative agent of epidemic and sporadic listeriosis, is routinely isolated from many sources, including cattle, yet information on the prevalence of Listeria in beef processing plants in the United States is minimal. From July 2005 through April 2006, four commercial cow and bull processing plants were sampled in the United States to determine the prevalence of Listeria and the serovar diversity of L. monocytogenes.

Microbiological characterization of lamb carcasses at commercial processing plants in the United States.

Although the United States produces 203 million lb (ca. 92.1 kg) of domestic lamb and mutton each year, thorough studies of the microbiological safety during lamb processing are lacking.

Microbiological characterization of imported and domestic boneless beef trim used for ground beef.

The United States imports lean boneless beef trim from Australia (AUS), New Zealand (NZL), and Uruguay (URY) to meet demand for ground beef production. The reported incidence of and etiological agents responsible for foodborne diseases differ between these countries and the United States. Our objective was to determine whether current U.

Transportation and lairage environment effects on prevalence, numbers, and diversity of Escherichia coli O157:H7 on hides and carcasses of beef cattle at processing.

Hide has been established as the main source of carcass contamination during cattle processing; therefore, it is crucial to minimize the amount of Escherichia coli O157:H7 on cattle hides before slaughter. Several potential sources of E. coli O157: H7 are encountered during transportation and in the lairage environment at beef-processing facilities that could increase the prevalence and numbers of E.

Rapid enrichment strategy for isolation of Listeria from bovine hide, carcass, and meat samples.

Since the outbreak of foodborne illness linked to Escherichia coli O157:H7 bacteria in ground beef in the early 1980s, the beef processing industry has focused on increasing the safety of beef products by implementing procedures for surveying live cattle, carcasses, and beef products for bacterial pathogens. Effective methods are in place for screening cattle and beef products for the presence of E. coli O157:H7 contamination, and recent work has established the acceptability of these methods for surveillance of Salmonella.

Improvement of immunomagnetic separation for Escherichia coli O157:H7 detection by the PickPen magnetic particle separation device.

Conventional immunomagnetic separation (IMS) procedures, which use an external magnetic source to capture magnetic particles against the side of a test tube, are labor-intensive and can have poor sensitivity for the target organism because of high background microflora that is not effectively washed away during the IMS process. This report compares the conventional IMS procedure to a new IMS procedure with an intrasolution magnetic particle transfer device, the PickPen. The IMS target for the majority of these studies is Escherichia coli O157:H7 in various types of samples, including cattle feces, hides, carcasses, and ground beef.

Evaluation of Escherichia coli O157:H7 growth media for use in test-and-hold procedures for ground beef processing.

Since the mid-1990s, the beef industry has used a process called test and hold, wherein beef trim and ground beef are tested to keep products contaminated with Escherichia coli O157:H7 out of commerce. Current O157:H7 detection methods rely on a threshold level of bacterial growth for detection, which is dependent on the growth medium used. Twelve media were examined for growth and doubling time: buffered peptone water (BPW), SOC (which contains tryptone, yeast extract, KCl, MgCl2, and glucose), buffered peptone water plus SOC (BPW-SOC), Bacto-NZYM, RapidChek E.

Biochemical and genetic analysis of the distinct proliferating cell nuclear antigens of Toxoplasma gondii.

The apicomplexa parasite Toxoplasma gondii expresses two distinct proliferating cell nuclear antigens (PCNA) that exhibit distinct patterns of subcellular localization during tachyzoite growth. In all cell cycle phases, TgPCNA1 is concentrated in the nucleus, while TgPCNA2 is only concentrated in the nucleus during S-phase and uniformly distributed throughout the cell during mitosis and early G1-phase. TgPCNA1-GFP and native TgPCNA2 display a punctate staining pattern that is consistent with assembly into replication foci during S-phase; however, TgPCNA2 disassociates from replication foci before TgPCNA1-GFP.

Genetic rescue of a Toxoplasma gondii conditional cell cycle mutant.

Growth rate is a major pathogenesis factor in the parasite Toxoplasma gondii; however, how cell division is controlled in this protozoan is poorly understood. Herein, we show that centrosomal duplication is an indicator of S phase entry while centrosome migration marks mitotic entry. Using the pattern of centrosomal replication, we confirmed that mutant ts11C9 undergoes a bimodal cell cycle arrest that is characterized by two subpopulations containing either single or duplicated centrosomes which correlate with the bipartite genome distribution observed at the non-permissive temperature.

A change in the premitotic period of the cell cycle is associated with bradyzoite differentiation in Toxoplasma gondii.

We have demonstrated that bradyzoites return to the tissue-cyst stage by a developmental pathway that is indistinguishable from that initiated by sporozoites. Mature bradyzoites, like sporozoites from oocysts, were non-proliferative as they contained uniform 1N DNA contents, and replication occurred only in parasites that de-differentiated back into tachyzoites. Moreover, tachyzoites emergent from the bradyzoite-initiated pathway underwent a spontaneous growth shift prior to the onset of tissue cyst formation in a timeframe that was identical to cultures infected with sporozoites.

Genetic complementation in apicomplexan parasites.

A robust forward genetic model for Apicomplexa could greatly enhance functional analysis of genes in these important protozoan pathogens. We have developed and successfully tested a genetic complementation strategy based on genomic insertion in Toxoplasma gondii. Adapting recombination cloning to genomic DNA, we show that complementing sequences can be shuttled between parasite genome and bacterial plasmid, providing an efficient tool for the recovery and functional assessment of candidate genes.

Isolation of a Toxoplasma gondii cyclin by yeast two-hybrid interactive screen.

GAL4-based yeast two-hybrid cDNA libraries from Toxoplasma gondii RH strain were constructed and screened for interactors of a putative T. gondii cdc2-related kinase, TgCRK2. A screen of 3.

Resistance of Capsicum annuum 'Avelar' to pepper mottle potyvirus and alleviation of this resistance by co-infection with cucumber mosaic cucumovirus are associated with virus movement.

Capsicum annuum cv. Avelar plants resist systemic infection by the Florida isolate of pepper mottle potyvirus (PepMoV-FL). Immuno-tissue blot analysis for detection of PepMoV-FL infection in selected stem segments revealed that virus moved down the stem in external phloem, and, over time, accumulated to detectable levels throughout stem sections (appearing to accumulate in external and internal phloem) taken from below the inoculated leaf.