Prevalence and concentration of verocytotoxigenic Escherichia coli, Salmonella enterica and Listeria monocytogenes in the beef production chain: a review.

This review examines the prevalence of three important pathogens, verocytotoxigenic Escherichia coli (VTEC), Salmonella enterica and Listeria monocytogenes, in cattle and beef from the farm to the final, ready-to-eat product. Factors affecting prevalence of pathogens in the beef chain, such as the season and cattle rearing method, are examined. Data from many key surveys are summarized in table form. The observed prevalence of pathogens in cattle and beef varies considerably from survey to survey. An indication of relative prevalence of pathogens at different stages can be obtained by calculating average prevalences observed over multiple surveys, weighted by sample number. Based on the data presented in the tables in this review, for E. coli O157 at selected processing stages the mean prevalences (and range of means from individual surveys) are faeces 6.2% (0.0-57%), hides 44% (7.3-76%), chilled carcasses 0.3% (0.0-0.5%), and raw beef products 1.2% (0.0-17%). For Salmonella the mean prevalence data are faeces 2.9% (0.0-5.5%), hides 60% (15-71%), chilled carcasses 1.3% (0.2-6.0%), and raw beef products 3.8% (0.0-7.5%). For L. monocytogenes the mean prevalence data are faeces 19% (4.8-29%), hides 12% (10-13%), and raw beef products 10% (1.6-24%). Seasonal variation was evident in many surveys, faecal prevalences of E. coli O157 and Salmonella generally being higher in the warmer months. The influence of animal type, animal age, feed and housing on pathogen carriage has also been examined. The significance of non-O157 serotypes of VTEC and their detection and classification are discussed.

Survey of Salmonella contamination of raw shell eggs used in food service premises in the United Kingdom, 2005 through 2006.

This survey was launched after an unusual number of Salmonella Enteritidis outbreaks associated with the use of eggs in food service premises in England and Wales. Between November 2005 and December 2006, 9,528 eggs (1,588 pooled samples of 6 eggs) were collected from 1,567 food service premises in the United Kingdom, most of which (89%) were produced in the United Kingdom. Salmonella was isolated from 6 (0.38%) pools of eggs. Of these, 5 (0.31%) were Salmonella Enteritidis, which were further characterized to phage types (PTs): PT 4 (0.19%), PT 8 (0.06%), and PT 12 (0.06%). Salmonella Mbandaka was also isolated (0.06%). Salmonella was detected from five and one of pooled eggs samples that were produced in the United Kingdom and Germany, respectively; these were from different producers. The study showed evidence of poor egg storage and handling practices in food service premises, in that 55% did not store eggs under refrigerated conditions; 20.7% of eggs had expired "best before" dates or were in use after 3 weeks of lay, indicating poor stock rotation; and 37.1% pooled eggs not intended for immediate service. Eggs are a commonly consumed food that may occasionally be contaminated with Salmonella at different rates, according to their country of origin. The food service sector needs to be aware of this continuing hazard, receive appropriate food safety and hygiene training on storage and usage of raw shell eggs, adopt appropriate control measures, and follow advice provided by national food agencies in order to reduce the risk of infection.

Microbiological quality of retail cheeses made from raw, thermized or pasteurized milk in the UK.

Two studies of retail fresh, ripened and semi-hard cheeses made from raw, thermized or pasteurized milk were undertaken in the UK during 2004 and 2005 to determine the microbiological quality of these products. Using microbiological criteria in European Commission Recommendations 2004/24/EC and 2005/175/EC, 2% of both raw, thermized (37/1819 samples) and pasteurized (51/2618 samples) milk cheeses were of unsatisfactory quality. Raw or thermized milk cheeses were of unsatisfactory quality due to levels of Staphylococcus aureus at 10(4)cfu g(-1), Escherichia coli at 10(5)cfu g(-1), and/or Listeria monocytogenes at 10(2)cfu g(-1), whereas pasteurized milk cheeses were of unsatisfactory quality due to S. aureus at 10(3)cfu g(-1) and/or E. coli at 10(3)cfu g(-1). Salmonella was not detected in any samples. Cheeses were of unsatisfactory quality more frequently when sampled from premises rated as having little or no confidence in management and control systems, and stored/displayed at above 8 degrees C. Raw or thermized milk cheeses were also more likely to be of unsatisfactory quality when they were unripened types, and pasteurized milk cheeses when they were: semi-hard types; from specialist cheese shops or delicatessens; cut to order. These results emphasize the need for applying and maintaining good hygiene practices throughout the food chain to prevent contamination and/or bacterial growth. Labelling of cheeses with clear information on whether the cheese was prepared from raw milk also requires improvement.

Caseinoglycomacropeptide inhibits adhesion of pathogenic Escherichia coli strains to human cells in culture.

Caseinoglycomacropeptide (CGMP) derived from kappa-casein was investigated for its ability to inhibit the adhesion of 3 strains of verotoxigenic Escherichia coli (VTEC) and 3 strains of enteropathogenic Escherichia coli (EPEC) to human HT29 tissue cell cultures. Effects on adhesion of Desulfovibrio desulfuricans, Lactobacillus pentosus, Lactobacillus casei, Lactobacillus acidophilus, and Lactobacillus gasseri were also investigated. Generally, CGMP exerted effective anti-adhesive properties at a dose of 2.5 mg/mL, albeit with a high degree of strain specificity. The CGMP reduced adhesion of VTEC strains to <50% of the control and reduced adhesion of EPEC strains to between 80 and 10% of the control. The CGMP also reduced the adhesion of L. pentosus and L. casei to 44 and 42%, respectively. A slight but significant reduction of L. acidophilus, to 81%, was observed, but no significant effects were detected with either Dsv. desulfuricans or L. gasseri. Further investigation of the dose response relationships with the E. coli strains gave IC50 values ranging between 0.12 and 1.06 mg/mL.

Effects of theophylline on human natural killer cells.

Theophylline has been shown previously to inhibit a number of cellular immune functions of granulocytes and T-lymphocytes. In the present report, we demonstrate that theophylline, in a dose-dependent fashion, suppresses human natural killer (NK) cell activity in vitro. To determine if theophylline produces quantitative or qualitative alterations in NK cells in vivo we quantitated peripheral blood NK cells with three monoclonal antibodies and FACS analysis and measured NK cytolytic activity in eight normal volunteers who took theophylline for eight days. No change was noted in the number of cytolytic activity of NK cells over the eight days of monitoring. We conclude that theophylline does not alter NK cells in vivo when given in therapeutic doses.