There has been a major shift in the types of students applying for veterinary schools in the U.S. and abroad. Requirements for training in animal sciences are now almost nonexistent in most programs. A new detailed survey from the School of Veterinary Medicine, University of Wisconsin–Madison covers the backgrounds and attitudes of 3rd or 4th year veterinary students in 6 universities in the U.S. and 11 other countries, including Asia and Europe. In addition, over 400 animal science students and 400 social science students were surveyed. The data show striking contrast in the types of students being trained at different universities, and their background and attitudes toward animal agriculture and food safety. The following is a sample of some of the findings regarding food safety.

Students were provided with a series of questions on food safety and asked to score as follows:
1 = strong interest/support/very adequate,
2 = some interest/support,
3 = little interest/somewhat negative,
4 = no interest/strongly opposed/not adequate at all, and
5 = no opinion/don't know.

Regarding food safety in the U.S., positive responses (score of 1 or 2) were 54%, with no opinion (5) being 29%. Within individual states, the positive responses ranged from a low of 27 (with 40% no opinion) to a high of 77% (with 17% no opinion). The student members of the American Association of Swine Practitioners (AASP) gave an 88% positive response, with only 5% responding with no opinion. Why is there such a wide range of attitudes toward food safety from state to state, and particularly why does it differ from the opinion of the AASP members?

Of the veterinarian students with the lowest positive attitude toward food safety, only 62% said that they consumed beef, versus 90% with the highest positive attitude. (AASP members recorded 100% as beef consumers.) Another surprising finding was that 14% of the state with the greatest negative attitude toward food safety expressed confidence in trustworthiness of animal rights organizations for information, as compared to 0% for the high positive state students. Not surprising was that only 21% of the students with the lowest positive response toward food safety had previous pre-college farm work experience, as compared to 59% of the high positive students and 75% of the student members of AASP.

Does experience or even the presence of animal agriculture education influence attitude? The universities with the students providing the lowest positive attitude to food safety were Tufts University, North Grafton, Mass., and University of Massachusetts–Amherst; the highest positive attitude came from North Carolina State University–Raleigh. Inspection of the membership directory for the Federation of Animal Science Societies seems to reveal that attitudes may be greatly influenced by the presence of mentors, educators and courses available at the universities. Prerequisite training of veterinarian students in animal sciences appears critical to the education and attitudes of our future veterinarians. A 40% no opinion rating with regards to food safety from Massachusetts veterinary students signals a lack of knowledge about animal agriculture, or not requiring animal experience for admission into veterinary schools.

The survey also examined attitudes of students with majors in animal sciences, veterinary medicine and non-agricultural sociology. Positive attitudes for food safety among these three groups was 65%, 56%, and 30%, respectively. The sociology students generally felt positive about food safety information from animal rights organizations, as compared to only 16% in the animal sciences group. Further, the sociology students were nearly twice as likely to have a negative attitude toward genetic engineering when compared to the animal sciences students.

• Contribution of Hemolysin BL, Phospholipase C, and Collagenase to Virulence of Bacillus cereus Endophthalmitis
• The Naturally Occurring, Biologically Active Isomers of CLA
• Use of Tween 20 to Potentiate the Antimicrobial Effects of Lactic Acid Spraying on Inoculated Escherichia coli O157:H7 and Indigenous Escherichia coli Biotype I on Beef

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Bacillus cereus is most commonly known for its involvement in food poisoning, though it also causes a variety of nongastrointestinal infections including endophthalmitis, abscess formation, bacteremia, endocarditis, meningitis, osteomyelitis, and pulmonary and wound infections. Bacillus cereus is one of the most common causes of trauma-associated and metastatic bacterial endophthalmitis. Among organisms that infect the eye, B. cereus has one of the most rapidly evolving courses of infection and is one of the most destructive. It is extremely refractory, and blindness often occurs even in instances where aggressive and appropriate antimicrobial therapy is instituted before serious loss of sight. It is generally believed that the activities of bacterial toxins directly influence the severity and visual outcome of these infections. We have suggested that the expression of exotoxins by B. cereus may account in large part for the ineffectiveness of antibiotics. Once the toxins are expressed, killing the bacteria does not prevent damage by toxins.

We previously concluded that hemolysin BL (HBL), a necrotizing pore-forming diarrheal toxin, is a probable endophthalmitis virulence factor because it is highly toxic to retina in vitro and in vivo. We also determined that B. cereus produces additional retinal toxins that might contribute to virulence. We fractionated crude B. cereus culture supernatant by anion exchange chromatography and found in vivo and in vitro retinal toxicity was also associated with phosphatidylcholine preferring phospholipase C (PC-PLC). We tested other potential virulence factors produced by B. cereus, phosphatidylinositol-specific phospholipase C, and sphingomyelinase, which were nontoxic, and two hemolysins, cereolysin O, and a novel hemolysin designated hemolysin IV, which were marginally toxic in vitro. The histopathology of experimental septic endophthalmitis in rabbits mimicked the pathology produced by pure HBL, and both HBL and PC-PLC were detected at toxic concentrations in the infected eyes. Bacterial cells were first seen associated with the posterior margin of the lens and eventually throughout the lens cortex. Collagenase detected in the eye suggests that infiltration was facilitated by breakdown of the protective collagen lens capsule by that enzyme.

Our findings demonstrated for the first time that suspected virulence factors are actually produced during experimental septic B. cereus endophthalmitis and support our conclusion that HBL contributes to B. cereus virulence, and implicate PC-PLC and collagenase as additional virulence factors.

Acute inflammation is also typical of B. cereus endophthalmitis. Inflammation alone may produce severe intraocular tissue damage and is thought to be an important mechanism in the loss of vision from endophthalmitis. We tested whether glucocorticoids might affect the in vivo retinal damage caused by B. cereus exotoxins. Cell-free crude exotoxins from B. cereus were injected intraocularly in rabbits at several doses, with and without 400 mg of dexamethasone. Rabbits were graded clinically and killed after 4 or 18 h.  Histological preparations of eyes were graded for retinal damage and inflammation. Retinal toxicity or inflammatory scores did not differ between dexamethasone-treated and untreated eyes for any toxin dose at 4 or 18 h. Retinal damage and inflammation were dose-dependent. Inflammation generally increased significantly with time, but retinal damage was nearly maximal after only 4 h. Our results showed that dexamethasone did not diminish retinal toxicity or inflammation in a sterile model of B. cereus endophthalmitis. Inflammation appeared secondary to rapid tissue destruction caused by bacterial toxins. Effective treatments of endophthalmitis caused by toxigenic bacteria will likely require direct neutralization of secreted toxins.

Numerous seemingly beneficial physiological effects have been attributed to CLA. These include: inhibiting chemically induced carcinogenesis in several rodent models; enhancing the immune response while reducing the catabolic effects of immune stimulation in rodents and chickens; reducing atherosclerosis in rabbits and hamsters; enhancing growth of rats and pigs; and reducing body fat gain in mice, rats, hamsters, pigs, dogs and most recently humans.

Most of these reports involved administering mixtures of CLA isomers that contained mostly the cis-9,trans-11 and trans-10,cis-12 isomers of CLA in approximately equal amounts, with other CLA isomers at considerably lower levels. Emerging evidence indicates that the numerous biological effects of CLA are due to both the separate actions and synergistic interactions of the biologically active isomers, cis-9,trans-11 and trans-10,cis-12. New studies confirm that the diet fed to cows/steers can have a profound effect on the levels of these CLA isomers in dairy and beef products.

Studies on the effect of diet on the CLA content of cow's milk have reported that certain high fat diets (particularly diets high in soybeans) substantially increased milk CLA content, and that cis-9,trans-11 CLA was the principal isomer that was modulated.

However, beef fat from steers fed a control diet or the same diet supplemented with 2% or 4% soybean oil, respectively, contained 0.1%, 1.2%, or 1%, respectively, of trans-10,cis-12 CLA. By contrast the cis-9,trans-11 isomer content of the beef fat in these groups was unaffected (4%, 4.1%, or 4.6%, respectively). Hence, not just the absolute amounts, but also the ratios of the biologically active CLA isomers produced in the rumen and subsequently found in tissue may be affected by diet.

Effects on carcinogenesis. The biological activity of CLA was discovered because of its inhibitory effects on chemically induced epidermal carcinogenesis in mice, and subsequent research expanded this finding to include other rodent carcinogenesis models. The biochemical mechanism whereby CLA inhibits carcinogenesis is not yet known, but may involve effects on the metabolism of linoleic acid and vitamin A.

The effects of the biologically active CLA isomers on carcinogenesis appear to be complementary. Butter enriched naturally for the cis-9,trans-11 CLA isomer has been shown to effectively reduce chemically induced rat mammary neoplasia. However, there is also evidence for a synergistic interaction between cis-9,trans-11 and trans-10,cis-12 CLA in inhibiting carcinogenesis at this site. It is possible that both isomers might affect linoleic acid metabolism in a manner that reduces mammary carcinogenesis in the rat model, as well as exerting separate individual anticancer effects.

Given the current pace of new discovery concerning CLA, it is likely that our current ideas and models will change regularly and considerably over the next several years. For a regularly updated listing of the scientific literature on CLA, see the internet address http://www.wisc.edu/fri/clarefs.htm.

The carcass quarters were stored at 4ºC with 85% relative humidity for up to 14 d. In experiments to assess the impact of tempering, two sponge samples were taken per quarter before and after inoculation, after spraying and/or tempering, and following 1, 3, 7, and 14 d of storage, and the numbers of E. coli Biotype I and serotype O157:H7 determined. Spraying carcasses with LA significantly reduced the numbers of E. coli Biotype I and serotype O157:H7. The tempering process did not affect the survival of either type E. coli or alter the effectiveness of the LA spray.

To examine the influence of LA in combination with the other test chemicals, two excision samples of subprimal cuts were taken following inoculation and then after 1 and 3 d of storage at 4ºC. Pre-spraying subprimal cuts with TW20 significantly increased the antimicrobial effect of LA and LA with SB, with reductions in E. coli O157:H7 numbers of 3.1 and 3.4 log₁₀ CFU/cm², respectively, compared to spraying with TW20 and then with water. In comparison, spraying subprimal cuts with water, LA or LA in combinations with SB or TW20 resulted in average reductions of E. coli O157:H7 ranging from 2.0–2.7 log₁₀ CFU/cm².

In a separate experiment, the incorporation of TW20 (0.1 or 0.25%) in buffered peptone water prior to stomaching excised carcass surface samples resulted in the recovery of significantly higher numbers (ca. >log₁₀ CFU/cm² of E. coli O157:H7) than the control without added TW20. These results demonstrate that treatment of beef carcasses with LA reduces the number of viable E. coli O157:H7 and that this inactivation or removal by LA is enhanced by pre-spraying the carcass with a 5% solution of TW20.

Irfan Erol, Ph.D. DVM,  Visiting Scientist	I am originally from Turkey. I received a DVM degree from the School of Veterinary Medicine, University of Ankara in Turkey in 1985. I worked for a short time in a veterinary clinic. I decided to make a career in research and began work as a research assistant at the Department of Food Hygiene of School of Veterinary Medicine, University of Ankara in 1986. After one year I got a doctoral scholarship from the German Academic Exchange Service, and I received my Ph.D. degree with the project title "Effect of starter cultures on the growth of pathogenic microorganisms in Turkish fermented sausage." The degree came from the Department of Food Hygiene in the School of Veterinary Medicine, Free University Berlin, Germany, in 1991. After my return to the School of Veterinary Medicine in Ankara, I obtained the associate professor and full professor degrees in 1993 and 1999, respectively. In the School of Veterinary Medicine I teach food hygiene and microbiology and am working mainly with foodborne bacterial pathogens, i.e., Salmonella spp., Listeria monocytogenes and E. coli in foods of animal origin.  I joined Dr. Kaspar's research team in August 2000, and my research involves the characterization of hns mutant of E. coli O157:H7. We have a wonderful team and I am happy to have more time for research in my one-year sabbatical. I have been married for 8 years. My wife, Meral, is working as a biologist at the Clinical Microbiology Department of a state hospital in Turkey. We have a 5-year-old son, Orkun, in preschool. We enjoy living in Madison except for the cold weather. We also love traveling, music and sports. My wife and son will join me here in April.
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I was born and raised in Glendale on Milwaukee's north side, so I am well acclimated to Wisconsin weather. I received my Bachelor of Science in Biochemistry at UW–Madison, during which I started as a student hourly in Dr. Kaspar's laboratory. He then gave me the opportunity to conduct research through independent study in my senior year, and during this time I decided to attend graduate school. I completed work on a Master of Science degree in Food Microbiology and Safety in December 2000. My work involved studying the gene dps from Escherichia coli O157:H7, and the contribution of this gene to acid tolerance. Additionally, I introduced dps from E. coli O157:H7 into the ethanol-producing bacterium Zymomonas mobilis to try to increase acid tolerance to allow it to ferment to lower pH values. Currently, I am pursuing my doctoral degree in Dr. Kaspar's laboratory working with the archaea Ferroplasma acidarmanus. The goal is to understand how this organism is able to thrive in acid drainage (pH 0.0–1.0) from iron mines. This work will involve characterizing the complex physiology of this organism to identify genes pivotal to survival in acid conditions. I have decided to become more involved in aspects other than my research. I currently serve as co-chair on the College of Agricultural and Life Sciences Graduate Student Council and will be the president next year. I am also the graduate student representative on the board of directors for the Wisconsin Agricultural and Life Sciences Alumni Association (WALSAA). When I am not in the laboratory I try to have fun the Madison way. I have been homebrewing beers, ciders, wines, and meads for the last four years. Some other interests of mine are snowboarding, wakeboarding, biking, playing squash, traveling, and music.	David J. Baumler,  Ph.D. candidate

FRI ANNUAL MEETING SLATED FOR MAY 16 AND 17 Food safety experts from government, industry and academia will gather in Madison, Wisconsin, on May 16 and 17 for the 2001 Annual Food Research Institute Meeting at the University of Wisconsin–Madison. The Institute has a long history of excellence in identifying and addressing food safety issues. This focus on food microbiology and toxicology has developed through academic pursuits with government and industry. The formal program will include guest and university presentations on the recently published E. coli O157:H7 genome, Listeria risk assessment, updates on mycotoxins, antibiotic resistance, genetically modified foods, bovine spongiform encephalopathy, and other research conducted at FRI. Dr. Charles Duncan, Vice President, Research and Development, Hershey Food Corporation and former FRI professor, will be presented the William C. Frazier Memorial Award for his contributions to food microbiology. FRI will host a barbecue on May 15 to welcome attendees and allow for networking with other participants.  To learn more about the meeting and how to register, contact Jean Johnson by sending an email to jljohns2@facstaff.wisc.edu or by calling (608)263-7777. You can also find more information about the meeting at the Food Research Institute's web site, www.wisc.edu/fri/. Since 1966 the Institute has been part of the UW–Madison's College of Agricultural and Life Sciences. Researchers at the Institute work collaboratively with other scientists in the University and other national and international institutions.

Dr. Charles Duncan,  Wm. C. Frazier  Memorial Award recipient

Kaspar	PRESENTATION: Professor Charles Kaspar was an invited speaker at the National Cattlemen's Beef Association annual meeting in San Antonio, TX. The title of his talk was "Waterborne transmission of E. coli O157:H7 in cattle — contribution to herd prevalence and possible control point."
Somers		AWARD: Eileen B. Somers, Senior Research Specialist in Professor Wong's section, will receive the 2001 College of Agricultural and Life Sciences Academic Staff Award for Excellence in Research. Presentation will be at an Awards Banquet in April where all CALS award programs are recognized. Dean Elton E. Eberle writes, "Congratulations on being selected as one of this year's recipients. Certainly the Selection Committee found your nomination papers a public testimony to your outstanding performance for our College. I want to personally thank you for your service, and I look forward to working with you in the many years ahead." Eileen has been here 30 years. Her current major projects include: Plasma modification of surfaces to prevent biofilm formation; Biofilm development by Listeria monocytogenes under ready-to-eat meat processing conditions, and control strategies; and Heterogeneity of B. cereus hemolysin HBL.

• Latex as a Foodborne Allergen
• Listeria and Fish
• Alternatives to Antibiotics in Animal Feed

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Since latex gloves are used by some food handlers, there has been a question whether these latex allergens can be transferred to foods. Several years ago there was a report of two persons with known latex allergies suffering symptoms after consuming foods handled by food service workers using latex gloves. Recently, a woman known to be allergic to latex was tested with orange juice stirred with a latex glove. She had no reaction to unstirred juice but within 35 min of consuming the stirred juice, she suffered wheezing, tightness of the chest, and flushing of the face. Another latex-allergic woman suffered respiratory and dermal symptoms after eating salad at a restaurant where employees used latex gloves. Although there are not many such cases reported, it appears that there are sensitive people who do react to latex particles deposited on foods from gloves.

To prove that latex allergens were transferred to foods from powdered gloves, several batches of latex gloves were analyzed for protein content and transfer of allergens to cheese and lettuce. Some powdered gloves, particularly older ones, contained nearly twenty times the protein content of unpowdered gloves. Immunoassays for latex allergens revealed that these compounds were indeed transferred to cheese by touching with gloved fingertips, and to lettuce by manipulation with gloved hands. Food handlers' gloves are not currently regulated, but these data indicate that use of vinyl or polyethylene gloves may be preferable in order to avoid contaminating food with latex allergens.

A 1994–1995 Swedish outbreak of listeriosis, with two fatalities, that was traced to vacuum packed "gravad" (raw, spiced rainbow trout/salmon fillets), sparked interest in possible routes of contamination of these fish during processing. Investigation revealed that vacuum-packed trout was an excellent medium for growth of L. monocytogenes and that packing machines in the fish processing plants harbored the same strains as detected in the victims. Another cluster of cases, traced to cold-smoked rainbow trout, occurred in Finland in 1998. Since these products may be stored for several weeks under refrigeration and are consumed without cooking, they can be an effective vehicle for foodborne listeriosis.

Recent survey information from other countries indicates that L. monocytogenes is indeed present in fishery products from many countries although reported incidence varies greatly. A survey in Italy indicated that 7.6% of raw fish, 38% of smoked fish and 28% of meat sausages contained L. monocytogenes. In Denmark, government surveys of preserved (uncooked) fish products found L. monocytogenes in 23.8% of 105 samples in 1997 and in 21.5% of 177 samples in 1998. This is somewhat higher than the incidence rates of 14–16% found in preserved, uncooked meat products during the same years. Smoked fish is apparently just as likely to harbor listeriae as sausage.

There are few published papers on the incidence of listeriae in fish and shellfish from Latin America. Listeria monocytogenes has been reported in some raw seafood from Argentina, Brazil, and Chile, but in most cases these were products which would be cooked before eating. Of more concern was the finding of L. monocytogenes in 7 of 15 Chilean salmon samples intended for production of a cured and spiced raw salmon product called "gravlax." This product would not be heat treated and listeriae might therefore reach dangerous levels during refrigerated storage.

Few listeria-positive samples of fish and shellfish have been detected in surveys done in India. It has been suggested that warm, tropical waters may not be hospitable environments for psychrotrophic L. monocytogenes. While this bacterium can outgrow most other species in the refrigerator, it may not compete well in warm waters where other bacteria proliferate. Even less data are available on the presence of listeriae in African seafood. In terms of world trade, Africa is a net exporter of fishery products and those products most likely to pose a problem would be bluefin tuna intended for sushi and sashimi, live shellfish, and cold, smoked fish, such as farmed trout from Morocco.

There is increasing recognition that fish may be contaminated with listeriae even though we have not witnessed any large outbreaks. This may be because smoked and preserved fish are not as widely consumed as some other ready-to-eat foods. These fish products are often produced in relatively small plants and this may limit the distribution of any contaminated product. However, the FDA/USDA draft assessment of the relative risk from foodborne L. monocytogenes (published in January 2001) predicts that the contamination level of smoked fish at the retail level would be relatively high while that of preserved fish is moderate. Raw seafood and cooked ready-to-eat crustaceans are predicted to have low levels of contamination.

Other ingredients have been investigated as possible substitutes for subtherapeutic antibiotics for enhancing growth and feed efficiency. Probiotic cultures containing yeast, lactobacilli, or other intestinal bacteria have been shown to protect piglets from intestinal pathogens and thereby enhance growth. These probiotics may act by competitive exclusion, i.e.,  preventing attachment of pathogens to intestinal mucosa, or producing antimicrobial compounds (bacteriocins and organic acids), or by stimulation of intestinal immune responses. Alteration of the permeability of the gut to increase uptake of nutrients is another possibility.

Enzymes which break down various feed components, such as mixtures containing cellulase, xylanase, glucanase, amylase and pectinase have improved nutrient utilization and performance of growing pigs fed barley. Phytase was also found to improve weight gain and feed conversion ratios in pigs. This enzyme degrades phytate, which binds 50–75% of the phosphorus in plant material. Since phytate prevents utilization of this phosphorus, pig feed is usually supplemented with phosphates. The use of phytase also decreases the amount of phosphate in swine manure which decreases detrimental effects of manure disposal.

Addition of antibodies or other immunoactive compounds to feed may inhibit pathogens causing subclinical infections in livestock. Such antibodies can be produced in hens' eggs which can then be used in feed. Spray-dried porcine plasma proteins (which contain immunoactive proteins) also reduce mortality and diarrhea and improve growth in piglets.

Organic acids added to feed generally improve growth, but the magnitude of the effect varies with the type of acid and other components of diet. These acids lower feed and gut pH, apparently acting to control bacterial populations in the upper intestinal tract. Organic acids also appear to improve the digestibility and absorption of proteins, minerals, and other nutrients. Fermentation can also effectively acidify diets. Several million tons of liquid by-products of food industries are recycled into pig feed in Europe, and these fermented products increase weight gain and improve feed conversion ratios.

In addition, minerals, vitamins, conjugated linoleic acid, amino acids, plant fibers and herbs have shown some promise in improving growth and feed efficiency in farm animals. One or more of these ingredients may prove to be an effective alternative for subtherapeutic doses of antibiotics in feeds, and thereby reduce the likelihood of development of antibiotic resistance in bacteria.