The use of digital games and simulators in veterinary education: an overview with examples.

In view of current technological possibilities and the popularity of games, the interest in games for educational purposes is remarkably on the rise. This article outlines the (future) use of (digital) games and simulators in several disciplines, especially in the veterinary curriculum. The different types of game-based learning (GBL)-varying from simple interactive computer board games to more complex virtual simulation strategies-will be discussed as well as the benefits, possibilities, and limitations of the educational use of games. The real breakthrough seems to be a few years away. Technological developments in the future might diminish the limitations and stumbling blocks that currently exist. Consequently, educational games will play a new and increasingly important role in the future veterinary curriculum, providing an attractive and useful way of learning.

Evaluation of four different diagnostic tests to detect Clostridium difficile in piglets.

Clostridium difficile is emerging as pathogen in both humans and animals. In 2000 it was described as one of the causes of neonatal enteritis in piglets, and it is now the most common cause of neonatal diarrhea in the United States. In Europe, C. difficile infection (CDI) in both neonatal piglets and adult sows has also been reported. Diagnosis of this infection is based on detection of the bacterium C. difficile or its toxins A and B. Most detection methods, however, are only validated for diagnosing human infections. In this study three commercially available enzyme immunoassays (EIAs) and a commercial real-time-PCR (Becton, Dickinson, and Company) were evaluated by testing 172 pig fecal specimens (139 diarrheic and 33 nondiarrheic piglets). The results of each test were compared to those of cytotoxicity assays (CTAs) and toxigenic culture as the "gold standards." Compared to CTAs, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were, respectively, as follows: for real-time PCR, 91.6, 37.1, 57.6, and 82.5%; for Premier Toxins A&B (Meridian), 83.1, 31.5, 53.1, and 66.7%; for ImmunoCard Toxins A&B kit (ICTAB; Meridian), 86.6, 56.8, 66.9, and 80.7%; and for VIDAS (bioMérieux), 54.8, 92.6, 85.0, and 72.8%. Compared to toxigenic culture, the sensitivity, specificity, PPV, and NPV were, respectively, as follows: for real-time PCR, 93.0, 34.7, 50.0, and 87.5%; for Premier Toxins A&B, 80.3, 27.7, 43.8, and 66.7%; and for ICTAB, 80.0, 46.2, 52.8, and 75.4%; and for VIDAS, 56.4, 89.8, 77.5, and 76.7%. We conclude that all tests had an unacceptably low performance as a single test for the detection of C. difficile in pig herds and that a two-step algorithm is necessary, similar to that in cases of human CDI. Of all of the assays, the real-time PCR had the highest NPV compared to both reference methods and is therefore the most appropriate test to screen for the absence of C. difficile in pigs as a first step in the algorithm. The second step would be a confirmation of the positive results by toxigenic culture.

Aerial dissemination of Clostridium difficile on a pig farm and its environment.

Clostridium difficile is increasingly recognized as an important enteropathogen in both humans and animals. The finding of C. difficile in air samples in hospitals suggests a role for aerial dissemination in the transmission of human C. difficile infection. The present study was designed to investigate the occurrence of airborne C. difficile in, and nearby a pig farm with a high prevalence of C. difficile. Airborne colony counts in the farrowing pens peaked on the moments shortly after or during personnel activity in the pens (P=0.043 (farrowing pens 1, 2), P=0.034 (farrowing pen 2)). A decrease in airborne C. difficile colony counts was observed parallel to aging of the piglets. Airborne C. difficile was detected up to 20 m distant from the farm. This study showed widespread aerial dissemination of C. difficile on a pig farm that was positively associated with personnel activity.

Reduction of Clostridium sporogenes spore outgrowth in natural sausage casings using nisin.

Preservation of natural sausage casings using dry salt or saturated brine is regarded as sufficient to inactivate vegetative pathogenic non-spore-forming bacteria present on the casings. Although the outgrowth of bacterial spores is prevented by salt or saturated brine preservation, these spores will remain present and develop into vegetative cells when conditions are more favourable. To prevent subsequent outgrowth additional preservation measures should be implemented. In the experiments described the use of nisin was evaluated to reduce outgrowth of spores in desalinated casings. The bacteriocin nisin was chosen because of its known efficacy against spore-forming bacteria and their spores in various foodstuffs. Clostridium spore suspensions (Clostridium sporogenes, ATCC 3584) were used in two concentrations to inoculate three nisin concentrations (10, 50, 100 µg/mL) in water containing gamma-irradiated casings. Additionally, the binding of nisin to casings, using (14)C-labeled nisin Z and subsequent availability of nisin were evaluated. Results demonstrate that nisin is partly reversibly bound to casings and can reduce the outgrowth of Clostridium spores in the model used by approximately 1 log(10) (90%). However, the biological relevance of these results needs to be determined further by conducting industrial trials before any recommendation can be made on the practical implementation of nisin in the preservation of natural sausage casings.

Short communication: Repeatability of differential goat bulk milk culture and associations with somatic cell count, total bacterial count, and standard plate count.

The aims of this study were to assess how different bacterial groups in bulk milk are related to bulk milk somatic cell count (SCC), bulk milk total bacterial count (TBC), and bulk milk standard plate count (SPC) and to measure the repeatability of bulk milk culturing. On 53 Dutch dairy goat farms, 3 bulk milk samples were collected at intervals of 2 wk. The samples were cultured for SPC, coliform count, and staphylococcal count and for the presence of Staphylococcus aureus. Furthermore, SCC (Fossomatic 5000, Foss, Hillerød, Denmark) and TBC (BactoScan FC 150, Foss) were measured. Staphylococcal count was correlated to SCC (r=0.40), TBC (r=0.51), and SPC (r=0.53). Coliform count was correlated to TBC (r=0.33), but not to any of the other variables. Staphylococcus aureus did not correlate to SCC. The contribution of the staphylococcal count to the SPC was 31%, whereas the coliform count comprised only 1% of the SPC. The agreement of the repeated measurements was low. This study indicates that staphylococci in goat bulk milk are related to SCC and make a significant contribution to SPC. Because of the high variation in bacterial counts, repeated sampling is necessary to draw valid conclusions from bulk milk culturing.

Integrating the issues of global and public health into the veterinary education curriculum: a European perspective.

Veterinary public health is an essential field in public health activities, based upon veterinary skills, knowledge and resources and which aims to protect and improve human health and welfare. This discipline has evolved through three stages, beginning with the fight against animal diseases, moving on to include meat inspection and control of zoonoses and now encompassing a much broader health sciences education, with the goal of guaranteeing a safe and wholesome food supply, protecting human wellbeing and conserving the environment. Within the veterinary medicine curriculum, veterinary public health has undergone a similar development. At first, it was mainly concerned with slaughterhouse-based courses but in time it included the teaching of such subjects as epidemiology, the control of communicable (zoonotic) diseases and emergency preparedness. Veterinary medical faculties in Europe have adjusted their curricula over the past few years to reflect these changes in the subject and to meet the need for specialisation. It could be said that veterinary public health education has literally moved from the local abattoir to the global community. In this paper, the authors briefly discuss examples of veterinary medicine curricula at different universities. The veterinary public health curriculum of the Faculty of Veterinary Medicine, Utrecht, is then discussed in detail, as an example of the European perspective on integrating global and public health issues into the veterinary curriculum.

Application of HACCP principles to control visitor health threats on dairy farms open to the general public.

An increasing number of Dutch dairy farmers have diversified their activities, often opening their farm up to visitors (tourist accommodation, farm shop, contact with livestock, etc). It is essential to prevent these visitors from having accidents or becoming ill, which could result in financial claims and might harm the reputation of the agricultural sector. This article describes how the hazard analysis critical control points concept and principles (HACCP) can be applied to these activities and integrated with on-farm operational herd health and production management programmes.

[Escherichia coli O157 in Dutch domesticated rabbits]. / Escherichia coli O157 bij gedomesticeerde Nederlandse konijnen.

Enterohaemorrhagic Escherichia coli (EHEC) has been detected in both wild and domesticated rabbits in other countries. The aim of this study was to determine whether the most pathogenic E. coli serotype, O157:H7, occurs in the Dutch domesticated rabbit population and thus could form a public health risk. To this end, faecal samples were collected from rabbits from two rabbit farms and 741 rabbits of different breeds and origin and analysed for E. coli O157:H7, using a combination of enrichment, immunomagnetic separation, selective culture, and PCR. E. coli O157:H7 was not detected in any of the samples. The results indicate that Dutch domesticated rabbits probably do not play a role in the infection of humans with E. coli O157:H7.

Potential routes of acquisition of Arcobacter species by piglets.

The aim of this study was to determine the prevalence and the transmission routes of Arcobacter spp. in sows and their offspring on a breeding farm. Twelve Arcobacter-positive sows and their litters were studied for this purpose. Analysis of rectal samples showed a high prevalence of Arcobacter spp. among the sows (approximately 42% of the sows carried one or more Arcobacter species). Intermittent excretion of one particular species and shifts in excretion from one species to another were observed in individual animals over time. The detection of Arcobacter spp. in amniotic fluid of the sows and in rectal samples from newborn piglets (ranging from 38.5-83.3% per litter), as well as the high similarity between PFGE profiles of Arcobacter isolates from sows and their respective newborns indicated the existence of an intra-uterine transmission route for Arcobacter spp. Specific antibodies against Arcobacter spp. were detected in colostrum by Western blot. At 2 weeks of age, only a few piglets were positive for Arcobacter. The reappearance of Arcobacter in these piglets at Week 3 and the shift in the Arcobacter species detected (from a prominent presence of A. cryaerophilus at birth to the presence of A. skirrowii and A. butzleri at 3 weeks after birth) showed that a post-natal infection route from their mothers, newcomers or the environment to the piglets existed. Thus, in this manuscript the transmission of Arcobacter spp. (both vertical and horizontal) from carrying sows to their offspring is demonstrated.

[Swimming in summer]. / Zwemmen in de zomer.

It happens every summer: 'Swimming prohibited because of cyanobacteria'. Blooming of these toxine producing bacteria in warm summer months is a well known risk for swimming human beings. But how big is this risk for swimming dogs? And how big are other risks? In this article these risks are assessed for dogs that occasionally swim in surface water during the summer in the Netherlands. Based on these findings an advice will be given for dog owners to keep these risks for waterborne infections as small as possible.

Sensitivity of Shiga toxin-producing Escherichia coli (STEC) strains for colicins under different experimental conditions.

Twenty Escherichia coli strains producing well-characterised colicins were tested for their inhibitory activity against five Shiga toxin-producing E. coli (STEC) strains using different media under aerobic and anaerobic conditions. The five STEC strains used were of serotype O26, O111, O128, O145 and O157:H7 which are frequently isolated serotypes associated with disease in humans. The main route of infection for humans is through the eating of badly cooked or handled beef. The major reservoir for STEC strains in cattle is the rumen. To mimic the situation in the rumen of cattle, overlay assays were also performed under anaerobic conditions in the presence of 30% rumen fluid. Colicins E1, E4, E8-J, K and S4 are most active against STEC strains under anaerobic conditions in the absence or presence of rumen fluid. These colicins will be used in future experiments with the aim to eradicate the presence of STEC in cattle.

Antagonistic activities of several bacteria on in vitro growth of 10 strains of Campylobacter jejuni/coli.

Chicken meat contaminated with Campylobacter jejuni can be the source of human enteritis. To decrease the risk of human infection, Campylobacter should be controlled at farm levels. Orally given probiotic bacteria could prevent colonisation of chicken with pathogenic bacteria like Campylobacter. The aim of this study was to investigate the effect of different bacteria on Campylobacter growth. Our results demonstrated that bacteria isolated from conventional chicken had potential inhibitory activities against Campylobacter. Other bacteria not isolated from chickens but with known antagonistic capacities, e.g. Enterococcus (56 strains) and Escherichia coli (20 strains), did not show any negative effect on Campylobacter. Interestingly, one Lactobacillus (P93) strain isolated from the chicken gut showed bactericidal activity against all tested Campylobacter. The bactericidal effect was characterised as the production of organic acids in combination with probably production of an anti-Campylobacter protein. In a co-culture study of Campylobacter and Lactobacillus (P93), the culturability of Campylobacter was under the detection limit after 48 h of incubation. A chicken experiment is needed to further evaluate the effect of the promising probiotic bacteria against Campylobacter colonisation in chicken.

Control of VTEC in Dutch livestock and meat production.

The Dutch government and the meat industry, recognising VTEC as having important public health, meat quality and economic implications, have taken a number of initiatives within the last 5 years to control VTEC in livestock and meat. These initiatives, brought together last year in a 'Masterplan VTEC', include short-, middle- and long-term priorities. Short-term priorities include advice on interventions in the cases of an outbreak of VTEC associated with a cattle herd, the implementation of handbooks for Good Manufacturing Practice (GMP) in slaughterhouses and deboning plants, and the execution of an action programme on zero-tolerance to faecal contamination of carcasses. Mid-term activities include surveillance of the occurrence of VTEC and other enteropathogens in livestock and meat, and the investigations of VTEC population dynamics in dairy farms, transportation and farm hygiene. In the longer term, this programme aims to produce a system of Integrated Quality Assurance, consolidating effective measures to control VTEC in Dutch livestock and meat, and integrating emerging means for control and prevention.

Isolation and identification of fimbriae and toxin production by Escherichia coli strains from cows with clinical mastitis.

A total of 20 Escherichia coli strains isolated from cases of bovine mastitis were examined for fimbriae production, for the presence of genes coding for enterotoxins (LT and ST1), verotoxins (VT), and for the production of cytotoxic necrotizing factors (CNF1 and CNF2). Fimbriae could be isolated from four strains. The N-terminal amino acid sequence of the fimbriae from two strains, was determined. The two sequences were almost identical and homologous to that of the major subunit of E. coli F17 fimbriae. A DNA probe was derived from this N-terminal sequence and used as probe in hybridization experiments with chromosomal DNA of the 20 strains. To test if the strains contained genes that code for the F17 adhesin and the F17 major subunit, a Polymerase Chain Reaction (PCR) assay was performed with primers based on the nucleotide sequence of the genes. Eleven of 20 strains contained sequences that were homologous with sequences for the F17 fimbrial subunit and the F17 adhesin. Strains were tested directly for toxin production on Hela cells and by PCR for the presence of toxin genes. One of the twenty strains, produced a CNF toxin. No strains reacted positive in the PCR for LT, ST1 and verotoxin genes.

Identification of Escherichia coli strains from cows with clinical mastitis by serotyping and DNA polymorphism patterns with REP and ERIC primers.

A number of Escherichia coli strains was isolated during a study of clinical mastitis on seven farms in the Netherlands. From these E. coli strains, 30 were characterised with regard to their serotype and their DNA polymorphism pattern with REP and ERIC primers. Special attention was given to recurrent E. coli mastitis in cows. The combination of serotype and DNA pattern observed, was used to study the epidemiology of clinical E. coli mastitis. The results demonstrated that the PCR reaction with the ERIC primers can be used for differentiation of E. coli strains. The DNA polymorphism patterns showed that E. coli strains isolated from cases of clinical mastitis have a great variability in genotype. More 3 than one case of clinical mastitis associated with E. coli during the same lactation period occurred infrequently. However when it took place, E. coli strains isolated from the separate episodes of inflammation, were in most instances of the same serotype and had the same DNA amplification pattern.

Genotyping by PCR, of Staphylococcus aureus strains, isolated from mammary glands of cows.

A total of 71 Staphylococcus aureus strains isolated from bovine mammary glands were identified and subtyped. The methods used to differentiate between the S. aureus isolates were the DNA polymorphism pattern after amplification with a Polymerase Chain Reaction using several primer combinations and phage typing. The DNA fingerprinting technique using RAPD, ERIC1R and ERIC primers proved to be useful in differentiating isolates of S. aureus. Differentiation of isolates using phage typing gave no additional information compared to the DNA technique. The outbreak of S. aureus in the herd studied was mainly caused by one S. aureus strain. Other strains were only found on three occasions, twice in subclinical infections and once from a case of clinical mastitis. In the latter case the dominant strain was isolated from a different quarter of the same cow. Four of the ten cows studied suffered from clinical mastitis. From those four cows, three remained infected with the same S. aureus strain despite antibiotic treatment.

Monitoring of transmission of Salmonella enterica serovars in pigs using bacteriological and serological detection methods.

The standard method to detect Salmonella positive pigs is bacteriological examination of the faeces, but in recent years the use of Salmonella-ELISA's have become available to screen pigs for serological evidence of infection. This study was conducted to monitor the transmission of five different Salmonella enterica serovars (S. Typhimurium, S. Brandenburg, S. Panama, S. Livingstone, and S. Goldcoast) in fattening pigs and to test the feasibility of Salmonella-ELISA, using seeder pigs as a mode of transmission. Serovar dependence in transmission was observed. The Salmonella-ELISA proved to be useful to detect S. Typhimurium and S. Brandenburg in herds but was of limited value to demonstrate S. Livingstone, S. Goldcoast, and S. Panama.

Epidemiological characteristics of bovine clinical mastitis caused by Staphylococcus aureus and Escherichia coli studied by DNA fingerprinting.

OBJECTIVE: To study the epidemiology of clinical mastitis caused by Escherichia coli and Staphylococcus aureus by differentiating isolates with DNA fingerprinting techniques, using polymerase chain reaction. DESIGN: Milk samples were collected from cases of clinical mastitis in dairy cows. Escherichia coli and S aureus isolates from these cases were compared within and between cows and herds. SAMPLE POPULATION: Seven dairy herds with an average bulk milk somatic cell count < 150,000/ml, and incidence of cows with clinical mastitis of > 25%/y. PROCEDURE: Chromosomal DNA was isolated from E coli and S aureus strains isolated from cases of clinical mastitis, and amplified by polymerase chain reaction, using enterobacterial repetitive intergenic consensus primers for E coli and a random amplified polymorphic DNA primer for S aureus. Escherichia coli and S aureus strains were identified and differentiated, using their DNA polymorphism pattern. RESULTS: Multiple E coli genotypes were found in each of the herds. Persistent infections with E coli were sporadic. Only a limited number of different S aureus genotypes was found in each of the herds studied. Recurrent cases of S aureus mastitis were found in 25% of quarters with clinical S aureus mastitis. Comparing S aureus isolates from different herds indicated that 1 S aureus genotype was most prevalent. CONCLUSIONS: Because different quarters were infected with different genotypes, it was concluded that E coli is an environmental pathogen, and does not generally spread from quarter to quarter. The hypothesis that S aureus mastitis is a contagious disease, spreading from infected to uninfected quarters, could not be rejected.

In vitro study on the effect of organic acids on Campylobacter jejuni/coli populations in mixtures of water and feed.

Gastroenteritis caused by Campylobacter spp. infection has been recognized as one of the important public health problems in the developed countries. Outbreaks mostly originate from the consumption of contaminated poultry or infected water. The aim of this study was to determine the bactericidal activity on Campylobacter spp. of organic acids individually and in combinations at different pH levels and times and to compare bactericidal activities with activities of commercially available products. Ten strains of Campylobacter spp. were added in a mixture of water with commercial broiler feed, separately adjusted by four acids: formic, acetic, propionic, and hydrochloric acids, into pH 4.0, 4.5, 5.0, and 5.5. A combination of three organic acids was used in two different formulation ratios: formic:acetic:propionic at 1:2:3 and 1:2:5, at pH 4.0, 4.5, 5.0, and 5.5. All organic acids showed the strongest bactericidal effect on Campylobacter at pH 4.0. In contrast, at pH 5.0 and 5.5, the bactericidal activity of the four acids was low. The combination of organic acids showed a synergistic bactericidal activity at pH 4.5. Interestingly, the effect of the combined organic acids was stronger than the commercial products. Morphological cell changes were studied by transmission electron microscopy to determine the effect of the organic acids on the cell structure of Campylobacter. Some loss of outer membranes of the bacteria could be found in treated groups. Therefore, it can be concluded that organic acids, individually or in combination, have a strong bactericidal effect on Campylobacter spp. Routine application of organic acids to the water supply on poultry farms could prevent or diminish Campylobacter transmission.