P.G.H. Bijker

Survival of Escherichia coli O157:H7 ATCC 43895 in a Model Apple Juice Medium with Different Concentrations of Proline and Caffeic Acid

ABSTRACT The effects of proline and caffeic acid on the survival of Shiga toxin-producing Escherichia coli (STEC) O157:H7 strain ATCC 43895 in a model apple juice medium were studied. It is hypothesized that the inhibitory effect of caffeic acid may explain why almost all outbreaks of STEC O157:H7 infections linked to apple juice or cider have occurred in October or November.

The transmission of campylobacter in piggeries; an epidemiological study

The campylobacter infection of 10 sows and their piglets was monitored. These pigs werekept on two multiplier farms. Rectal faeces samples were taken from the sows shortly beforelittering and at different intervals after littering. Swab samples of rectal content were taken fromsix piglets per sow at different intervals after birth. Nine sows were shown to be infected withcampylobacter before litter and all sows after litter, with an average colony count of 4·1in log N g–1 of faeces. Half of the piglets became infected withcampylobacter during the first week of life and 85%, after four weeks. Two genetic subtypingmethods (ERIC‐PCR and RFLP) were used to study the relationships between campylobacterisolates from sows and piglets. A large diversity of campylobacter subtypes was found.Nevertheless, piglets and their mothers often harboured campylobacter isolates with identicalgenetic subtyping profiles, suggesting that piglets become infected via their mothers. However,observed similarities in genetic subtyping profiles between campylobacters isolated on differentfarms made this difficult to prove.

Prevalence of campylobacter in pigs during fattening; an epidemiological study

Numerous epidemiological reports implicate foods of animal origin as vehicles of human campylobacteriosis. Pigs are probably an important reservoir of campylobacter and a potential source of human infection. In order to improve our knowledge of the epidemiology of campylobacter in pigs, the prevalence of campylobacter and its contamination of feed were monitored in eight pig farms. Faeces samples of pigs aged 11 and 22 weeks, and samples of rectal, ileal and gastric content at a slaughterhouse were collected for bacteriological examination. On 5 farms, subsequent groups of pigs housed in the same stalls was sampled, too. A selection of the campylobacter isolates was characterized with a genetic typing method (RFLP). More than 85% of the sampled porkers were shown to be intestinal carriers of campylobacter at all stages of fattening. Subsequent groups of pigs housed in the same stalls were all carriers, too. The level of campylobacters in the faeces tended to decrease as the pigs got older. There was no difference in the frequency and level of infection with campylobacter between porkers on different farms. The feeding system (wet feed versus dry pellets) did not seem to influence the prevalence of campylobacter although wet feed gave lower counts of Enterobacteriaceae in the faeces. RFLP-typing showed a high diversity of campylobacter strains at each sampling on the farm. Similarities were seen between strains isolated during two subsequent samplings of the same group of pigs, but not between strains isolated on the same farm from subsequent groups of pigs housed in the same stall. This suggests that the piglets were already infected at a young age on the breeding farm.

Microbial and nutritional aspects of feeding fermented feed (poultry by‐products) to pigs

Broiler by-products (heads, feet, and viscera) mixed with 4% dextrose were pasteurized for 4 min at 90 degrees C core temperature, cooled to 20 degrees C, and fermented with Lactobacillus plantarum as starter culture. These fermented poultry by-products were fed to 12 individually housed fattening pigs as part (17.6% of the dry matter) of their fattening ration, the remainder composed of compound pig feed. Control pigs received a compound pig feed only. Both groups of pigs were fed restrictively on the basis of body weight. The technical results of the pigs fed the experimental diet showed a significantly improved feed:gain ratio (2.46 vs 2.57), a significantly higher carcass weight (86.1 vs 81.8 kg), a lower meat percentage (50.9 vs 52.5%) and an increased backfat thickness (21.5 vs 18.7%). The bacterial flora in the intestinal tract of the pigs fed the experimental diet differed significantly from the control animals. Decreased colony counts of mesophilic aerobic bacteria, Enterobacteriaceae, enterococci and lactobacilli were found in the rectal content and the prevalence of salmonella was lower. It is suggested that the improved feed:gain ratio and the reduced bacterial activity of the measured groups of bacteria is a result of 1) the higher energy content of the diet, and(or) 2) an assumed enhanced digestibility of nutritional components in the diet, and(or) 3) the lower incidence of diarrhea in the pigs fed with fermented poultry by-products. This resulted in a lower contamination level of enteropathogenic bacteria like, salmonella and Escherichia coli, in the gastro-intestinal tract of the pigs fed fermented poultry by-products.

Pathogenic micro-organisms in slaughterhouse sludge—a survey

During slaughtering of animals and subsequent meat processing the process water used becomes polluted with organic matter of animal origin (i.e. protein and fat). This organic sludge is, in principle, a product suitable for animal feeding. To investigate the microbiological contamination level of sludge, raw sludge was collected at pig (n = 8) and poultry (n = 5) slaughterhouses. Both flocculated and aerobically activated sludge was monitored. Slaughterhouse sludge was heavily contaminated with Enterobacteriaceae (6.3-10.0 in log10 N/gram dry matter) and enterococci (4.6-7.9). Clostridia were present in sludge at a level of 3.1-5.8 (in log10 N/g DM). Salmonella was present in the sludge from all slaughterhouses examined. Yersinia enterocolitica serotypes O:3 and O:9 were found in sludge from seven out of thirteen slaughterhouses. The prevalence of Campylobacter jejuni/coli was higher in flocculated poultry sludge than in both flocculated pig sludge and aerobically activated pig sludge. Obviously, decontamination of the sludge is mandatory when it is to be applied as a feed constituent, to prevent bacterial cycles from occurring in livestock, as well as the spread of human pathogenic zoonoses like campylobacter, salmonella and yersinia, to minimize loss of protein quality by the microbial breakdown of amino acids and the formation of possible toxic metabolites in sludge during storage.

Slaughter by‐products: Problems, preliminary research and possible solutions

The collection, storage, disposal and processing of slaughterhouse by-products is an important part of veterinary care in regions with intensive animal husbandry and meat production. Transmission of diseases and environmental pollution through an improper and/or incorrect handling of slaughterhouse by-products needs to be prevented. The use of animal by-products as feedstuff could be of economical benefit to slaughterhouses and could add nutritive value to animal feed. As a results of the centralisation and intensification of slaughtering, the amount of slaughter by-products produced at a single location is increasing. Until now, hardly any attention, in practice or in research, has been paid to the collection and disposal of these by-products. There are important socio-economic reasons to increase scientific knowledge about the handling of slaughter by-products. Several animal by-products were contaminated with Salmonella. We also showed that rapid breakdown of amino acids in poultry by-products occurs during storage at 20 degrees C. It is concluded that as far as safety, environmental care and nutritive value of animal by-products is concerned, diversification and separation of slaughter by-product collection, storage, disposal and processing is necessary. Measures at source, the slaughterline, and some technologies are suggested for future use.

Fermentation of aerobically activated pig slaughterhouse sludge for animal feed purposes

Abstract Aerobically activated sludge from a pig slaughterhouse wastewater-treatment plant was mixed with 0.35 or 0.5% (wt/wt) dextrose, with 0.5% (wt/wt) dextrose and 0.05 or 0.2% (v/v) formic acid, or with 2.5% (wt/wt) molasses and 0.1% (v/v) formic acid, and was pasteurized at 95°C for 5 min. After cooling to approximately 20°C the sludge was inoculated with 10 6 –10 7 cfu Lactobacillus plantarum /g sludge. Fermentation was performed at 20°C for 21 days. When 0.05% (v/v) formic acid or less was added, the initial pH of the sludge was favourable for the germination and outgrowth of clostridia spores and resulted in amino acid breakdown. In the case of the addition of 0.2% (v/v) formic acid and 0.5% (wt/wt) dextrose the initial pH was below 4 and the number of lactobacilli did not substantially increase. No amino acid breakdown was observed. Concerning the safety of the fermented product, it was concluded that pasteurized activated sludge from a pig slaughterhouse can be effectively fermented into a stable product, suitable for animal feed purposes, with 2.5% (wt/wt) molasses, 0.1% (v/v) formic acid and L. plantarum as the inoculum.

The Prevalence of Campylobacter in Pigs during Fattening

The aim of this study was to improve our knowledge of the epidemiology of campylobacters in pigs. This can help in understanding whether it is possible to reduce the prevalence of campylobacters in the pig population and, ultimately, to produce campylobacter-free pork. For this purpose the prevalence of campylobacters in porkers in 8 farms was monitored. A selection of campylobacter isolates was characterised by a genetic typing method known as RFLP (Restriction Fragment Length Polymorphism).

Some aspects of the gastrointestinal microflora of veal calves fed different rations: a pilot study.

The gastrointestinal microflora of veal calves reared on different diets was studied because the nature of this microflora affects the quality of veal as a result of contamination of carcass surfaces with intestinal contents during slaughter. Diet A consisted of a milk substitute, diet B of milk substitute + straw pellets and diet C of milk substitute + straw pellets + concentrates. In the rumen fluid of calves reared on diet A significantly higher counts of Gram-negative bacteria but lower counts of thermotrophic enterobacteriaceae were found than in calves reared on diets B or C. As for the faecal flora, diets B and C seem to result in significantly lower counts of Gram-negative bacteria and thermotrophic enterobacteriaceae. In 46% of the faecal specimens and 62% of the specimens of rumen fluid from calves fed on milk substitute only, Pseudomonas aeruginosa was isolated in mean counts of 4.1 log cfu/g and 5.2 log cfu/g respectively. P. aeruginosa could not be isolated from any specimen from calves receiving straw pellets. These results indicate that the inclusion of straw pellets in the diet of veal calves may increase the bacteriological safety and keeping quality of veal.

Bacteriological quality assurance (BQA) of mechanically deboned meat (MDM).

Adequacy of bacteriological quality assurance during the commercial production of mechanically deboned meat (MDM) was assessed. Lax standards of hygiene during production were observed, resulting in high numbers of Staphylococcus aureus, viz. 10(4) to 10(5) cfu g(-1), and severe contamination with Enterobacteriaceae: 10(5) to 10(6) cfu g(-1). These data indicate that measures of hygiene observed during boning of carcasses and during collection, storage and transport of bones or poultry parts should be markedly tightened, while conditions of refrigerated storage of raw materials and MDM should be improved. Use of bones of poor sensory quality (discoloration, abnormal smell) generally resulted in MDM of inferior bacteriological quality. Phage typing, biotyping and assessment of enterotoxin production was carried out with 136 St. aureus cultures, isolates from mechanically deboned pork produced at one plant. Fifty-five per cent of the isolates was not typable, 28% was typable with human phages, 8% with bovine phages. The majority of the strains could not be explicitly assigned to any Meyer and/or Hájek and Marŝálek types. Applying the simplified system of Devriese to eighteen strains isolated in our investigation, ten were found to belong to the poultry ecovar, one to the bovine ecovar, while seven strains were non-host specific. None of the isolates produced enterotoxins A-E. Microbiological inspection of end products is recommended as part of an integrated quality assurance system. The following reference values for the final product (maximal colony counts to be expected under GMP conditions expressed as 95th percentile) were calculated: Pig MDM: log(10) mesophilic colony count 6·8 and log(10) cfu mesophilic Enterobacteriaceae g(-1) 4·8; Poultry MDM: log(10) mesophilic colony count 6·6 and log(10) cfu mesophilic Enterobacteriaceae g(-1) 4·7.