Safe poultry meat production in the next century.

The revolutionary industrialisation of the poultry industry in the last 30 years has made the food poultry meat available for large groups of consumers. Due to its nutritional, sensory and economical characteristics, poultry meat is by far the most popular animal food product world-wide. Epidemiological reports, however, incriminate poultry meat as a source for outbreaks of human food poisoning. The organisms involved are Salmonella spp., Campylobacter spp. and, to a lesser extent, Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, Yersinia enterocolitica, Clostridium perfringens and Aeromonas spp. Contamination of the end-product with pathogenic microorganisms is a reflection of the contamination of the live birds and, therefore, measures to be taken by industry to avoid contamination of the consumer-ready product should start at that level. In terms of the critical control point approach of the HACCP concept, the quantitative contribution of critical phases in the production chain towards end-product contamination should be estimated in order to take the necessary intervention or corrective steps. To guarantee the production of safe poultry meat, knowledge of the capability of microorganisms to colonise the gastrointestinal tract is needed and the use of vaccines, antimicrobials and competitive exclusion microfloras as well as the implementation of new processing technology should be encouraged.

Epidemiology of Campylobacter spp. at two Dutch broiler farms.

Broiler flocks on two Dutch poultry farms were screened weekly for the presence of campylobacter in fresh caecal droppings during eight consecutive production cycles. Hatchery and fresh litter samples were taken at the start of each new cycle. Water, feed, insects, and faeces of domestic animals, present on the farms were also included in the sampling. Penner serotyping of isolates was used to identify epidemiological factors that contribute to campylobacter colonization in the broiler flocks. Generally, broiler flocks became colonized with campylobacter at about 3-4 weeks of age with isolation percentages of 100%, and stayed colonized up to slaughter. A similar pattern of serotypes was found within the various broiler houses on one farm during one production cycle. New flocks generally showed also a new pattern of serotypes. Most serotypes isolated from the laying hens, pigs, sheep and cattle were different from those isolated from the broilers at the same time. Campylobacter serotypes from darkling beetles inside the broiler houses were identical to the ones isolated from the broilers. No campylobacter was isolated from any of the hatchery, water, feed or fresh litter samples. Conclusive evidence of transmission routes was not found, but results certainly point towards horizontal transmission from the environment. Horizontal transmission from one broiler flock to the next one via a persistent contamination within the broiler house, as well as vertical transmission from breeder flocks via the hatchery to progeny, did not seem to be very likely.

In vitro susceptibility of Campylobacter and Salmonella isolates from broilers to quinolones, ampicillin, tetracycline, and erythromycin.

Recently, an increased resistance of Campylobacter to fluoroquinolones, a newer class of antimicrobial agents in both human and veterinary medicine, has been reported. Campylobacter isolates (617) from 150 broiler flocks were tested for their susceptibility to cephalothin (control), ampicillin, tetracycline, erythromycin, and the quinolones nalidixic acid, flumequine, enrofloxacin, and ciprofloxacin by a disc diffusion method. Almost complete cross-resistance was found between the quinolones tested. Campylobacter isolates (181, 29%), originating from 55 flocks (37%), were quinolone resistant. Salmonella isolates (94) from 40 flocks were also tested for their antimicrobial susceptibility. Eight isolates (8.5%), from three broiler flocks (7.5%), showed resistance to nalidixic acid and flumequine (and tetracycline), but not to ciprofloxacin or enrofloxacin.

Cecal carriage of Campylobacter and Salmonella in Dutch broiler flocks at slaughter: a one-year study.

From March 1992 to March 1993, 187 Dutch broiler flocks were screened to assess their Campylobacter and Salmonella carriage. Every 4 wk at least 10 flocks, at three different slaughterhouses, were screened for presence of these bacteria. Twenty-five cecal samples were taken from each flock. Campylobacter spp. were isolated from 153 out of 187 broiler flocks (82%). Campylobacter carriage of flocks showed seasonal variation, with the highest contamination rate (100%) during the period June to September and the lowest (50%) in March. Salmonella carriage of the flocks did not show a distinct seasonal variation. Salmonella spp. were isolated from 49 out of 181 broiler flocks (27%). A positive correlation was found between Campylobacter and Salmonella colonization within flocks. Data on farming conditions and husbandry practices were studied to identify possible risk factors for Campylobacter and Salmonella colonization of Dutch broiler flocks.

Impact of animal husbandry and slaughter technologies on microbial contamination of meat: Monitoring and control.

The microbial flora transferred to carcasses during slaughter is a reflection of the care taken on the slaughter floor and of the types and numbers of microorganisms acquired by the animal on the farm or during the period of transportation to the slaughter house. These microogranisms may include those able to cause illness in the consumer, or microorganisms responsible for spoilage of the product. Considerable progress has been made in reducing contamination at slaughter and thereby extending the shelf-life of meat. In contrast, international statistics still clearly show that meat and meat products are responsible for a major proportion of all foodborne infections. This latter aspect is not determined by the overall number of microorganisms present but by the bacterial composition of the animal's gut flora at slaughter. Preventive quality assurance along the whole productions and processing line is therefore the only effective means of controlling the microbiological safety and quality of meat. This includes hazard analysis techniques to identify critical control points and procedures for monitoring the microbiological status of both animals and carcasses since most of the critical points cannot be totally controlled. At early stages in the production line, colonisation of meat animals with pathogens should be prevented. Subsequently, good slaughter practices will ensure carcasses of good overall microbiological quality. This paper deals with microbiological monitoring systems that can be used at different stages of production and processing to control the microbiological quality of poultry and pig meat.

Prevention of colonization by Salmonella enteritidis PT4 in broiler chickens.

Field experiments in The Netherlands and in Scandinavian countries have shown that an undefined microflora originating from SPF adult poultry will reduce considerably the colonization of young chicks by Salmonella. A commercial product from this so-called Nurmi concept, Broilact, was studied for its effectiveness in preventing infection of broilers with Salmonella enteritidis PT4 (S.e.). Two trials were carried out, in which the birds were exposed to S.e. via 'seeder' birds placed among them. The trial period was 21 days and each week one third of the chicks was killed and their caecal contents examined for salmonellas. The results of the first trial can be summarized as follows. (1) After 2 weeks the number of 'seeder' birds carrying the Salmonella decreased sharply; (2) the proportion of infected chicks in the Broilact-treated group was lower than in the non-treated group; (3) Counts of S.e. in the non-treated group were higher than in the Broilact group. Results of the second trial were comparable, although no salmonellas could be isolated after the second week.

Adaptation of Listeria in liquid egg containing sucrose resulting in survival and outgrowth.

Survival of Listeria species was tested in liquid egg products such as albumen, yolk, whole egg and whole egg containing 25% sucrose. At an incubation temperature of 4 degrees C Listeria survived in all products, and even increased slightly in yolk, whole egg and whole egg containing 25% sucrose. However, at 20-22 degrees C, in whole egg containing sucrose, a rapid an dramatic decrease in numbers of Listeria was observed. Following this initial decrease, an increase in the numbers of Listeria was observed. The ability to grow in liquid egg containing sucrose was maintained upon reinoculation into a freshly prepared product. However, this property disappeared after subculturing in brain heart infusion broth. The significance of these findings is discussed.

Reduction of salmonella infection of broilers by spray application of intestinal microflora: a longitudinal study.

The Nurmi concept for diminishing salmonella infection of poultry by application of gastrointestinal microflora from adult birds into newly hatched chicks was tested in a field study in which 8 million broilers were involved. Half of the 284 flocks was treated in the hatchery by spray application of an undefined microflora propagated in SPF chicks. A significant reduction in salmonella-contaminated flocks, as well as in the number of infected broilers in these flocks was demonstrated. No undesirable side effects were detected. It was concluded that hygienic improvements in transportation and slaughtering of broilers are needed in order to maintain the reduced salmonella contamination rate.

Salmonella decontamination of broiler carcasses with lactic acid, L-cysteine, and hydrogen peroxide.

Experiments on salmonella decontamination of broiler carcasses with lactic acid, L-cysteine, and hydrogen peroxide were performed. Treatment with lactic acid (1%) and hydrogen peroxide (.5%) resulted in a 4-log cycle reduction in colony forming units of Salmonella typhimurium both with pure cultures and with artificially inoculated broiler carcasses. L-cysteine was nonbactericidal in these experiments.

[The use of flocculation sludge in poultry feed. Chemical and microbiological composition]. / Het gebruik van vlokkingsslib in pluimveevoeders. Chemische en microbiologische samenstelling.

For the purpose of making inventories, the chemical and microbiological composition of samples of flocculated sludge of poultry, pig and cattle-stock slaughter-houses were examined. This was required to study the possibilities of using flocculated sludge as raw material in animal feed. Chemical studies showed that the dry matter (dm) levels of the various specimens of sludge varied markedly. (Broiler sludge 7.1% of dm, pig sludge 7.5%, cattle-stock sludge 5.5% and laying-hen sludge 13.3%). Broiler- and laying-hen sludge contained more crude fat than did the other samples of sludge. Measured by the concentrations of lysine, methionine and cystine, the sludge product was most similar to the protein of meal-and-bone meal and soy-bean meal. The iron content of almost all samples examined was very high. In view of the current standards for concentrations of metal in complete animal feeds, the concentrations of iron and lead will have to be taken into account in using this sludge product. The proportion of total polymers in the fat fractions of samples of sludge varied from 2.4% to 39.2%, less than 10% only being observed in two samples. The microbiological composition of broiler and pig sludge did not differ. Both the total aerobic bacterial count and the number of Enterobacteriaceae, Escherichia coli and Salmonella were found to be high. Species of Campylobacter were not isolated; however, a number of samples were found to be positive for adenovirus. Prior to deciding to use flocculated sludge in livestock feeding, the product will have to undergo thorough decontamination.

[The use of flocculation sludge in poultry feed. The effect of feeding flocculation sludge on the quality of broiler chickens]. / Het gebruik van vlokkingsslib in pluimveevoeders. De invloed van het voederen van pluimveevlokkingsslib op de kwaliteit van slachtkuikens.

Broiler chickens were fattened for six weeks with feeds, to which 0%, 7.5% or 15% of dried flocculated sludge had been added. Tests were performed on the slaughtered birds with regard to microbiological and sensory characteristics. In addition, the concentrations of various (heavy) metals in the meat of the breast and leg were determined. Specimens of the tissues of various organs were also subjected to histopathological examination. Except for a still unaccountable increase in juicyness of the flesh of the legs of the 7.5% group and a reduction of the zinc level in that of the breast and legs, any other effects attributable to the incorporation of dried flocculated poultry sludge in the diets were not detectable.

[A comparison of 3 isolation methods for the demonstration of Salmonella bacteria in fryer-chicken feed]. / Een vergelijking van drie isolatie-methoden voor het aantonen van Salmonella-bacteriën in braadkuikenvoeders.

167 Samples of fryer chicken feed were examined for the presence of Salmonella using three different methods of isolation. These methods consisted in the isolation of Salmonella using procedure ISO-3565, this method but supplemented by treatment with hydrogen sulphide (ISO + H2S) and the membrane filter disc immuno-immobilisation method (MFDI). In addition, thirty-three samples were examined by the ISO and ISO + H2S techniques. 200 Grams of feed of each sample were studied. A total number of fifteen samples (7.5 per cent) were found to be positive for Salmonella, thirteen of which were examined by the ISO-3565 method of isolation of Salmonella. When the other methods were employed, only five samples were found to be positive for Salmonella using the ISO + H2S technique and two using the MFDI method. When all three methods were used, they failed to produce positive results in each sample which had been found to be positive for Salmonella. The differences in the number of positive samples were found to be significantly (P less than 0.01) in favour of the ISO method. When a choice has to be made between the method used in the detection of Salmonella, the ISO-3565 method of isolating Salmonella is to be preferred.

The effect of different bird washers on the microbiological quality of broiler carcasses.

The effect of spray washers and inside-and-outside bird washers on the microbiological quality of broiler carcasses was examined in 13 poultry slaughterhouses. The carcasses were sampled by means of the carcass rinse method; total and Enterobacteriaceae counts were estimated. The decrease in total and Enterobacteriaceae counts due to spray washing was as high as with the use of an inside-and-outside bird washer. From this investigation the conclusion can be drawn that the use of an inside-and-outside bird washer does not guarantee a better microbiological cleaning of the inside of the carcasses made 'mandatory' by EEC regulations.

[Cross-infection during scalding and plucking of broiler chickens (author's transl)]. / Kruisbesmetting tijdens het broeien en plukken van slachtkuikens

In two poultry-processing plants, experiments were carried out to detect cross-infection during scalding and plucking of broiler chickens. These trials showed that cross-infection was only detectable when experimental infection with the indicator micro-organism Escherichia coli K12 was applied externally to the broiler chickens. When infection was applied internally, only a small degree of transmission was observed. Indicator micro-organisms applied externally to broiler chickens prior to scalding and plucking, were present on the cooled product in larger numbers than those applied internally in the intestines of broilers. The number of carcasses which were positive after cooling was found to have decreased in poultry-processing plant B compared with the situation after plucking, whereas this number was not affected to any appreciable extent in processing plant A.

[Destruction of Salmonella in fresh and deepfrozen broiler chickens by gamma irradiation (author's transl)]. / Destructie van Salmonella-kiemen bij verse en diepbevroren slachtkuikens door middel van gamma-bestraling

Salmonella organisms present on poultry carcases after processing, were almost totally destroyed by gamma irradiation using a dose of 250 krads. This was the case with carcases irradiated in the fresh as well as with those irradiated in the deepfrozen state.

[Antibiotic residues in organs and muscle tissues of broilers. I. Bacitracin, flavomycin, spiramycin and viriniamycin residues following administration of diets containing low levels of these antibiotics (author's transl)]. / Residuen van antibiotica in organen en pluimveevlees. I. Residuen van bacitracine, flavomycine, spiramycine en virginiamycine na nutritieve dosering in het voer tijdens de mestperiode

Two groups of broilers were fed two different feed mixtures. A feed containing a mixture of bacitracin, flavomycin, spiramycin and virginiamycin (20 ppm each) was administered to sixity broilers. Sixty other broilers were given a similar feed not containing any antibiotics. After slaughter, samples of kidney, liver and breast were examined for the presence of antibiotic residues. All samples were found to be negative for antibiotic residues. Four micro-organisms were used in performing the tests: Bacillus cereus Kiel, Bacillus subtilis 165, Bacillus subtilis BGA and Micrococcus luteus ATCC 9341.