Measurement of Campylobacter numbers on carcasses in British poultry slaughterhouses.

An assessment of the proposed new International Organization for Standardization quantitative method for Campylobacter was undertaken on poultry carcass samples collected after the chilling phase of processing. Using a critical differences method, we determined the uncertainty associated with log-transformed Campylobacter numbers by dual analyses of 346 samples collected from 22 processing plants located throughout the United Kingdom. Overall, using log-transformed Campylobacter numbers that ranged between -1 and 5 log, we calculated the expanded measurement of uncertainty (EMU) to be 3.889 for the new method. The EMU changed when ranges of bacterial numbers were grouped for analyses. For low numbers of Campylobacter (< 1 log), the EMU was calculated to be 5.622. There was less measurement error with higher bacterial numbers because the EMU was found to be 0.612 for samples containing Campylobacter numbers of 3 log or above. The draft method was used to measure numbers of Campylobacters on poultry carcasses collected from 18 United Kingdom processing plants in summer and winter. Numbers were significantly lower in winter. We conclude that, although the new method is adequate at quantifying high numbers of Campylobacter on poultry carcasses, further development is required to improve the measurement of small numbers of this causative agent of foodborne illness.

An assessment of sampling methods and microbiological hygiene indicators for process verification in poultry slaughterhouses.

Studies to determine the appropriateness of the use of populations of indicator bacteria on poultry carcasses for process verification were undertaken in commercial slaughterhouses. Samples were collected from neck skin by excision or from whole carcass rinses and were examined for a range of presumptive process hygiene indicator bacteria. Coefficients of variation were calculated for each bacterial indicator and were significantly lower in excised samples, indicating more reproducible bacterial recovery by this sampling method. Total viable counts of aerobic bacteria, Enterobacteriaceae, and Pseudomonas in samples collected by excision had the lowest coefficients of variation when compared with other indicators and were therefore used for further study. The uncertainties associated with the quantification of each bacterial indicator were calculated and were lowest overall for total viable counts of aerobic bacteria. In general, uncertainty was higher for lower bacterial numbers. Results of microbiological testing on pooled excised neck skin samples were not significantly different from the mean of individually analyzed samples. Bacterial numbers increased by 1 log unit when cultures were stored under chilled conditions typical of those used for transporting samples to external laboratories, but the increases were not significant for Pseudomonas and aerobic bacteria when storage time was less than 17 h. Weak relationships were identified between bacterial indicator numbers and duration of processing, although cleanliness of the processing environment diminished visibly during this time. In the plants visited for this study, there was a poor relationship between presumptive bacterial indicator numbers and process hygiene. Consequently, bacterial analyses for process verification purposes may be of limited value.

Epidemiological analysis of Salmonella enterica ssp. enterica serovars Hadar, Brancaster and Enteritidis from humans and broiler chickens in Senegal using pulsed-field gel electrophoresis and antibiotic susceptibility.

AIMS: Salmonella Hadar, Salmonella Brancaster and Salmonella Enteritidis are the main Salmonella enterica ssp. enterica serovars isolated from poultry in Senegal. Our objective was to analyse the pulsed-field gel electrophoresis (PFGE) and antibioresistance patterns of strains belonging to these serovars and to assess the significance of broiler-chicken meat as a source of human infection. METHODS AND RESULTS: A total of 142 Salmonella isolates were analysed: 79 were isolated from Senegalese patients with sporadic diarrhoea (11 S. Hadar, nine S. Brancaster and 59 S. Enteritidis) and 63 from poultry (30 S. Hadar, 17 S. Brancaster and 16 S. Enteritidis). The PFGE of XbaI- and SpeI-digested chromosomal DNA gave 20 distinct profiles for S. Hadar, nine for S. Brancaster and 22 for S. Enteritidis. Each serovar was characterized by a major pulsotype which was X3S1 in 42% of S. Hadar, X8S1 in 53.8% of S. Brancaster and X1S2 in 43% of S. Enteritidis isolates. Human and poultry isolates of Salmonella had common PFGE patterns. Antibiosensitivity tests showed multiresistance (more than two drugs) was encountered in 14.5% of S. Hadar and in 5% of S. Enteritidis isolates. Resistance to quinolones was considered to be of particular importance and 14.5% of S. Hadar isolates were found to be resistant to nalidixic acid. CONLCUSIONS: The sharing of similar PFGE profiles among isolates from humans and poultry provided indirect evidence of Salmonella transmission from contaminated broiler meat. But most of the Salmonella isolates remained drug sensitive. SIGNIFICANCE AND IMPACT OF THE STUDY: Efforts are needed to eliminate Salmonella from poultry meat intended for human consumption. This study has also highlighted the importance of continuous surveillance to monitor antimicrobial resistance in bacteria associated with animals and humans.

Microbial cross-contamination by airborne dispersion and contagion during defeathering of poultry.

1. A readily identifiable strain of Escherichia coli K12 was used as a 'marker' organism to determine the sources, routes and patterns of microbial cross-contamination during mechanical defeathering of broiler chicken carcases. 2. Inoculation of scald water with the marker organism led to a relatively even pattern of carcase contamination during subsequent defeathering. Microbial cross-contamination was greater by this route of inoculation than by either surface inoculation of a 'seeder' carcase or oral inoculation of a live bird one day before slaughter. 3. Dispersal of the marker organism was strongly influenced by the mechanical action of the defeathering machines. Forward transmission of the marker occurred by aerosol or large airborne droplets and particulates such as feathers. Moving carcases through the defeathering machines when these were non-operational clearly reduced backward transmission of the marker. 4. Although microbial dispersal was unaffected by increasing the spacing between individual carcases or installing a water curtain at the entry and exit of the defeathering machines, shielding of carcases with aluminium baffles reduced counts of the marker organism from contaminated carcases by > 90%. 5. The results imply that microbial cross-contamination of broiler chicken carcases during defeathering occurs mainly via the airborne route, which could be contained by physical means.

Comparison of three commercial competitive-exclusion products for controlling Salmonella colonization of broilers in Brazil.

In this study, a new competitive-exclusion (CE) product, Mucosal Starter Culture (MSC), was compared with two other CE products (Aviguard and Avifree) commercially available in Brazil to evaluate their ability to protect newly hatched chicks against colonization by a strain of Salmonella Kedougou. This study was based on a previously published and recommended method for such products. Separate groups of the chicks were dosed orally with the respective treatment materials and challenged 24 h later, and their ceca were examined for Salmonella 5 days after challenge. Under the test conditions, only MSC and Aviguard gave statistically significant (P < 0.05) protection to the chicks, but the MSC treatment yielded the lowest mean level of cecal carriage and the smallest proportion of Salmonella-positive birds.

Distribution of Campylobacter spp. in selected U.S. poultry production and processing operations.

A study was conducted of 32 broiler flocks on eight different farms, belonging to four major U.S. producers. The farms were studied over I complete calendar year. Overall, 28 (87.5%) of the flocks became Campylobacter positive, and only four (12.5%) remained negative throughout the 6- to 8-week rearing period. In the majority of flocks, sampled every 2 weeks throughout production, Campylobacter-positive fecal and cecal samples were not detected until 4 to 8 weeks of age. In only six of the flocks were environmental samples found to be positive before shedding of Campylobacter was detected in the birds. Even in some of the Campylobacter-negative flocks, contamination of the rearing environment was positive for Campylobacter but did not result in the birds subsequently excreting the organism. These findings are discussed in relation to U.S. husbandry practices and present uncertainty about sources of Campylobacter infection for poultry flocks. Birds were often transported to the processing plant in coops that were already contaminated with Campylobacter, and the organisms were sometimes found in samples of scald water and chill water. After chilling, the proportions of Campylobacter-positive carcasses from different producers ranged from 21.0 to 40.9%, which is lower than in other studies, and possible reasons are considered.

Hygiene aspects of modern poultry chilling.

An evaluation was made of six commercial poultry chilling systems in relation to factors affecting microbial-contamination of carcasses. These systems included water immersion chilling, air chilling and air chilling with evaporative cooling using water sprays. Samples of neck skin and body cavity were taken from carcasses, together with samples from the chilling environment. These were examined for total aerobic mesophilic microbes and counts of presumptive coliform bacteria and Pseudomonas spp. at specific points in the chilling process. Physical measurements included surface and deep-muscle temperatures of carcasses, water temperatures and chlorine concentrations in the immersion system and air speed and temperature during air chilling. The results obtained for water immersion chilling confirmed previous experience that the washing effect reduces microbial contamination of carcasses, although initially the numbers of pseudomonads tended to increase. The air chillers varied in design and mode of operation, but had little overall effect on microbial contamination of the skin. When a completely dry process was used, microbial numbers were reduced approximately ten-fold in the body cavity. However, the use of water sprays tended to increase contamination of the cavity, while relatively heavy spraying using non-chlorinated water, resulted in a substantial increase in the numbers of pseudomonads.

Microbial cross-contamination during air chilling of poultry.

1. Cross-contamination during air chilling of poultry carcases was investigated using a nalidixic acid-resistant strain of Escherichia coli K12 as a marker organism. 2. Experiments were carried out on 2 types of commercial chiller, with and without the use of water sprays (evaporative cooling), and a pilot-scale chiller in which conditions could be varied as required. 3. In the commercial chillers, the marker was dispersed in all directions from a single inoculated carcase and transmission was increased by the use of chlorinated water sprays. 4. Similar results were obtained with the pilot-scale chiller, where the marker was recovered from 45/54 uninoculated carcases; cross-contamination was not prevented by spraying carcases with water containing 50 mg/l of free available chlorine. 5. Despite the ease of microbial transmission from inoculated carcases, cross-contamination during air chilling is likely to be less than that occurring at earlier stages of poultry processing, when carcases are more heavily contaminated.

Prospects for 'competitive exclusion' treatment to control salmonellas and other foodborne pathogens in poultry.

In newly hatched chicks, the rapid establishment of an adult-type intestinal microflora, via the oral route, produces almost immediate resistance to colonization by any food poisoning salmonellas that gain access to the rearing environment. Exploitation of the 'competitive exclusion' (CE) effect is now an accepted part of the overall strategy by which poultry-associated salmonellas are being controlled in some countries. This review covers practical aspects of CE treatment and factors affecting efficacy in both laboratory-scale trials and field studies. It also considers possible applications in preventing colonization of poultry with Escherichia coli O157 and Campylobacter jejuni. For the latter, evidence suggests that the 'protective' organisms are different from those involved in salmonella control.

Investigation of hygiene aspects during air chilling of poultry carcases using a model rig.

1. An experimental rig, designed and built to simulate conditions found in commercial poultry chilling systems, was used to investigate the effects of varying air temperature and chilling duration, and the effect of chlorinated water sprays, on the microbial load present on the skin and in the body cavity of freshly eviscerated poultry carcases; deep muscle and skin temperatures were monitored during chilling at three different temperatures. 2. During dry chilling for 2 h, total viable microbe counts (TVC) and counts of coliforms and pseudomonads from the body cavity fell by between half and one log unit; smaller reductions were observed in samples from the breast skin. 3. The situation changed when chlorinated water sprays (50, 100 or 250 ppm available chlorine) were applied for the first hour of chilling; spraying carcases enhanced the reduction in numbers on the skin; the effect was most pronounced with 250 ppm chlorine; conversely in the body cavity, the general effects of sprays was to increase contamination by up to one log unit. 4. There was no evidence that sprays increased the rate of chilling. 5. When carcases were held overnight in the rig at 11 degrees C after chilling, microbe counts on dry-chilled carcases remained stable, but increased on carcases that had been sprayed with chlorinated water.

Determination of farm-level risk factors for abnormalities observed during post-mortem meat inspection of lambs: a feasibility study.

To investigate the feasibility of using information about the health and management of lambs on farms to predict the risk of gross abnormalities at post-mortem meat inspection, 6732 lambs from 30 different farms in Great Britain were followed through to slaughter in 1995/6. The farm-level data were collected during farm visits at the beginning of the study. Routine meat inspection findings for the lambs were obtained from the 10 participating abattoirs. The most common abnormalities found during post-mortem inspection were pneumonia/pleurisy (53% of cohorts), lungworm (40%), abscesses (30%), liver fluke (27%) and nephritis/nephrosis (27%). The farm-level risk factors associated with abnormalities at slaughter varied with the type of lesion. The most significant risk factor was the age of the lambs at slaughter. Lambs slaughtered at an older age were more likely to have an abnormality, especially pneumonia, abscesses and liver fluke. After age, environmental factors appeared to be better predictors of those cohorts that would have lesions at slaughter than health and disease control variables. However, a much larger study would be required to identify a set of farm-level factors that adequately discriminated between lambs with high and low risks of lesion at slaughter. At the end of the study, the farmers were informed of the meat inspection findings for their lambs and a third indicated that they would improve their animal husbandry as a result of the information.

Assessing abattoir hygiene with a marker organism.

A study was made to evaluate the use of a marker organism for assessing whether hygienic slaughter practices were being followed at red meat abattoirs. The organism, a nonpathogenic strain of Escherichia coli K12 that was resistant to nalidixic acid, was detected and counted on a highly specific isolation medium. With beef carcases, the practice of bagging the excised anus reduced, but did not prevent the spread of the organism from an inoculum applied in the anal region before the hide was removed. The carcases of sheep that were processed at a low-throughput abattoir, were contaminated with the marker after the fleece had been inoculated at a single site. The contamination was significantly reduced (P<0.001) when the operative responsible for flaying had cleaned his hands, arms and apron before and during the handling of each carcase, and used a knife which was freshly pasteurised on several occasions. However, the subsequent washing of carcases had little or no effect on the levels of the marker organism. It was concluded that the marker may be of value in assessing hygiene control, improving present practices, and training abattoir staff.

The bacteriological quality of British beef 1. Carcasses sampled prior to chilling.

During a survey of 11 beef abattoirs in England 2200 swab samples were taken from carcasses just before chilling. Geometric mean aerobic plate counts at 30°C on each of four carcass sites ranged from log(10) 2·45 to 4·29cfu cm(2) with the brisket and flank samples tending to be more highly contaminated than those from the fore-rib and groin. Presumptive coliforms were isolated from 24% of the samples and the proportion of positive samples among the abattoirs varied between 1·5% and 43%. Analysis of variance confirmed that the bacteriological status of beef carcasses may be influenced by a number of interacting factors, including abattoir, visit, and sampling site. However, the results showed that working methods alone were not critical factors in the production of beef of superior bacteriological quality.

Meat inspection: an overview of present practices and future trends.

This is a review of meat inspection literature, its history, current concerns and needs for the future. The value and limitations of meat inspection are discussed, along with the possible modifications or changes that are being developed to modernize an increasingly outdated method of safeguarding public health. The potential of on-farm risk assessment of slaughter animals and the practical considerations that need to be overcome are outlined. The needs of the consumer and subsequent challenges to the meat and farming industry are proposed as the driving force behind the changes occurring in veterinary public health. The current risk to consumers, from such microbial pathogens as Salmonella, Escherichia coli O157:H7 and Campylobacter infection, are highlighted.

Spread of an enteric 'marker' organism during evisceration of New York dressed poultry in a simulated kitchen environment.

1. Five volunteers, with experience of eviscerating poultry or game birds in the home, each eviscerated three New York dressed chicken carcases that had been artificially inoculated in the colon with a readily identifiable "marker' strain of Escherichia coli. 2. In all cases, evisceration resulted in breakage of the intestines at one or more sites, often with leakage of gut contents, or extrusion of faeces from the cloaca because of pressure on the colon during the manipulations involved. 3. The marker organism was detected in the vent region and abdominal cavity of each carcase and sometimes on the breast and back, which appeared to reflect the degree of handling during evisceration, because the hands of each individual became heavily contaminated. 4. With some individuals, the marker also spread beyond the immediate preparation area and was detected on exposure plates. 5. Results support the view that evisceration of poultry in a domestic environment could lead to cross-contamination of other foods with any food-borne human pathogens present.

Relevance of abattoir hygiene assessment to microbial contamination of British beef carcases.

Eleven beef abattoirs were visited, each on five separate occasions. On each occasion, an audit was carried out according to the official Hygiene Assessment System (HAS) and 10 carcases were sampled at four different sites to assess total viable counts and counts of presumptive coliform bacteria. The HAS scores ranged from 11 to 84 (maximum 100), and the logarithmic mean total viable counts for all sampling sites on each batch of carcases varied between 1.98 and 4.14 colony forming units/cm2. The mean prevalence of coliform contamination ranged from 0 to 85 per cent. There was a significant negative correlation (P < 0.001) between the mean HAS scores and the mean total viable count for each abattoir, but not between the HAS scores and the numbers of coliforms. Within the HAS, the mean scores for all five categories, before weighting, showed a significant correlation with the mean total viable count (P < 0.001); however, the categories concerned with slaughter and dressing, and personnel and practices were of most value in determining trends in carcase contamination. A new advisory classification is proposed for levels of microbial contamination on beef carcases.

Incorporation of elements of quantitative risk analysis in the HACCP system.

Foodborne bacterial diseases cause considerable morbidity and mortality throughout the world. Preventive measures such as good manufacturing practices (GMP), supplemented by the hazard analysis critical control point (HACCP) system, have been introduced as a means of ensuring the production of safe food. However, their use does not necessarily provide quantitative information on the risks associated with the consumption of a particular food product. To obtain such information, elements of quantitative risk analysis (QRA) need to be used. QRA is defined as a stepwise analysis of the health risks associated with a specific type of food product, resulting in an estimation of the probability of occurrence of adverse effects on health following consumption of the food in question. It also includes an analysis of the nature of the risks. Taking this definition, five successive steps can be recognized: hazard identification, exposure assessment, dose response assessment, risk characterization and risk management. Food production is a dynamic activity, involving changes in, e.g. the composition and microbial quality of raw materials due to seasonal variation. Also, there may be continuing changes in processing conditions and in product composition due to consumer demands. Therefore, it will be desirable to incorporate QRA in existing safety assurance systems, such as HACCP, when sufficient information is available to permit this approach.

Food products and consumer protection: a conceptual approach and a glossary of terms.

There is greatly increased activity in measures being taken to ensure the production of safe food. Several concepts, increasingly based on quantitative risk analysis, are being introduced and new terminology and definitions are being proposed. This article presents a general approach to the production of microbiologically safe food and a glossary of appropriate terms. Where possible, an attempt is made to provide a more adequate terminology, based on that used in risk analysis; background information is also presented.

Observations on the control of Campylobacter jejuni infection of poultry by 'competitive exclusion'.

Various bacteria were isolated aerobically from caecal mucus of campylobacter-free broilers sampled at slaughter. The organisms were mainly presumptive coliform bacteria, enterococci and Micrococcus/Staphylococcus spp. None showed any inhibitory activity against Campylobacter jejuni in a plate assay. On the other hand, adult hens yielded nine strains of Escherichia coli and one strain of Enterococcus faecium that were positive in the plate assay and most of which utilized mucin as an energy source. Coliform bacteria with these properties were also isolated from samples of pig colon and faeces and associated environmental samples. All of the strains from chickens or pigs failed as separate mixtures to protect chicks against a challenge dose of 10(4)-10(5) cfu/bird of C. jejuni. By contrast, chicks dosed with anaerobic preparations of caecal mucus from campylobacter-free adult hens were partly protected against C. jejuni, as shown by values for Protection Factor (mean log(10) of camplylobacters/g in caecal content of control chicks divided by corresponding mean for treated group). Materials from three hens gave values of 7.3, 1.4 and 3.6, respectively.

Effect of changes in processing to improve hygiene control on contamination of poultry carcasses with campylobacter.

Examination of neck skin and caecal samples taken at a commercial processing plant from 15 randomly chosen poultry flocks showed that all flocks were contaminated initially with thermophilic Campylobacter spp., even in the apparent absence of caecal carriage. During processing, numbers of campylobacter on skin samples were reduced by between 10 and 1000-fold. To improve hygiene control generally, chlorinated-water sprays were used to limit microbial contamination on equipment and working surfaces. In addition, chlorine concentrations in process water were increased and any unnecessary carcass contact surfaces in the processing plant were removed. When comparing flocks before and after the changes, it was found that numbers of campylobacter on packaged carcasses were significantly lower after the changes had been made (P 0.001). In practice, however, the reduction would be likely to have little impact on consumer exposure to campylobacter infection.