Microbiological contamination of reindeer carcasses in different reindeer slaughterhouses

The microbiological contamination of reindeer carcasses was studied in 10 Finnish reindeer slaughterhouses. Six of the slaughterhouses were field slaughterhouses and four were plant slaughterhouses. In each slaughterhouse 11 to 30 carcasses were sampled, with abdomen, brisket, and foreleg as sampling sites. Sampling was performed immediately after slaughter, using a nondestructive swabbing method. The overall mean bacterial count of carcasses was 3.12+/-0.61 log CFU/cm2. The mean bacterial value of the carcasses and the bacterial counts of abdomen and brisket were significantly lower in field slaughterhouses than in plant slaughterhouses, suggesting that the controlled conditions of plant slaughterhouses do not necessarily improve the microbiological quality of reindeer carcasses. However, the highest bacterial contamination was found in a field slaughterhouse where the slaughter was performed after rain when the ground was without snow. Carcass contamination seemed to be increased by the use of an evisceration apron, the unnecessary washing of forelegs, and the unnecessary handling of carcasses with hands and arms.     

Zero-tolerance for faecal contamination of carcasses as a tool in the control of O157 VTEC infections.

The Dutch government, the meat producers organisation and the meat industry have recognised O157 VTEC as an important public health hazard, and agreed on the necessity to improve the hygiene in Dutch cattle- and calf-slaughtering establishments. This paper reports activities within a national action programme to achieve this objective, "Zero-tolerance for faecal contamination during slaughter of cattle and calves". The study included inspection of hygienic performances in slaughterhouses, and visual and microbiological (aerobic plate counts, Enterobacteriaceae counts and O157 VTEC presence/absence on visually clean cattle and calf carcasses) assessment of carcass cleanliness. Initial studies concluded that the hygienic performances in the Dutch cattle and calf slaughterhouses should be immediately improved. In 52% of the slaughterhouses inspected, carcasses were observed to be contaminated with hide, hair or faeces. Around 45% of the slaughterhouses had constructural deficiencies likely to lead to structural cross-contamination of carcasses, by direct carcass-carcass contact, or by indirect contacts with floors, walls or steps. In 39% of the slaughterhouses, cleaning and disinfection procedures were inadequate. Visual inspection of chilled carcasses found that in 11 of the 27 slaughterhouses visited, more than 10% of the carcasses were visibly contaminated. In 6 of the 27 slaughterhouses visited, more than 50% of the carcasses inspected were visibly contaminated. Microbiological analysis of visually clean carcasses noted contamination levels similar to those reported from other countries. O157 VTEC were not isolated during this study. Circulation of these findings lead to increased efforts by all parties to fulfil the requirements of the statutory "Zero-tolerance" programme. A follow-up study noted a significant decrease in the proportions of faecally contaminated carcasses, i.e., 7% of chilled carcasses were visibly contaminated with faeces, as opposed to 22% contamination during the initial study. The follow-up study also noted a greater awareness of the importance of good hygienic practices among slaughterhouse personnel and government meat inspectors.     

A novel method for assessing the role of air in the microbiological contamination of poultry carcasses

This paper describes a novel method of measuring the contamination of raw foods with airborne bacteria during primary processing. To demonstrate the approach, this study aimed to quantify the role of airborne bacteria in the contamination of broiler chicken carcasses undergoing processing in an evisceration room. Settle plates and broiler carcasses were exposed to the evisceration room air or to ultra-clean air provided by a high efficiency particulate air (HEPA) unit located within the room. The use of ultra-clean air reduced the total aerobic counts on horizontal settle plates by 68-fold, and on vertical settle plates by 14-fold. The use of ultra-clean air had no significant effect on the total aerobic counts on carcasses as measured by sponging (3.5 log(10) CFU cm(-2)) or skin excision (4.0 log(10) CFU cm(-2)). The novel approach was able to show that the carcasses entering the room were so heavily contaminated that the airborne bacteria in the evisceration room contributed less than 1% of the total numbers of bacteria on the carcasses.     

SOURCES OF CONTAMINATION DURING SLAUGHTER AND MEASURES FOR CONTROL

This paper is concerned with processes and procedures involved in the contamination of beef, lamb and pork carcasses during slaughter. The hides of beef and the fleece of sheep are major sources of carcass contamination. The spread of pathogens from beef hides to the carcass, operatives and surfaces in the abattoir is demonstrated. Efforts to clean the hide of cattle and the fleece of sheep are outlined, with reference to the success of these treatments in reducing carcass contamination. The effect of bringing very dirty or dungy animals to slaughter is considered in terms of the effect on carcass contamination after slaughter. The influence of tying the bung (or rectum) in reducing carcass contamination is discussed, as is the use of plastic bags as an additional control in preventing pathogen spread on pig carcasses. The relationship of this revised procedure in reducing the occurrence of yersiniosis in Norway is shown. The use of a commercially automated system to tie beef bungs is discussed in relation to reducing carcass contamination. A comparison between the removal of faecal contamination on carcasses by trimming or using a new steam-vacuumized system is presented. The effect of preevisceration washing of beef carcasses is described and the rationale relating to bacterial removal using this treatment is discussed. The influence of evisceration as a source of carcass contamination is demonstrated in relation to sheep slaughter. The processes of carcass decontamination using washing with water at different temperatures, steam pasteurization and hot lactic acid are compared in relation to their ability to remove bacteria from beef carcass surfaces. Finally, the effect of line speed and the impact of technology advances on beef and sheep carcass contamination is reviewed.     

Determination of the principal points of product contamination during beef carcass dressing processes in Northern Ireland

To determine the principal points of microbial contamination of carcasses during beef carcass dressing in Northern Ireland, 190 carcasses were sampled by swabbing 1,000 cm2 of the brisket. A detailed survey of one abattoir was initially conducted, with sampling of a total of 100 carcasses immediately after hide removal (H), after carcass splitting (S), and immediately after washing (W) before dispatch to the chiller. The total bacterial counts after incubation at both 22 and 37 degrees C indicated that there was no significant increase in the numbers of bacteria after the first sampling point, H (P > 0.05). To determine whether this was the case in the majority of Northern Ireland abattoirs, 15 carcasses were then sampled at each of an additional six abattoirs, at points H and W only. Total bacterial counts were significantly higher (P < 0.05) at H than at W, indicating that hide pulling was the major point of bacterial contamination of beef carcasses and hence a critical control point for the final microbiological quality of the carcasses. Mean counts of Enterobacteriaceae at both incubation temperatures were very low (< 10 CFU/cm2) but were higher at W than at H, probably indicating that washing was redistributing bacteria from the posterior to the anterior region.     

Prevalence and serovars of Salmonella enterica on pig carcasses,slaughtered pigs and the environment of four Spanish slaughterhouses

The purpose of this study was to investigate the prevalence of Salmonella contamination and main serovars in pig slaughterhouses in Spain including carcasses, live animals and the environment. A total of 896 pig carcasses were randomly selected and swabbed before chilling in 3–5 visits to four pig slaughterhouses (A, B, C and D). Salmonella contamination was detected in 39.7% of the carcasses. The prevalence of positive carcasses was similar amongst slaughterhouses but significant differences were observed when taking sampling day into consideration within each of the slaughterhouses. Furthermore, a significant reduction in the prevalence of Salmonella contaminated carcasses (10.8%) was demonstrated in slaughterhouses C and D after chilling and cooling procedures.Sixteen batches of 10 animals were tracked from farm-to-slaughterhouse in slaughterhouses A and B to investigate the relationship between carcass contamination and contamination in live animals entering the slaughterhouse. No difference was found between infected and uninfected animals with respect to Salmonella contamination of the carcass although an increase in Salmonella contamination during the processing of live pigs into pork carcasses was evident. Regarding contamination in the slaughterhouse environment, Salmonella was isolated from most of the evaluated points in the slaughter line of the four studied slaughterhouses. Holding pens were identified as highly contaminated and what is more the ineffectiveness of the routinely cleaning protocols at this level was demonstrated in slaughterhouses C and D.The predominant Salmonella serovars found in carcasses, live pigs entering the slaughterhouse and the environment of the slaughterhouse were S. Typhimurium, S. Rissen, S. Derby and S. 4,[5],12:i:-. The same serovars were found in all the stages supporting the hypothesis that infected pigs are the main source of Salmonella contamination within slaughterhouses.     

Microbial assessment of an upward and downward dehiding technique in a commercial beef processing plant

Preventing microbial contamination during dehiding is challenging, and skinning methods are of critical importance for the hygienic status of beef carcasses. Two skinning methods are usually employed: upward hide pulling (UHP) and downward hide pulling (DHP). This study has compared the microbiological contamination of carcasses using both systems in a beef processing plant in the process of changing its dehiding method from UHP to DHP. 100 cm² areas from eight carcass sites (ham, chuck, rump, bung, flank, brisket, shin and neck) were sampled on 36 skinned carcasses dehided by each technique. Total viable counts (TVCs) and Enterobacteriaceae counts for each site were determined. No significant differences were observed in total (pooled-samples) carcass contamination regardless of the method used. However, significant differences (p < 0.05) in TVCs were observed at the flank, shin, brisket and neck. These differences can be attributed to possible deficiencies in the implementation of the HACCP pre-requisite programmes, and are not necessarily associated with the skinning method per se.     

The development of a 'clean sheep policy' in compliance with the new Hygiene Regulation (EC) 853/2004 (Hygiene 2)

The aim of this research was to identify the risk factors associated with the transfer of bacterial contamination from the fleece to the ovine carcass thereby providing the scientific basis for the development and validation of a clean sheep policy. Two hundred sheep in lairage were graded into five categories each consisting of 40 sheep. The categories were as follows; (A) clean and dry; (B) clean and wet; (C) dirty and dry; (D) dirty and wet and (E) visible dags (dung-clotted tufts of wool) categorized by the chief veterinary inspector at the slaughter plant based on the visual inspection of the hygienic status of the fleece. Microbiological evaluations of the carcasses were conducted using swab sampling methods. Total viable counts (TVCs), Enterobacteriaceae and coliform counts were obtained from 40 animals per category at four separate sites (brisket, shoulder, flank and rump) immediately after pelt removal. Statistical analysis of TVC data obtained from the carcass indicated that the dirt level of the fleece had a significant effect on contamination levels when the fleece was dry. Enterobacteriaceae and coliform counts suggest that dirt was a contributing risk factor regardless of wetness or dryness of the animal. The clean sheep policy should therefore differentiate between clean and dirty sheep and mandate additional hygiene measures for the latter.     

Visual evaluation of cattle cleanliness and correlation to carcass microbial contamination during slaughtering

The aim of the study was to establish whether the visual cleanliness of cattle slaughtered was correlated to hide and carcass contamination as indicated by aerobic colony count (ACC), Enterobacteriaceae count (EC) and Escherichia coli count (ECC). Cattle in a slaughterhouse were visually inspected and assigned to a category from 1 (very clean) to 5 (very dirty) based on cleanliness. Fifteen animals for each category were randomly selected, hide and carcass sampled and analyzed for ACC, EC and ECC. Results showed that increasing dirt on cattle was associated with higher ACC, EC and ECC on hide and carcasses. Carcass ACC and ECC belonging to animals classified in cleanliness categories 3, 4 or 5 have a higher probability of exceeding the limits set by the Reg. EU 2073/2005. The study supports the conclusion that the pre-slaughter visual evaluation of animal cleanliness and application of corrective actions can be an effective aid to reduce carcass contamination.     

Airborne bacteria and carcass contamination in slaughterhouses.

Microbiological contamination of air and carcasses was studied in four slaughterhouses by using impactor samples taken at the back-splitting and weighing areas and by sampling carcasses with the swabbing method. Air flow was determined by an air-flow detector, and the movement of workers was observed. The air contamination level in the back-splitting areas (2.25 log CFU/100 liters of air) was generally higher than that in the weighing areas (2.03 log CFU/100 liters of air). Associations between the microbiological contamination of air and carcasses with the movements of workers were found. Layout of the slaughtering line was shown to be important in decreasing airborne contamination. Separation of the clean and unclean parts of the line as well as separation of the weighing area from the other clean parts of the line decreased the contamination level. It appears that airborne bacteria have an important role in carcass contamination.     

拉萨地区牦牛屠宰过程中的微生物污染

为探明拉萨地区牦牛胴体屠宰过程中的微生物污染程度,明确微生物关键控制点,对拉萨地区某具有代表 性的规范屠宰企业屠宰前车间空气中的微生物、各屠宰工艺环节牦牛胴体表面以及人员用具的菌落总数和大肠菌群 数量进行测定。结果表明：屠宰前车间微生物污染严重;随着剥皮和去内脏工艺的进行,牦牛胴体的菌落总数和大 肠菌群数量显著增加;斧劈四分体后胴体的菌落总数和大肠菌群数量均显著高于剥皮和去内脏后;牦牛屠宰过程中 微生物的主要来源是垫板和斧头。     

Prediction of Salmonella carcass contamination by a comparative quantitative analysis of E. coli and Salmonella during pig slaughter

Faecal contamination of carcasses in the slaughterhouse is generally considered to be the source of Salmonella on pork. In this study the hygiene indicator Escherichia coli is used to quantify faecal contamination of carcasses and it is hypothesized that it can be used to predict the quantitative carcass contamination with Salmonella, when the distribution of Salmonella concentrations in faeces is known. Paired pig sample data (faecal samples and carcass swabs) were obtained from five slaughterhouses and analysed for prevalence and concentrations of E. coli and Salmonella. A simple model was developed to describe the faecal contamination of carcasses using the E. coli data. The E. coli results suggested different hygiene performances in different slaughterhouses, and showed that a model assuming that carcasses are predominantly contaminated by their own faeces was not appropriate. Observed Salmonella prevalences were low (on average 1.9% on carcasses) and between slaughterhouses the prevalences ranked differently than the hygiene performance based on the E. coli data suggested. Also, the Salmonella concentrations predicted using E. coli as a faecal indicator were lower than the observed Salmonella concentrations. It is concluded that the faecal carriage of Salmonella together with the faecal contamination of carcasses, as predicted from E. coli data in the animal faeces and hygiene performance of the slaughterhouse, is not sufficient to explain carcass contamination with Salmonella. Our extensive data set showed that other factors than the observed faecal carriage of Salmonella by the individual animals brought to slaughter, play a more important role in the Salmonella carcass contamination of pork.     

The effect of abattoir design on aerial contamination levels and the relationship between aerial and carcass contamination levels in two Irish beef abattoirs

This study investigated the relationship between aerial and beef carcass contamination and examined the effect of abattoir design and time of slaughter on the aerobiology of slaughter operations in two commercial beef abattoirs. A dual head impaction air sampler and swab samples taken from 100 cm² of the brisket of beef carcasses, were used to examine Total Viable, Psychrotrophic, Enterobacteriaceae and Pseudomonad numbers. In Abattoir A, with a straight-line single-floor design, airborne bacterial numbers were generally lower in the “clean” than in the “dirty” area of the plant. In Abattoir B, which had a serpentine two-floor design, this trend was generally reversed. Both abattoirs displayed a similar pattern in airborne counts over the production day, with numbers generally being lower before slaughter, than in the morning and afternoon. Correlations between aerial and carcass contamination for each of the bacterial groups on the slaughter line in Abattoirs A and B were poor. The data suggest that it is difficult to make a definitive evaluation of the relationship between aerial and carcass contamination levels. Methods currently used to determine the relationship between aerial and carcass contamination need to be reconsidered.     

Effect of chemical dehairing on the prevalence of Escherichia coli O157:H7 and the levels of aerobic bacteria and enterobacteriaceae on carcasses in a commercial beef processing plant

The objective of this experiment was to test the hypothesis that cleaning cattle hides by removing hair and extraneous matter before hide removal would result in improved microbiological quality of carcasses in commercial beef processing plants. To test this hypothesis, we examined the effect of chemical dehairing of cattle hides on the prevalence of Escherichia coli O157:H7 and the levels of aerobic bacteria and Enterobacteriaceae on carcasses. Samples from 240 control (conventionally processed) and 240 treated (chemically dehaired before hide removal) hides (immediately after stunning but before treatment) and preevisceration carcasses (immediately after hide removal) were obtained from four visits to a commercial beef processing plant. Total aerobic plate counts (APC) and Enterobacteriaceae counts (EBC) were not (P > 0.05) different between cattle designated for chemical dehairing (8.1 and 5.9 log CFU/100 cm2 for APC and EBC, respectively) and cattle designated for conventional processing (8.0 and 5.7 log CFU/100 cm2 for APC and EBC, respectively). However, E. coli O157:H7 hide prevalence was higher (P < 0.05) for the control group than for the treated group (67% versus 88%). In contrast to hides, the bacterial levels were lower (P < 0.05) on the treated (3.5 and 1.4 log CFU/100 cm2 for APC and EBC) than the control (5.5 and 3.2 log CFU/100 cm2 for APC and EBC) preevisceration carcasses. Prevalence of E. coli O157:H7 was lower (P > 0.05) on treated than on control preevisceration carcasses (1% versus 50%). These data indicate that chemical dehairing of cattle hides is an effective intervention to reduce the incidence of hide-to-carcass contamination with pathogens. The data also imply that any effective hide intervention process incorporated into beef processing procedures would significantly reduce carcass contamination by E. coli O157:H7.     

Prevalence and risk factors for Salmonella and Campylobacter spp. carcass contamination in broiler chickens slaughtered in Quebec, Canada

An observational study was conducted to estimate prevalence and risk factors for Salmonella and Campylobacter spp. carcass contamination in broiler chickens. Eighty-two lots were sampled in four slaughterhouses located in the province of Québec, Canada, over a 10-month period. Carcass contamination was evaluated by the carcass rinse technique for about 30 birds per lot. Exposure to potential risk factors was evaluated based on data from questionnaires, meteorology, and cecal cultures. Multivariable binomial negative regression models were used for risk factor analysis at the lot level. The prevalence of Salmonella-positive carcasses was 21.2% (95% confidence interval: 15.7 to 26.7%). Significant risk factors (P < 0.05) associated with a higher proportion of positive carcasses within lots were Salmonella-positive cecal culture, low rainfall during transportation to the slaughterhouse, temperature of > or = 0 degree C during transportation to the slaughterhouse, and a > or = 4-h waiting period in shipping crates before slaughtering. The prevalence of Campylobacter-positive carcasses was 35.8% (95% confidence interval: 27.1 to 44.5%). Lots containing birds with Campylobacter-positive cecal culture results, lots of birds that were slaughtered at the end of the week, and lots with at least 20% of birds with digestive contents detected in the jejunum at time of slaughtering had a significantly higher proportion (P < 0.05) of contaminated carcasses. These results support the importance of preharvest control measures implemented during rearing to reduce contamination of the final product. Weather during transportation to slaughter and the day of the week that birds were slaughtered also were associated with carcass contamination; further studies are needed to determine the underlying mechanisms by which these factors influence carcass contamination.     

Microbial contamination on beef in relation to hygiene assessment based on criteria used in EU Decision 2001/471/EC

Thirty-six carcasses were sampled over a 12-month period at an Irish beef abattoir. Between one and five carcass sites (including the hock, brisket, cranial back, bung, inside round and outside round) were sampled after hind leg skinning, hide removal, bung tying, evisceration, splitting, washing, chilling for 24 h and boning, using a wet and dry, cotton wool swab technique. For each sample, total viable counts (TVC), Escherichia coli, total coliforms and Enterobacteriaceae were enumerated. The results are considered in relation to European Union Decision 2001/471/EC which sets performance criteria for TVCs and Enterobacteriaceae in samples taken by excision. Though not explicitly stated in the Decision, it has been proposed that microbiological performance criteria for samples taken by swabbing be set at 20% of the values set for excision samples. Therefore, log mean TVCs in carcass swab samples taken before chilling are acceptable, marginal and unacceptable when they are <2.8, 2.8-4.30 and >4.30 cm(-2), respectively. By these criteria, TVCs on carcasses in the present study were in the marginal range. The marginal result for TVCs was due in the most part to hide removal operations, particularly at the hock and brisket sites. Bacterial contamination on post-chill carcasses was similar or lower to that on pre-chill carcasses, while boning resulted in general increases in TVCs and in E. coli, total coliform and Enterobacteriaceae numbers. In Decision 2001/471/EC, the effects of chilling and boning are not included in the assessment of process control. Data from this study indicate that performance criteria based on log mean Enterobacteriaceae values are unsuitable because of the infrequent occurrence of these organisms on the carcass.     

Incidence of Salmonella on beef carcasses relating to the U.S. meat and poultry inspection regulations.

This article is part of a major study designed to collect baseline contamination data by sampling beef carcasses in seven slaughtering plants (four steer-heifer and three cow-bull plants) during both a dry season (November to January) and a wet season (May to June). Samples (n = 30) were excised from each of three carcass anatomical sites (brisket, flank, and rump) at each of three points in the slaughtering chain (pre-evisceration, following final carcass washing, after 24-h carcass chilling). A total of 3,780 samples (100 cm2 each) were analyzed for presence of Salmonella; aerobic plate counts, total coliform counts, and Escherichia coli counts were also made. After 24-h chilling, average incidence (expressed as a percentage) of Salmonella in the brisket, flank, and rump samples, respectively, for steer-heifer carcasses was 0.8+/-1.7, 0, and 2.5+/-5.0 for the wet season and 0.8+/-1.7, 0, and 0 for the dry season; the corresponding percentages for cowbull carcasses were 4.4+/-2.0, 2.2+/-3.9, and 1.1+/-1.9 for the wet season and 2.2+/-3.9, 1.1+/-1.9, and 0 for the dry season. Depending on plant and season, ranges of probabilities of chilled steer-heifer carcasses passing the U.S. regulatory requirements for Salmonella contamination were 0.24 to 1.0 for the brisket, 1.0 for the flank, and 0.002 to 1.0 for the rump; the corresponding ranges for the chilled cow-bull carcasses were 0.25 to 1.0, 0.25 to 1.0, and 0.70 to 1.0. When the number of positive brisket, flank, and rump samples were combined, the probabilities of passing the regulatory requirements were 0.242 to 1.0 and 0.772 to 1.0 for the wet and dry seasons, respectively, in steer-heifer plants and 0.368 to 0.974 and 0.865 to 1.0 in cow-bull plants. Correlation coefficients of aerobic plate counts, total coliform counts, and E. coli counts with Salmonella incidence were higher (P< or =0.05) for cow-bull samples that had increased incidence of the pathogen when compared to steer-heifer samples.     

Microbial performance of food safety management systems implemented in the lamb production chain

The actual microbial status of the lamb production chain at three slaughterhouses, one processing plant, and five butcher shops selling whole or cut lamb carcasses to consumers was assessed with a previously developed microbial assessment scheme. All studied establishments had a food safety management system (FSMS) that was implemented according to legislative requirements. Microbial safety level profiles were constructed for each establishment and provided clear indications of which pathogens, hygiene indicators, or utility parameters required attention to improve the performance of the microbiological control protocols of the implemented FSMS. The highest contamination was found in the slaughterhouses in samples taken from the meat products (aerobic mesophilic plate counts [AMPs] of 3.40 to 6.63 log CFU/cm(2) and Enterobacteriaceae counts of 1.00 to 4.62 log CFU/cm(2)), contact surfaces (AMPs of 2.44 to 8.92 log CFU/cm(2)), and operators' hands and/or gloves (AMPs of 2.84 to 8.09 log CFU/cm(2)), especially after hide removal and evisceration. The microbial assessment scheme is a useful tool for providing insight into the actual microbiological results achieved with an FSMS implemented in establishments at various stages along the lamb production chain.     

Incidence of coagulase positive Staphylococcus on beef carcasses in three Australian abattoirs.

The contamination of beef carcasses with coagulase-positive staphylococci (CPS) was studied at three beef abattoirs (A, B and C). The incidence and the number of CPS were determined on cattle hides immediately after slaughter and on three carcass sites (brisket, flank and round) at different points during processing along the slaughter line. The incidence of CPS on cattle hides ranged from 20 to 68.6%. At abattoir A, 6.5% of the carcasses sampled before evisceration were contaminated with CPS, compared to 40% of the carcasses after evisceration. The incidence on carcasses changed little during further processing; however, after chilling for 72 h, the incidence increased to 83%. After evisceration, the brisket and flank areas were more often contaminated than the round. A similar pattern of contamination was observed at abattoir B. At abattoir C, 26.7% of the samples collected before evisceration were contaminated and this fell to 16.7% after evisceration. After chilling for 72 h, the incidence of carcass contamination with CPS increased to 46.7%. The average number of CPS on contaminated carcasses prior to and after overnight chilling was less than 50 colony-forming units (cfu)/cm2 and, after weekend chilling, increased to 64 and 112 cfu/cm2 in abattoirs A and B, respectively. Of the isolates tested, 71.4% produced staphylococcal enterotoxin and 21% could not be classified phenotypically. The hands of workers and environmental sites associated with the evisceration process were examined for CPS at abattoir A. Hands were heavily contaminated and were the likely source of CPS contamination at this abattoir.     

An investigation of Escherichia coli O157 contamination of cattle during slaughter at an abattoir

The extent of contamination with Escherichia coli O157 was determined for 100 cattle during slaughter. Samples from 25 consecutively slaughtered cattle from four unrelated groups were collected from the oral cavity, hide, rumen, feces after evisceration, and pre- and postchill carcass. Ten random fecal samples were collected from the pen where each group of animals was held at the abattoir. E. coli O157 was detected using automated immunomagnetic separation (AIMS), and cell counts were determined using a combination of most probable number (MPN) and AIMS. E. coli O157 was isolated from 87 (14%) of the 606 samples collected, including 24% of 99 oral cavity samples, 44% of 100 hides, 10% of 68 fecal samples collected postevisceration, 6% of 100 prechill carcass swabs, and 15% of 40 fecal samples collected from holding pens. E. coli O157 was not isolated from rumen or postchill carcass samples. E. coli O157 was isolated from at least one sample from each group of cattle tested, and the prevalence in different groups ranged from less than 1 to 41%. The numbers of E. coli O157 differed among the animals groups. The group which contained the highest fecal (7.5 x 10(5) MPN/g) and hide (22 MPN/cm2) counts in any individual animal was the only group in which E. coli O157 was isolated from carcasses, suggesting a link between the numbers of E. coli O157 present and the risk of carcass contamination. Processing practices at this abattoir were adequate for minimizing contamination of carcasses, even when animals were heavily contaminated with E. coli O157.