Extent of beef carcass contamination with Escherichia coli and probabilities of passing U.S. regulatory criteria

In the 1996 U.S. Meat and Poultry Inspection Regulations, Escherichia coli biotype I counts were included as "performance criteria" of the slaughtering process. The criteria were based on a three-class attributes sampling plan applied in a moving window. The values for m and M and c and n were set at 5 and 100 CFU/cm2, and 3 and 13 samples, respectively, for beef carcasses after overnight chilling following slaughter. In this study, beef carcasses were analyzed for counts of E. coli, and the results were expressed according to the above criteria. Furthermore, probabilities of passing E. coli performance criteria were determined. Carcasses were sampled in seven slaughtering plants (four steer and heifer; three cow and bull), during two seasons, and at three plant locations (pre-evisceration, after final carcass washing, and after 24 h of carcass chilling). Each entire carcass sample (100 cm2 from the brisket, flank, and rump) was analyzed individually for E. coli counts. Compared with the regulation, which set the value of m and the acceptable range based on the 80th percentile of E. coli contamination data from U. S. Food Safety and Inspection Service nationwide baseline studies, our results showed that, on the average and depending on plant and season, 84.2 to 100% of the chilled carcass samples were in the acceptable range. The average percentages of chilled samples in the unacceptable range, set at the 98th percentile, were 0 to 6.7%. Depending on plant and season, the overall probabilities of chilled carcasses passing the regulatory requirement were 0.597 to 1.0 (brisket), 0.471 to 1.0 (flank), and 0.485 to 1.0 (rump). The results indicated substantial variation among plants and between seasons in ability to meet the E. coli performance criteria.     

Sources and extent of microbiological contamination of beef carcasses in seven United States slaughtering plants

This study determined microbiological loads of beef carcasses at different stages during the slaughtering to chilling process in seven (four steer/heifer and three cow/bull) plants. Potential sources of contamination (feces, air, lymph nodes) were also tested. Each facility was visited twice, once in November through January (wet season) and again in May through June (dry season). Carcasses were sampled by aseptic excision of surface tissue (100 cm2) from the brisket, flank, and rump (30 samples each) after hide removal (pre-evisceration), after final carcass washing, and after 24-h carcass chilling. The samples were analyzed individually by standard procedures for aerobic plate counts (APC), total coliform counts (TCC), Escherichia coli biotype I counts (ECC), and presence of Salmonella. Incidence of Salmonella was higher on dry feces of older compared to younger animals, fresh feces of younger compared to older animals, and on cow/bull carcasses compared to steer/heifer carcasses. Most factors and their interactions had significant (P < or = 0.05) effects on the bacterial counts obtained. Depending on plant and season, APC, TCC, and ECC were < or =10(4), < or =10(2), and < or =10(1) CFU/cm2 in 46.7 to 93.3, 50.0 to 100.0, and 74.7 to 100.0% of the samples, respectively. TCC exceeded 10(3) CFU/cm2 in 2.5% (wet season) and 1.5% (dry season) of the samples. ECC exceeded 10(2) CFU/cm2 in 8.7%, 0.3%, and 1.5% of the pre-evisceration, final carcass-washing, and 24-h carcass-chilling samples, respectively, during the wet season; the corresponding numbers during the dry season were 3.5%, 2.2%, and 3.0%, respectively. These data should serve as a baseline for future comparisons in measuring the microbiological status of beef carcasses, as the new inspection requirements are implemented.     

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.     

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.     

In-Plant evaluation of a lactic acid treatment for reduction of bacteria on chilled beef carcasses.

The effectiveness of a lactic acid treatment consisting of spraying a 4% L-lactic acid solution (55 degrees C at source) on chilled beef carcasses to reduce bacterial populations was tested in a commercial slaughter environment. All carcasses had been treated with a proprietary decontamination treatment composed of a hot water spray followed by a lactic acid spray prior to chilling. Bacterial groups used to indicate reductions included aerobic plate count (APC), total coliform count, and Escherichia coli count, and samples were examined from the brisket, the clod, and the neck regions of 40 untreated and 40 treated carcass sides. Depending on the carcass surface region, APCs were reduced by 3.0 to 3.3 log cycles. Log coliform and E. coli counts were consistently reduced to undetectable levels. The small reductions observed for coliforms are attributable to counts on untreated carcasses already being near the lower detection limit of the counting method. The percentage of samples with detectable numbers of coliforms (positive samples) on untreated carcasses ranged from 52.5 to 92.5%, while 0.0% of the samples collected from treated carcasses contained detectable coliforms. Percent E. coli-positive samples ranged from 7.5 to 30.0% on untreated carcasses and 0.0% after treatment of carcass sides. These results indicate that a hot lactic acid spray with increased concentration and time of application may be effectively implemented for an additional decontamination treatment of chilled beef carcasses prior to fabrication.     

FECAL COLIFORM CONTAMINATION OF BEEF CARCASSES DURING THE SLAUGHTERING PROCESS

The purpose of this study was to determine the fecal coliform counts of beef carcasses during different stages in the slaughter process. A total of nine carcasses were selected at random in the abattoir. The samples were taken by excision from three different sites; rump, brisket and shoulder. The samples were collected from the same carcasses at four different stages of processing; after dressing, after evisceration, after washing and after chilling for 24 h in a chilling room. The processing steps did not increase the fecal coliform counts on the rump samples. There were no significant differences in the samples of rump and shoulder among different processing steps. The contamination level of the brisket after washing was significantly higher than other processing steps. Brisket and shoulder parts are critical points for microbiological sampling as these sites showed higher microbial counts after chilling steps. The data obtained have relevance for the planning of washing methods for the production of clean and safe carcasses.     

Hygiene indicator microorganisms for selected pathogens on beef, pork, and poultry meats in Belgium

Several bacterial indicators are used to evaluate hygiene during the meat slaughtering process. The objectives of this study were to assess the Belgian baseline data on hygienic indicators and the relationship between the indicators and zoonotic agents to establish hygiene indicator criteria for cattle, pig, and chicken carcasses and meat. The study used the results from the official Belgian surveillance plan from 2000 to 2003, which included the monitoring of Escherichia coli counts (ECC), Enterobacteriaceae counts (EC), aerobic colony counts (ACC), and Pseudomonas counts (PC). The sampling method was the wet and dry swabbing technique for cattle and pig carcasses and neck skin excision for broiler and layer chicken carcasses. The 75th and 95th percentiles of ECC were -0.20 and 0.95 log CFU/cm2 for cattle carcasses, 1.20 and 2.32 log CFU/cm2 for pig carcasses, and 4.05 and 5.24 log CFU/g for chicken carcasses. The ACC were 2.1- to 4.5-log higher than the ECC for cattle, pigs, and chickens. For cattle and pig carcasses, a significant correlation between ECC, EC, and ACC was found. ECC for pork and beef samples and EC in pig carcasses were significantly higher in samples contaminated with Salmonella. In poultry samples, ECC were in general higher for samples containing Salmonella or Campylobacter. Thus, E. coli may be considered as a good indicator for enteric zoonotic agents such as Salmonella for beef, pork, and poultry samples and for Campylobacter in poultry samples.     

Microbiological quality of chilled beef carcasses in Northern Ireland: a baseline survey

To standardize the assessment of the hygienic quality of beef carcasses in Northern Ireland (NI) abattoirs, swabbing techniques were evaluated. Six materials, including two commercially produced swabs, were compared for their ability to recover spoilage and pathogenic bacteria and for their ease of use as carcass swabs. A sponge retailed for domestic use was selected on the basis of efficiency of recovery of microorganisms, ease of use, and cost. On sample carcasses, 1,000 cm2 of the brisket was swabbed, since this site is normally readily contaminated. For 9 months, 420 carcasses in seven of the nine European Union-approved abattoirs in NI were sampled while in the chiller (24 to 48 h after kill). Total viable count (TVC), yeasts and molds, and Enterobacteriaceae were enumerated after incubation at 22 (48 h) and 37 degrees C (48 h), and the results were expressed as log CFU/cm2. The mean TVC results at 22 and 37 degrees C were 2.80+/-0.70 and 2.75+/-0.64, respectively. Although 63% of samples had yeasts that grew at 22 degrees C, only 35% were positive at 37 degrees C. The respective mean yeast counts were 1.12+/-0.59 and 0.46+/-0.51. Enterobacteriaceae were present in 15% of samples at 22 degrees C and 21% of samples at 37 degrees C. The mean counts for positive samples were 0.41+/-0.37 and 0.40+/-0.30, respectively. Molds were found in less than 4% of samples. Given that the brisket is normally one of the most heavily contaminated parts of the carcass, these results suggest that good hygienic practices are in operation in NI abattoirs. The results also enabled the abattoirs with the cleanest carcasses to be identified, hence permitting best practices to be found.     

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.     

Improvement of the hygienic performance of the hindquarters skinning operations at a beef packing plant

The hindquarters skinning operations in a commercial beef carcasses dressing process were modified, and for short trial periods reorganized for the purpose of reducing the numbers of bacteria deposited on the carcasses. During performance of modified or reorganized operations, samples were obtained from randomly selected carcasses, by swabbing specified sites related to opening cuts, rump skinning or flank skinning operations, randomly selected sites along the lines of the opening cuts, randomly selected sites on the skinned hindquarters of carcasses, or randomly selected sites on carcass sides leaving the dressing process. For each form of the hindquarters skinning operations, a set of 25 samples of each type was collected, with a single sample being obtained from each selected carcass or side. Aerobic counts, coliforms and Escherichia coli were enumerated in each sample, and a log mean value was estimated for each set of 25 counts on the assumption of a log normal distribution of the counts. The data indicated that the log numbers of total aerobes, coliforms and E. coli that were deposited on carcasses during the modified hindquarters skinning operations were generally about 0.5, 1.0 and 1.0 log unit less, respectively, than the log numbers that had been deposited on the carcasses during the unmodified operations. Reorganization of the modified operations gave further small but consistent reductions in the numbers of bacteria. It, therefore, appears that changes to dressing procedures which are guided by appropriate microbiological data can produce consistent reductions in the microbiological contamination of carcasses.     

肉牛屠宰工序微生物污染状况分析和喷淋减菌技术

以减少冷却后牛胴体表面的微生物数量为目标,在企业实际生产条件下,以菌落总数为指标分析屠宰过程中各工序胴体表面的微生物变化状况,探讨不同喷淋方式的减菌效果。结果表明,屠宰工序中初始剥皮操作对胴体造成的污染最严重,其次为去脏工序。高压清水清洗对全胴体的减菌量为0.62(log10CFU/cm2);2%的乳酸喷淋对胸口部位菌落总数的减少量为1.06(log10CFU/cm2)。采用2%的乳酸喷淋可以有效减少肉牛屠宰过程中的胴体污染。     

One-year (2003) nationwide pork carcass microbiological baseline data survey in Taiwan

From January through December 2003, swab samples from 1,650 pork carcasses were collected from 39 slaughter plants in Taiwan. These samples were analyzed for the prevalence of indicator microorganisms and specific pathogens. Viable aerobic bacteria, total coliforms, and Escherichia coli were recovered from 100, 95.3, and 87.5% of these carcasses, respectively. Of those carcasses that harbored bacteria, the mean aerobic plate, total coliform, and Escherichia coli counts were 4.0, 0.6, and 0.1 log CFU/cm2, respectively. Staphylococcus aureus, Clostridium perfringens, Campylobacter jejuni, Campylobacter coli, Listeria monocytogenes, and Salmonella were recovered from 4.8, 0.3, 13.8, 0.7, and 1.7 of 1,038 carcasses, respectively. E. coli O157:H7 was not detected from any carcass. When positive for a specific pathogen, the mean carcass concentration was 0.57 log CFU/cm2 for S. aureus, 0.66 most probable number (MPN)/cm2 for C. jejuni and C. coli, and 0.18 MPN/cm2 for Salmonella. The findings of this study will help provide a reference for establishing hygienic standards and a criterion for evaluating the effects of slaughtering operations in Taiwan.     

Effects of simulated dry and wet chilling and aging of beef fat and lean tissues on the reduction of Escherichia coli O157:H7 and Salmonella

The efficacy of dry and wet chilling and aging of beef as methods for the reduction of Escherichia coli O157:H7 and Salmonella on lean and fat tissues was studied. Samples were obtained from a harvest facility prior to antimicrobial interventions and were inoculated with a cocktail mixture of E. coli O157:H7 or Salmonella to achieve a target inoculation of 6 log CFU/cm(2). Wet chilled and aged samples were then suspended, sprayed (10 °C) continuously for 15 min and then sprayed for 1 min every 17 min for 17 h, and vacuum packed after 48 h. Dry chilled and aged samples were suspended in refrigeration (3 °C) with an air velocity of 0.25 m/s and a relative humidity of 80%. A large initial reduction of E. coli O157:H7 and Salmonella was observed, regardless of tissue type and chilling method. Fewer E. coli O157:H7 microorganisms were detected on wet chilled samples at 24 and 36 h; however, plate counts were higher from wet aged samples excised at 7 through 28 days. The final plate counts were 1.03 and 3.67 log CFU/cm(2) for dry and wet aged samples, respectively. Fewer E. coli O157:H7 microorganisms were detected on fat samples from each sampling time, with the exception of 28 days, compared with lean samples. Similar trends were observed in the reduction of Salmonella for chilling or aging method and tissue type, resulting in final plate counts of 1.25 and 3.67 log CFU/cm(2) for dry and wet aged samples, respectively. The findings reaffirmed wet or dry chilling and aging as potential interventions for small plants as a critical control point.     

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.     

Impact of a novel spray-chilling system on surface microflora, water activity and weight loss during beef carcass chilling

Commercially slaughtered and dressed beef carcass sides (n=30) were followed through a standard commercial chill unit fitted with a new "Jasca" air humidification system adjusted to provide intermittent water spraying of carcass sides (spray cycle 2 min on, 1 min off) for 15 h. Immediately after dressing, and after 24h in the chill unit, the surface water activity, and the weight of each side was measured, and 5 cm2 samples were recovered from four locations, i.e. rump, flank, brisket and neck on the surface of each side. These samples, and similar samples from control sides (n=30) processed in a standard commercial chill unit, were subjected to microbiological examination by direct and resuscitation counts on plate count agar (PCA), MacConkey agar (MAC) and violet red bile glucose agar (VRBGA). No significant differences were observed between bacterial numbers on test and control samples on each of the above agars, at each sample point/occasion. Comparison of direct and resuscitation counts suggested the presence of substantial numbers of injured cells, at both stages (pre- and post-chill), on test and control sides. After 24 h in chill units, test sides exhibited an average weight loss of 1.36% (+/-0.36%), which is significantly less (P<0.001) than the average weight loss (1.55%+/-0.24%) from control sides. These results suggest that the Jasca spray-chilling system can limit carcass shrinkage (on average by 0.19%) without significantly increasing the surface populations of selected bacterial groups.     

不同工艺条件对猪胴体和冷却猪肉微生物去污染效果的影响

调查了冷却猪肉生产企业现有生产工艺下微生物污染的状况 ;研究了对现有生产工序 (冲淋工序、冷却工序 )采用新的处理工艺 ,包括水冲洗、乳酸喷淋、冷分割以及联合处理等对猪胴体和冷却猪肉微生物去污染的效果。结果表明 ,在现有生产工艺下 ,冷却猪肉微生物污染随季节发生显著变化 ,且达不到HACCP体系微生物控制要求 ;水冲淋、乳酸喷淋、冷分割单独处理或联合处理 ,均有显著的微生物去污染效果。如果采用热分割 ,劈半后冲洗 1min ,乳酸喷淋 1min ,则微生物去污染效果显著 ,可基本达到HACCP对微生物控制要求。如果采用冷分割 ,劈半后冲洗 1min ,冷却 2 4h ,再次采用冷分割效果较好 ,冷却猪肉可基本达到HACCP对微生物控制要求 ;若劈半后冲洗 1min ,乳酸喷淋 1min ,冷却 2 4h则可完全达到HACCP对微生物控制要求。     

Microbial populations on animal hides and beef carcasses at different stages of slaughter in plants employing multiple-sequential interventions for decontamination

Multiple-sequential interventions were applied commercially to reduce beef carcass contamination in eight packing plants. The study evaluated microbial populations on animal hides and changes in carcass microbial populations at various stages in the slaughtering process. Sponge swab samples yielded mean (log CFU/100 cm2) total plate counts (TPC), total coliform counts (TCC), and Escherichia coli counts (ECC) on the exterior hide in the ranges of 8.2 to 12.5, 6.0 to 7.9, and 5.5 to 7.5, respectively, while corresponding contamination levels on carcass surfaces, after hide removal but before application of any decontamination intervention, were in the ranges of 6.1 to 9.1, 3.0 to 6.0, and 2.6 to 5.3, respectively. Following the slaughtering process and application of multiple-sequential decontamination interventions that included steam vacuuming, pre-evisceration carcass washing, pre-evisceration organic acid solution rinsing, hot water carcass washing, postevisceration final carcass washing, and postevisceration organic acid solution rinsing, mean TPC, TCC, and ECC on carcass surfaces were 3.8 to 7.1, 1.5 to 3.7, and 1.0 to 3.0, respectively, while corresponding populations following a 24 to 36 h chilling period were 2.3 to 5.3, 0.9 to 1.3, and 0.9, respectively. The results support the concept of using sequential decontamination processes in beef packing plants as a means of improving the microbiological quality of beef carcasses.     

Occurrence of selected foodborne pathogens on poultry and poultry giblets from small retail processing operations in Trinidad

We conducted a study to determine quantitatively and qualitatively the presence of Campylobacter spp., Escherichia coli, staphylococci, total coliforms, total aerobic bacteria, and Salmonella on broiler carcasses from selected small retail processors in Trinidad. We used standard media and procedures for detection and quantification. All carcass and weep samples were positive for aerobic bacteria, E. coli, total coliforms, and staphylococci. Significant differences in the mean counts of aerobic bacteria were observed for samples of carcass (P = 0.001), weep (P = 0.038), and liver and heart (P = 0.017). There was a significant difference (P < 0.05) in the prevalence of E. coli and Campylobacter for liver and heart samples and gizzard samples across various areas (health divisions) in Trinidad and for Campylobacter jejuni and Campylobacter coli for offal samples. The prevalence of Salmonella in carcass, drip, gizzard, and liver and heart samples was 7.3, 3.1, 2.1, and 1.0%, respectively, and three serotypes, Salmonella Kiambu (53.8%), Salmonella Kentucky (38.5%), and Salmonella Mbandaka (7.7%) were isolated. Of the six groups of microbes considered with respect to sale activity, the differences in the prevalence of Campylobacter in medium-activity sale shops (95.8%) and low-activity sale shops (83.3%) and the mean counts of staphylococci for medium-activity sale shops (5.5 +/- 0.9) and low-activity sale shops (5.1 +/- 0.8) were statistically significant (P < 0.05). Carcasses rinsed in a stagnant system had a significantly higher (P < 0.05) prevalence (92.3%) and mean count per milliliter (3.1 +/- 0.7) for Campylobacter compared with 77.8% and 2.7 +/- 0.7 for shops that rinsed with constantly running water. The frequency of rinse water change significantly (P = 0.04) affected the prevalence of Salmonella on carcasses. It is recommended that a quality control system be introduced for these shops, particularly with respect to evisceration and rinsing practices.     

Microbiological contamination of pig and cattle carcasses in different small-scale Swiss abattoirs

A total of 750 pig carcasses and 535 cattle carcasses from 17 small-scale abattoirs were sampled by excision at four sites (pig: neck, belly, back, ham; cattle: neck, brisket, flank, rump). Samples were examined for total viable counts (TVC) and Enterobacteriaceae. Mean TVCs ranged from 2.4 to 4.2 log(10)CFUcm(-2) on pig carcasses and from 2.7 to 3.8 log(10)CFUcm(-2) on cattle carcasses. With regard to EU Regulation (EC) No 2073/2005, TVCs were mainly considered satisfactory (pig: 81.3%; cattle: 71.4%). Amongst sites, the back (pigs) and neck (cattle) tended to yield higher TVCs. Enterobacteriaceae were detected in low counts on 23.9% of pig carcasses and 21.7% of cattle carcasses. Amongst abattoirs, Enterobacteriaceae prevalence on pig and cattle carcasses ranged from 2.0% to 56.0% and from 0.0% to 55.0%, respectively. Consequently, criteria of the EU Regulation proved to be a suitable tool for the appraisal of microbiological results (TVCs) from pig and cattle carcasses from small-scale abattoirs. Because the occurrence of Enterobacteriaceae on carcasses was too infrequent to ensure log normality, frequencies should be compared for these organisms.     

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.