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Biomedical subjects

S C Hathaway

Publications and source records attributed to S C Hathaway.

At least 19 recordsLinked to original sources
PubMed2006

The role and functionality of Veterinary Services in food safety throughout the food chain.

Both national Veterinary Services and international standard-setting organisations have now embraced risk assessment as an essential tool for achieving their goals. Veterinarians have key roles in all aspects of the control of food-borne hazards of animal origin, but additional specialist skills are necessary for assessing, managing and communicating risk. Further, the deployment of Veterinary Services must reflect the multi-functional aspects of public and animal health activities. A generic risk management framework provides a systematic process whereby food safety standards and other measures are chosen and implemented on the basis of knowledge of risk and evaluation of other factors relevant to protecting human health and promoting non-discriminatory trade practices. In this context, a number of countries are exploring new administrative and structural arrangements for competent authorities. The traditional focus of veterinary involvement in food safety has been in meat hygiene at the level of the slaughterhouse. While this role continues, the emerging 'risk-based' approach to food control requires increased involvement in other segments of the meat food chain, as well as other areas such as production of milk and fish. This more extensive role requires a wider skill base and establishment of effective networks with a different range of stakeholders.

Animal Welfare↗
PubMed2002

Risk-based evaluation of postmortem inspection procedures for pigs in Australia.

The results of traditional (incision) and risk-based (visual) postmortem inspection procedures were compared on groups of approximately 30,000 pigs. The performance characteristics used as a basis for comparison included the non-detection rates of grossly detectable abnormalities, the microbiological contamination rates of carcases and boned product, the association of reactive lymph nodes with carcase condemnation and the achievement of 'finished product standards' for 'wholesomeness'. It was estimated that 6 per cent of all cases of abscessation and 28 per cent of all cases of arthritis were undetected by the traditional method, and the comparable figures for the risk-based procedure were 19 per cent and 39 per cent. However, when the rates of contamination of undetected abnormalities with foodborne hazards and other carcase contamination parameters were taken into account, it was concluded that both inspection systems were likely to result in a very similar level of consumer protection. Any increase in potential exposure to foodborne hazards in the abnormalities undetected by risk-based inspection would be insignificant in comparison with the potential exposure to foodborne hazards resulting from contaminated 'normal' lymph nodes and carcase surfaces. There were no statistically significant differences between the two procedures in the contamination rates of pre-chill carcases or boned retail products with Salmonella and Yersinia species.

Animals↗
PubMed1998

A HACCP-based approach to hygienic slaughter and dressing of lamb carcasses.

AIMS: This paper compares changes in visible and microbiological contamination on lamb carcasses dressed using one system which includes process factors previously identified as potential critical control points for HACCP-based approaches to hygienic slaughter and dressing, and another system which excludes those factors. METHODS: Longitudinal changes in microbiological and visible contamination of lamb carcasses were quantified in two slaughterhouses, one utilising clean, shorn, unwashed lambs in an inverted dressing system, the other utilising dirty, woolly, washed lambs in a traditional dressing system. Excision samples (5 cm2 each) for microbiological analyses were taken from two sites on 25 carcasses per treatment group immediately after pelting, at the completion of dressing, after overnight chilling and after boning and packaging. Visible contamination on the surface of 300 carcasses per treatment group was assessed after pelting and after overnight chilling. RESULTS: Mean aerobic plate counts and Escherichia coli counts on the leg and loin in the inverted dressing system were low after pelting (log10/cm2 1.86 and 1.71; log10/cm2 0.13 and 0.05 respectively) but generally showed statistically significant increases through to final packaging. In the conventional dressing system, there were much higher counts on the leg and loin after pelting (log10/cm2 4.66 and 2.71; log10/cm2 2.21 and 0.24 respectively), but subsequent handling of the carcass by slaughter line workers had no measurable deleterious effects. The inverted dressing system resulted in final mean aerobic plate counts on meat at packaging that were 1.38% (leg) and 48.98% (loin) of those derived from the conventional dressing system. Mean E. coli counts from the inverted system were 21.37% (leg) and 67.61% (loin) of those from the conventional system. There was an inverse relationship between the prevalence of carcasses with visible faecal contamination and their microbiological status. CONCLUSION: Significant reductions in microbiological contamination of sheep carcasses can be brought about by HACCP-based systems. Possible critical control points are pre-slaughter presentation status (including avoidance of pre-slaughter washing), inverted dressing, handling by slaughter line workers and meat inspectors, and chilling. Use of levels of visual faecal contamination as an on-line monitoring parameter for slaughter hygiene can give erroneous results. Interactions between different process steps may alter the effectiveness of the HACCP plan, and successful design and application depends on a detailed knowledge of the specific process utilised in each slaughterhouse.

Journal Article↗
PubMed1997

A regulatory perspective on the potential uses of microbial risk assessment in international trade.

The recent ratification of the World Trade Organisation Agreement will arguably be the most important factor in developing new sanitary measures for the international trade in food over the next decade. There is a markedly increased desire for quantitative data on the microbial risks associated with different classes of foods, and traditional good manufacturing practice (GMP)-based food hygiene requirements are coming under increasing challenge. As the risk assessment paradigm is increasing applied and as decision-making criteria for risk management become established, more emphasis will be placed on predictive microbiology as a means of generating exposure data and establishing critical limits for Hazard Analysis Critical Control Point (HACCP) plans. In this respect, developing international guidelines for risk management arguably presents the greatest challenge in establishing and maintaining quantitative Sanitary and Phytosanitary (SP) measures for food in international trade, and for judging their equivalence. Where specific industry sectors and regulators do not have jurisdiction over the entire food chain, from production of raw materials through to consumption, it will be difficult to apply the risk assessment paradigm in the design of HACCP plans. Thus, it appears that default to food safety objectives for many segments of food production chains subject to application of HACCP plans is inevitable in the medium term.

Food Microbiology↗
PubMed1997

Intensive (pasture) beef cattle operations: the perspective of New Zealand.

Beef production in New Zealand has characteristics typical of a temperate climate and pasture-based animal husbandry. The specific pathogens which may contaminate fresh beef and which are empirically considered to be of public health importance are similar to those in other countries with temperate climates, i.e. Salmonella, Campylobacter, Escherichia coli O157:H7, Listeria monocytogenes and Toxoplasma gondii. With the exception of T. gondii, it is likely that almost all transmission of these hazards through consumption of beef results from unseen microbial cross-contamination from gastrointestinal sources during slaughter, dressing and further processing. Gaining comprehensive information on carcass contamination levels is an essential first step in establishing food safety objectives for a particular beef production system, and in designing risk-based hazard analysis and critical control point (HACCP) plans. It is likely that the lower mean and maximum numbers of indicator micro-organisms on New Zealand carcasses (when compared with other countries) are in part due to the pre-slaughter cleanliness status of cattle reared under temperate, pasture conditions. Similarly, the failure to detect specific pathogens of gastrointestinal origin in a comprehensive baseline survey most probably reflects the limited pathway for faecal contamination during slaughter and dressing under processing conditions in New Zealand. The New Zealand example provides strong evidence for the need to design HACCP plans according to the specific national (or regional) situation. Reducing all pathways for faecal contamination of products to the maximum extent practicable will be the most important factor in achieving desired food safety objectives for fresh beef. Variable densities of microbial pathogens in gastrointestinal contents are also likely to have a significant effect on subsequent contamination levels of beef carcasses: however, effective controls for limiting the presence of most pathogens of concern in the live animal have yet to be identified.

Animal Husbandry↗
PubMed1996

Effect of pre-slaughter washing of lambs on the microbiological and visible contamination of the carcases.

Studies in four slaughterhouses with contrasting dressing systems showed that microbiological contamination with total aerobic bacteria and Escherichia coli was greater on carcases which had been washed before slaughter, irrespective of wool length, and was generally higher on carcases derived from woolly lambs than on those derived from shorn lambs. The effects of pre-slaughter washing on the forequarters compared with the hindquarters were not consistent, and this was attributed to differences between the dressing systems applied in the slaughterhouses. Over all trials the mean total aerobic count ranged from 3.45 to 5.36 log10/cm2, and the mean counts of E coli ranged from 0.39 to 2.11 log10/cm2. There was less visible contamination on the carcases of washed lambs than on those of unwashed lambs. The differences in contamination with wool were largely dependent on the level of contamination of individual carcases, whereas the differences in contamination with faecal material and dirt or sand were largely dependent on the prevalence of affected carcases. The use of pre-slaughter washing to compensate in visual terms for poor pre-slaughter presentation results in a detrimental effect on microbiological loads on ovine carcases.

Abattoirs↗
PubMed1996

The effect of different on-line dressing practices on microbiological and visible contamination of lamb carcasses.

Three dressing practices were assessed in traditional lamb carcass dressing systems for their ability to improve control of microbiological and visible contamination. The routine removal of a piece of skin from the perineal area reduced total aerobic plate counts and Escherichia coli counts on carcasses derived from both woolly and shorn groups of lambs. Similar results were found when the "Y-cut" was delayed in the dressing sequence, but E. coli counts increased slightly in one group. The use of a wide-blow shear prior to the opening cut on the hindleg of carcasses derived from woolly lambs resulted in a slight increase in the microbiological contamination on the leg. The removal of a piece of skin from the perineal area reduced scores for faecal contamination despite a small increase in contamination with wool. Changes in visible contamination in response to the two other dressing procedures were principally effected through changes in levels of contamination with wool. Irrespective of dressing procedures, levels of microbiological and visible contamination were lower on carcasses derived from shorn compared with woolly lambs. These studies demonstrated that, although they are reasonable indicators, the use of parameters of visible contamination as a measure of carcass hygiene must be treated with caution. This is especially the case if a genuine HACCP-based system for the control of dressing hygiene for a particular class of slaughtered livestock is to be implemented.

Journal Article↗
PubMed1996

Microbiological contamination of ovine carcasses associated with the presence of wool and faecal material.

The microbiological contamination of ovine hind legs at sites which were visibly clean (control carcasses), sites immediately adjacent to and below visually contaminated sites, and sites contaminated with visible faecal material or wool were determined by excision sampling immediately after pelting and immediately after a pre-evisceration wash. The mean aerobic plate count (APC) and Escherichia coli count (EC) at clean sites immediately after pelting ranged from log10 cm-2 3.98 to 4.44 and log10 cm-2 0.96 to 1.51, respectively. These levels of contamination were significantly lower than those on sites contaminated with faecal material (log10 cm-2 6.00 and 3.00, respectively) or wool (log10 cm-2 5.44 and 2.45, respectively). The presence of faecal material or wool on the carcass was not associated with increased bacterial numbers on visually clean areas of the carcass. This indicates that the presence of faecal material or wool alone cannot be used as an indicator of the hygienic status of the carcass as a whole, particularly in the role of on-line monitoring parameters for HACCP systems. Pre-evisceration washing of carcasses had very little effect on the uncontaminated areas of the carcasses, but reduced the mean APC and EC at the site of visible contaminants. There was little evidence of redistribution of bacteria to immediately adjacent but visually clean sites. However, the residual levels of both APCs and ECs directly at sites of faecal contamination after washing were still significantly higher than at visually clean sites. Application of HACCP principles to ovine slaughter and dressing suggests that visible faecal material should be removed by trimming, whereas pre-evisceration washes can have a practical and microbiologically validated role in the removal of wool. There was generally a good correlation between APCs and ECs at the uncontaminated sites prior to pre-evisceration washing, suggesting that in some situations APCs can act as a useful indicator of both general carcass hygiene and the presence of faecal indicators.

Abattoirs↗
PubMed1996

The hygienic efficiency of conventional and inverted lamb dressing systems.

Aerobic plate counts (APC 37 degrees C and APC 25 degrees C) and Escherichia coli enumerations (Petrifilm) were used to determine sources of bacterial contamination during sheep dressing, determine the hygienic efficacy of hand wash and knife 'sterilization' procedures and compare the hygiene efficiency of conventional and inverted sheep dressing systems. The major slaughterline sources of microbial contamination were: fleece > workers' hands > faecal pellets > knife blades. Aerobic plate counts (APC 37 degrees C) exceeding log 4.4 cfu cm-2 were considered indicative of direct fleece contact, whereas E. coli numbers exceeding log 3.3 cfu cm-2 were considered indicative of direct faecal contact. A 44 degrees C water hand rinse removed 90% of the microbial contamination from workers' hands, but rinsed hands, particularly those contacting the fleece, still carried a microbial population exceeding log 4.0 cfu cm-2. A 44 degrees C rinse followed by an 82 degrees C water dip reduced the contamination on knife blades to less than log 3.0 cfu cm-2. Inverted dressing systems produced carcasses with a lower contamination level than conventional systems. With both systems little increase in contamination occurred after pelt removal. The areas of highest contamination were the forequarter region with inverted dressing and the hindquarter with conventional dressing. In both cases these regions are the sites where cuts are made through the skin. With both systems contamination around these cuts was entirely consistent with direct fleece contact resulting from 'rollback'.

Animals↗
PubMed1994

Drug-induced meningitis. A case involving trimethoprim-sulfamethoxazole.

Drug-induced meningitis should be considered in differential diagnosis of meningeal irritation in patients receiving therapy with anti-infective, nonsteroidal anti-inflammatory, immunosuppressive, or other selected agents. This report describes a case of aseptic meningitis associated with use of trimethoprim-sulfamethoxazole in a patient without apparent underlying autoimmune disease. The patient recovered promptly after the offending agent was withdrawn. No specific treatment other than symptomatic and supportive care need be given. In all instances, however, infection must be excluded.

Adult↗
PubMed1994

Lesions in the carcasses and viscera of very young slaughter calves condemned at post-mortem meat inspection.

The carcasses of 370 very young slaughter calves condemned for various diseases and defects at routine post-mortem meat inspection were subjected to further and more detailed macroscopic examination as well as histopathological examination of some tissues. Of the carcasses examined, 138 were condemned for navel ill, and in the majority of these cases the lesions extended beyond the umbilicus, particularly involving the umbilical vein and the urachus. Enzootic pneumonia was the most common cause of pleuritic lesions in the carcass, and 75 carcasses were condemned for this lesion. Arthritis, whether localised or involving a number of joints, was the primary lesion in 32 carcasses. Focal interstitial nephritis was observed in the kidneys of 36 carcasses, while 23 carcasses were condemned for wounds and bruising. A number of other miscellaneous diseases and defects, including generalised peritonitis, jaundice, hepatic abscesses and fever, were observed at low rates in condemned carcasses. Resolution or localisation of lesions had occurred at the time of slaughter on average in 35% of the condemned carcasses and the judgment of total condemnation was difficult to justify on a scientific basis and would not have been applied to other classes of slaughtered livestock. In the case of wounds and bruising, 95.6% of the carcasses could have been trimmed. There was also considerable variation in the likely pathogenesis and systemic effects of the diseases and defects observed. A need for clear and specific judgment criteria to be applied to the carcasses of very young slaughter calves at post-mortem meat inspection was identified.

Journal Article↗
PubMed1994

Wastage due to diseases and defects in very young calves slaughtered in New Zealand.

Analysis of disease and defect data from a national meat inspection database for very young calves slaughtered in New Zealand up to 1987 revealed low prevalences of diseases and defects but relatively high condemnation rates within particular disease and defect categories. Calves slaughtered between 1987 and 1992 showed a decrease in the total condemnation rate of carcasses from 2.20% to 1.17%. The greatest reductions in condemnation rates were seen in the categories of wounds and bruises and "other" reasons; navel ill (omphalophlebitis) was initially included in the latter category and condemnations due to this condition persisted as the most frequent cause of wastage. The decrease in condemnation rates occurred subsequent to implementation of a national farm-gate quality assurance programme and a scientific investigation of traditional meat inspection carcass condemnation criteria. The former led to an increase in the quality of calves submitted for slaughter and the latter to changes in specifications for meat inspection judgments for several localised and resolved diseases and defects. Alterations to the disease and defect recording categories of the database have resulted in more appropriate national statistics and such a database can be used to identify inconsistencies in the application of meat inspection judgments between slaughterhouses.

Journal Article↗
PubMed1994

Impact of intensive lipid modulation on angiographically defined coronary disease: clinical implications.

We reviewed all randomized, controlled angiographic trials to assess the impact of intensive lipid modulation on the progression or regression of angiographically defined coronary disease. Five of seven trials satisfied selection criteria: Cholesterol-Lowering Atherosclerosis Study, Program on the Surgical Control of the Hyperlipidemias, Familial Atherosclerosis Treatment Study, Regression of Coronary Atherosclerosis During Treatment of Familial Hypercholesterolemia, and St. Thomas' Atherosclerosis Regression Study. We compared patient selection, baseline and on-trial lipid values, changes in angiographic disease scores, and clinical outcomes. In all five trials, treatment reduced levels of low-density lipoprotein (LDL) cholesterol substantially (range -32% to -46%). Treatment reduced risk of angiographic progression by almost 50% compared to controls. Furthermore, nearly one third of drug-treated patients showed angiographic regression of disease. Regression correlated well with reduction in LDL cholesterol. Although overall improvement in stenosis was modest, reduction in clinical events was impressive. Intensive lipid modulation may "stabilize" existing lesions, making them less "active" (ie, less prone to rupture or thrombosis), thereby reducing risk of acute coronary syndromes. These studies clearly support intensive lipid modulation in patients with established coronary disease.

Angiography↗
PubMed1993

Characteristics of the carcases and meat of slaughtered calves as indicators of 'immaturity'.

Arbitrary age limits and offal weights are often used to classify meat and offals from 'bobby' calves as 'immature' and hence unfit for human consumption. Such age limits were not scientifically validated in a comparative study of the ante mortem characteristics, and the physical characteristics of the carcases and offals of groups of Jersey calves aged one, five, 14 and 21 days. The quality characteristics of muscle (pH and water-holding capacity) did not change with increasing age, and the changes in chemical composition (water, protein, fat and ash) were minimal, particularly between the five-day-old and 21-day-old groups. Small changes in muscle colour measured objectively were not detectable visually.

Abattoirs↗
PubMed1993

A pathological and microbiological evaluation of omphalophlebitis in very young calves slaughtered in New Zealand.

Omphalophlebitis, generally referred to as navel ill, is a common post-mortem meat inspection finding in very young calves slaughtered in New Zealand, and a gross pathological, histopathological and bacteriological evaluation of 147 carcasses condemned for this condition at routine post-mortem meat inspection was undertaken. Localised lesions restricted to the umbilicus alone were present in 29.9% of cases. The majority of cases included gross pathological change in the umbilical vessels and other tissue sites beyond the umbilicus. Most hepatic nodes were grossly normal but histological examination revealed that 61.5% of nodes from other than localised cases of navel ill were hyperplastic. However, there was little difference in the prevalence of hyperplastic hepatic nodes from cases of localised navel ill (21.4%) compared with normal calves (15.9%). Despite the wide range of bacteria isolated from umbilical lesions, Salmonella typhimurium recovered from the navel, liver and hepatic nodes of a single extended case of navel ill was the only isolation of known public health importance. Given the separation of cases of navel ill into different gross pathological, histopathological and microbiological categories, current meat inspection judgments whereby all calves with navel ill are condemned should be revised. In particular, routine condemnation of the carcass and viscera in all cases of localised navel ill (lesions restricted to the umbilicus alone) should be reassessed.

Journal Article↗
PubMed1993

Risk analysis and meat hygiene.

Meat hygiene consists of three major activities: post-mortem inspection; monitoring and surveillance for chemical hazards; and maintenance of good hygienic practice throughout all stages between slaughter and consumption of meat. Risk analysis is an applied science of increasing importance to these activities in the following areas: facilitating the distribution of pre-harvest, harvest and post-harvest inspection resources, proportional to the likelihood of public health and animal health hazards; establishing internationally-harmonized standards and specifications which are consistent and science-based; and improving the safety and wholesomeness of meat and meat products in local and international trade. Risk analysis, in one form or another, is well developed with respect to establishing standards and specifications for chemical hazards; methods for risk analysis of post-mortem meat inspection programmes are beginning to emerge. However, risk analysis of microbiological hazards in meat and meat products presents particular difficulties. All areas of application currently suffer from a lack of international agreement on risk assessment and risk management methodology.

Animals↗
PubMed1992

Development of a control strategy for Leptospira hardjo infection in a closed beef herd.

Serological evidence of infection with a leptospire belonging to the Sejroe serogroup was identified in a closed population of Luing cattle in the west of Scotland, and the geographical isolation of the population presented an opportunity to control and possibly eradicate the infection in a large beef herd farmed under extensive conditions. Serological and bacteriological studies revealed that infection was present at a high level throughout the herd, and that the infecting serovar was hardjo. Unlike endemic hardjo infection in dairy herds, new infections were still occurring in older age-groups. Investigations of other domestic and free-living species sharing the habitat demonstrated that the maintenance of an endemic focus of hardjo was restricted to the cattle. Changes in management to prevent the transmission of infection to successive cohorts of young animals were impractical and risky, and antibiotic treatment followed by removal to clean pasture failed to prevent new cases. Thus vaccination offered the only means of control and possible eradication, and the epidemiological characteristics of the infection dictated that the programme be applied to the whole herd.

Age Factors↗