Search

The objective of this study was to develop sensory accepted low-salt cooked ham by the application of response surface methodology (RSM). A Box-Behnken experimental design was used to assess the effects of the independent factors salt replacer (Artisalt™) (0–100%), high pressure treatment (0.1–600 MPa) and a mix of organic acids (Inbac™) (0.2–0.4%) on hardness, flavour, saltiness and overall sensory acceptability (OSA) of the cooked ham. The main factor that affected all response variables was salt replacement. The optimum parameters to maximise salt reduction and produce hams with similar OSA associated with this type of products were Artisalt™ (53%), HPP (535 MPa) and Inbac™ (0.3%) and the cooked ham manufactured using the optimum parameters contained 1.4% total salt which is a 46% reduction compared to control samples which contained 2.6% total salt. Overall, a combination of salt replacer, HPP and organic acids showed great potential for the development of cooked ham with significantly reduced salt content. Industrial relevance Consumer studies have shown that meat consumption is being more and more influenced by health, nutritional and environmental considerations; therefore, companies are constantly searching for new and emerging technologies to reduce salt in meat products and enhance shelf life to reduce food waste. In this study we used a novel approach which showed great potential in salt reduction of ham as the quality and sensory acceptability of the ham were similar and/or better after salt was replaced by 53%. The hurdle approach used in this study is expected to improve the safety and shelf life of the low-salt optimised ham and this confirmatory study is underway.

Water misting/showers are used in abattoir lairages to improve meat quality, and to cool and calm pigs after transport and during hot weather. One novel approach, which has not been investigated to date, is to add a disinfectant to the misting water as a means of topically reducing Salmonella on pigs prior to slaughter, thereby potentially controlling this organism in the abattoir. The objective of this study was therefore to evaluate misting with water or with Virkon® S (an approved disinfectant for use in the presence of animals), for their ability to topically reduce Salmonella on high seroprevalence pig herds before stunning and to reduce Enterobacteriaceae. Three experimental groups were investigated: control group (i.e., no misting); water group (misting with cold, 15–17 °C, water, herein referred to as water); and a disinfectant group (misting with 0.5% Virkon® S). As pigs entered the abattoir, each animal was swabbed along its back before being allocated to its experimental group. Each group was randomly assigned to one of 3 lairage pens that were separated by non-trial pens. After 30 min of misting with water or disinfectant, pigs were moved to the stunning area, where each pig was again swabbed, as above. Swabs were analyzed for the presence of Salmonella and enumeration of Enterobacteriaceae. Before misting, Salmonella prevalence on the pigs was 79.0%, 72.1% and 83.6% for the control, water and disinfectant groups, respectively. After misting, Salmonella prevalence increased to 94.3% in the water group; whereas for the disinfectant group, the prevalence increased marginally to 85.9%. No change in Salmonella prevalence was detected for the control group. In line with the Salmonella results, no significant differences were observed in Enterobacteriaceae counts in the control group at either time point (4.37 and 5.01 log10 CFU/cm2, respectively) or in the disinfectant group before and after misting (4.02 and 4.26 log10 CFU/cm2, respectively). However, a 2.3 log10 CFU/cm2 increase in Enterobacteriaceae was recorded for the water group after misting as compared to before misting (p Since misting with water alone increased topical Salmonella contamination on pigs before slaughter, a risk assessment based on known Salmonella data, meat quality and welfare is recommended to determine whether its use is justifiable. On the other hand, the findings from this study suggest that misting with Virkon® S at 0.5% could have a role in topical antisepsis of pigs contaminated with Salmonella prior to slaughter and as such this warrants further investigation.

This study investigated several cleaning and disinfection protocols for their ability to eliminate Salmonella and to reduce levels of Enterobacteriaceae, within the lairage pens of a commercial pig abattoir. Eight protocols were evaluated in each of 12 lairage pens at the end of the slaughtering day on 3 occasions (36 pens/protocol): (P1) high-pressure cold water wash (herein referred to as high-pressure wash); (P2) high-pressure wash followed by a quaternary ammonium compound (QAC)-based disinfectant without rinsing; (P3) high-pressure wash followed by a chlorocresol-based disinfectant without rinsing; (P4) high-pressure wash followed by a sodium hydroxide/sodium hypochlorite detergent with rinsing; (P5) P4 followed by P2; (P6) P4 followed by P3; (P7) P5 with drying for 24-48h; and (P8) P6 with drying for 24-48h. Two floor swabs and one wall swab were taken from each lairage pen before and after each protocol was applied, and examined for the presence of Salmonella and enumeration of Enterobacteriaceae. High-pressure washing alone (P1) did not reduce the prevalence of Salmonella in the lairage pens. When high-pressure washing, the probability of detecting Salmonella following application of the chlorocresol-based disinfectant (P3) was lower than with the QAC-based disinfectant, P2 (14.2% versus 34.0%, respectively; p

Herein we report on the development of an electrochemical sensor for silver ions detection in tap water using anodic sweep voltammetry with in-situ pH control; enabled by closely spaced interdigitated electrode arrays. The in-situ pH control approach allowed the pH of a test solution to be tailored to pH 3 (experimentally determined as the optimal pH) by applying 1.65 V to a protonator electrode with the subsequent production of protons, arising from water electrolysis, dropping the local pH value. Using this approach, an initial proof-of-concept study for silver detection in sodium acetate was undertaken where 1.25 V was applied during deposition (to compensate for oxygen production) and 1.65 V during stripping. Using these conditions, calibration between 0.2 and 10 μM was established with the silver stripping peak ∼0.3 V. The calculated limit of detection was 13 nM. For the final application in tap water, 1.65 V was applied to a protonator electrode for both deposition and stripping of silver. The chloride ions, present in tap water (as a consequence of adding chlorine during the disinfection process) facilitated silver detection and caused the striping peak to shift catholically to ∼0.2 V. The combination of the complexation of silver ions with chloride and in-situ pH control resulted in a linear calibration range between 0.25 and 2 μM in tap water and a calculated limit of detection of 106 nM without the need to add acid or supporting electrolytes.

Pork is an important source of human salmonellosis and low-cost on-farm control measures may provide a useful element in reducing the prevalence of this pathogen in food. This study investigated the effectiveness of dietary supplementation with sodium butyrate administered to finisher pigs for ∼4-weeks prior to slaughter to control Salmonella shedding on highly contaminated farms. Two trials (A and B) were conducted on two commercial pig farms, which had a history of high Salmonella seroprevalence. In both trials, pens (14 pens of 12 pigs/pen in Trial A and 12 pens of 12-17 pigs/pen in Trial B) were randomly assigned to a control (finisher feed without additive) or a treatment group (the same feed with 3kg sodium butyrate/t) for 24-28days, depending on the trial. Faeces were collected from each pig on days 0, 12 and 24/28, and blood, caecal digesta and ileocaecal/mesenteric lymph nodes were collected from the slaughterhouse. Pigs were weighed at the start and end of the trials, feed intake was recorded, and carcass quality parameters were recorded at slaughter. In Trial A, Salmonella shedding was reduced in the treatment compared to the control group at the end of the trial (30% versus 57% probability of detecting Salmonella in faeces, respectively; p0.001). This reflected the serology results, with detection of a lower seroprevalence in the treatment compared to the control group using the 20% optical density cut-off (69.5% versus 89%; p=0.001). However, no effect on faecal shedding or seroprevalance was observed in Trial B, which may be explained by the detection of a concomitant infection with Lawsonia intracellularis. No significant differences in Salmonella recovery rates were observed in the caecal digesta or lymph nodes in either trial. Furthermore, feed intake, weight gain, and feed conversion efficiency (FCE) did not differ between groups (p0.05) in either trial. Numerical improvements in weight gain and FCE were found with sodium butyrate treatment, which gave a cost benefit of €0.04/kg of live-weight gain. Overall, results suggest that strategic feeding of sodium butyrate, at 3kg/t of feed, to finishing pigs for 24-28days prior to slaughter was effective in reducing Salmonella shedding and seroprevalance but perhaps only in the absence of co-infection with other pathogens. However, sodium butyrate supplementation at this rate did not influence intestinal carriage, nor did it reduce seroprevalence to below the cut-off used for the high Salmonella risk category in Ireland (50%), or significantly improve growth performance.

Consumer demands for high quality, safe, nutritious and convenient meat products has provided important insights into the development of a host of processed meat products including fermented meats. It offers unique perspectives for the application of novel functional microbial cultures and promising emerging technologies in the manufacture of fermented meats. Novel non-thermal and thermal technologies, including high pressure processing, pulsed-UV light, irradiation can be utilized for processing and decontamination of meat products to improve process efficiency, product safety and product quality and composition. Application of novel technologies and culture in the development of functional fermented meat products are discussed.

Escherichia coli O157 and O26 shedding patterns in cattle are known to vary widely. To address gaps in the understanding of the underlying factors which impact on shedding dynamics, sensitive and rapid quantitative methods which can be applied in surveillance studies on cattle are required. Current approaches for enumeration of verocytotoxigenic E. coli (VTEC) in cattle faeces are based on direct plating onto selective agars, most probable number (MPN) or real time PCR applied directly to faecal samples, all of which have limitations in terms of the labour involved or their sensitivity. The objective of this study was to develop a sensitive real time quantitative PCR assay, to quantify O157 and O26 in bovine recto-anal junction (RAJ) swabs. The approach was to target serogroup specific genes rfbE and wzx, and to couple a short enrichment, with the use of a standard calibration curve relating real time PCR cycle threshold (Ct) values against the initial concentration of the pathogen in the sample. Following initial experiments in broth culture, a 5h enrichment in modified tryptone soya broth with novobiocin (20 mg/l) (mTSBn) was found to be optimal, and a linear correlation between inocula (Log10 1 to 6 CFU ml(-1)) and the PCR Ct values for both E. coli O157 (R(2)=0.99, rsd=0.58) and E. coli O26 (R(2)=0.99, rsd=0.44) was confirmed. The developed method was then applied to bovine RAJ swab samples (n=153), which were inoculated with E. coli O157 or O26 (Log10 1 to 7 CFU swab(-1)). Calibration curves yielded correlations for E. coli O157 of R(2)=0.86, rsd=0.72 and for O26 (R(2)=0.88, rsd=0.69). In conclusion, a sensitive method for detection and enumeration of two significant VTEC serogroups in bovine RAJ samples has been developed and validated, and will support studies on the bovine shedding dynamics of these pathogens in cattle.

This study investigated the thermal inactivation of five Campylobacteraceae species (Campylobacter coli, Campylobacter helveticus, Campylobacter concisus, Campylobacter fetus subsp. fetus and Arcobacter butzleri) at 55 and 60 °C using an immersed coil heating apparatus. The applicability of nine different models, including log linear and Weibull type models, some of which accounted for shoulders and tailing populations at the start or end of the heat treatment, was assessed to describe the thermal inactivation of each species. The Weibull model with tailing effect provided a good fit with low RMSE value (0.07–0.27), AICc (−88.12 to −6.82) and high R2 values (0.97–0.99) depending on the temperature and the species. The Weibull + tail model showed a significantly high D value for Arcobacter butzerli (180.2 s) at 55 °C and a low D value for C. helveticus (23.9 s) at 60 °C, with a high degree of variability in thermal tolerance noted across the species. Moreover, the Weibull + tail model also indicated high thermal sensitivity for C. fetus subsp. fetus at both temperatures investigated. This study highlights the value of assessing various inactivation models to describe the D value to get the model which best describes the survival data. These model predictions enhance knowledge about the survival characteristics and behaviour of fastidious Campylobacteraceae in the food chain.

The objective of this study was to investigate the growth of Listeria monocytogenes in semi-soft rind washed cheese made from raw and pasteurised milk at different storage temperatures (4, 10 and 15 °C) over a 28 day period simulating storage following ripening. Changes in water activity (aw) and pH in cheeses were also monitored during storage. Response surface models were used to model the interaction of storage temperature and time on aw, pH and L. monocytogenes population. Growth curves were fitted using Baranyi, modified Gompertz and Logistic models at all storage temperatures for both cheeses, and model parameters were statistically analysed. In raw and pasteurised milk cheeses, all models showed a significant (P 0.87. Overall, the L. monocytogenes population increased up to 3 log10 cfu−g−1 for both cheeses during storage following ripening. The fitted models confirmed different L. monocytogenes growth behaviour between raw and pasteurised milk cheeses, which could support the Food Business Operator in predicting growth during storage following ripening.

A quantitative PCR method is described for the detection and quantification of E. coli O157 and O26 in sheep recto-anal junction swabs. The method incorporated a short enrichment step (5 h) and the use of a developed standard calibration curve relating the real time PCR cycle threshold (Ct) values to the initial concentration of pathogen in the sheep sample.

The objective of this study was to determine the efficacy of HPP to accelerate marinade (piri-piri) absorption in pork chops and to study the effects on the physicochemical, sensory and microbiological characteristics during storage. HPP (300 MPa, 400 MPa or 500 MPa) and organic acids Inbac™ (0.3%) were used as hurdles to extend the shelf life. The results showed that HPP ≥ 400 MPa increased (P

The purpose of this study was to investigate carriage and transfer of verocytotoxigenic Escherichia coli (VTEC) O157, O26, O111, O103 and O145 from fleece to dressed carcasses of 500 sheep, and to establish the virulence potential of recovered VTEC. Individual sheep were tracked and sampled (10 g fleece, full carcass swab) through the slaughter process. Samples were examined for the presence of verotoxin ( vt1 and vt2 ) genes using a duplex real-time PCR assay and positive samples were further screened for the presence of the above five serogroups by real-time PCR. VTEC cells were recovered from PCR positive samples by serogroup specific immunomagnetic separation and confirmed by serogroup specific latex agglutination and PCR. Isolates were subject to a virulence screen ( vt1 , vt2 , eaeA and hlyA ) by PCR and isolates carrying vt genes were examined by Pulsed-Field Gel Electrophoresis (PFGE). VTEC O26 was recovered from 5/500 (1.0%) fleece and 2/500 (0.4%) carcass samples. VTEC O157 was isolated from 4/500 (0.8%) fleece samples and 3/500 (0.6%) carcass samples. E. coli O103 was recovered from 84/500 (16.8%) fleece and 68/500 (13.6%) carcasses, but only one E. coli O103 isolate (0.2%) carried vt genes. E. coli O145 was recovered from one fleece sample, but did not carry vt genes. E. coli O111 was not detected in any samples. For the four serogroups recovered, the direct transfer from fleece to carcass was not observed with PFGE showing that VTEC O26 isolates from a matched fleece/carcass “pair” were not identical. This study shows that while VTEC O157 are being carried by sheep presented for slaughter in Ireland, other potentially clinically significant verotoxin producing strains (particularly VTEC O26) are emerging.

This study investigated the prevalence and characteristics of Campylobacteraceae including a range of fastidious species in porcine samples. Over a thirteen month period caecal contents (n=402) and pork carcass swabs (n=401) were collected from three pork abattoirs and pork products (n=399) were purchased at point of sale in the Republic of Ireland. Campylobacteraceae isolates were recovered by enrichment, membrane filtration and incubation in antibiotic free media under a modified atmosphere (3% O2, 5% H2, 10% CO2 and 82% N2). Campylobacteraceae isolates were identified as either genus Campylobacter or Arcobacter and then selected species were identified by Polymerase Chain Reaction (PCR). Campylobacteraceae were isolated from 103 (26%) caecal samples, 42 (10%) carcass swabs, and 59 (15%) pork products. Campylobacter coli was the most commonly isolated species found in (37%) all sample types but many fastidious species were also isolated including Campylobacter concisus (10%), Arcobacter butzleri (8%), Campylobacter helveticus (8%), Campylobacter mucosalis (6%), Arcobacter cryaerophilus (3%), Campylobacter fetus subsp. fetus (1%), Campylobacter jejuni subsp. jejuni (1%), Campylobacter lari (0.5%), Campylobacter curvus (0.5%) and Arcobacter skirrowii (0.5%). Among all isolates, 83% contained cadF and 98% flaA. In this study 35% of porcine C. coli were resistant to ciprofloxacin but none of the fastidious species demonstrated any resistance to this drug. The level of resistance to erythromycin was very high (up to 100%) in C. concisus and C. helveticus and this is a real concern as this is the current empiric drug of choice for treatment of severe gastroenteritic Campylobacter infections. The study shows that there is a much wider range of fastidious Campylobacteraceae present in porcine samples than previously assumed with C. concisus the second most common species isolated. The majority of fastidious Campylobacteraceae isolates obtained contained virulence genes and antibiotic resistance indicating potential public health significance.

Biocides are used at all stages of the farm-to-fork continuum to reduce or eliminate both pathogens and spoilage microorganisms. Currently there is limited understanding of the mechanisms which contribute to biocide tolerance. Also, the impact of this phenotype may affect other risk reduction measures applied across the food chain. Tolerance to one or more biocides may contribute to an increase in the persistence of foodborne pathogens and other bacteria in the food chain. A panel of verocytotoxigenic and non toxigenic Escherichia coli strains were screened for their tolerance to eight commercial biocides and three biocidal active compounds (triclosan, benzalkonium chloride and chlorhexidine). Minimum inhibitory concentrations (MIC) for the commercial biocides were lower than the working concentration recommended by the manufacturers, while the MICs for the biocidal active components ranged from 0.78 to 12.5 μg/ml. As a means of exploring the associated phenotypes, mutant strains were selected which had an increased tolerance to biocides. A stepwise broth method was used to isolate biocide tolerant mutants. No stable mutants could be selected when commercial biocide preparations were used. In contrast, three stable mutants were isolated displaying an increased tolerance to the biocidal active component triclosan with growth observed at >8 mg/ml in comparison to the MIC for the wildtype strain (6.25 μg/ml). One isolate showed an increased tolerance to benzalkonium chloride. The responses of both isogenic wildtype and mutant isolates were compared to stresses often encountered across the food production chain. The strains were exposed to acid at pH 2 and 4, and to temperatures of 55 and 62 °C. No significant differences were observed in the survival of the wildtype and mutant strains under these environmental conditions, except in the case of E. coli O103 (T11 2EF1) at 55 °C (P

The antimic robial activities of caseicin A and B antimicrobial peptides (AMPs) were assessed against a selection of verocytotoxigenic Escherichia coli (VTEC) strains (n = 11), other bacterial pathogenic and spoilage bacteria (n = 7), using a model broth system. The ability of the AMPs to retain their antimicrobial activities against a strain of E. coli O157:H7 380-94 under various test conditions (pH, temperature, water activity, sodium chloride concentrations, inoculum size and the presence of competitive microflora) was assessed and the minimum inhibitory concentrations (MIC) and number of surviving E. coli O157:H7 calculated. The mean number of VTEC surviving after exposure to 2 mg/ml caseicin A and B was reduced by 4.96 and 4.19 log10 cfu/ml compared to the respective controls. The susceptibility of E. coli O157:H7 to the caseicin AMPs decreased as temperature, pH, water activity and inoculum size were reduced. The presence of sodium chloride (0.5–2.5%) did not affect the activity of caseicin A (p > 0.05), however it did inhibit the activity of caseicin B. The presence of a competitive microflora cocktail did not significantly (p > 0.05) affect the activities of the AMPs for the majority of the concentrations tested. Using a quantitative PCR assay, the levels of verotoxins (vt1 and vt2) expressed by E. coli O157:H7 following exposure to a sub-inhibitory concentration (0.5 mg/ml) of caseicin A showed that the verotoxin levels did not differ from the levels produced by the control cultures. The antimicrobial activity of caseicin A against E. coli O157:H7 was also tested in a model rumen system, however concentrations of ≥ 2 mg/ml did not significantly (p > 0.05) reduce E. coli O157:H7 numbers in the model system over a 24 h period. The application of caseicin AMPs in food and/or animal production may be valuable in combination with other antimicrobials although further research is required.

The purpose of this study was to investigate carriage and transfer of verocytotoxigenic Escherichia coli (VTEC) O157, O26, O111, O103 and O145 from faeces and hide to dressed carcasses of Irish cattle as well as establishing the virulence potential of VTEC carried by these cattle. Individual cattle was tracked and faecal samples, hide and carcass (pre-evisceration and post-wash) swabs were analysed for verotoxin (vt1 and vt2) genes using a duplex real-time PCR assay. Positive samples were screened for the five serogroups of interest by real-time PCR. Isolates were recovered from PCR positive samples using immunomagnetic separation and confirmed by latex agglutination and PCR. Isolates were subject to a virulence screen (vt1, vt2, eaeA and hlyA) by PCR. Isolates carrying vt genes were examined by Pulsed-Field Gel Electrophoresis (PFGE). Of the VTEC isolated, E. coli O157 was the most frequently recovered from hide (17.6%), faeces (2.3%) and pre-evisceration/post-wash carcass (0.7%) samples. VTEC O26 was isolated from 0.2% of hide swabs and 1.5% of faeces samples. VTEC O145 was isolated from 0.7% of faeces samples. VTEC O26 and VTEC O145 were not recovered from carcass swabs. Non-VTEC O103 was recovered from all sample types (27.1% hide, 8.5% faeces, 5.5% pre-evisceration carcass, 2.2% post-wash carcass), with 0.2% of hide swabs and 1.0% of faeces samples found to be positive for VTEC O103 isolates. E. coli O111 was not detected in any samples. For the four serogroups recovered, the direct transfer from hide to carcass was not observed. This study shows that while VTEC O157 are being carried by cattle presented for slaughter in Ireland, a number of other verotoxin producing strains are beginning to emerge.

The antimicrobial activities of thymol and carvacrol were assessed against a selection of verocytotoxigenic Escherichia coli (VTEC) strains (n = 11) and other bacterial species and spoilage bacteria (n = 7) using a model broth system. The effects of pH, temperature, water activity, sodium chloride concentrations, inoculum size and the presence of competing microflora on the activities of thymol and carvacrol against E. coli O157:H7 strain 380-94 were also determined. The minimum inhibitory and bactericidal concentrations (MIC and MBC, respectively) and numbers of surviving E. coli O157:H7 were determined following incubation. The mean numbers of VTEC surviving exposure to thymol or carvacrol at concentrations of ≥ 500 μg/ml were between 2.0 and 7.8 log cfu/ml less than the numbers in the corresponding controls. The susceptibility of E. coli O157:H7 to carvacrol or thymol was found to increase with decreasing storage temperature, water activity, pH and E. coli O157:H7 inoculum size. Sodium chloride (0.5–2.5%) and the presence of a microflora cocktail did not significantly (p > 0.05) affect the antimicrobial activities of thymol or carvacrol against E. coli O157:H7. The antimicrobial activity of carvacrol against E. coli O157:H7 was also tested in a model rumen system. A MIC of 500 μg/ml carvacrol reduced E. coli O157:H7 inoculated at levels of 103 and 106 cfu/ml to undetectable levels in the system after 24 h incubation. This concentration of carvacrol significantly (p

Cronobacter spp. (formally Enterobacter sakazakii) has been linked to illness in infants from contaminated powdered infant formula, however, there is limited information on the environmental sources and potential transmission routes of this pathogen. The aim of this study was to establish if food production animals (cattle, pigs), and the wider farm environment were playing a role in the transmission of Cronobacter spp. and also to assess the risk of cross contamination in the home where infant formula is prepared, from the presence of the pathogen on other foods and the general domestic environment. A wide range of samples (n=518) was collected at dairy farms, meat abattoirs, retail food stores and domestic environs and examined for the pathogen using an adapted ISO/DTS 22964 cultural protocol. The modified method included incubation at 42 degrees C instead of 44 degrees C and serial dilution of the enriched media prior to plating on Druggan-Forsythe-Iversen agar. Presumptive Cronobacter spp. colonies were confirmed by Real Time PCR targeting the dnaG on the MMS operon. All Cronobacter spp. isolated were speciated using biochemical tests, tested for resistance to 8 antibiotics and characterised using pulsed field gel electrophoresis. Cronobacter spp. was not recovered from cattle faeces, farm soil or trough water but isolates (n=33) were recovered from a variety of other sample types including cattle feed, pork and beef cuts, beef burgers and beef mince, green vegetables as well as organic breakfast cereals and domestic vacuum cleaner dust. The species recovered included C. Sakazakii (n=21), C. malonaticus (n=1) and C. turicensis (n=1). Of the 33 isolates 51% were resistant to Cephalothin but sensitive to all other 7 tested antibiotics. Sub-typing of the recovered isolates by PFGE showed considerable clonal diversity, though a number of persistent PFGE profiles were observed. In conclusion the study showed that Cronobacter spp. was not carried by food production animals but was present in a range of diverse sample types and environs with particular association with dry environments.

This review examines the prevalence of three important pathogens, verocytotoxigenic Escherichia coli (VTEC), Salmonella enterica and Listeria monocytogenes, in cattle and beef from the farm to the final, ready-to-eat product. Factors affecting prevalence of pathogens in the beef chain, such as the season and cattle rearing method, are examined. Data from many key surveys are summarized in table form. The observed prevalence of pathogens in cattle and beef varies considerably from survey to survey. An indication of relative prevalence of pathogens at different stages can be obtained by calculating average prevalences observed over multiple surveys, weighted by sample number. Based on the data presented in the tables in this review, for E. coli O157 at selected processing stages the mean prevalences (and range of means from individual surveys) are faeces 6.2% (0.0–57%), hides 44% (7.3–76%), chilled carcasses 0.3% (0.0–0.5%), and raw beef products 1.2% (0.0–17%). For Salmonella the mean prevalence data are faeces 2.9% (0.0–5.5%), hides 60% (15–71%), chilled carcasses 1.3% (0.2–6.0%), and raw beef products 3.8% (0.0–7.5%). For L. monocytogenes the mean prevalence data are faeces 19% (4.8–29%), hides 12% (10–13%), and raw beef products 10% (1.6–24%). Seasonal variation was evident in many surveys, faecal prevalences of E. coli O157 and Salmonella generally being higher in the warmer months. The influence of animal type, animal age, feed and housing on pathogen carriage has also been examined. The significance of non-O157 serotypes of VTEC and their detection and classification are discussed.

A combination of factors including changes in the agri-food chain, social changes, advances in detection and reporting systems coupled with bacterial adaptation and evolution have in recent years lead to the emergence of a number of zoonotic microorganisms in the food and water chain. These include multi-antibiotic resistant bacteria, verocytotoxigenic Escherichia coli, parasites such as Cyclospora on fruit, and Cyrptosporidium and Giardia in water, Enterobacter sakazakii in infant milk formula, and emergent species of Campylobacteraceae. In this paper, Enterohaemorrhagic E. coli and Campylobacteraceae are taken as examples of emergent pathogens in the meat chain. Specific factors which may have lead to their emergence are deliberated, in addition to an overview of tools for their detection and tracking, and their epidemiology and survival characteristics. Approaches to managing and controlling emergent pathogens in the agri-food chain are also discussed.

Since Escherichia coli O157:H7 first emerged as a food borne pathogen in the mid 1980s, it has been linked to many cases of food poisoning across the world. While multiple sources and routes of transmission for this pathogen are now recognised, beef and beef products remain an important vehicle of the pathogen and continue to be linked to outbreaks across the developed world. Much research has been directed at E. coli O157:H7 transmission, survival and control in the beef chain and this paper presents an overview of current knowledge on this pathogen in the beef chain from primary production through slaughter, processing, distribution, final preparation and cooking. In order to strategically manage E. coli O157:H7 and to devise approaches to reduce the public health risk posed, many national and international groups have applied quantitative risk assessment techniques to model the risk posed by E. coli O157:H7 in beef, particularly in ground/minced beef which is most often linked with infection. This paper reviews these quantitative risk assessments and their application in managing the risk posed by E. coli O157:H7 in beef.

This study compared an immuno-magnetic separation (IMS)/culture method and a real-time PCR method to detect Verocytotoxigenic Escherichia coli (VTEC) serovar O26 and/or O111 in minced beef. A total of 65 samples were examined, 40 of which were frozen beef samples previously established as containing E. coli O157, and 25 were samples of fresh minced beef, purchased from butcher shops in the Dublin area. After selective enrichment, all samples were (a) subjected to IMS, plated on differential media and identified as E. coli O26 or O111 using biochemical and immuno-logical methods; and (b) subjected to DNA extraction and real-time PCR analysis using primers and probes against E. coli O111 and O26 serovar specific genes, and verotoxin genes. Overall, from the 65 minced beef samples collected, three were positive for E. coli O26 by real-time PCR, with only one of these samples positive for E. coli O26 by the culture method. One sample was positive for E. coli O111 by both real-time PCR and the culture method. The two samples found positive for E. coli O26 by real-time PCR method but not by culture method belonged to the group of frozen beef samples, indicating that the previously developed culture method for the detection of E. coli O26 may not be suitable for the detection of freeze injured cells. In conclusion, this study highlights the role of beef meat in the transmission of non-O157 VTEC. The results of the study emphasize that the analyses for emergent pathogens should be included in food safety surveillance systems and that the development of standard methods for the detection of E. coli O26 and O111 in routine food testing is needed in order to reduce the consumer exposure to contaminated food.

The prevalence of Cryptosporidium spp. in 50 l samples of water used to wash beef carcasses at (a) an abattoir with a borehole water (BH) supply (n = 46) and (b) an abattoir with a river water (RW) supply (n = 48) was determined. In addition, a 100 l water sample and post-wash carcass samples (n = 24) were collected from the RW supply on a single day in July. Cryptosporidium spp. was detected in 0% and 26.1% of samples from the BH and RW supply abattoirs, respectively, with oocyst concentrations ranging from 0.02 to 8.6/l. Cryptosporidium spp. was not isolated from post-wash beef carcasses, while it was detected in water samples from that day at a concentration of 0.06 oocysts/l. The species of 3/5 isolates were identified as C. parvum, and the remaining were C. andersoni. This study has demonstrated that water used to wash beef carcasses can be contaminated with Cryptosporidium of human health importance and is a potential source of carcass contamination.

This paper describes the first reported method for the recovery and detection of Cryptosporidium parvum oocysts from beef carcasses. C. parvum oocysts were mobilized from beef surfaces into phosphate buffer saline-Tween 80, and subsequently recovered from this suspending medium by membrane filtration. Oocysts were removed from the membrane, concentrated by centrifugation, labelling with an FITC conjugated monoclonal antibody and enumerated using fluorescence microscopy. The study compared ‘pulsification’, a novel method, with ‘stomaching’ an established method, as processes for resuspending the target microorganisms from beef. Both yielded similar levels of recovery of oocysts, but pulsification produced less suspended sample debris, allowing easier oocyst detection. Membrane filter pore size (0.45, 1.0 or 3.0 μm) did not significantly affect the number of oocysts detected (P>0.05). Centrifugation at 2500g for 15 min using a swing out no brake (SONB) during deceleration rotor gave higher recoveries than a fixed angle with braking (FAB) rotor during centrifugation (P

A rapid and sensitive method for the detection of Campylobacter in meat products was developed. Campylobacter were isolated from a range of Irish retail meats (n=80) and poultry (n=100) samples by direct plating on Campylobacter Selective Agar (CCDA, Oxoid). A total of 30·5% of samples tested positive for Campylobacter and Campylobacter jejuni was the most commonly identified species. The pathogen was detected in 39 (65%) poultry, 12 (60%) offal and 4 (20%) minced beef samples examined. Estimates derived from direct plate counts ranged from log 10 0·7 to log 10 2·75 cfu g −1 . The data from this study was used in the development of a rapid and sensitive method for the detection of Campylobacter in poultry. A rapid method was developed based on an initial sample enrichment for 24 h in Campylobacter Enrichment Broth (CEB), recovery of the pathogen from the enriched sample by surface adhesion onto a polycarbonate membrane, phenol:chloroform extraction of DNA from the adherent bacteria, and PCR analysis using primers specific for the flagellin A gene (present in C. jejuni and C. coli ). The developed surface adhesion PCR (SA-PCR) technique had a detection limit of log 10 4–5 and could be completed within 29 h. Results from SA-PCR analysis of a number of retail samples (n=50) correlated favourably with traditional plate culture results, i.e. 34 samples were found to contain Campylobacter by both methods.

A Concerted Action project titled “A European study on animal, food and biomedical aspects of verocytotoxigenic Escherichia coli including serotype O157:H7, an emerging pathogen’’ is funded within the European Agriculture and Fisheries Framework IV Programme (CT98-3935) and runs for three years (May 1998 to May 2001). This paper summarises the main objectives and activities of this programme. The project involves 31 participants representing 12 European countries and brings together groups from academia and industry who have an active interest in verocytoxigenic Escherichia coli . Five main thematic areas are being addressed in this project including methods for VTEC, survival and growth of VTEC, pathogenicity and virulence of VTEC and epidemiology of VTEC. These thematic areas are being addressed principally via six monthly research meetings and workshops. Dissemination of information from the project is by conference proceedings, technical booklets reviewing the thematic areas and a project web site (http://www.research.teagasc.ie/vteceurope).

Irish retail meat ( n =74) and poultry samples ( n =106) were tested for the presence of naturally occurring Salmonella spp. The pathogen was detected in 28 poultry ( n =106), two pork ( n =22) and one cooked meat samples ( n =20) examined. Salmonella was not isolated from minced beef or lamb samples tested. Initial counts on samples ranged from 0 to log 10 2·5 cfu g −1 . The most commonly isolated serotype was S. bredeney accounting for 48·4%, followed by S. kentucky (35·5%) and S. enteritidis (6·5%). Salmonella spp. ( n =31) isolated from food products were also examined for antibiotic resistance. A total of 155 strains (five strains from each isolate) were tested for resistance to 26 antibiotics using the Bauer method. The percentage of samples showing antibiotic resistance amongst Salmonella isolates were as follows: Riampicin (100%); Tetracycline (92·92%); Oxytetracycline (86·26%); Sulphamethoxazole (86·25%) and Streptomycin (80·92%).

A procedure combining enrichment surface adhesion and polymerase chain detection (SA-PCR) was developed and applied in the detection of Listeria monocytogenes in meat products. Minced beef samples were inoculated with L. monocytogenes (log(10)3 cfu g(-1)) and incubated for 10 h at 30 degrees C in buffered peptone water. L. monocytogenes was recovered from the culture by attachment to a polycarbonate membrane immersed for 15 min in the enriched meat culture. The membrane and attached bacteria were removed from the culture and the membrane dissolved in phenol:chloroform. The DNA was extracted from the bacteria and a PCR assay was carried out using primers directed against the listerolysin O gene of L. monocytogenes. The combined (SA-PCR) technique had a detection limit of log10 4.0 cfu ml(-1) in enriched meat cultures. The rapid technique was applied to a small number of retail samples (n = 100) and was found to compare favourably to the standard cultural method. A total of 12 samples were confirmed positive for L. monocytogenes using the standard cultural method and the SA-PCR assay. No false positives or negatives were recorded by either method.

Growth curves were generated for Escherichia coli O157:H7 in brain–heart infusion broth incubated at 37 or 15°C in the presence of individual and combinations of competing microflora. Broths were inoculated withE. coli O157:H7 (log103·00 cfu ml−1) and competitors (log104·00 cfu ml−1) and the initial pH of the broth was either neutral (7·0) or adjusted to 5·8 and then sequentially reduced to 4·8 over 10 h to simulate fermentation conditions. Growth curves were also generated for the competitors in these cultures, including Pseudomonas fragi, Hafnia alvei, Pediococcus acidilactici (pepperoni starter culture) and Brochothrix thermosphacta . Gompertz equations were fitted to the data and growth kinetics including lag phase duration, exponential growth rates and maximum population densities (MPD) calculated. In pure culture, the growth parameters for E. coli O157:H7 in neutral pH broths were significantly different from those recorded in simulated fermentation broths (P

A membrane filtration epifluorescent technique was investigated as a method for determining the total viable count of fresh and processed meats. This method involved pretreating the meat sample by centrifugation, surfactants and a proteolytic enzyme, alcalase 2.5 L. The treated sample was filtered through a polycarbonate membrane, stained with a fluorescent dye and viewed under UV light. Two fluorescent stains, acridine orange and Baclight, a viability stain, were compared for use in the method. A recovery step that involved placing the polycarbonate membrane from filtered meat samples for 1 h on the surface of plate count agar at 25°C was included in the procedure for processed meat samples, to allow recovery of injured and stressed cells. The acridine orange direct count (AODC) without the recovery step yielded a poor correlation with the standard plate count (SPC) for all processed meats (r2=0.62–0.72), but the inclusion of a recovery step into the AODC significantly improved the correlation with the SPC (r2=0.83–0.87) for these sample types. A good correlation was reported between the Baclight direct count (BLDC) and the SPC for all sample types with and without the use of the recovery step (r2=0.87–0.93). Validation of the prediction equations using a second set of samples yielded good correlations (r2=0.80–0.92) for all sample types and for both rapid methods. Overall, the Baclight stain performed better than acridine orange in the direct count method for processed samples.

A total of 549 samples of meat, fish and poultry products purchased from retail outlets in the Dublin area were examined for the presence of Listeria spp., using a standard recovery method and a new resuscitation method. Listeria spp. were most frequently isolated from frozen beef burgers (97%) and fish fingers (95%). Cooked meats which were prepackaged by the manufacturer were negative for Listeria spp. The pathogen was isolated from 21% of cooked meats which were sold retail unpackaged indicating post-process contamination. Standard recovery methods gave Listeria counts of between 0.7 and log10 5.0 cfu/g on frozen products. Using a resuscitation method, counts were up to log10 2.5 cfu/g higher, indicating the presence of large numbers of injured Listeria cells. The significance of the numbers of Listeria found in the various foods as well as the recovery of injured cells with the new resuscitation method is discussed.

In this study, a combined enrichment/real-time PCR method for the rapid detection of Salmonella on fresh meat carcasses, was designed, developed and validated in-house following requirements outlined in ISO 16140:2003. The method included an 18h non-selective enrichment in buffered peptone water (BPW) and a 6h selective enrichment in Rappaport Vasilliadis Soya (RVS) broth, based on the traditional culture method, ISO 6579:2002. The real-time PCR assay included an internal amplification control (IAC), was 100% specific and was sensitive to one cell equivalent. The alternative method was validated against the traditional culture method and relative accuracy of 94.9%, sensitivity of 94.7% and specificity of 100% were determined using 150 fresh meat carcass swabs. This alternative method had a detection limit of 1-10CFU/100cm(2) for fresh meat carcass swabs and was performed in 26h. Following further inter-laboratory studies, this alternative method could be suitable for implementation in testing laboratories for the analysis of carcass swabs.