Cryptosporidium in commercially produced turkeys on-farm and postslaughter.

AIMS: To determine the presence of Cryptosporidium species in commercially produced turkey flocks on farm and postslaughter. METHODS AND RESULTS: Three separate turkey flocks were sampled at a single farm and again postslaughter at a commercial processing facility. DNA was extracted and purified from faecal (farm) or caecal (postslaughter) samples and a fragment of 18S rDNA was amplified using a nested PCR approach. Amplified fragments were sequenced, aligned and a neighbour joining tree was constructed. Cryptosporidium meleagridis was not identified in any of the flocks tested. However, all flocks tested positive for Cryptosporidium parvum species. One of the flocks tested positive at the farm and postslaughter. CONCLUSIONS: While C. parvum was present in birds at the farm and postslaughter, turkeys at this facility are not likely to be a significant reservoir for this species. SIGNIFICANCE AND IMPACT OF THE STUDY: Cryptosporidium meleagridis infects avian and human hosts and is increasingly being recognized as a significant human pathogen. However, this study found no evidence of C. meleagridis in commercially produced turkeys at a single location.

Cross contamination of turkey carcasses by Salmonella species during defeathering.

Salmonella present on the feathers of live birds could be a source of contamination to carcass skin during defeathering. In this study, the possibility of transfer of Salmonella from the feathers of live turkeys to carcass tissue during the defeathering process at a commercial turkey processing plant was investigated. The contribution of scald water and the fingers of the picker machines to cross contamination were also examined. Over 4 visits, swab samples were collected from 174 randomly selected tagged birds before and after defeathering. Two swab samples from the fingers of the picker machines and a sample of scald water were also collected during each visit. Detection of Salmonella was carried out following standard cultural and identification methods. The DNA fingerprints obtained from pulsed field gel electrophoresis of Salmonella serotypes isolated before and after defeathering, from scald water, and from the fingers of the picker machines were compared to trace cross contamination routes. Salmonella prevalence was similar before and after defeathering during visits 2 and 3 and significantly increased after defeathering during visits 1 and 4. Over the 4 visits, all Salmonella subtypes obtained after defeathering were also isolated before defeathering. The results of this study suggest that Salmonella was transferred from the feathers to carcass skin during each visit. On each visit, the Salmonella subtypes isolated from the fingers of the picker machines were similar to subtypes isolated before and after defeathering, indicating that the fingers facilitate carcass cross contamination during defeathering. Salmonella isolated from scald water during visit 4 was related to isolates obtained before and after defeathering, suggesting that scald water is also a vehicle for cross contamination during defeathering. By using molecular subtyping, this study demonstrated the relationship between Salmonella present on the feathers of live turkeys and carcass skin after defeathering, suggesting that decontamination procedures applied to the external surfaces of live turkeys could reduce Salmonella cross contamination during defeathering.

Adding a selective enrichment step to the iQ-Check real-time PCR improves the detection of Salmonella in naturally contaminated retail turkey meat products.

AIMS: The aim of this study was to compare the real-time iQ-Check Salmonella kit (Bio-Rad) with the immunocapture assay RapidCheck Salmonella method, and a conventional culture method (FSIS, USDA) in detecting Salmonella in naturally contaminated turkey meat products. This study was also designed to determine if a selective enrichment step might improve the real-time detection of Salmonella. METHODS AND RESULTS: Using the culture method, Salmonella was recovered from 49 out of 99 retail turkey meat samples collected. RapidCheck failed to detect 11 Salmonella samples that were positive by the culture method. The iQ-Check real-time PCR also failed to detect three samples that were positive by the culture method. However, when carried out after a selective enrichment step, the iQ-Check real-time PCR detected all 49 Salmonella samples recovered by the culture method. The iQ-Check real-time PCR detected the presence of Salmonella in some samples that were not recovered by the culture method. CONCLUSIONS: Adding a selective enrichment step to the iQ-Check real-time PCR improves the detection of Salmonella in naturally contaminated turkey meat samples. SIGNIFICANCE AND IMPACT OF THE STUDY: The iQ-Check Salmonella real-time PCR can be used as a rapid method to monitor Salmonella in turkey meat, together with conventional culture methodology.

The prevalence and characterisation of Cryptosporidium spp. in beef abattoir water supplies.

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.

Prevalence and characterisation of Cryptosporidium species in cattle faeces and on beef carcases at slaughter.

Cattle are known reservoirs and asymptomatic excretors of Cryptosporidium, a protozoan parasite that causes severe and protracted diarrhoea in people. The incidence of Cryptosporidium was investigated in 288 matched samples taken from beef carcases of 1 g samples of faeces retrieved immediately after de-legging, 25 cm2 samples of beef excised from the rump of uneviscerated carcases, and 25 cm2 samples of beef excised from the brisket area of eviscerated carcases. Cryptosporidium species were detected in 21 of the faecal samples after salt flotation and immunofluorescent microscopy. The species isolated from the positive samples were identified by restriction fragment length polymorphism and PCR as Cryptosporidium andersoni (54.5 per cent) and Cryptosporidium parvum genotype 2 (45.5 per cent). In the faecal samples, there was a significantly higher prevalence of the parasite in samples taken in summer (May to July) and winter (November to January) than in spring or autumn. No Cryptosporidium species were recovered from any of the beef samples.

The effect of thermal treatments on the viability and infectivity of Cryptosporidium parvum on beef surfaces.

AIMS: The aim of this research was to examine the effect of thermal treatments on the viability and infectivity of Cryptosporidium parvum oocysts attached to a beef surface. METHODS AND RESULTS: This study examined the effects of heat treatment (60 or 75 degrees C) on the viability of C. parvum oocysts inoculated onto the surface of beef muscle estimated by vital dye assay. The infectivity of the oocysts was assessed against monolayers of HCT-8 cells. At 60 degrees C viability of the oocysts decreased from 100% at T0 to 64.2% at T60. At 75 degrees C the viability of the oocysts decreased from 100% at T0 to 53.7% at T15 and finally to 11.2% at T60. Oocysts were rendered noninfective against monolayers of HCT-8 cells following treatments of 60 degrees C/45 s and 75 degrees C/20 s. CONCLUSION: The washing of carcasses with hot water and standard thermal treatments is sufficient to kill C. parvum on beef. SIGNIFICANCE AND IMPACT OF THE STUDY: This study found that relatively mild heat, currently used to decontaminate and heat treat beef carcasses and to cook meat products, is capable of inactivating C. parvum.

An evaluation of sampling methods for the detection of Escherichia coli and Salmonella on Turkey carcasses.

The efficacy of rinse, excision, and swab methods for the microbiological analysis of prechill turkey carcasses was investigated. Aerobic plate counts from a 50-cm2 area of the breast sampled by excision and by swabbing were compared. Escherichia coli and Salmonella recoveries were determined from turkeys sampled by a carcass rinse (CR), a modified rinse with the carcass supported in a swing (MCR), a two-site swab of 50 cm2 at the back and thigh (2S), a one-site swab of 50 cm2 beneath the wing (1S), a whole-carcass swab of the inner and outer carcass surface (WS), and excision of 25 g of neck skin tissue (NE). The effect of diluent volume (25, 50, and 100 ml) on E. coli counts from swab samples was also assessed. The aerobic plate count from breast tissue sampled by excision was greater than that by swabbing (P < 0.05). E. coli recoveries by the MCR method were similar to those by CR. E. coli counts from IS and WS samples were higher when swabs were stomached in 50 rather than 25 ml of diluent (P < 0.05). For swabs stomached in 50 ml of diluent, E. coli recoveries by the MCR, 2S, 1S, and WS methods were similar. For swabs stomached in 50 ml of diluent, Salmonella recoveries by the WS and MCR methods were higher than those by the 2S and 1S methods. Excision was more effective than swabbing for obtaining total bacterial counts from reduced turkey carcass areas. Whole-carcass sampling by rinsing or swabbing is necessary for optimum Salmonella recovery. Sampling a reduced area of the carcass is sufficient for E. coli analysis.

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.

Effect of a commercial freeze/tempering process on the viability of Cryptosporidium parvum oocysts on lean and fat beef trimmings.

Lean and fat beef trimmings (25 cm(-2)) were inoculated with approximately 250,000 Cryptosporidium parvum oocysts, placed in commercial packages (28 kg boxes) and subjected to normal commercial processes i.e. blast frozen (to -20 °C within 60 h), stored (-20 °C, 21 days), tempered (48 h at -3 °C), and held at 0 °C for 10 h. Inoculated areas were then excised, pulsified (30 s in 50 ml PBST), and centrifuged (2500×g, 15 min). The resultant pellet was resuspended in 10 ml water and subjected to immunomagnetic separation and viability dye assay. Following the commercial freeze/tempering process the viability of the oocysts had decreased from 90.6% viable in the working stock suspension to 7.17% and 9.46% viable on lean and fat trimmings, respectively. The results of this study indicate that if C. parvum oocysts were present on beef trimmings their viability would be substantially reduced as a result of the freeze/tempering process.

The effects of treating bovine hide with steam at subatmospheric pressure on bacterial numbers and leather quality.

AIMS: To examine the effect of subatmospheric steam treatment on total viable counts (TVCs) on bovine hide and on the quality of derived leather. METHODS AND RESULTS: Pieces of bovine hide were heated to 75 degrees C (+/-2 degrees C) (n = 3) or 80 degrees C (+/-2 degrees C) (n = 3) for periods of 1, 10 or 20 s by the application of steam at subatmospheric pressure in a laboratory scale apparatus. Treated hide pieces and untreated controls were tanned and the quality of leather was assessed. Treatment at 80 degrees C (T80) reduced the TVC on hide pieces by 2.95 (1 s), 3.33 (10 s) and 3.99 (20 s) log10 CFU cm-2 (P > 0.05). Treatment at 75 degrees C (T75) reduced the TVC on hide pieces by 1.87 (1 s), 2.51 (10 s) and 2.56 (20 s) log10 CFU cm-2 (P > 0.05). The grain on all treated hides was damaged resulting in sueding on derived leather. Sueding was observed on 100% of surfaces from T80-treated samples and on 18 (1 s) to 84% (20 s) of the surfaces of T75 samples. CONCLUSIONS: The magnitude of TVC reductions achieved using T75 and T80 could limit the impact and scale of contamination transfer to the carcass during dehiding. However, because of the sueding observed on derived leather, it is unlikely that either T75 or T80 would be a commercially valid operation during routine slaughter operations. SIGNIFICANCE AND IMPACT OF THE STUDY: Hide decontamination would provide an important critical control point for beef processing, however there are currently no commercially available treatments.

The prevalence and spread of Escherichia coli O157:H7 at a commercial beef abattoir.

AIMS: To investigate the prevalence and virulence characteristics of Escherichia coli O157:H7 after a number of beef process operations at a commercial Irish abattoir. METHODS AND RESULTS: Two 12-month studies were carried out. The first study (study 1) examined the prevalence of E. coli O157:H7 at up to six sites on carcasses at eight stages of the dressing, washing, chilling and boning process. The second study (study 2) examined the prevalence of E. coli O157:H7 in bovine faeces and rumen contents post-slaughter and on dressed, washed carcasses. Isolates from both studies were phage-typed and the presence of genes encoding verocytotoxin, enterohaemolysin and intimin production was determined. E. coli O157:H7 was isolated from four of 36 carcasses in study 1. E. coli O157:H7 was detected during hide removal and was detected at multiple carcass sites and multiple process stages, including boning. On two carcasses, contamination was first detected at the bung following its freeing and tying. All isolates from study 1 were phage type (PT) 2, eaeAO157 and ehlyA positive, but were verocytotoxin 1 (VT1) and verocytotoxin 2 (VT2) negative. In study 2, E. coli O157:H7 was isolated from 2.4% of faecal, 0.8% of rumen and 3.2% of carcass samples. In some cases, isolates recovered from the faeces of a particular animal, the resulting carcass and adjacent carcasses on the line had the same phage typing and virulence characteristic profile patterns. All isolates from study 2 were eaeAO157 and ehlyA positive and only one isolate was VT1 and VT2 negative. Most isolates were PT 32. A higher frequency of positive isolations was noted from samples taken during spring and late summer. CONCLUSION: These studies show that in a typical Irish beef abattoir, carcass contamination with E. coli O157:H7 can occur during hide removal and bung tying and this contamination can remain on the carcass during subsequent processing. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides data that is necessary for the understanding of how E. coli O157:H7 contamination of beef occurs.

The prevalence of Salmonella spp. in bovine faecal, rumen and carcass samples at a commercial abattoir.

AIMS: To determine the prevalence, serotype and antibiotic resistance profile of Salmonella isolates in cattle and on carcasses at a commercial Irish abattoir. METHODS AND RESULTS: Faecal, rumen and carcass samples were collected from a beef abattoir over a 12-month period and examined for the presence of Salmonella spp. Isolates were serotyped, phage typed (when serotype was found to be S. Typhimurium) and tested for susceptibility to a panel of antibiotics. Salmonella was isolated from 2% of faecal, 2% of rumen and 7.6% of carcass samples. Salmonella was most frequently isolated from samples taken during the period August to October. S. Dublin was isolated from 72% of positive samples. S. Agona and S. Typhimurium definitive type (DT)104 were each isolated from 14% of positive samples. All S. Typhimurium DT104 isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulphafurazole and tetracycline (ACSSuT). On occasion, from a single animal, the same serotype was isolated from more than one sample (i.e. faeces and rumen; faeces and carcass; rumen and carcass; faeces, rumen and carcass). CONCLUSIONS: Salmonella is present in cattle at slaughter and on beef carcasses at an Irish abattoir, with a higher frequency of occurrence during the period August to October. Most isolates from the study are not commonly associated with human clinical infection, with the exception of S. Typhimurium DT104 (R-type ACSSuT). SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides epidemiological data that is necessary for the understanding of beef as a source of human Salmonella infection.

Use of steam condensing at subatmospheric pressures to reduce Escherichia coli O157:H7 numbers on bovine hide.

This study used a laboratory-scale apparatus to apply subatmospheric steam to bovine hide pieces inoculated with Escherichia coli O157:H7 in maximum recovery diluent (MRD) and in high-liquid content and low-liquid content fecal suspensions (HLC fecal and LLC fecal, respectively). The survival of the organism in fecal clods, which were stored for 24 days in a desiccated state, was assessed. Inoculated fecal clods were also treated with subatmospheric steam. Steam treatment at 80 +/- 2 degrees C for 20 s reduced E. coli O157:H7 concentrations on hide inoculated to initial concentrations of approximately 7 log10 CFU/g by 5.46 (MRD inoculum), 4.17 (HLC fecal inoculum), and 5.99 (LLC fecal inoculum) log10 CFU/g. The reductions achieved in samples inoculated with LLC feces were larger than in samples inoculated with HLC feces (P < 0.05). Treatment at 80 +/- 2 degrees C for 10 s resulted in significantly smaller reductions (P < 0.05) on hide pieces of 2.54 (MRD), 1.94 (HLC fecal), and 2.15 (LLC fecal) log10 CFU/g. There were no significant differences among the reductions observed in all inoculum types in samples treated for 10 s. E. coli O157:H7 inoculated in fecal clods to 7.78 log10 CFU/g and stored at 4 or 15 degrees C survived for at least 24 days. Steam treatment (20 s) of 3-day-old clods reduced surviving E. coli O157:H7 numbers from 4.20 log10 CFU/g to below the limit of detection of the assay used (1.20 log10 CFU/g). This study shows that steam condensing at or below 80 +/- 2 degrees C can reduce E. coli O157:H7 when present on bovine hide, reducing the risk of cross contamination to the carcass during slaughter and dressing.

The relationship between hide cleanliness and bacterial numbers on beef carcasses at a commercial abattoir.

Cattle were visually inspected in the lairage of a commercial abattoir and assigned to a category ranging from 1 (very clean) to 5 (very dirty) depending on the observed cleanliness of the hide. Animals from categories 2, 3 and 5 were slaughtered and total viable counts (TVCs) enumerated at five sites (hock, brisket, cranial back, bung and inside round) on the subsequent carcasses. The TVCs at the hock were significantly higher on category 5 than on category 2 carcasses (P < 0.05). Similarly, TVCs at the brisket were significantly higher on categories 3 and 5 than on category 2 carcasses (P < 0.05). There were no differences in counts among the categories at any of the other sites. The TVCs averaged over the five carcass sites were higher for category 5 than for category 2 carcasses (P < 0.05). The TVCs at the brisket were significantly higher than all other sites (P < 0.01). In general, carcasses from category 2 animals slaughtered in a batch with dirtier animals (categories 3 and 5) did not have higher TVCs than carcasses of category 2 animals slaughtered at the beginning of the day in the absence of dirtier animals. The introduction of improved hygienic practices during the dehiding of category 4 animals resulted in reduced TVCs at the brisket (P < 0.001).

A double-blind clinical trial of mianserin versus amitriptyline: differentiation by adverse symptomatology.

A 6-week double-blind comparison of mianserin, a new antidepressant, and amitriptyline allowed us to explore the problem of demonstrating main effect differences in drug/drug trials when the focus is primarily only upon efficacy or upon common adverse symptomatology. Statistical analyses of standard psychiatric rating scales revealed no significant treatment differences, while both treatment groups exhibited significant parallel improvement across time. Examination of treatment emergent symptoms indicated that, while it evoked fewer anticholinergic symptoms than amitriptyline, mianserin exhibited a different profile of adverse symptomatology. The usefulness of a measure of the benefit/risk ratio was described as a means of clarifying drug/drug comparisons.