Contamination of freshly slaughtered pig carcasses with human pathogenic Yersinia enterocolitica

Evidence is presented for the extent of contamination of freshly slaughtered pig carscasses with human pathogenic Yersinia enterocolitica and shows the significance of faecal contamination as a source of infection. Swab samples collected from the rectum and the surface of a total of 1458 pig carcasses were examined for the presence of human pathogenic Y. enterocolitica Y. enterocolitica, biovar IV, serogroup 0:3, were isolated from the rectum of 360 pigs (24.7%). The organism was isolated from carcass surfaces with varying frequencies depending on the evisceration technique. Manual evisceration was found to correspond with high frequencies of contamination: 26.3% on the medial hind limb and 12.9% on the split sternum. The use of a mechanised bung cutter was found to reduce the rate of contamination, especially when the bung cutter was used in connexion with enclosing the anus and rectum in a plastic bag to minimise faecal contamination. When carcasses were eviscerated in this way, it was possible to reduce carcass contamination to 1.9% on the medial hind limb, 1.0% in the pelvic duct, and 2.2% on the split sternum.     

Slaughter pigs and pork as a source of human pathogenic Yersinia enterocolitica.

Pathogenic Yersinia enterocolitica strains (serogroups 0:3;0:9 and 0:5.27) were isolated from 36 (42%) of 86 porcine tonsils, 8 (20%) of 40 tongues, 17 (17%) of 100 rectal swabs and from 4 (1%) of 400 pork samples. Pathogenic Yersinia strains were not isolated from samples of 210 pig carcasses and from 20 samples of porcine head meat. These results confirm that pigs are an important reservoir of pathogenic Y. enterocolitica. However, contamination of carcasses during the slaughtering process with Yersinia from either faecal material or from the tonsillary region does not seem to occur frequently and this may also explain the low contamination rate of pathogenic Y. enterocolitica found for pork. For the isolation of pathogenic Y. enterocolitica strains from foods, enrichment in irgasan-ticarcillin-chlorate broth (ITC) and isolation on SS-deoxycholate-calcium agar (SSDC) is recommended.     

Counts of Campylobacter spp. on U.S. broiler carcasses

Foodborne Campylobacter-associated gastroenteritis remains a public health concern, and the Centers for Disease Control and Prevention suggests that improperly handled poultry is the most important source of this human disease. In response to these concerns, 10 of the largest U.S. poultry integrators cooperatively determined the incidence and counts of Campylobacter on processed broiler carcasses. Prior to conducting the survey, laboratory personnel were trained in a direct Campy-Cefex plating procedure for enumeration of the organism. Before and after the survey enumeration, consistency in reporting was compared among the participating laboratories. Participating laboratories were able to consistently estimate inoculated concentrations of Campylobacter in carcass rinses. Within the central study, we determined the potential exposure of U.S. consumers to Campylobacter spp. associated with broiler carcasses during a 13-month period. Among each of the 13 participating poultry complexes, rinses from 25 randomly selected fully processed carcasses were sampled monthly from individual flocks. Among 4200 samples, approximately 74% of the carcasses yielded no countable Campylobacter cells. Campylobacter spp. were isolated from approximately 3.6% of all commercially processed broiler carcasses at more than 10(5) CFU per carcass. Acceptable counts of these organisms on raw poultry carcasses remain to be determined. Nevertheless, this survey indicates industry recognition of its responsibility to assess and reduce public exposure to Campylobacter through broiler chickens.     

Testing of pathogenic Yersinia enterocolitica in pig herds based on the natural dynamic of infection

This study was performed to evaluate testing methods of pathogenic Yersinia enterocolitica in pigs at different ages. Relevant tools and procedures are crucial if pig herds should be declared free from pathogenic Y. enterocolitica. Historical data based on serology showed that the two farms investigated in this study (herds A and B) were contaminated with Y. enterocolitica O:3 since at least 1995. Laboratory investigations of 60 pigs were sampled one to four times (herd A) and 20 pigs were sampled one to three times (herd B) at different ages were the basis for this report. The following testing procedures could be used to conclude that a herd is free from pathogenic Y. enterocolitica:--serological testing of pigs could be performed as a basis for categorisation for all ages from about 100 days including at slaughter when the pigs are 150-180 days old, --bacteriological examination of faeces could be used as a basis for categorisation at all ages from 85 days until about 135 days, --bacteriological examination of tonsils could be used as a basis for categorisation at all ages from 85 days including at slaughter when the pigs are 150-180 days old. However, due to animal welfare aspects, one should avoid sampling of tonsils. Accordingly, the serological method or bacteriological examination of faeces at relevant ages should be preferred. One aspect related to slaughter hygiene is that in pigs slaughtered at the age of 135 days or more, the tonsils may be a more significant source of human pathogenic Y. enterocolitica than faeces.     

The effects of Campylobacter numbers in caeca on the contamination of broiler carcasses with Campylobacter

For the presence and number of Campylobacter, 18 broiler flocks were sampled over a period of 18 months. A total of 70% of the flocks were positive for Campylobacter, with higher prevalence found in summer and autumn, compared to winter and spring. Positive flocks showed contamination rates above 90%, in negative flocks this was lower, mostly below 50%. The enumeration showed a decrease in Campylobacter during processing of positive flocks. The numbers were highest in carcasses after scalding/defeathering (mean 5.9 log(10) cfu/carcass) and dropped by 0.7 log(10) cfu/carcass after chilling. A positive correlation was observed between the number of Campylobacter present in the caeca and the number of bacteria present on carcasses and cut products. When a negative flock was slaughtered after Campylobacter positive flocks, the number of positive samples was higher compared to the case when a negative flock had been slaughtered previously. C. jejuni was isolated from 73.6% of the poultry samples.     

A meta-analysis study of the effect of chilling on prevalence of Salmonella on pig carcasses

In the field of food safety, meta-analysis can be used to combine results of prevalence studies of pathogens at critical stages within the food processing chain so that policy makers can access reliable and concise information on the effectiveness of interventions for controlling and preventing foodborne illnesses in humans. The objective of this work was to demonstrate the applicability of a parametric approach of meta-analysis to the specific case of determining the overall effect of chilling on Salmonella prevalence on pig carcasses. A meta-analysis was performed on each of two parameters measuring effect size for binary outcomes (relative risk and risk difference). Both meta-analyses confirmed that the chilling operation has a significant beneficial effect (P < 0.001) on the reduction of Salmonella prevalence on pig carcasses. Because risk difference is a parameter sensitive to the differences across studies in carcass swab areas and Salmonella detection methods, its meta-analysis highly reflected this heterogeneity (P < 0.001). However, parameterization of relative risk, not being biased by the above sources of variability, did not give rise to heterogeneity among studies and produced a fixed-effects meta-analysis solution, which is deemed more suitable for compilations based on a small number of individual studies (n = 9). Because of the systematic approach of meta-analysis (i.e., individual studies are weighed according to precision) and its reliance for actual data, the output distribution of the relative risk effect size (approximately eN(-0.868,0.166)) merits consideration for inclusion in the chilling stage of quantitative risk assessments modeling the prevalence of this pathogen along the pork production chain.     

Contamination of carcasses, offals, and the environment with yadA-positive Yersinia enterocolitica in a pig slaughterhouse

This study was carried out in order to evaluate the contamination of the pig-slaughtering line with pathogenic Yersinia enterocolitica carrying the yadA gene. A total of 292 samples were collected from the slaughterhouse; 131 swab samples from pig carcasses, ears, livers, kidneys, and hearts; 89 swab samples from the environment; and 72 sedimentation samples from the air. All surface samples were studied with both the polymerase chain reaction (PCR) and culture methods. The contamination rate of edible pig offals was high with both methods. Using PCR, the detection rates of yadA-positive Y. enterocolitica for livers, kidneys, and hearts were 38, 86, and 63%, respectively, and using the culture method, the detection rates were 31, 69, and 50%, respectively. Pathogenic Y. enterocolitica was also detected from different environmental sites in the slaughterhouse. Using PCR, 13% of the surface samples from the environment were contaminated with yadA-positive Y. enterocolitica. PCR-positive samples were found on the brisket saw, the hook from which the pluck set (heart, lungs, esophagus, trachea, diaphragm, liver, kidneys, and tongue with tonsils) hang, the knife used for evisceration, the floors in the eviscerating area and the weighing area, the meat-cutting table, the aprons used by trimming workers, the computer used in the meat-inspection area, and the coffeemaker used by slaughterhouse workers. The respective detection rate (6%) was considerably lower when we used the culture method. Pathogenic Y. enterocolitica was isolated from the air in the bleeding area. Bioserotype 4/O:3 was the only pathogenic bioserotype isolated in this study. A total of 113 isolates of type 4/O:3 were characterized with pulsed-field gel electrophoresis using NotI and XbaI digests. By combining these profiles, nine different pulsotypes were obtained, the most common of which (1a) was found in 19 (61%) of 31 samples from different sites. This is the same type that has dominated in pig tonsils, which suggests that tonsils may be the source of Y. enterocolitica contamination in the slaughterhouse. The four pulsotypes (1a, 4g, 6g, and 19q) found on edible offals were the same as those found in tonsils, which supports our hypothesis that tonsils are the contamination source for the liver, heart, and kidneys.     

Effect of chilling applied to suckling lamb carcasses on hygienic, physicochemical and sensory meat quality

The effect of post mortem temperature treatment on suckling lamb carcass and meat quality was study. Conventional (2°C for 24h), ultra-rapid (-20°C for 3.5h, 2°C until 24h) and slow chillings (12°C for 7h, 2°C until 24h) were compared. Total viable counts (TVC), weight losses, and pH and temperature falls were recorded on carcasses. Meat colour, water holding capacity (WHC), Warner-Bratzler shear force, sarcomere length and sensory analysis were evaluated in M. longissimus. Ultra-rapid treatment reduced TVC and weight losses. The pH decline was faster in slow chilled carcasses than in faster chilled carcasses. No significant differences were found for colour and WHC. Slow treatment carcasses showed significantly lower shear force and higher sarcomere length. In the sensory analysis, tasters also rated the early post mortem slow-treated meat as more tender, less fibrous and chewy. Therefore, delay chilling in suckling lamb carcasses made it possible to obtain meat with better organoleptic characteristics, without affecting weight loss or hygienic quality.     

Campylobacter spp. contamination of chicken carcasses during processing in relation to flock colonisation

The presence and numbers of campylobacters on chicken carcasses from 26 slaughter groups, originating from 22 single-house flocks and processed in four UK plants, were studied in relation to the level of flock colonisation determined by examining the caecal contents of at least ten birds per group. The prevalence of campylobacters on carcasses from five campylobacter-negative flocks processed just after other negative flocks was low (8.0 log(10) cfu) than carcasses originating from low prevalence flocks (average of 2.3 log(10) cfu; range: <1.1 to 4.1 log(10) cfu). There was a reduction in the numbers of campylobacters on carcasses between plucking and chilling in eight of ten fully colonised flocks. In another eight flocks, a significant (P<0.001) decrease (0.8 log(10) cfu) in the number of campylobacters on carcasses from just before to after chilling was detected. Campylobacter spp. could be isolated from aerosols, particles and droplets in considerable numbers in the hanging-on, defeathering and evisceration areas but not in the chillers. This was the case even when campylobacters were not isolated from the target flock. Campylobacters on carcasses from two partly colonised flocks were either the same subtype, as determined by speciation, Multi-Locus Sequence Typing (MLST) and flaA Restricted Fragment Length Polymorphism (RFLP) typing, as those in the fully colonised flocks processed previously, although not necessarily the most prevalent ones; or were the same subtypes as those found in the caeca of the flock itself. The prevalences of the different campylobacter subtypes found on carcasses from two fully colonised flocks did not closely reflect those found in the caeca. MLST combined with flaA RFLP provided a good method for ascertaining the relatedness of strains isolated from carcasses and caecal contents. This study showed that carcass contamination is related to the within-flock prevalence of campylobacter colonisation, but that contamination from previously processed flocks was also significant, especially on carcasses from low prevalence flocks. Forced dry air cooling of carcasses reduced contamination levels.     

Enumeration of Campylobacter spp. in broiler feces and in corresponding processed carcasses

Twenty north Georgia commercial flocks of broiler chickens sampled in 1995 and 11 flocks sampled in 2001 were tested for Campylobacter spp. Direct plating on Campy-Cefex agar was carried out to determine levels of Campylobacter colonization within each flock through the enumeration of the organism in 50 fresh fecal samples 1 day prior to slaughter. The next morning, these flocks were the first to be processed, and levels of the organism per carcass before the chilling operation (50 carcasses per flock) in 2001 and after the chilling operation (50 carcasses per flock) in both 1995 and 2001 were estimated. Levels of the organism on freshly processed broiler carcasses were estimated by the same methods in 1995 and 2001, and a significant reduction from an average of 10(4.11) CFU per carcass in 1995 to an average of 10(3.05) CFU per carcass in 2001 was observed. Levels of Campylobacter spp. found in production and in processing were not strongly correlative, indicating the existence of complex parameters involving production factors and variables associated with flock transport and the processing of the broilers. The reduction in Campylobacter levels on processed carcasses may have contributed to the reduction in the frequency of human disease observed by the Centers for Disease Control during the same period. These data characterize the distribution of Campylobacter in north Georgia poultry operations and should assist in the development of risk assessment models for Campylobacter spp. The results obtained in this study suggest that the implementation of antimicrobial interventions by the poultry industry has already reduced consumer exposure to the organism.     

Occurrence of Yersinia enterocolitica and Campylobacter spp. in slaughter pigs and consequences for meat inspection,slaughtering, and dressing procedures

The purpose of the present investigation was to assess the occurrence of Yersinia enterocolitica and Campylobacter spp. in the lymphoid tissues and intestinal tract in pigs and the risk for contamination during the compulsory meat inspection procedures and the procedures during slaughtering and dressing. Another objective of the investigation was to compare traditional isolation methods, the use of a polymerase chain reaction (PCR) method (BUGS'n BEADS™ bacterial DNA isolation kit) and an ELISA method (VIDAS CAM) as tools in risk management in the slaughterhouse.

The results indicate that the compulsory procedure for the incision of the submaxillary lymph nodes represents a cross-contamination risk for virulent Yersinia. In the screening of 97 animals in 1999, 5.2% of the samples were positive, and by the sampling of 24 samples in 2000–2001, 12.5% of the samples were positive. In the last case, Y. enterocolitica O:3 was found in the kidney region in one of the subsequent carcasses that was only touched by the meat inspection personnel before sampling. In addition, incision of the mesenteric lymph nodes might represent a cross-contamination risk since 8.3% of the samples were positive.

The association between antibody titres and the occurrence of virulent yersiniae in the tonsils (21–18) was striking, with virulent yersiniae found in the tonsils in most pigs with high titres.

The contents of the stomach, ileum, caecum, and colon also represent contamination risks for Y. enterocolitica O:3 if the slaughterhouse personnel cuts into the viscera with their knives by accident; the frequency of virulent Yersinia varied from 4.2% to 16.7% within these sections.

Campylobacter was detected in the gastrointestinal tract of all pigs, and the high contamination of tonsils (66.7%) and intestinal tract (100%) might represent an occupational health hazard.

There was no statistical difference between the traditional method for isolation of Y. enterocolitica [International Organization for Standardization, 1994. Microbiology—General Guidance for the Detection of Presumptive Pathogenic Yersinia enterocolitica (ISO 10273). International Organization for Standardization, Genève, Switzerland (16 pp.)] and the BUGS'n BEADS™ detection method for virulent Y. enterocolitica. Likewise, there was no statistical difference between the traditional method for isolation of Campylobacter spp. [Nordic Committee on Food Analysis, 1990. Campylobacter jejuni/coli. Detection in Food. Method No. 119, 2nd ed. Nordic Committee on Food Analysis, Esbo (7 pp.)] and the BUGS'n BEADS™ detection method or the VIDAS CAM method for detection of Campylobacter spp.     

The contamination of pork with spoilage bacteria during commercial dressing, chilling and cutting of pig carcasses.

Swab samples from the surfaces of carcasses and cuts were obtained at various stages of the dressing, chilling and cutting operations in three pig processing plants. The aerobic microflora obtained from those swabs were enumerated and characterized. The flora on the skins of carcasses exiting the scalding tanks were dominated by Gram-positive organisms, with numbers about 10(3)/cm2. After dehairing, numbers were about 10(4)/cm2 with major fractions of Gram-negative organisms. Flora numbers and compositions were largely unaltered after the singeing operations, but lesser numbers were recovered after the carcasses were polished. Carcass dressing did not change the numbers on the skin. During the chilling of carcasses, the flora at two large plants altered little, but drying of the carcass surfaces at a smaller plant reduced the Gram-negative fraction of the flora. Numbers on serous and fat surfaces exposed during the dressing and cutting of carcasses were initially about 10(2)/cm2. That number was approximately maintained on finished skinned cuts produced at the smaller plant, but further contamination with lactobacilli and Brochothrix thermosphacta occurred during cutting. At the larger plants, the flora on skinned cuts were similar to those on skins, although further contamination with B. thermosphacta occurred at one plant.     

Survey of thermotolerant Campylobacter spp. and Yersinia spp. in three surface water sources in Norway.

We investigated the occurrence of thermotolerant Campylobacter and Yersinia spp. in three surface water sources in Norway which represented different levels of pollution and eutrophication. Samples were collected every fortnight during a 14-month period. In addition, samples from 100 private wells were examined for campylobacters only. Campylobacter was recovered from 42 (43.8%) of the 96 samples of surface water, whereas Yersinia spp. were isolated from four (4.2%) of the samples. Campylobacter was not isolated from the well water samples. The highest isolation rate of Campylobacter was obtained from the two most polluted water sources. The proportion of positive samples was significantly higher in the autumn (71.4%) than in the spring (36.4%) or summer (22.2%). The highest overall isolation rate was obtained at water temperatures ranging from 2.1 to 8.0 degrees C, and the lowest at temperatures greater than 15 degrees C. Logistic regression analysis showed a highly significant relationship between the prevalence of Campylobacter and the number of three types of indicator bacteria: faecal coliforms, faecal streptococci and sulphite-reducing clostridia. Of the 60 Campylobacter isolates obtained, 51.7% belonged to C. jejuni biotype 1, 20.0% belonged to C. jejuni biotype 2, 21.7% to C. coli, 3.3% to C. lari and 3.3% were non-typable. All four Yersinia isolates were non-pathogenic variants.     

Effects of postchill application of acidified sodium chlorite to control Campylobacter spp. and Escherichia coli on commercial broiler carcasses

Experiments were performed to assess the reduction of Campylobacter spp. and Escherichia coli in commercial broiler carcasses by postchill dip applications of acidified sodium chlorite. Carcass rinses were collected before the inside-outside-bird washer (IOBW), post-IOBW, postchill, and after the postchill application of acidified sodium chlorite. Prevalence and counts of Campylobacter spp. and E. coli were determined. The mean values for Campylobacter spp. and E. coli counts differed significantly at sampling sites. The IOBW reduced the bacterial counts significantly in only one experiment. The chiller reduced Campylobacter counts significantly in both experiments but failed to significantly reduce the counts of E. coli in one experiment. No major reduction in the prevalence after enrichment for Campylobacter spp. was detected post-IOBW or postchill. However, a significant reduction in Campylobacter spp. and in E. coli counts and Campylobacter spp. prevalence was seen after the postchill application of acidified sodium chlorite. These results demonstrate that the antimicrobial effect of acidified sodium chlorite applied postchill may be used to significantly reduce Campylobacter spp. and E. coli in commercial broiler carcasses. Postchill systems may eventually be used in different applications, such as mist, spray, or bath, which could be applied closer to the final stages in processing.     

Prevalence and numbers of Salmonella and Campylobacter spp. on raw,whole chickens in relation to sampling methods

Salmonella and Campylobacter continue to be major foodborne pathogens and raw poultry is considered to be an important source of these bacteria. In this study, the prevalence and numbers of Salmonella and Campylobacter spp. in relation to isolation/sampling methods were determined in 241 whole raw chickens purchased from retail outlets in England during the winters of 1998/1999 (101 chickens) and 1999/2000 (140 chickens). The packaging of the 140 chickens was also examined for the presence of the above pathogens. The prevalence and numbers of enterococci were examined in 21 of the 101 chickens. In total, Salmonella and Campylobacter spp. were present in 25% and 83% of the chickens, respectively. Salmonella were isolated from a sample representing both the inside and outside of the packaging in 19% of the chickens, while the corresponding figure for Campylobacter spp. was 56%. Both of these pathogens were isolated from the outside of the packaging in 6% of the chickens. Salmonella was more frequently isolated from samples containing chicken skin in comparison with those containing carcass-rinse fluid only. Two chickens (0.8%) were positive for Salmonella by direct enumeration methods with contamination levels of log10 3.8 and 4.5 colony forming units (cfu) per carcass, respectively. The most prevalent serotypes were S. Hadar, S. Enteritidis and S. Indiana and two different serotypes were identified in 5/20 salmonella-positive chickens. Resistance to at least one antibiotic was found in 70% of the strains, 46% were multiresistant (resistant to > or = four drugs) and 52% showed a lowered susceptibility to ciprofloxacin. The likelihood of isolating Campylobacter spp. from neck-skin, carcass-rinse or carcass-rinse plus whole skin samples was similar, Campylobacter spp. were found in higher levels in carcass-rinse or carcass-rinse plus whole skin samples than in neck-skin. The log10 cfu of Campylobacter spp. were 2.70-4.99 in 18% of the chickens and 5.00-6.99 in 20%. Campylobacter isolates (425) comprised Campylobacter jejuni (98%) and C. coli (2%) and 98 different sero/phagetypes of these two species were identified. Resistance to at least one antibiotic was found in 73% of the strains and 13% were multiresistant. Thirteen percent of the strains showed lowered susceptibility to ciprofloxacin, while 4.9% were resistant to erythromycin. Vancomycin-resistant enterococci (VRE), able to grow on agar containing 15 mg l(-1) vancomycin (VRE15), were present in 19 chickens. The log10 cfu of VRE15 was 2.90-3.99 in 10 chickens and between 4.00 and 4.99 in two chickens. The data presented here contribute to risk assessment and highlight the need to continue to emphasise the safe handling of raw retail poultry.     

The effect of slaughter operations on the contamination of chicken carcasses with thermotolerant Campylobacter

To evaluate the effect of specific slaughter operations on the contamination of broiler carcasses with naturally occurring thermotolerant Campylobacter, experiments were carried out in two Danish commercial slaughter plants (Plant I and Plant II). Six broiler flocks determined Campylobacter positive prior to slaughter were investigated at four sampling locations within each slaughter plant. Quantification of thermotolerant Campylobacter in 30 neck skin samples per flock per sampling location showed that the evisceration operation in Plant I led to a significant increase in the Campylobacter concentration of 0.5 log(10) cfu/g in average, whereas no significant changes were observed during this operation in Plant II. Air chilling (Plant I) and water chilling (Plant II), both including a carcass wash prior to the chilling operation, caused similar, but significant reductions of 0.83 and 0.97 log(10) cfu/g, respectively. In packed frozen chickens (Plant II) an additional reduction of 1.38 log(10) cfu/g in average was obtained due to the freezing operation. In packed chilled chickens (Plant I), however, the number of thermotolerant Campylobacter per gram remained at the same level as after air chilling. Enumeration of thermotolerant Campylobacter in 30 intestinal samples per flock showed that in two of the six flocks examined the within flock colonization was very low (<3% and 27% positive samples). The remaining four flocks were colonized at percentages of 100 (three flocks) and 97 (one flock) and had intestinal mean counts ranging from 6.65 to 8.20 log(10) cfu/g. A correlation between Campylobacter concentrations in intestinal content and on chicken carcasses after the defeathering operation was documented. This finding indicates that a reduction in the Campylobacter concentration on chicken carcasses may also be obtained by interventions aimed at reducing the concentration of Campylobacter in the intestines of the living birds.     

Prevalence and numbers of Campylobacter on broiler carcasses collected at rehang and postchill in 20 U.S. processing plants

Campylobacter is a human pathogen associated with chicken and chicken meat products. This study was designed to examine the prevalence and number of Campylobacter on broiler chicken carcasses in commercial processing plants in the United States. Carcass samples were collected from each of 20 U.S. plants four times, roughly approximating the four seasons of 2005. At each plant on each sample day, 10 carcasses were collected at rehang (prior to evisceration), and 10 carcasses from the same flock were collected postchill. A total of 800 carcasses were collected at rehang and another 800 were collected postchill. All carcasses were subjected to a whole-carcass rinse, and the rinse diluent was cultured for Campylobacter. The overall mean number of Campylobacter detected on carcasses at rehang was 2.66 log CFU per ml of carcass rinse. In each plant, the Campylobacter numbers were significantly reduced by broiler processing; the mean concentration after chill was 0.43 log CFU/ml. Overall prevalence was also reduced by processing from a mean of > or =30 of 40 carcasses at rehang to > or =14 of 40 carcasses at postchill. Seven different on-line reprocessing techniques were applied in the test plants, and all techniques resulted in <1 log CFU/ml after chilling. Use of a chlorinated carcass wash before evisceration did not affect the postchill Campylobacter numbers. However, use of chlorine in the chill tank was related to lower numbers on postchill carcasses. Overall, U.S. commercial poultry slaughter operations are successful in significantly lowering the prevalence and number of Campylobacter on broiler carcasses during processing.     

Isolation of Campylobacter spp. from a pig slaughterhouse and analysis of cross-contamination

The purpose of this study was to establish the prevalence and possible contamination routes of Campylobacter spp. in a pig slaughterhouse. Swab samples were taken from the last part of rectum, from the carcasses surface before meat inspection and from slaughter line surface from 4 different pig herds during slaughtering. Identification of Campylobacter isolates was determined by the use of phase-contrast microscopy, hippurate hydrolysis, indoxyl acetate hydrolysis tests and PCR based restriction fragment length polymorphism method (PCR-RFLP). Pulsed-field gel electrophoresis (PFGE) typing using two macro-restriction enzymes SmaI and SalI was applied to in-slaughterhouse contamination analysis of pig carcasses. The study showed that 28 (63.6%) of the 44 samples collected at slaughterhouse were contaminated by Campylobacter spp. Up to 5 different colonies were obtained from each swab sample and a total of 120 different isolates were collected. 23.4% (28 of 120) isolates were identified as C. jejuni (19 from carcasses and 9 from slaughter line surfaces) and 76.6% (92 of 120) isolates as C. coli (28 from faeces, 47 from carcasses and 17 from slaughter line surfaces). The typing results showed identity between isolates from successive flocks, different carcasses, and places in the slaughterhouse in contact with carcasses. The results suggest that cross-contamination originated in the gastro-intestinal tract of the slaughtered pigs and that cross-contamination happened during the slaughter process.     

Detection of chromosomal and plasmid--encoded virulence determinants in Yersinia enterocolitica and other Yersinia spp. isolated from food animals in Greece

The distribution of Yersinia strains in animal reservoirs was examined in 835 food animals (pigs, chickens, sheep, cows) from different Greek departments (Attica, Fthiotida, Viotia and Evia) over a one year period. The isolated strains were characterized with respect to the presence of chromosomal (yst) and plasmid-encoded virulence determinants (virF, yadA) and their antimicrobial susceptibility was tested.In total, Yersiniaspp. were obtained from 9.94% of the 835 food animals at slaughter that were sampled in this study. There was no statistically significant seasonal distribution, nor was any significant departmental distribution observed. From the 83 isolated Yersinia strains, 76 (91,57%) belonged to Y. enterocolitica (58 were of serotype O:3/biotype 4 and 18 strains were non O:3, non O:9), 3 belonged to Y. pseudotuberculosis, 2 to Y. kristensenii and 2 to Y. intermedia. Y. enterocolitica O:3/4 was mainly isolated from the pigs, while Y. enterocolitica non O:3, non O:9 was from the chickens. The strains were grouped into 5 genotypes, with respect to the presence or absence of the virulence genes. A significant predominance of genotype V, the one carrying all the three virulence genes, was observed in the strains isolated from the pigs. Complete susceptibility to most of the 3rd and to the 4th generation cephalosporins and to ciprofloxacin, was observed among the isolates. Remarkable was the association between the presence of each virulence gene separately and resistance to some antimicrobials, a matter of further investigation.