Tracing Campylobacter jejuni strains along the poultry meat production chain from farm to retail by pulsed-field gel electrophoresis, and the antimicrobial resistance of isolates

In this study Campylobacter jejuni isolates were recovered from birds, carcasses and carcass portions from two broiler chicken flocks and from equipment used for carcass and meat processing along the production chain from farms to retail stores. Isolates were subjected to pulsed-field gel electrophoresis (PFGE) using SmaI and KpnI restriction enzymes and their antimicrobial susceptibilities were determined. C. jejuni was recovered from product and equipment used with both flocks at each point in the production chain. The prevalence of C. jejuni in poultry products at retail stores was 58.97% (flock 1) and 69.23% (flock 2). SmaI divided 122 C. jejuni strains from flock 1 and 106 from flock 2 into 17 and 13 PFGE types, respectively. PFGE types H and F were present at all steps along the chain, from farms to retail products. Similarly, for both flocks PFGE type D was detected in crates, slaughterhouse and retail stores. Moreover, the PFGE types were highly diverse at the processing and retail steps. Most PFGE types were resistant to ciprofloxacin (95.45%) and tetracycline (81.82%); and multidrug resistant PFGE types were found in the final products. Our study showed that there were several points of cross-contamination of product along the chain, and a high diversity of PFGE types with antimicrobial resistance to ciprofloxacin and tetracycline in the retail products.     

Predominant strains of thermophilic Campylobacter spp. in a German poultry slaughterhouse

Campylobacter causes bacterial diarrhoea in man and is a common foodborne pathogen, that has been associated mainly with poultry carcasses and processed poultry products as well as with drinking water. Genotyping of Campylobacter spp. from poultry was done in order to prove if predominant stable strains in the food chain are present. The influence of the slaughter process on the stability should be determined. Thermophilic Campylobacter spp. from eight poultry flocks were isolated from cloacal swabs, carcasses and offal at different abattoir processing steps to determine their stability. DNA-fingerprinting was done using Pulsed-Field Gel Electrophoresis (PFGE) with two enzymes (SmaI and KpnI) and ribotyping. More than 150 Campylobacter strains were ribotyped and these data were combined with the results of PFGE. Molecular typing showed that strains found in cloacal swabs before processing could also be isolated from carcasses and offal at different processing steps representing predominating stable strains. Strains with varying molecular pattern could additionally be detected at different processing steps. Both genotyping methods identified in agreement flock-specific strains. These remained stable through the slaughter of poultry and were not altered through the slaughter process. Despite the known genetic variability of thermophilic Campylobacter, stable predominant strains could be identified in the poultry slaughter process and those strains can thus enter the food chain.     

Diversity of flaA genotypes among Campylobacter jejuni isolated from six niche-market poultry species at farm and processing

PCR-restriction fragment length polymorphism of the flagellin (flaA) gene in Campylobacter jejuni was used to determine the relationships of isolates collected at the farm and throughout processing for six niche-market poultry species. This study focused on two specialty chicken products, poussin and free range, and four other specialty products, squab, duck, guinea fowl, and quail. Cloacal and carcass samples were collected from three flocks from each of the six niche species. Three processing plants in California participated in a 2-year investigation. A total of 773 isolates from farm, posttransport, and the processing plants were genotyped, yielding a total of 72 distinct flaA profiles for the six commodities. Genetic diversity of C. jejuni at the farm was greatest for ducks with up to 12 distinct flaA types in two flocks and least for squab 1 flaA type between two farms. For two of the guinea fowl flocks, one free-range flock, two squab flocks, and all three poussin flocks, the flaA types recovered at the prepackage station matched those from the farm. Cross-contamination of poultry carcasses was supported by the observation of flaA types during processing that were not present at the farm level. New C. jejuni strains were detected after transport in ducks, guinea fowl, and free-range chickens. Postpicker, postevisceration, and prewash sampling points in the processing plant yield novel isolates. Duck and free-range chickens were the only species for which strains recovered within the processing plant were also found on the final product. Isolates recovered from squab had 56 to 93% similarity based on the flaA types defined by PCR-restriction fragment length polymorphism profiles. The 26 duck isolates had genetic similarities that ranged from 20 to 90%. Guinea fowl and free-range chickens each had 40 to 65% similarity between isolates. Poussin isolates were 33 to 55% similar to each other, and quail isolates were 46 to 100% similar. Our results continue to emphasize the need to clean processing equipment and posttransport crates in order to decrease cross contamination between flocks. This study also determined that several strains of C. jejuni had unique flaA types that could only be recovered in their host species.     

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.     

Campylobacter contamination during poultry slaughter in Belgium

The relation between internal carriage and surface contamination with thermophilic Campylobacter species in broilers was examined by molecular typing methods. Samples from 39 flocks were collected in three Belgian poultry slaughterhouses. From each flock, crop swabs before slaughter and intestines and neck skins during slaughter were collected. A total of 309 isolates were identified at species level and further characterized by flagellin gene A PCR/restriction fragment length polymorphism and pulsed-field gel electrophoresis. Isolates were identified as Campylobacter jejuni (90%), Campylobacter coli (8.7%), and Campylobacter lari (2.2%), and 27 genotypes could be distinguished by combining the two molecular methods. Seventy-two percent of the flocks arriving at the abattoir were colonized with campylobacters. After slaughter, 79% of the flocks had contaminated neck skins. In six flocks, genotypes isolated from the neck skins were also found in the alimentary tract from previously slaughtered flocks. Four of these flocks were initially free of Campylobacter. These four flocks might have had no contaminated carcasses after logistic slaughtering.     

From farm to fork follow-up of thermotolerant campylobacters throughout the broiler production chain and in human cases in a Hungarian county during a ten-months period

A study tracking thermotolerant campylobacters from the setting of the broilers throughout the whole rearing period, slaughter and sale of chicken products in five consecutive broiler rotations of the same henhouse as well as in two different other farms was conducted in a well-defined geographic area (Hajdú-Bihar county, Hungary) between March 2006 and Feb 2007. All notified cases of human campylobacteriosis in this area during the study period were also included. One hundred and one, 44, 23 and 282 Campylobacter jejuni and 13, 15, 20 and 60C. coli were isolated from broiler houses, slaughterhouses, retail shops and human samples, respectively. Sixty-two isolates collected from broilers or their environment selected from different flocks (57C. jejuni, 5C. coli), 92 isolates collected from abattoirs and retail shops (72C. jejuni, 20C. coli), as well as 85 randomly selected human isolates (74C. jejuni, 11C. coli) were subjected to PFGE analysis using restriction enzymes KpnI and SmaI. Sixty-six of the isolates produced unique Sma-Kpn profiles; the majority (46) of these were of human origin. The remaining isolates formed PFGE clusters of between 2-25 isolates with 14 (12C. jejuni and 2C. coli) main clusters comprised of five or more isolates with identical KpnI-SmaI patterns. Two genetic clones of C. jejuni (clone A, n=25; clone B, n=20) included 18% of isolates from different sources. Generally, isolates from one cluster were found in 1-3 different flocks, notably, clone B was present in three rotations including those from the two independent farms. Six of the seven investigated flocks had one or two characteristic prevalent clones. Transmission of clones between consecutive flocks was frequently seen. Spread of both C. jejuni and C. coli was traced multiple times along the food chain; eight C. jejuni, but no C. coli clones were detected both in broilers and humans. These data suggest that broilers were the major source for C. jejuni but not for C. coli in the studied area and period. For C. jejuni the carryover of strains between consecutive flocks may be a common event, but the strain is eventually replaced by another and consecutive carryover events seem to be infrequent. The majority of the human disease was due to nonepidemic strains; some clones were transmitted from more than one broiler flocks (including epidemiologically unrelated flocks) to humans multiple times.     

Contamination of carcasses with Salmonella during poultry slaughter

Successively slaughtered poultry flocks were sampled for Salmonella to study the relationship between gastrointestinal colonization of the birds and contamination of the carcasses after slaughter. Samples from 56 broiler flocks and 16 spent layer and breeder flocks were collected in six slaughterhouses. Salmonella isolates were serotyped and further characterized by pulsed-field gel electrophoresis (PFGE). Although only 7 (13%) broiler flocks were colonized with Salmonella at slaughter, carcasses of 31 (55%) broiler flocks were contaminated after slaughter. Concerning the layer and breeder flocks, 11 (69%) flocks were colonized in the gastrointestinal tract, but after slaughter, carcasses of all flocks were contaminated. The Salmonella status determined at the farm did not always correlate to the status at slaughter. On the other hand, the slaughter of Salmonella-colonized flocks did not always result in the contamination of the carcasses with the same PFGE types isolated from the gastrointestinal tract. When only uncolonized flocks were slaughtered, the carcasses of flocks were on some occasions still contaminated with Salmonella. This indicates possible cross-contamination from the slaughter equipment or transport crates. These observations show that it is difficult to reach the benefits of logistic slaughter in commercial poultry slaughterhouses.     

Occurrence and genotypes of Campylobacter in broiler flocks, other farm animals, and the environment during several rearing periods on selected poultry farms

On 15 Swiss poultry farms, broiler flocks, other farm animals, and the environment were examined during consecutive rearing periods to investigate the occurrence and genetic diversity of Campylobacter. Of the 5154 collected samples, 311 (6%) from 14 farms were Campylobacter positive by culture. Amongst the positive samples, 228 tested positive for Campylobacter jejuni and 92 for Campylobacter coli. Positive samples originated from broilers, the broiler houses, cattle, pigs, bantams, laying hens, a horse, and a mouse. Feed, litter, flies, and the supply air to the broiler house tested negative. By flagellin gene typing (fla-RFLP) and pulsed-field gel electrophoresis (PFGE), 917 Campylobacter isolates were genotyped. Additionally, amplified fragment length polymorphism (AFLP) analysis was performed on 15 assorted strains. On eight farms, matching genotypes were isolated from broiler flocks and other farm animals: Certain genotypes from cattle (farms H, K, L, and M), pigs (farms D and P), or laying hens (farm L) were subsequently found in the broiler flocks, whereas other genotypes initially present in the broiler flocks turned up in cattle (farms A, D, and O). These results emphasize the importance of other farm animals on poultry farms for broiler flock colonization. Indications of persistent contamination of the broiler house were evident on four farms (C, D, I, and L) where matching genotypes were detected in consecutive broiler flocks, but not concurrently in other samples. By fla-RFLP, PFGE, and confirmed by AFLP, some genotypes proofed to be identical across different farms.     

Campylobacter colonization of sibling turkey flocks reared under different management conditions

Uncertainty exists concerning the key factors contributing to Campylobacter colonization of poultry, especially the possible role of vertical transmission from breeder hens to young birds. A longitudinal study of Campylobacter colonization was performed in two sibling pairs of turkey flocks (four flocks total). Each pair of sibling flocks shared breeder hen populations and was obtained from the same hatchery. One flock of each pair was grown on a commercial farm, and the other was grown in an instructional demonstration unit (Teaching Animal Unit [TAU]). Flocks were located within a 60-mi (96.8-km) radius. The time of placement, feed formulations, stocking density, and general husbandry were the same for both flocks, and each flock was processed at a commercial processing plant following standard feed withdrawal and transport protocols. Both flocks grown on the commercial farms became colonized with Campylobacter between weeks 2 and 3 and remained colonized until processing. Between 80 and 90% of isolates were Campylobacter coli, and the remainder were Campylobacter jejuni. In contrast, neither C. coli nor C. jejuni were isolated from either of the TAU flocks at any time during the production cycle. None of the fla types of Campylobacter from the breeders that provided poults to one of the commercial flocks matched those from the progeny. These results failed to provide evidence for vertical transmission and indicate that this type of transmission either did not occur or was not sufficient to render the TAU turkey flocks Campylobacter positive. Management practices such as proper litter maintenance, controlled traffic between the TAU farm and other turkey flocks, and other less well-defined aspects of turkey production were likely responsible for the absence of Campylobacter in the TAU flocks before harvest.     

Characterization of Campylobacter isolates recovered from clinically healthy pigs and from sporadic cases of campylobacteriosis in humans

Campylobacter spp. were recovered from 660 (77.6%) of 850 swine cecal contents at the abattoir and from 24 (8.6%) of 278 specimens from sporadic cases of human diarrhea during the same period in the same geographical area. Campylobacter coli represented 95.7% of Campylobacter isolates recovered from pigs and 8.3% of those isolated from humans. Genetic profiles were determined by pulsed-field gel electrophoresis (PFGE) using KpnI enzyme to characterize the isolates in combination with phenotypic assays to detect production of cytotoxins, enterotoxins, and hemolysins. Among a subset of isolates (n = 10), up to five colonies from the same animal were characterized by PFGE. In 5 (50%) of 10 of the isolates, more than one genetic profile was observed per pig. Among the 100 isolates from pigs selected for further analysis, 81 different genetic profiles were observed, whereas 20 different genetic profiles were found among the 24 isolates of human origin. Cytotoxicity on Chinese hamster ovary cells was observed in 11 (11%) of 98 isolates from pigs and in 5 (21%) of 24 Campylobacter isolates from humans. No enterotoxin production was detected in Campylobacter isolates in this study, but 17 (71%) of 24 human and 61 (63%) of 97 pig isolates showed hemolytic activity. The study of genotypic and phenotypic profiles of swine and human isolates revealed no epidemiological relationship between isolates. The low genomic relatedness observed between groups of isolates and the weak toxicity level of swine isolates suggest that the hazard of contamination of humans by Campylobacter associated with swine production is low.     

Summary of the Swedish Campylobacter program in broilers, 2001 through 2005

A Campylobacter monitoring program in broiler chickens was carried out in Sweden from 2001 through 2005. The objective was to reduce the occurrence of Campylobacter in the food chain through preventive measures, starting with primary production. The program involved collecting samples from all broiler flocks at slaughter and occasional additional times. The annual incidence of Campylobacter-positive slaughter batches progressively decreased from 20% in 2002 to 13% in 2005. Most of the positive batches had a high within-flock prevalence of Campylobacter. However, about 18% of the positive batches had a low-within-flock prevalence; Campylobacter spp. were isolated from at most 50% of the cloacal samples. The incidence of batches contaminated at slaughter ranged between 6 and 9% during the study period. During all 5 years, a seasonal peak of incidence was observed in the summertime. In an additional study, quantitative analyses were performed on neck skin samples and carcass rinse samples. Those results were compared with the positive and negative findings of the cloacal, cecum, and neck skin samples at slaughter. When Campylobacter was found in the cecum, there was a higher level of Campylobacter in the quantitative analyses. Those batches where Campylobacter already had been found on the farm had a higher concentration of Campylobacter than those batches in which Campylobacter was found only at slaughter. During the study period, about one-third of producers seldom delivered Campylobacter-positive batches (< 10% positive batches per year). Thus, it is possible to produce Campylobacter-free broilers in Sweden.     

An evaluation of sampling- and culturing methods in the Norwegian action plan against Campylobacter in broilers

The Norwegian Action Plan against Campylobacter in broilers was implemented in May 2001 with the objective of reducing human exposure to Campylobacter through Norwegian broilers. From each flock, samples collected at the farm about one week prior to slaughter, and then again at the slaughter plant, are examined for the presence of Campylobacter. All farmers with positive flocks are followed up with bio-security advice. Sampling of broiler products at retail level is also included in the Action Plan. The aim of this study was to evaluate the existing sampling and culturing methods of the Norwegian Action Plan against Campylobacter in broilers. The material collected was pooled faecal samples, pooled cloacae samples and caecae samples from individuals. The highest number of positives, from culturing of the pooled faecal samples, the pooled cloacae swabs and the caecae swabs from individuals, were obtained at incubation temperature 41.5 degrees C. When comparing the results at incubation temperature 37 and 41.5 degrees C, the faecal samples from the farms demonstrated a high concordance, with a kappa value of 0.88. The results from culturing cloacae swabs and caecae samples from slaughter plant level at two temperatures did not agree very well with a kappa value of 0.21 and moderate value of 0.57, respectively, but were both disconcordant at a level of 0.05. Modelling farm level data indicated that if increasing the number of pooled samples per flock from two (in existing regime) to three, the flock sensitivity increases from 89% to 95%. Modelling of slaughter plant data indicated that three pooled cloacae swabs are needed to identify 90% of the positive flocks. The results from the modelling of caecae data indicated that samples from seven individuals are sufficient to identify 90% of the positive flocks and caecae samples could thus be an alternative to cloacae sampling at slaughter plant level.     

Ecology of Listeria spp. in a fish farm and molecular typing of Listeria monocytogenes from fish farming and processing companies

This study focused on the ecology of Listeria monocytogenes in a fish farm by following the changes in its occurrence in different types of samples for a three year period. In addition, L. monocytogenes isolates from different seafood industry areas were compared with pulsed field gel electrophoresis (PFGE) typing to discover possible associations between primary production, further processing and final products. Weather conditions were found to have a strong influence on the probability of finding Listeria spp. in a fish farm environment. The number of samples contaminated with Listeria spp. was typically bigger after rainy periods. Brook and river waters as well as other runoff waters seemed to be the main contamination source at the farm studied. The farmed fish originally found to carry L. monocytogenes become gradually Listeria free. The time needed for the purification of the fish was several months. The sea bottom soil samples were the ones that preserved the L. monocytogenes contamination the longest time. It can be stated that the fish and fish farm equipment studied did not spread listeria contamination. On the contrary, they were found to suffer from listeria contamination coming from outside sources like the brook water. There was a wide range of different L. monocytogenes PFGE-pulsotypes (30) found at 15 Finnish fish farms and fish processing factories. L. monocytogenes isolates from the final products often belonged to the same pulsotypes as did the isolates from the processing environment as well as from the raw fish. This suggests that, in addition to the fish processing factory environment, the fish raw materials are important sources of L. monocytogenes contamination in final products.     

A longitudinal study of Salmonella and Campylobacter jejuni isolates from day of hatch through processing by automated ribotyping

Comparisons of bacterial populations over long periods of time allow researchers to identify clonal populations, perhaps those responsible for contamination of farms or humans. Salmonella and Campylobacter can cause human illness, and our objective was to use a library typing system to track strains that persist in the poultry house and through the processing plant. Two farms, over four consecutive flocks, were studied. Multiple samples were taken of the poultry house environment, feed mill, transport crates, and carcasses in the processing plant. Sample collection on the farm took place on chick placement day, midgrowout, and the day of harvest. This study found that 80.3% of isolates belonged to a single strain of Salmonella Kentucky that persisted in several environmental samples for all flocks at both farms, from chick placement day to the final product at the plant. Surgical shoe covers produced most isolates (n = 26), and processing day yielded the highest recovery (n = 68). Additional serotypes were recovered, but the Salmonella Kentucky-positive eggshells and chick mortality appeared to be the source of the organism for both farms. All Campylobacter isolates recovered were identified as C. jejuni. Most Campylobacter isolates (90.1%) belonged to one of three core strains. C. jejuni was not recovered on chick placement day. Cecal droppings yielded all nine strains. Most isolates (98.2%) were from one farm. Cluster analysis grouped C. jejuni and Salmonella isolates into four and six distinct clusters, respectively, on the basis of a similarity level of 80%.     

Genetic diversity of Arcobacter and Campylobacter on broiler carcasses during processing

Broiler carcasses (n=325) were sampled at three sites along the processing line (prescalding, prechilling, and postchilling) in a commercial poultry processing plant during five plant visits from August to October 2004. Pulsed-field gel electrophoresis (PFGE) was used to determine the genomic fingerprints of Camospylobacter coli (n=27), Campylobacter jejuni (n=188), Arcobacter butzleri (n=138), Arcobacter cryaerophilus 1A (n=4), and A. cryaerophilus 1B (n=31) with the restriction enzymes SmaI and KpnI for Campylobacter and Arcobacter, respectively. Campylobacter species were subtyped by the Centers for Disease Control and Prevention PulseNet 24-h standardized protocol for C. jejuni. A modification of this protocol with a different restriction endonuclease (KpnI) and different electrophoresis running conditions produced the best separation of restriction fragment patterns for Arcobacter species. Both unique and common PFGE types of Arcobacter and Campylobacter strains were identified. A total of 32.8% (57 of 174) of the Arcobacter isolates had unique PFGE profiles, whereas only 2.3% (5 of 215) of the Campylobacter isolates belonged to this category. The remaining Arcobacter strains were distributed among 25 common PFGE types; only eight common Campylobacter PFGE types were observed. Cluster analysis showed no associations among the common PFGE types for either genus. Each of the eight common Campylobacter types consisted entirely of isolates from one sampling day, whereas more than half of the common Arcobacter types contained isolates from different sampling days. Our results demonstrate far greater genetic diversity for Arcobacter than for Campylobacter and suggest that the Campylobacter types are specific to individual flocks of birds processed on each sampling day.     

Evaluation of logistic processing to reduce cross-contamination of commercial broiler carcasses with Campylobacter spp

Cross-contamination of broiler carcasses with Campylobacter is a large problem in food production. Here, we investigated whether the contamination of broilers carcasses from Campylobacter-negative flocks can be avoided by logistic scheduling during processing. For this purpose, fecal samples were collected from several commercial broiler flocks and enumerated for Campylobacter spp. Based on enumeration results, flocks were categorized as Campylobacter negative or Campylobacter positive. The schedule of processing included the testing of Campylobacter-positive flocks before or after the testing of Campylobacter-negative flocks. During processing, flocks were also sampled for Campylobacter spp. before and after chilling. Campylobacter strains were identified with multiplex PCR and analyzed for relatedness with pulsed-field gel electrophoresis. Our results show that Campylobacter-negative flocks were indeed contaminated with Campylobacter strains originating from previously processed Campylobacter-positive flocks. Campylobacter isolates collected from carcasses originating from different farms processed on the same day showed similar pulsed-field gel electrophoresis patterns, confirming cross-contamination. These findings suggest that a simple logistic processing schedule can preserve the Campylobacter-negative status of broiler carcasses and result in products with enhanced food safety.     

The temporal,PFGE and resistance pattern associations suggest that poultry products are only a minor source of human infections in Western Finland

In order to compare human and retail poultry meat thermophilic Campylobacter isolates originating in a regional area in Western Finland, minimum inhibitory concentration (MICs) for six antimicrobials (96 isolates) and pulsed-field gel electrophoresis (PFGE) (102 isolates) were analysed. Campylobacter spp. were detected in 10.5% out of 305 fresh poultry products studied; 29 (90.5%) isolates were identified as Campylobacter jejuni. Among the 70 human isolates, 66 (94.3%) isolates were identified as C. jejuni. Only one C. jejuni domestic poultry isolate showed resistance (ampicillin), whereas domestic human C. jejuni isolates were more commonly resistant to ciprofloxacin, nalidixic acid, ampicillin and tetracycline. The resistance in foreign human isolates was significantly more common than among domestic isolates. PFGE analysis with KpnI restriction enzyme resulted in 59 different PFGE types among the poultry and human isolates. Three types were detected first in poultry meat and thereafter during the following month in domestic human samples, whereas the other conjoint types were detected only after many months. This study suggests that poultry products play only a minor role in human campylobacteriosis in the study area and that the resistance found in domestic human isolates is not likely related to retail poultry meat products.     

Prevalence of methicillin-resistant Staphylococcus aureus in a fresh meat pork production chain

The objective of this study was to investigate the prevalence of methicillin-resistant Staphylococcus aureus on different stages of a fresh pork production chain to reveal potential carryover from live animals to meat. Samples were collected at different stages of the production process in a large German abattoir with an integrated processing unit for fresh pork. Samples included nasal swabs from pigs at stunning, environmental samples from the slaughter line, surface samples from carcasses, environmental and meat samples from the processing unit, and samples from final products. Samples were analyzed with an established two-step selective enrichment method, and isolates were characterized with respect to their S. aureus protein A gene (spa) and staphylococcal cassette chromosome mec (SCCmec; which harbors the mecA gene) types. Contamination rate was highest (64.7%) in nasal swabs and lower (6.0%) on carcasses, meat at processing (4.2%), and final products (2.8%). Environmental samples were positive along the slaughter line (12%) but not in the processing unit. spa types t011 and t034 and SCCmec type V predominated the isolates. Heterogeneity of spa types was highest in nasal swabs. Results show that methicillin-resistant S. aureus can be identified at all stages of the production chain. Further studies are needed to identify potential control points to reduce the carryover from farm animals to the final products.     

Sources and spread of thermophilic Campylobacter spp. during partial depopulation of broiler chicken flocks

The practice of partial depopulation or thinning (early removal of a portion of birds from a commercial broiler flock) is a reported risk factor for Campylobacter colonization of residual birds because of the difficulty in maintaining biosecurity during the thinning process. The effect of this practice was studied in detail for 51 target flocks, each at a different growing farm belonging to one of seven major poultry companies throughout the United Kingdom. On 21 of these farms, the target flock was already colonized by Campylobacter, and at slaughter all cecal samples examined were positive, with a mean of 8 log CFU/g. An additional 27 flocks became positive within 2 to 6 days of the start of thinning and had similarly high levels of cecal carriage at slaughter. Just before the thinning process, Campylobacter was isolated frequently from the farm driveways, transport vehicles, equipment, and personnel. Strains from seven farms on which flocks became colonized after thinning were examined by pulsed-field gel electrophoresis typing. An association was found between strains occurring at specific sampling sites and those isolated subsequently from the thinned flocks. The results indicated that particular strains had spread from one farm to another when the farms were jointly owned by the same company and employed the same bird-catching teams and/or vehicles. These results highlight the need for better hygiene control in relation to catching equipment and personnel and more effective cleaning and disinfection of vehicles and bird-transport crates.     

Recovery of Campylobacter jejuni from surfaces of poultry slaughterhouses after cleaning and disinfection procedures: analysis of a potential source of carcass contamination

Campylobacters are a primary cause of human bacterial enteritis worldwide. They are usually considered susceptible to the disinfectant molecules used in the food industry. The purpose of this study was to see if campylobacters could survive cleaning and disinfection in poultry slaughterhouses and whether the strains recovered could contaminate carcasses during processing. Samples obtained from the environment before and after cleaning and disinfection (transport crates, processing equipment surfaces, scald tank water) and from birds (fresh droppings, neck skins) were collected during 7 investigations in 4 different slaughterhouses. Out of 41 samples collected, 30 Campylobacter jejuni strains were recovered from the surfaces of processing equipment before cleaning and disinfection procedures in three slaughterhouses and 9 C. jejuni out of 51 samples collected were found after cleaning. The study was then focused on one slaughterhouse to trace passage of the pathogen on poultry carcasses. The antimicrobial resistance phenotypes (P) (minimum inhibitory concentration, MIC) of the C. jejuni isolates collected in this slaughterhouse were determined. Nine phenotypes could be distinguished. Three of these were of interest as they were found in isolates recovered after cleaning and disinfection procedures. The genotypes (G) were determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) of isolates with one of the three phenotypes of interest. Clusters constructed by combining the phenotype and genotyping observations (PG type) were compared between isolates obtained after cleaning and disinfection, and isolates from droppings, neck skin and transport crate samples of slaughtered poultry flocks. Only one PG type of strain was recovered from surfaces after cleaning and disinfection and from neck skin samples but was also recovered from transport crates. Our findings indicate that C. jejuni is able to survive overnight on food processing equipment surfaces, after cleaning and disinfection procedures, and that these strains may contaminate carcasses during the slaughter process. These results add to our understanding of poultry carcass contamination and highlight the need to develop ways of reducing the risk of human infection with Campylobacter through the consumption of poultry products.