Campylobacter infection in poultry-processing workers, Virginia, USA, 2008-2011

During a health hazard evaluation, we investigated 29 cases of laboratory-diagnosed Campylobacter infection among workers at a poultry-processing plant. Most infected employees worked at the plant <1 month, worked as live hangers, and lived at a state-operated center. To lessen the infection risk, we recommended improvements to engineering and administrative controls at the plant.

In-house validation of a multiplex real-time PCR method for simultaneous detection of Salmonella spp., Escherichia coli O157 and Listeria monocytogenes

A wide variety of qPCR methods currently exist for Salmonella spp., Escherichia coli O157 and Listeria monocytogenes detection. These methods target several genes and use different detection chemistries, either in simplex or in multiplex formats. However, the majority of these methods have not been carefully validated, and the number of validated methods that use multiplex qPCR is even lower. The aim of the present study was to develop and validate a multiplex qPCR method from previously validated simplex qPCR primers and probes. A modified broth medium was selected and primary and secondary enrichment times were further optimized. Efficiency of the newly combined qPCR system was comprised between 91% and 108%, for simplex and multiplex analyses. A total of 152 food and environmental, natural and spiked samples, were analyzed for the evaluation of the method obtaining values above 91% that were reached for all the quality parameters analyzed. A very low limit of detection (5 cfu/25 g after enrichment) for simultaneous identification of these 3 pathogens was obtained.

Microbiological quality of broiler carcasses during slaughter processing

Microbial contamination of poultry carcasses can be influenced by many factors during transport and slaughtering. The aim of this study was to evaluate the impact of four processing steps (plucking, evisceration, washing and chilling) on the total viable counts (TVC), counts ofEscherichia coli,Salmonellaspp. andListeriaspp. incidence on broiler carcasses. A total of 160 broiler carcasses originating from one farm were collected during one year period at a Czech slaughterhouse and examined. Both TVC andE. colicounts decreased during processing from 4.6 log cfu/cm2and 3.5 log cfu/cm2to 3.7 log cfu/cm2and 1.8 log cfu/cm2, respectively, with a major impact of washing on TVC and washing and chilling onE. colidecrease (P< 0.001). BothSalmonellaspp. (6 strains) andListeriaspp. (12 strains, none ofL. monocytogenes) were found sporadically in all processing steps followed. However, a decreasing trend was observed inSalmonellacounts andListeriaspp. incidence during the processing. Thus, this study brings new valuable information on the dynamics of microflora during modern poultry processing.

Phenotypic and genotypic methods for typing Campylobacter jejuni and Campylobacter coli in poultry

Human campylobacteriosis, an infection caused by the bacterium Campylobacter, is a major issue in the United States food system, especially for poultry products. According to the Center for Disease Control, campylobacterosis is estimated to affect over 2.4 million people annually. Campylobacter jejuni and Campylobacter coli are 2 species responsible for the majority of campylobacterosis infections. Phenotypic and genotypic typing methods are often used to discriminate between bacteria at the species and subspecies level and are often used to identify pathogenic organisms, such as C. jejuni and C. coli. This review describes the design as well as advantages and disadvantages for 3 current phenotypic techniques (biotyping, serotyping, and multilocus enzyme electrophoresis) and 6 genotypic techniques (multilocus sequence typing, PCR, pulse-field gel electrophoresis, ribotyping, flagellin typing, and amplified fragment length polymorphisms) for typing pathogenic Campylobacter spp.

Molecular tracking, through processing, of Campylobacter strains colonizing broiler flocks

Many of the poultry flocks produced in the United Kingdom are colonized with Campylobacter, and the intensive nature of poultry processing usually results in contaminated carcasses. In this study, a previously reported molecular oligonucleotide probe method was used to track a specific flock-colonizing strain(s) on broiler carcasses during processing in two United Kingdom commercial poultry processing plants. Five Campylobacter-positive flocks were sampled at four points along the processing line, postbleed, postpluck, prechill, and postchill, and two Campylobacter-negative flocks processed immediately after positive flocks were sampled prechill. flaA was sequenced from Campylobacter strains isolated from these flocks, and strain-specific probes were synthesized. Skin and cecal samples were plated onto selective agar to give individual colonies, which were transferred onto membranes. These were then hybridized with the strain- and genus-specific probes. For all the 5 positive flocks, there was a significant reduction in campylobacters postbleed compared to postpluck but no subsequent fall on sampling pre- and postchill, and the strain(s) predominating on the carcasses throughout processing came from the flock being processed. This indicates that strains from the abattoir environment were not a significant cause of carcass contamination in flocks with well-established campylobacter colonization. However, negative flocks that were preceded by positive flocks were contaminated by strains that did not generally originate from the predominating strains recovered from the ceca of the previous positive flocks. This suggests that the abattoir environment has a significant role in the contamination of carcasses from negative but not fully colonized flocks.

Occurrence of Campylobacter spp. in poultry and poultry products for sale on the Polish retail market

In 2007 and 2008, a monitoring study was carried out in Poland to examine the occurrence of thermotolerant Campylobacter spp. in raw and cooked chicken products available on the retail market. A total of 912 samples were tested: 443 samples of raw chicken meat, 146 samples of giblets, and 323 ready-to-eat poultry products (150 samples of spit-roasted chicken, 56 samples of smoked chicken, and 117 samples of pâté and cold meats). A high level of contamination of raw chicken meat (51.7% of samples) and chicken giblets (47.3% of samples) was detected. However, thermotolerant Campylobacter spp. were found in only 1.2% of the ready-to-eat poultry products.

Use of bioluminescence imaging to monitor Campylobacter survival in chicken litter

AIM

The aim of this study was to develop a novel approach for characterizing the growth and persistence of Campylobacter in different poultry-rearing environments. Specifically, we constructed bioluminescent Campylobacter strains and used them to monitor the survival of these pathogens in litter (bedding) material.

METHODS AND RESULTS

We inserted shuttle plasmids carrying the luminescence genes (luxCDABE) into C. jejuni and C. coli to construct bioluminescent strains of these pathogens. The strains were spiked into microcosms containing samples of litter-washings and dry litter collected from different enclosures that housed broiler chickens. Our results show that C. jejuni and C. coli survived for at least 20 days in reused (old) litter while the growth of these pathogens was inhibited in clean (new) litter. Furthermore, our results suggest that the availability of nutrients and the condition of the litter (reused vs new) are important factors in the persistence of these pathogens.

CONCLUSIONS

Reused litter can potentially predispose chickens to Campylobacter contamination and maintaining clean litter might reduce the incidences of colonization with these pathogens.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bioluminescence provided a simple, sensitive, and rapid approach for analysing the growth dynamics of Campylobacter. Using this technology, we highlighted the potential role of litter material in maintaining these pathogens in the chicken environment.

Antimicrobial edible apple films inactivate antibiotic resistant and susceptible Campylobacter jejuni strains on chicken breast

Campylobacter jejuni is the leading cause of bacterial diarrheal illness worldwide. Many strains are now becoming multidrug resistant. Apple-based edible films containing carvacrol and cinnamaldehyde were evaluated for bactericidal activity against antibiotic resistant and susceptible C. jejuni strains on chicken. Retail chicken breast samples inoculated with D28a and H2a (resistant strains) and A24a (a sensitive strain) were wrapped in apple films containing cinnamaldehyde or carvacrol at 0.5%, 1.5%, and 3% concentrations, and then incubated at 4 or 23 °C for 72 h. Immediately after wrapping and at 72 h, samples were plated for enumeration of viable C. jejuni. The antimicrobial films exhibited dose- and temperature-dependent bactericidal activity against all strains. Films with ≥1.5% cinnamaldehyde reduced populations of all strains to below detection at 23 °C at 72 h. At 4 °C with cinnamaldehyde, reductions were variable for all strains, ranging from 0.2 to 2.5 logs and 1.8 to 6.0 logs at 1.5% and 3.0%, respectively. Films with 3% carvacrol reduced populations of A24a and H2a to below detection, and D28a by 2.4 logs at 23 °C and 72 h. A 0.5-log reduction was observed for both A24a and D28a, and 0.9 logs for H2a at 4 °C at 3% carvacrol. Reductions ranged from 1.1 to 1.9 logs and 0.4 to 1.2 logs with 1.5% and 0.5% carvacrol at 23 °C, respectively. The films with cinnamaldehyde were more effective than carvacrol films. Reductions at 23 °C were greater than those at 4 °C. Our results showed that antimicrobial apple films have the potential to reduce C. jejuni on chicken and therefore, the risk of campylobacteriosis. Possible mechanisms of antimicrobial effects are discussed.

PRACTICAL APPLICATION

  Apple antimicrobial films could potentially be used in retail food packaging to reduce C. jejuni commonly present on food.

Simulation model for Campylobacter cross-contamination during poultry processing at slaughterhouses

Broiler meat is regarded as the most common source of Campylobacter infection and risk management measures are required to reduce broiler meat contamination. Among the quantitative risk assessments for Campylobacter in broiler meat, evaluation of the poultry processing stage is particularly important for predicting the contamination level of broiler meat and the effects of control measures. In this study, we built a simulation model for cross-contamination during poultry processing focusing on Campylobacter contamination at the individual carcass level. Using this model, we examined changes in the prevalence of contaminated carcasses and the number of Campylobacter per carcass after processing. As a result, it was found that the prevalence and number of Campylobacter after processing were largely influenced by the number of Campylobacter on the contaminated carcasses before processing. In the baseline model, where it was assumed that the mean number of Campylobacter on contaminated carcasses before processing was 4.7 log₁₀ cfu per carcass, the prevalence after processing was less than that before processing. Although the median value of Campylobacter on contaminated carcasses was reduced after processing, the distributions after processing became wider and the upper limit of the 95% credible interval of Campylobacter on contaminated carcasses remained elevated. The individual-based simulation model can trace individual level changes considering discrete interactions, while models tracing mean values cannot handle these interactions in detail. The individual-based approach is considered useful for modelling cross-contamination among individual carcasses during poultry processing.

Updating parameters of the chicken processing line model

A mathematical model of chicken processing that quantitatively describes the transmission of Campylobacter on chicken carcasses from slaughter to chicken meat product has been developed in Nauta et al. (2005). This model was quantified with expert judgment. Recent availability of data allows updating parameters of the model to better describe processes observed in slaughterhouses. We propose Bayesian updating as a suitable technique to update expert judgment with microbiological data. Berrang and Dickens's data are used to demonstrate performance of this method in updating parameters of the chicken processing line model.

Effect of temperature and contact time on Campylobacter jejuni attachment to, and probability of detachment from, stainless steel

The effect of temperature and contact time on attachment of six Campylobacter jejuni strains to, and probability of their detachment from, stainless steel were determined. Triplicate stainless steel coupons (SSC) were exposed to C. jejuni cell suspensions at 4, 25, 37, and 55 degrees C for 30 min. An increase in temperature enhanced the numbers of cells of all strains of C. jejuni attaching to stainless steel from approximately 4 log/cm(2) at 4 degrees C to approximately 5 log/cm(2) at 55 degrees C. Cells attached to SSC at 4 and 25 degrees C for 30 min were detached by the successive blotting technique on a series of Campylobacter blood-free selective agar plates. The probability of detachment was significantly (P < 0.05) higher at 4 degrees C (> or = 0.219) than at 25 degrees C (> or = 0.111) for five of the six strains tested, suggesting the strength of attachment was weaker at 4 degrees C than at 25 degrees C for these strains. C. jejuni cells were allowed to attach to SSC at 4 degrees C for 1, 15, 30, 45, 60, 120, 180, 240, and 300 min. The numbers of cells attaching to SSC reached approximately 4 log/cm(2) after 1 min of contact and increased slowly thereafter to approximately 5 log/cm(2) after 300 min of contact. The probability of detachment significantly (P < 0.05) decreased from 0.443 after 1 min to 0.134 after 240 min of contact, indicating bacterial attachment was strengthened over time. These data suggest that to reduce the numbers of adhered cells on processing surfaces, low-temperature and early bacterial detachment procedures should be applied.

Reduction of Campylobacter jejuni and Campylobacter coli in poultry skin by fruit extracts

Campylobacter spp. are a major cause of foodborne bacterial gastroenteritis in humans, and current methods to control Campylobacter contamination in foods are not completely successful. Plants are a promising source of antimicrobial agents, particularly given the growing interest in "all natural" foods. In this study, the antimicrobial activity of extracts from 28 edible plants against Campylobacter jejuni and Campylobacter coli was evaluated in vitro and in a poultry skin model. Nine of 28 extracts exhibited antimicrobial activity in a diffusion assay, and MBCs were determined for the three most active extracts, i.e., lime, plum, and sour orange peel (MBCs of 2 to 3 mg/ml). Mixtures of the lime, plum, and sour orange peel extracts were applied to chicken skin inoculated with 10(5) CFU of Campylobacter to test for synergistic or antagonist effects. After incubation (48 h at 4 degrees C) with any extract mixture, no Campylobacter CFUs were detectable. A panel of tasters determined that the mixture of lime and plum gave the best flavor to chicken wings. These active extracts from edible fruits are simple to prepare and are alternatives to reduce or eliminate Campylobacter contamination of chicken products.

Campylobacter species occurrence within internal organs and tissues of commercial caged Leghorn laying hens

Campylobacter spp. are frequently present in the intestinal tract and internal tissues of broiler breeder and broiler chickens. Campylobacter spp. ecology in commercial Leghorn laying hens has not been extensively studied. The objectives of the current study were to determine 1) Campylobacter spp. presence in the reproductive tract, lymphoid organs, liver-gallbladder, and ceca of commercial Leghorn laying hens; 2) species of Campylobacter present; and 3) antimicrobial resistance pattern of Campylobacter isolates. In study 1, three flocks ranging from 94 to 105 wk of age were sampled from a commercial laying complex. In study 2, two flocks, 82 and 84 wk of age, were sampled from a separate complex. Hens were killed, defeathered, aseptically necropsied, and the spleen, liver-gallbladder, ovarian follicles, and upper (infundibulum, magnum, and isthmus) and lower (shell gland and vagina) reproductive tracts were aseptically removed before the ceca. Samples were packed on ice and transported to the laboratory for evaluation. For speciation, a standard BAX real-time PCR method was used while susceptibility testing was performed using US National Antimicrobial Resistance Monitoring System (NARMS) standards and recommended quality control organisms. Isolates were examined for susceptibility using a semi-automated testing system (Sensititer) to the following 9 antimicrobials: azithromycin, clindamycin, ciprofloxacin, erythromycin, florfenicol, gentamicin, nalidixic acid, telithromycin, and tetracycline. In study 1, the isolation rate was 13, 67, 53, 3, 13, and 57% from the ovarian follicles, lower reproductive tract, upper reproductive tract, spleen, liver-gallbladder, and ceca, respectively. In study 2, the isolation rate was 17, 43, 33, 20, 17, and 73% from the ovarian follicles, lower reproductive tract, upper reproductive tract, spleen, liver-gallbladder, and ceca, respectively. Overall, 50% of isolates were Campylobacter jejuni, 49% Campylobacter coli, and 1% Campylobacter lari. In study 1, all of the isolates were pan-susceptible. In study 2, thirty-seven percent of the isolates were resistant to tetracycline. Commercial table egg laying hens housed in colony cages on wire floors had diverse Campylobacter spp. recovered from different tissues and these isolates were not resistant to a broad range of antimicrobials.

Ciprofloxacin-sensitive and ciprofloxacin-resistant Campylobacter jejuni are equally susceptible to natural orange oil-based antimicrobials

A total of 10 ciprofloxacin-sensitive (ciprofloxacin minimum inhibitory concentration, MIC < 0.5 micro g/ml) and 10 ciprofloxacin-resistant (MIC 16 to 32 micro g/ml) presumptive C. jejuni were further characterized and evaluated for their inhibition by natural orange oil fractions. Partial species identification was performed by using a hippuricase gene-based polymerase chain reaction (PCR) assay. One of the isolates appeared to be atypical and failed to hydrolyze hippurate. Of the ciprofloxacin-resistant C. jejuni isolates tested, six were found to have their quinolone resistance determined by a C --> T mutation in codon 86 of gyrA. Both groups of ciprofloxacin-sensitive and -resistant C. jejuni isolates were most susceptible to cold-pressed terpeneless Valencia orange oil (C4) which yielded inhibition zones from 44.0 +/- 1.4 to 80 +/- 0.0 mm. Less inhibitory responses were recorded for 5-fold concentrated Valencia orange oil (C3) and distilled d-limonene (C7) which exerted similar effects on both ciprofloxacin-sensitive and -resistant C. jejuni isolates. In general, ciprofloxacin-resistant and -sensitive C. jejuni isolates were equally susceptible to the respective orange oil fractions.

Evaluation of TECRA broth, Bolton broth, and direct plating for recovery of Campylobacter spp, from broiler carcass rinsates from commercial processing plants

The purpose of this study was to compare a conventional culture broth method (Bolton enrichment), a newly developed proprietary broth method (TECRA Campylobacter enrichment), and direct plating for recovery of Campylobacter spp. from chicken carcass rinsates. Whole carcass rinses were taken from 140 carcasses at rehang (immediately after defeathering but before evisceration) and from 140 carcasses at postchill from eight different processing plants in the United States. The rinsate samples were packed in ice and shipped overnight to the laboratory. Aliquots of the rinsate were transferred into Bolton and TECRA enrichment broths and were direct plated. Standard laboratory procedures with Campy-cefex plates were followed for recovery of Campylobacter spp. For rehang carcasses, 94% were positive for Campylobacter spp. with the TECRA enrichment broth and 74% were positive with the Bolton enrichment broth. For postchill carcasses, 74% were positive for Campylobacter spp. with the TECRA enrichment broth and 71% were positive with the Bolton enrichment broth. Compared with the Bolton enrichment broth, TECRA enrichment broth significantly suppressed non-Campylobacter microflora (P < 0.05). Overall, TECRA enrichment broth yielded an 11% higher total number of Campylobacter-positive samples compared with the Bolton enrichment broth. Campylobacter spp. detection in postchill samples was significantly greater (P < 0.05) by enrichment (84%) than by direct plating (19%). The high number of Campylobacter-positive samples obtained with all procedures indicated that 99% of the carcass rinsates obtained at rehang and 84% obtained at postchill contained Campylobacter spp.

Survival at refrigeration and freezing temperatures of Campylobacter coli and Campylobacter jejuni on chicken skin applied as axenic and mixed inoculums

Campylobacter is considered to be the most common cause of bacterial diarrhoeal illness in the developed world. Many cases are thought to be acquired from consumption of undercooked poultry. The aim of this study was to compare the effect of the rate of cooling on the survival, at 4 degrees C and -20 degrees C, of Campylobacter coli and Campylobacter jejuni strains, inoculated on chicken skin from axenic culture or as mixed inoculums. Strains chilled in a domestic refrigerator varied in their tolerance to storage at 4 degrees C. Statistically significant differences between strains applied as axenic or mixed inoculums were observed for specific strain combinations using two-way ANOVA, including the enhanced survival of antibiotic resistant C. coli 99/367 at 4 degrees C. The use of rapid cooling (at -20 degrees C/min) enhanced the survival of all the Campylobacter strains chilled to 4 degrees C compared to standard refrigeration. Freezing to -20 degrees C reduced viable counts by 2.2-2.6 log10 CFU/cm(2) in 24 h. Rapid cooling to -20 degrees C (at -30 degrees C/min) enhanced the survival of C. coli 99/367 compared to freezing in a domestic freezer. Statistically significant interaction terms between specific strains were observed in mixed inoculums chilled to -20 degrees C by freezing in a domestic freezer and by rapid chilling to -20 degrees C. Rapid chilling of poultry, particularly for 4 degrees C storage may enhance survival of Campylobacter and although this is an issue that affects meat quality, it should be considered by poultry processors.

Antimicrobial resistance in Campylobacter, Salmonella, and Escherichia coli isolated from retail turkey meat from southern Ontario, Canada

This study estimated the prevalence of Campylobacter, Salmonella, and Escherichia coli isolated from fresh retail turkey purchased at grocery stores in Ontario, Canada. The antimicrobial susceptibility patterns were determined and assessed for potential public health risk. From February 2003 to May 2004, 465 raw turkey meat samples were collected. Antimicrobial susceptibility testing was performed for Campylobacter isolates with a concentration gradient test and for Salmonella and E. coli isolates with a broth microdilution assay. Campylobacter isolates were recovered from 188 (46%) of 412 samples. The prevalence of resistance to one or more antimicrobials was 168 (81%) of 208. For antimicrobials of very high human health importance (category I of Health Canada's antimicrobial categorization), 12 (6%) of 208 Campylobacter isolates were ciprofloxacin resistant. Salmonella isolates were recovered from 95 (24%) of 397 samples. The prevalence of resistance to one or more antimicrobials was 50 (49%) of 102, and 13 (13%) of 102 samples were resistant to five or more antimicrobials. For category I antimicrobials, 14 (14%) of 102 and 1 (1%) of 102 isolates were resistant to ceftiofur and ceftriaxone, respectively. E. coli isolates were recovered from 392 (95%) of 412 turkey samples. The prevalence of resistance to one or more antimicrobials was 906 (71%) of 1,281, and 225 (18%) of 1,281 samples were resistant to five or more antimicrobials. For category I antimicrobials, 30 (2%) of 1,281 samples were resistant to ceftiofur. This study demonstrated that raw turkey pieces are a potential source of human exposure to enteric pathogens, including antimicrobial-resistant bacteria, if undercooked or improperly handled.

Bacterial flora of processed broiler chicken skin after successive washings in mixtures of potassium hydroxide and lauric acid

Changes in the size of populations of different groups of bacteria composing the normal flora of processed broiler skin were examined after each of five consecutive washings in mixtures of potassium hydroxide (KOH) and lauric acid (LA). Portions of skin from commercially processed broiler carcasses were washed in distilled water (control) or in mixtures of 0.25% KOH-0.5% LA or 0.5% KOH-1% LA by using a stomacher laboratory blender to agitate the skin in the solutions. After each wash, skin was transferred to fresh solutions, and washing was repeated to provide samples washed one to five times in each solution. Bacteria in rinsates of the washed skin were enumerated on plate count (PC) agar, Staphylococcus (STA) agar, Levine eosin methylene blue (EMB) agar, lactic acid bacteria (LAB) agar, and Perfringens (PER) agar with TSC supplement. Selected isolates recovered on each medium were identified. Overall, no significant differences were observed in numbers of bacteria recovered on PC, STA, or EMB agars from skin after repeated washing in water, but there were significant reductions in the number of bacteria recovered on LAB and PER agars. Repeated washing of skin in 0.25% KOH-0.5% LA or 0.5% KOH-1% LA generally produced significant reductions in the number of bacteria recovered on all media. Furthermore, no bacteria were recovered on PER agar from skin washed five times in 0.25% KOH-0.5% LA. Likewise, no bacteria were recovered on EMB or LAB agars from skin washed three or more times in 0.5% KOH-1% LA or on PER agar from skin washed four or five times in this solution. Staphylococcus spp. were identified as the skin isolates with the highest degree of resistance to the bactericidal activity of KOH-LA. Findings indicate that although bacteria may be continually shed from poultry skin after repeated washings, bactericidal surfactants can be used to remove and kill several types of bacteria found on the surface of the skin of processed broilers.

Predictive models for reduction of Salmonella Hadar on chicken skin during single and double sequential spraying treatments with acetic acid

AIMS

The response surface methodology was used to evaluate the effect of acetic acid concentration, spraying time and temperature on the reduction of Salmonella Hadar on poultry skin in a laboratory spraying process, and to identify the best conditions required to develop this operation.

METHODS AND RESULTS

A comparative analysis was carried out to ascertain the effects of the application of single (SS) and double sequential decontamination (DSS) treatments on skin samples inoculated with Salm. Hadar. While on the SS treatment, the linear and quadratic acid concentration terms and the interaction of the temperature and time term of the model are statistically significant at P < or = 0.001, P < or = 0.01 and P < or = 0.05, respectively, the other terms do not significantly affect (P > 0.05) the reduction of Salm. Hadar. On the DSS model the acid concentration and time linear terms significantly affected (P < or = 0.001 and P < or = 0.01) the Salm. Hadar reduction within the experimental range assayed.

CONCLUSION

Any of the models could be used as an approach to optimize spray washing during chicken processing.

SIGNIFICANCE AND IMPACT OF THE STUDY

Neither the SS or the DSS treatment has the capability of eliminating Salm. Hadar from carcasses. However, reductions of approx. 99% initial load could be attained if DSS treatment were put into practice.

Validation of individual and multiple-sequential interventions for reduction of microbial populations during processing of poultry carcasses and parts

Changes in aerobic plate counts (APC), total coliform counts (TCC), Escherichia coli counts (ECC), and Salmonella incidence on poultry carcasses and parts and in poultry processing water were evaluated. Bacterial counts were estimated before and after individual interventions and after poultry carcasses were exposed to multiple-sequential interventions at various stages during the slaughter process. Individual and multiple-sequential interventions were evaluated at three processing plants: (i) plant A (New York wash, postevisceration wash, inside-outside bird washes 1 and 2, chlorine dioxide wash, chlorine dioxide wash plus chlorine chiller, chiller exit spray, and postchiller wash), (ii) plant B (New York wash, inside-outside bird washes 1 and 2, trisodium phosphate wash, and chlorine chiller), and (iii) plant C (trisodium phosphate wash and chlorine chiller). The majority of individual interventions effectively or significantly (P < 0.05) reduced microbial populations on or in carcasses, carcass parts, and processing water. Reductions in APC, TCC, and ECC due to individual interventions ranged from 0 to 1.2, 0 to 1.2, and 0 to 0.8 log CFU/ml, respectively. Individual interventions reduced Salmonella incidence by 0 to 100% depending on the type of process and product. Multiple-sequential interventions resulted in significant reductions (P < 0.05) in APC, TCC, ECC, and Salmonella incidence of 2.4, 2.8, and 2.9 log CFU/ml and 79%, respectively, at plant A; 1.8, 1.7, and 1.6 log CFU/ml and 91%, respectively, at plant B; and 0.8, 1.1, and 0.9 log CFU/ml and 40%, respectively, at plant C. These results enabled validation of in-plant poultry processing interventions and provide a source of information to help the industry in its selection of antimicrobial strategies.

Quantification of thermophilic Campylobacter spp. in broilers during meat processing

Campylobacter spp. is a common cause of gastrointestinal illness. Since animal products, especially poultry meat, are an important source of human outbreaks of campylobacteriosis, tracing back to processing and initial production is of great interest. Samples were collected at a German poultry slaughterhouse for the estimation of the prevalence of Campylobacter at different processing steps. Quantification of Campylobacter in each of the samples was also performed. Out of 99 samples examined, 51 (51.5%) were positive for Campylobacter, with bacterial counts ranging from log(10) 6.5 cfu sample(-1) for carcasses to log 3.6 cfu ml(-1) for scalding water. The Campylobacter isolates (n = 51) were subtyped by pulsed-field gel electrophoresis using SmaI and KpnI restriction enzymes. Molecular typing showed a multitude of strains with different molecular patterns. Strains found in cloacal swabs before processing could also be isolated from carcasses at different processing steps.

Novel Campylobacter isolation method using hydrophobic grid membrane filter and semisolid medium

Culture procedures for isolation of thermophilic campylobacters from food matrices are complex, labor intensive, and time-consuming. Most available methods include the use of antibiotics as selective agents to prevent the growth of competing microflora. A simple procedure for isolation of thermophilic campylobacters after enrichment in Rosef's enrichment broth was developed using a hydrophobic grid membrane filter (HGMF) on semisolid medium (SSM). SSM contains no antibiotics, and the HGMF physically separates Campylobacter from the enrichment broth, allowing isolation based on differential motility. The HGMF-SSM method was compared to the Agriculture and Agri-Food Canada Food Safety Procedures Manual (FSPM-10) method (Isolation of Thermophilic Campylobacters from Fresh Pork, Beef Veal, Poultry and Ready-to-Eat Meat Products), which includes the use of selective antibiotics. During the initial study, after enrichment the HGMF-SSM method yielded pure cultures of campylobacters after 16 to 18 h (overnight) compared with 48 h for the FSPM-10 method. Ninety-four turkey samples collected at local retail stores and 38 frozen pig fecal samples were processed by both methods. Thirty-five samples (26.5%) were positive by the HGMF-SSM method; 24 (18.2%) of these positive samples contained Campylobacter jejuni and 11 (8.3%) contained Campylobacter coli. With the FSPM-10 method, 25 samples (18.9%) were positive: 21 (15.9%) with C. jejuni and 4 (3%) with C. coli. For a subsequent field study, only the HGMF-SSM method was used to isolate Campylobacter from 1,200 chicken samples and 454 turkey samples sold at retail. Analysis of five subisolates from various samples indicated that only one type of Campylobacter was recovered by the HGMF-SSM method, as ascertained by MICs for 10 antimicrobials, sequencing of the short variable region of the flaA gene, and fingerprinting based on amplified fragment length polymorphism. The absence of antibiotics in the SSM may explain the higher recovery of thermophilic campylobacters. The HGMF-SSM method resulted in improved isolation of campylobacters and is simpler, faster, cheaper, and less labor intensive than the FSPM-10 method. The recovery of one type of Campylobacter from the chicken samples may have important implications, particularly in epidemiological studies.

A seven-year survey of Campylobacter contamination in meat at different production stages in Belgium

The presence of Campylobacter was assessed in different samples of poultry, pork and beef meat and carcasses from slaughterhouses, production plants and retail level. An introductory study from 1997 to 1999, had the purpose of establishing the optimum dilution to detect changes in prevalence and allowed a semi-quantitative estimation of poultry and pork contamination. Following this, between 2000 and 2003, 4254 samples were taken in order to study the trends. The poultry matrixes represented the greatest number and the most highly contaminated samples, with 30.9% (in 0.01 g) positive samples, 18.7% (in 1 g), 46.9% (in 25 g) and 19.6% (in 0.01 g) for broiler carcasses, broiler fillets, prepared chicken and layer carcasses, respectively. Broiler carcasses and fillets sampled at retail level were significantly less contaminated than samples from production plants. Pork, beef and veal samples were rarely contaminated and, where contamination existed, it was at a low prevalence (maximum 5.0%). The high and unvarying prevalence of Campylobacter in poultry necessitates the implementation of intervention measures at the primary production level, in addition to methods of minimizing cross-contamination at the processing level. A survey plan in line with the present study could be used in the future to monitor the effects of the planned measures and performance objectives and to follow the evolution of Campylobacter contamination at all stages of the food chain, in accordance with European legislation.

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 (</=30%). Campylobacters were isolated from 90 to 100% of carcasses from three flocks which were partly colonised, with 5, 5 and 30% of caecal contents positive, and which were processed after fully colonised flocks. All carcasses from the remaining fully colonised flocks were contaminated with campylobacters, and they had significantly (P<0.001) higher numbers per carcass (average of 5.3 log(10) cfu; range: 1.3 to >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.

Prevalence and molecular profiles of Salmonella collected at a commercial turkey processing plant

In this study, whole carcasses were sampled at eight stages on a turkey-processing line and Salmonella prevalence was determined using enrichment techniques. Recovered Salmonella was further characterized using serotyping and the molecular profiles were determined using pulsed-field gel electrophoresis (PFGE). Prevalence data showed that contamination rates varied along the line and were greatest after defeathering and after chilling. Analysis of contamination in relation to serotypes and PFGE profiles found that on some visits the same serotype was present all along the processing line while on other days, additional serotypes were recovered that were not detected earlier on the line, suggesting that the birds harbored more than one serotype of Salmonella or there was cross-contamination occurring during processing. Overall, this study found fluctuations in Salmonella prevalence along a turkey-processing line. Following washing, Salmonella prevalence was significantly reduced, suggesting that washing is critical for Salmonella control in turkey processing and has significant application for controlling Salmonella at the postdefeathering and prechill stages where prevalence increased.

Postchill campylobacter prevalence on broiler carcasses in relation to slaughter group colonization level and chilling system

Data from an ongoing national surveillance program of Campylobacter prevalence in broiler slaughter groups were related to results from a 1-year baseline study of broiler carcasses postchill. The goals were to establish the relation between Campylobacter prevalence in slaughter groups and on carcasses and to determine the effect of various chilling systems on Campylobacter prevalence. Pooled cloacal and neck skin samples from the surveillance program were analyzed after enrichment. Carcass rinse samples from the baseline study were analyzed after enrichment and by direct plating. Data from both studies were available for 614 carcasses. Direct-plating analyses indicated that the percentages of carcasses positive for Campylobacter jejuni and other Campylobacter spp. in slaughter groups with negative cloacal samples were 2 and 10%, respectively, whereas enrichment analyses indicated prevalences of 2% in both cases. Campylobacter prevalence in slaughter groups with a high degree of intestinal colonization (more than half of the pooled cloacal samples positive) was significantly higher than in slaughter groups with a low degree of colonization (76 to 85% and 30 to 50%, respectively, depending on Campylobacter spp. and analytical method). The prevalence of Campylobacter-positive carcasses postchill was at the same level as the prevalence of carcasses that originated from slaughter groups with positive neck skin samples at four of the six slaughterhouses. Only at one slaughterhouse, with an air-chilling system, was the postchill prevalence (13%) lower than that expected from slaughter group data (23%). The postchill prevalence (43%) was higher than that expected from slaughter group data (33%) at one slaughterhouse with immersion chilling.

Influence of inoculation levels and processing parameters on the survival of Campylobacter jejuni in German style fermented turkey sausages

This study investigated the influence of inoculum levels and manufacturing methods on the survival of Campylobacter (C.) jejuni in raw fermented turkey sausages. Sausages were prepared and inoculated with C. jejuni. After inoculation, these sausages were processed and ripened for 8 days. Samples were taken throughout the ripening process. The presence of C. jejuni was established bacteriologically. Additionally, lactic acid bacteria were enumerated, pH values and water activity were measured to verify the ripening process. To detect changes in genotype and verify the identity of the recovered clones, AFLP analysis was carried out on the re-isolated strains. Whereas no C. jejuni were detectable when inoculating the sausages with the lowest inoculum (0.08-0.44 log(10) cfu/g sausage emulsion), C. jejuni were detectable for 12-24h by enrichment when inoculated with approximately 2 log(10) cfu/g. After inoculation with 4 and 6 log(10) cfu/g respectively, C. jejuni were detectable without enrichment for 12-48 h and by enrichment for 144 h at the most. The greatest decrease of the C. jejuni population occurred during the first 4 h of ripening. Only a very high inoculum level allowed the survival of the organism during a fermentation process and during ripening to pose a potential risk for consumers. Lower initial Campylobacter inoculums will be eliminated during proper ripening of the sausages, if sufficient decrease in water activity and pH-value is ensured.

Predictive model for reduction of Escherichia coli during acetic acid decontamination of chicken skin

AIMS

The response surface methodology was used to evaluate the effect of operating variables (acetic acid concentration, spraying time and temperature) on the reduction of Escherichia coli populations on poultry breast skin in a laboratory showering process, as well as to identify the best conditions that are required to develop this operation.

METHODS AND RESULTS

Skin samples were inoculated with a 24-h E. coli culture and afterwards treated according to experimental design under selected acetic acid concentration, spraying time, and solution temperature. The E. coli reduction model was significantly affected by the acetic acid concentration and spraying time (P < or = 0.05 and < or =0.01), while temperature did not show a significant effect (P > 0.05).

CONCLUSION

The predictive model obtained was validated through additional confirmatory experiments and showed to be adequate, and it could be used as an approach to optimize the acetic acid spray washes during poultry carcasses processing.

SIGNIFICANCE AND IMPACT OF THE STUDY

The use of acetic acid washes in the processing of poultry does not have the capability of eliminating E. coli populations from carcasses. However, significant reductions in the initial load could be achieved.