Contamination of raw poultry with pathogens

Enterotoxigenicity and genetic relatedness of Staphylococcus aureus in a commercial poultry plant and poultry farm

Raw (fresh) and frozen poultry products are frequently associated with Staphylococcus aureus contamination. New Zealand is among the developed countries with high incidences of staphylococcal food poisoning. The study investigated the S. aureus isolates obtained from various stages of poultry production, to determine the primary source of contamination. Viable cell counts of S. aureus were enumerated using Petrifilm™ Staph Express Count Plates, and the isolates were confirmed by Gram-stain and coagulase-positive test. Sixty S. aureus isolates were further confirmed by PCR. The PCR analysis used primers that specifically amplifies a fragment of the femA gene, unique to S. aureus. The confirmed S. aureus strains were further examined for enterotoxigenicity by PCR. Multilocus Sequence Typing (MLST) was then used to identify sequence types (STs) of the sixty isolates of S. aureus. The relatedness of the sequence types was investigated by eBURST. In this study, it was observed that all samples from the processing plant and live chickens at the farm were contaminated by S. aureus. Fifty-nine (59) of the 60 isolates were enterotoxigenic carrying enterotoxin genes: seg, sei, seh, sek, sel, sem, sen, or seo. The sixty isolates were categorised into six different sequence types: ST5, ST2594, ST101, ST83, ST398, ST1; where ST5, ST83 and ST2594 belonged to the Clonal Complex (CC) 5 with ST5 being the clonal ancestor. The sources of S. aureus contamination in the final poultry products were linked to fresh mechanically separated meat, fresh skin, fresh skin-on-breast fillet, rubber fingers on mechanical pluckers, and live chickens at the farm. The skin of live chickens at the farm was most likely the origin of S. aureus contamination on equipment and final products. Not all identified S. aureus strains at the farm were observed in the final products. Therefore, further investigation on other potential contamination sources such as gloves and knives used at the processing plant, and feeders and drinkers at the farm level is recommended.

Microbial loads and antibiotic resistance patterns of Staphylococcus aureus in different types of raw poultry-based meat preparations

The hygiene status of raw chicken-meat preparations from retail outlets in North-Western Spain was investigated. Microbial counts (aerobic plate counts (APCs), psychrotrophs, Enterobacteriaceae, fecal coliforms, enterococci, pseudomonads, fluorescent pseudomonads, yeasts and molds, and Staphylococcus aureus) were determined for minced meat, hamburgers, nuggets, white sausages, red sausages, escalope, and roll-ups. S. aureus isolates were tested for susceptibility to twenty antimicrobials of veterinary and human clinical significance (disc diffusion method, CLSI). Average microbial loads (log10 cfu/g) ranged from 2.63 ± 0.80 (enterococci) to 6.66 ± 1.09 (psychrotrophs). Average APCs (6.44 ± 1.16 log10 cfu/g) were regarded as acceptable according to EU microbiological criteria. The type of product had an influence (P < 0.05) on microbial loads, samples of escalope showing the highest counts for most microbial groups. Two-thirds (66.7%) of the samples tested harbored S. aureus. All the S. aureus isolates were multi-resistant (to between three and fifteen antibiotics). The greatest prevalence of resistance was shown for ampicillin, oxacillin, penicillin G, ceftazidime, and nalidixic acid. The results of this study show that poultry-based meat preparations present high microbial loads and are a major reservoir of antibiotic-resistant S. aureus strains. This highlights the need for correct handling of such foodstuffs with a view to reducing risks to consumers.

Food Grade Pimenta Leaf Essential Oil Reduces the Attachment of Salmonella enterica Heidelberg (2011 Ground Turkey Outbreak Isolate) on to Turkey Skin

Salmonella attached to the poultry skin is a major source of carcass contamination during processing. Once attached to the poultry skin, it is difficult to detach and inactivate Salmonella by commonly used antimicrobial agents since the pathogen is entrapped deeply in the feather follicles and the crevices on the skin. Essential oils could be natural, safe, and effective alternatives to synthetic antimicrobial agents during commercial and organic processing setup. The present study evaluated the efficacy of pimenta (Pimenta officinalis Lindl.) leaf essential oil (PEO), and its nanoemulsion in reducing Salmonella Heidelberg attachment on to turkey (Meleagris gallopavo) skin during simulated scalding (65°C) and chilling (4°C) steps in poultry processing. A multidrug resistant S. Heidelberg isolate from the 2011 ground turkey outbreak in the United States was used in the study. Results showed that PEO and the nanoemulsion resulted in significant reduction of S. Heidelberg attachment on turkey skin. Turkey skin samples treated with 1.0% PEO for 5 min resulted in >2 log10 CFU/sq. inch reduction of S. Heidelberg at 65 and 4°C, respectively (n = 6; P < 0.05). Similarly, skin samples treated with 1.0% pimenta nanoemulsion (PNE) for 5 min resulted in 1.5- and 1.8- log10 CFU/sq. inch reduction of S. Heidelberg at 65 and 4°C, respectively (n = 6; P < 0.05). In addition, PEO and PNE were effective in reducing S. Heidelberg on skin during short-term storage at 4 and 10°C (temperature abuse) (n = 6; P < 0.05). No Salmonella was detected in the dipping solution containing 0.5 or 1.0% PEO or PNE, whereas a substantial population of the pathogen survived in the control dipping solution. The results were validated using scanning electron -, and confocal - microscopy techniques. PEO or PNE could be utilized as an effective antimicrobial agent to reduce S. Heidelberg attachment to turkey skin during poultry processing.

Influence of Dietary Sorghum (Sorghum vulgare) and Corn Supplemented with Methionine on Cut-Up Pieces Weights of Broiler Carcass and Quality Properties of Breast and Drumsticks Meat

This research was carried out to determine the effects of sorghum (BS = basal diets containing 30% sorghum), corn (BC = basal diets containing corn) and supplemental methionine (BSM = diet BS plus 0.69% methionine, BCM = diet BC plus 0.69% methionine) in broiler diets on the cold carcass weight and cut-up pieces weight of broilers and some chemical, physical and microbiological properties of breast and drumstick meats. A total 240 male (120) or female (120) broiler chicks (Ross-308) were allocated to four dietary treatments (BS, BSM, BC, and BCM groups) in a completely randomized experimental design. At the end of the trial all chicks were slaughtered, and then were stored at 3°C for 24 h. After standard dissection of carcasses, cut-up pieces are weighed. The breasts and drumstick muscles were analyzed for moisture, pH, ash, fat, thiobarbituric acid reactive substances (TBARS), color (L*, a*, and b*), total psychrotrophic, lactic acid, Micrococcus/Staphylococcus, S. aureus, and Enterobacteriaceae counts. Although cold carcass and cut-up pieces weights were positively affected from supplemental methionine containing corn diet. However, weight were not influenced by supplemental methionine in diet containing sorghum and the other groups. While the highest whole breast weight is determined from broilers fed with corn and 0.69% methionine (BCM), the highest drumstick weight was determined from broilers fed with only sorghum (BS). The weights of cold carcasses and cut-up pieces of male broilers were higher than that of female. Except for redness (a* value), other parameters are affected by treatments. The effects of type of meat (breast and drumstick meats) and gender were also variable. The moisture, pH, TBARS, fat, a*, Micrococcus/Staphylococcus and Enterobacteriaceae count were lower ( p<0.05) in breast fillets than drumstick muscles. The moisture, fat, L*, lactic acid bacteria, Micrococcus/Staphylococcus and S. aureus counts were lower ( p<0.05) in female broiler meats than male broiler meats.

Prevalence and characterization of multi-drug resistant Salmonella Enterica serovar Gallinarum biovar Pullorum and Gallinarum from chicken

AIM

Salmonella is an important zoonotic pathogen responsible for animal and human diseases. The aim of the present study was to determine the prevalence and stereotyping of Salmonella isolates isolated from apparently healthy poultry. Furthermore, the clonal relatedness among the isolated Salmonella serovars was assessed.

MATERIALS AND METHODS

A total of 150 cloacal swab samples from apparently healthy chickens were collected, and were subjected for the isolation and identification of associated Salmonella organisms. The isolated colonies were identified and characterized on the basis of morphology, cultural characters, biochemical tests, slide agglutination test, polymerase chain reaction, and pulsed-field gel electrophoresis (PFGE). Antibiotic sensitivity patterns were also investigated using commonly used antibiotics.

RESULTS

Of the 150 samples, 11 (7.33%) produced characteristics pink colony with black center on XLD agar medium, and all were culturally and biochemically confirmed to be Salmonella. All possessed serovar-specific gene SpeF and reacted uniformly with group D antisera, suggesting that all of the isolates were Salmonella Enterica serovar Gallinarum, biovar Pullorum and/or Gallinarum. Antimicrobial susceptibility testing revealed that 54.54% of the isolated Salmonella Enterica serovars were highly sensitive to ciprofloxacin, whereas the 81.81% isolates were resistant to amoxycillin, doxycycline, kanamycin, gentamycin, and tetracycline. Pulsed-field gel electrophoresis of the XbaI-digested genomic DNA exhibited identical banding patterns, suggesting that the multidrug resistant Salmonella Enterica serovars occurring in commercial layers are highly clonal in Bangladesh.

CONCLUSION

The present study was conducted to find out the prevalence of poultry Salmonella in layer chicken and to find out the clonal relationship among them. The data in this study suggest the prevalence of Salmonella Enterica, which is multidrug resistant and highly clonal for commercial layers of Bangladesh.

Thermal inactivation of Salmonella Enteritidis on chicken skin previously exposed to acidified Sodium chlorite or tri-sodium phosphate

Thermal inactivation of normal and starved cells of Salmonella Enteritidis on chicken skin previously exposed to different concentrations of acidified sodium chlorite (ASC) or tri-sodium phosphate (TSP) was investigated. Inoculated skin was pretreated with different concentration of ASC or TSP, packaged in bags, and then immersed in a circulating water bath at 60 to 68 °C. The recovery medium was Hektoen enteric agar. D-values, determined by linear regression, for normal cells on chicken skin, were 2.79, 1.17 and 0.53 min whereas D-values for starved cells were 4.15, 1.83 and 0.66 at 60, 64 and 68 °C, respectively. z-values for normal cells were 3.54 and for starved cells were 2.29. Pretreatment of Salmonella Enteritidis cells with 0 to 200 ppm of ASC or 0 to 1.0 % TSP resulted in lower D-values at all temperatures. Sensory results indicated no significance differences for control and treatments. Thus, results of this study indicated that pretreatment of chicken skin with ASC or TSP increased sensitivity of Salmonella Enteritidis to heat without affecting organoleptic quality of chicken meat.

Prevalence and Serogroup Diversity of Salmonella for Broiler Neck Skin, Whole Carcass Rinse, and Whole Carcass Enrichment Sampling Methodologies following Air or Immersion Chilling

The purpose of this study was to evaluate neck skin (NS), whole carcass rinse (WCR), and whole carcass enrichment (WCE) sampling procedures for Salmonella isolation and serogroup identification from the same broiler chicken carcass treated with air or immersion chilling. Commercially processed and eviscerated broiler carcasses were collected from a commercial processing plant, individually bagged, and transported to the pilot processing plant. In experiment 1, carcasses were air chilled to 4°C. In experiment 2, carcasses were immersion chilled with or without chlorine. After air chilling, Salmonella was detected on 78% of NS and 89% of WCE samples. Only one Salmonella serogroup was detected from each of 13 Salmonella-positive NS samples, and two serogroups were detected on 1 Salmonella-positive NS sample. Only one Salmonella serogroup was detected from each of 13 Salmonella-positive WCE samples, and two serogroups were detected from 3 Salmonella-positive WCE samples. After immersion chilling without chlorine, Salmonella was detected on 38% of NS, 45% of WCR, and 100% of WCE samples. Without chlorine, the 15 Salmonella-positive NS samples included 14 samples with one serogroup and 1 sample with two serogroups. Only one Salmonella serogroup was detected from WCR samples after immersion chilling. Of 40 Salmonella-positive WCE samples, 23 had a one, 14 had two, and 3 had three Salmonella serogroups. After immersion chilling with chlorine, Salmonella was detected on 35% of NS, 0% of WCR, and 90% of WCE samples. With chlorine, the 14 Salmonella-positive NS samples included 11 samples with one serogroup and 3 samples with two serogroups. No Salmonella serogroups were detected from WCR samples after immersion chilling with 20 mg/liter free chlorine. The 36 Salmonella-positive WCE samples included 21 samples with one serogroup and 15 samples with two serogroups. NS and WCE sampling methodologies yielded similar prevalence and serogroup diversity after air chilling. However, after immersion chilling with or without chlorine, WCE sampling yielded significantly higher (α ≤ 0.05) prevalence and serogroup diversity than either NS or WCR sampling methodologies.

Effect of Melissa officinalis supplementation on growth performance and meat quality characteristics in organically produced broilers

1. A trial was conducted to study the effect of Melissa officinalis supplementation on organic broiler performance and meat chemical, microbiological, sensory and nutritional quality. 2. Male and female day-old Ross 308 chicks were fed on a standard commercial diet containing 0, 2.5, 5 or 10 g/kg feed ground M. officinalis for 84 d before slaughter. 3. Weight gain and feed conversion ratio were significantly improved in the broilers receiving either 5 or 10 mg M. officinalis/kg feed. 4. Inclusion of M. officinalis did not affect muscle chemical and fatty acid composition. 5. On the basis of microbiological and sensory experimental data and subsequent extension of meat shelf life, M. officinalis did not reduce the microbial populations of the meat, but was effective in limiting lipid oxidation.

Effect of the temperature of the dipping solution on the antimicrobial effectiveness of various chemical decontaminants against pathogenic and spoilage bacteria on poultry

The influence of the temperature of the dipping solution on the antimicrobial effectiveness of several chemical poultry decontaminants was assessed. A total of 765 poultry legs were inoculated with gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, or Brochothrix thermosphacta) or gram-negative bacteria (Salmonella enterica serotype Enteritidis, Escherichia coli, Yersinia enterocolitica, or Pseudomonas fluorescens). Samples were dipped for 15 min in solutions (wt/vol) of trisodium phosphate (12%), acidified sodium chlorite (1,200 ppm), citric acid (2%), peroxyacids (220 ppm), chlorine dioxide (50 ppm), or tap water or were left untreated (control). The temperatures of the dipping solutions were 4, 20, or 50°C. Microbiological analyses and pH determinations were carried out after 0, 1, 3, and 5 days of storage at 4°C. In comparison with the control samples, all chemical solutions were effective for reducing microbial loads. The temperature of treatment affected the microbial reductions caused by all chemicals (P < 0.001). The lowest average bacterial reductions caused by trisodium phosphate, acidified sodium chlorite, citric acid, and peroxyacids were observed at 4°C, all sampling days and microbial groups being considered simultaneously. The highest and the lowest effectiveness for chlorine dioxide were observed at 4 and 50°C, respectively. These results may be of use to meat processors for selecting the best conditions for decontamination treatments and may help the European Regulatory Authorities make their decisions for authorization of poultry decontamination treatments.

Development and validation of a predictive microbiology model for survival and growth of Salmonella on chicken stored at 4 to 12 °C

Salmonella spp. are a leading cause of foodborne illness. Mathematical models that predict Salmonella survival and growth on food from a low initial dose, in response to storage and handling conditions, are valuable tools for helping assess and manage this public health risk. The objective of this study was to develop and to validate the first predictive microbiology model for survival and growth of a low initial dose of Salmonella on chicken during refrigerated storage. Chicken skin was inoculated with a low initial dose (0.9 log) of a multiple antibiotic-resistant strain of Salmonella Typhimurium DT104 (ATCC 700408) and then stored at 4 to 12 °C for 0 to 10 days. A general regression neural network (GRNN) model that predicted log change of Salmonella Typhimurium DT104 as a function of time and temperature was developed. Percentage of residuals in an acceptable prediction zone, from -1 (fail-safe) to 0.5 (fail-dangerous) log, was used to validate the GRNN model by using a criterion of 70% acceptable predictions. Survival but not growth of Salmonella Typhimurium DT104 was observed at 4 to 8 °C. Maximum growth of Salmonella Typhimurium DT104 during 10 days of storage was 0.7 log at 9 °C, 1.1 log at 10 °C, 1.8 log at 11 °C, and 2.9 log at 12 °C. Performance of the GRNN model for predicting dependent data (n=163) was 85% acceptable predictions, for predicting independent data for interpolation (n=77) was 84% acceptable predictions, and for predicting independent data for extrapolation (n=70) to Salmonella Kentucky was 87% acceptable predictions. Thus, the GRNN model provided valid predictions for survival and growth of Salmonella on chicken during refrigerated storage, and therefore the model can be used with confidence to help assess and manage this public health risk.

Frequency of thermophilicCampylobacterin broiler chickens during industrial processing in a Southern Brazil slaughterhouse

1. The frequency of thermophilic Campylobacter spp. on broiler carcases was determined during processing in a Southern Brazil slaughterhouse. Samples were collected after defeathering, evisceration, water chilling and freezing. In addition, samples were obtained from the water of the chiller tank and from the surface of equipment in direct contact with the chicken. 2. Samples (335) were analysed and 71.3% were positive for Campylobacter. The frequency of Campylobacter spp. on carcases rinsed in BPW and skin samples from carcases was 49 of 72 (68.0%) after defeathering, 50 of 72 (69.4%) after evisceration, 61 of 72 (84.7%) after chilling, and 46 of 72 (63.9%) after freezing. Campylobacter was positive for 21 of 23 (91.3%) samples in the chilling water and for 12 of 24 (50.0%) samples on the table surface. 3. The frequency of qualitative analysis for Campylobacter spp. was reduced in frozen chickens, but not during the slaughtering process. The use of drinking water alone as a decontaminant to reduce the incidence of Campylobacter spp. during slaughter is therefore not sufficient. Furthermore, to ensure food safety, chickens must be cooked properly before consuming.

Scientific and technical factors affecting the setting of Salmonella criteria for raw poultry: a global perspective

Concerns about foodborne salmonellosis have led many countries to introduce microbiological criteria for certain food products. If such criteria are not well-grounded in science, they could be an unjustified obstacle to trade. Raw poultry products are an important part of the global food market. Import and export ambiguities and regulatory confusion resulting from different Salmonella requirements were the impetus for convening an international group of scientific experts from 16 countries to discuss the scientific and technical issues that affect the setting of a microbiological criterion for Salmonella contamination of raw chicken. A particular concern for the group was the use of criteria implying a zero tolerance for Salmonella and suggesting complete absence of the pathogen. The notion can be interpreted differently by various stakeholders and was considered inappropriate because there is neither an effective means of eliminating Salmonella from raw poultry nor any practical method for verifying its absence. Therefore, it may be more useful at present to set food safety metrics that involve reductions in hazard levels. Such terms as "zero tolerance" or "absence of a microbe" in relation to raw poultry should be avoided unless defined and explained by international agreement. Risk assessment provides a more meaningful approach than a zero tolerance philosophy, and new metrics, such as performance objectives that are linked to human health outcomes, should be utilized throughout the food chain to help define risk and identify ways to reduce adverse effects on public health.

Microbial quality of food available to populations of differing socioeconomic status

BACKGROUND

Low SES has been shown to be linked to poorer-quality diets, decreased consumption of fresh produce, and an increased reliance on small retail stores.

PURPOSE

The objective of this research was to determine if there is a difference in the microbial quality and potential safety of food available to low-SES versus high-SES populations at the retail level.

METHODS

Aerobic plate count (APC); yeast and mold counts (Y & M); and total coliforms were determined in ready-to-eat (RTE) greens, pre-cut watermelon, broccoli, strawberries, cucumbers, milk, and orange juice and compared among products purchased in stores in low- versus those purchased in high-SES neighborhoods between June 2005 and September 2006. APC, fecal coliforms, and E. coli in ground beef and the presence of Salmonella and Campylobacter in chicken were also compared.

RESULTS

Results showed higher microbial loads on produce from markets in low-SES areas. Significant differences observed included (1) APC and Y&M in RTE greens, (2) APC and Y&M in strawberries, and (3) YMCs in cucumbers. No difference was detected in the level of pathogens in raw meat and poultry; however, the APC in ground beef available in high-SES markets was significantly higher compared with that found in low-SES markets.

CONCLUSIONS

The results presented here indicate that populations of low SES may be more likely to experience produce of poorer microbial quality, which may have an impact on both the appeal and potential safety of the produce.

Safety and quality of some chicken meat products in Al-Ahsa markets-Saudi Arabia

One hundred samples of 10 poultry meat products were collected from AL-Ahsa markets (Kingdom of Saudi Arabia). The samples were ranked from carcass cuts (chilled, frozen, fillet and thigh) to minced meat or further processed products as burger, nuggets, frankfurter and meat paste loaf. Samples were collected in triplicate for sensory, chemical and microbiological analysis to assure their quality and safety. The obtained results revealed variation in chemical composition; some products with high fat percentage had a high thiobarbituric acid value, which resulted in the appearance of an unacceptable flavor. Bacteriological analysis revealed that the mean total bacterial count was ranged from 2.7 × 10(4) cfu/g for nuggets(A) to 3.3 × 10(7) cfu/g for burger(B) and the other products in the range of 10(5)-10(6) cfu/g. While Staphylococcus aureus mean count ranged from less than 10(2) cfu/g for all samples, accept 10(4) and 10(6) cfu/g for mince(B) and frankfurter samples, respectively. Escherichia coli isolated from 70% of the samples and Salmonella arizona was isolated at once from thigh samples. Thirty percentages of samples not comply with Saudi Standards due to sensory unacceptability and 21% of samples nonconforming with bacteriological specifications.

Study on the microbial status of unseasoned ground turkey meat from an EU producer-a new product with risk potential?

1. The aim of this study was to point out potential risks associated with a product new to the market in the European Union: unseasoned minced turkey meat. 2. On 6 d of sampling, minced turkey meat from a large-scale EU producer was analysed at 4 processing stages. 3. The packaged minced meat was examined during 10 d of storage, once using the legally recommended conditions (<+2 degrees C), and then under simulated consumer handling; one batch was stored for 3 d at +2 degrees C then kept for 45 min at 25 degrees C and then stored at +7 degrees C. Microbiological and physical variables were tested on 5 d. 4. Results showed that the mean total aerobic plate count (APC) of the unprocessed material was 3.8 log CfU/g and did not rise significantly, although the temperature rose briefly after the material left the meat chopper. Listeria monocytogenes was the pathogen detected most often, in 7 (14.6%) of 48 samples, followed by Salmonella in one (2.1%). No Campylobacter were found. 5. Initial contamination (APC) of about 4.5 log CfU/g was common in stored minced meat, conforming to European Union Regulations EC 2073/2005 and 1441/2007. Brochothrix thermosphacta and Pseudomonas spp. were the bacteria found most frequently. Under strict maintenance at a storage temperature of +2 degrees C, the maximum microbiological stability of the material was 7 d. Under simulated consumer handling, the microbial counts increased significantly, immediately after transport. 6. Our findings indicate that unseasoned minced turkey meat is a risky, perishable product, especially if the raw material does not have a low APC, is not pathogen-free and is kept under typical consumer handling and storage conditions.

Effectiveness of trisodium phosphate, acidified sodium chlorite, citric acid, and peroxyacids against pathogenic bacteria on poultry during refrigerated storage

The effects of dipping treatments (15 min) in potable water or in solutions (wt/vol) of 12% trisodium phosphate (TSP), 1,200 ppm acidified sodium chlorite (ASC), 2% citric acid (CA), and 220 ppm peroxyacids (PA) on inoculated pathogenic bacteria (Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, Salmonella Enteritidis, Escherichia coli, and Yersinia enterocolitica) and skin pH were investigated throughout storage of chicken legs (days 0, 1, 3, and 5) at 3 +/- 1 degrees C. All chemical solutions reduced microbial populations (P < 0.001) as compared with the control (untreated) samples. Similar bacterial loads (P > 0.05) were observed on water-dipped and control legs. Type of treatment, microbial group, and sampling day influenced microbial counts (P < 0.001). Average reductions with regard to control samples were 0.28 to 2.41 log CFU/g with TSP, 0.33 to 3.15 log CFU/g with ASC, 0.82 to 1.97 log CFU/g with CA, and 0.07 to 0.96 log CFU/g with PA. Average reductions were lower (P < 0.001) for gram-positive (0.96 log CFU/g) than for gram-negative (1.33 log CFU/g) bacteria. CA and ASC were the most effective antimicrobial compounds against gram-positive and gram-negative bacteria, respectively. TSP was the second most effective compound for both bacterial groups. Average microbial reductions per gram of skin were 0.87 log CFU/g with TSP, 0.86 log CFU/g with ASC, 1.39 log CFU/g with CA, and 0.74 log CFU/g with PA for gram-positive bacteria, and 1.28 log CFU/g with TSP, 2.03 log CFU/g with ASC, 1.23 log CFU/g with CA, and 0.78 log CFU/g with PA for gram-negative bacteria. With only a few exceptions, microbial reductions in TSP- and ASC-treated samples decreased and those in samples treated with CA increased throughout storage. Samples treated with TSP and samples dipped in CA and ASC had the highest and lowest pH values, respectively, after treatment. The pH of the treated legs tended to return to normal (6.3 to 6.6) during storage. However, at the end of storage, the pH of legs treated with TSP remained higher and that of legs treated with CA remained lower than normal.

Microbiological baseline study of broiler chickens at Swedish slaughterhouses

This 1-year study was conducted to estimate the prevalence and concentrations of pathogenic and indicator bacteria on Swedish broiler chickens. A total of 636 chilled carcasses were collected from 10 slaughterhouses and sent to the National Food Administration for analyses of carcass rinses. No carcasses were positive for Salmonella. Campylobacter, predominantly Campylobacter jejuni, were detected on 15% (by enrichment) or 14% (by direct plating) of the carcasses. With one exception, all samples from late December through April were Campylobacter negative. The 10th and 90th percentiles of Campylobacter numbers per carcasses were 3.0 and 5.0 log CFU, respectively, and the maximum was 7.1 log CFU. Coagulase-positive staphylococci were detected on 68% of the carcasses, with a maximum of 3.5 log CFU/cm2. The 10th and 90th percentiles were 3.4 and 4.4 log CFU/cm2 for total aerobic microorganisms, 1.8 and 3.3 log CFU/cm2 for Enterobacteriaceae, and 2.0 and 3.6 log CFU/cm2 for Escherichia coli. No correlation was found between numbers of any indicator bacteria and numbers of pathogenic bacteria. Subsets of the samples were analyzed for Listeria monocytogenes, Clostridium perfringens, pathogenic Yersinia enterocolitica, and Enterococcus, resulting in prevalence estimates of 29, 18, 9 (as determined by a PCR assay), and 97%, respectively. L. monocytogenes was most common at slaughterhouses with a low prevalence of coagulase-positive staphylococci, and vice versa. These results will improve the ability of researchers to assess the importance of chicken as a source of foodborne pathogens and can serve as a basis for risk management actions.

Development and validation of primary, secondary, and tertiary models for growth of Salmonella Typhimurium on sterile chicken

Models are used in the food industry to predict pathogen growth and to help assess food safety. However, criteria are needed to determine whether models provide acceptable predictions. In the current study, primary, secondary, and tertiary models for growth of Salmonella Typhimurium (10(4.8) CFU/g) on sterile chicken were developed and validated. Kinetic data obtained at 10 to 40 degrees C were fit to a primary model to determine initial density (N0), lag time (lambda), maximum specific growth rate (micromax), and maximum population density (Nmax). Secondary models for N0, lambda, micromax, and Nmax as a function of temperature were developed and combined with the primary model to create a tertiary model that predicted pathogen density (N) at times and temperatures used and not used in model development. Performance of models was evaluated using the acceptable prediction zone method in which experimental error associated with growth parameter determinations was used to set criteria for acceptable model performance. Models were evaluated against dependent and independent (validation) data. Models with 70% prediction or relative errors (RE) in an acceptable prediction zone from -0.3 to 0.15 for micromax, -0.6 to 0.3 for lambda, and -0.8 to 0.4 for N, N0, and Nmax were classified as acceptable. All secondary models had acceptable goodness of fit and were validated against independent (interpolation) data. Percent RE in the acceptable prediction zone for the tertiary model was 90.7 for dependent data and 97.5 for independent (interpolation) data. Although the tertiary model was validated for interpolation, an unacceptable %RE of 2.5 was obtained for independent (extrapolation) data obtained with a lower N0 (10(0.8) CFU/g). The tertiary model provided overly fail-dangerous predictions of N from a lower N0. Because Salmonella concentrations on chicken are closer to 10(0.8) than 10(4.8) CFU/g, the tertiary model should not be used to help assess chicken safety.

Prevalence and Characterization of Staphylococcus aureus and Enterotoxigenic Staphylococcus aureus in Retail Raw Chicken Meat Throughout Japan

A total of 444 samples of raw chicken meat (thighs, breasts, wings, livers, gizzards, hearts and ovaries) that retailed at 145 different supermarkets in 47 prefectures in Japan were examined for contamination with Staphylococcus aureus in association with its enterotoxigenicity. S. aureus was isolated from 292 (65.8%) of the samples, and from 131 of the 145 supermarkets. There was no significant difference in the detection rate of S. aureus according to the type of meat examined. About 80% of 714 isolates belonged to the poultry (57.1%) and human biotypes (22.1%). Seventy-eight (21.7%) of 360 isolates were enterotoxigenic and isolated from 78 samples in 53 supermarkets in 31 prefectures. Staphylococcal enterotoxins (SEs) produced were SEB (50 isolates), SEA (14), SEC (8), SED (2), SEA+SEB (2), and SEA+SEC (2). Most of the enterotoxigenic isolates belonged to the human and poultry biotypes, coagulase type VII, VIII or IV, and were lysed by phages of group III. Identical SE types, biotypes, coagulase types and pulsed-field gel electrophoresis (PFGE) patterns were shown in isolates from different types of meat at the same supermarket and from samples taken from different supermarkets in the same prefectures or in isolates from samples obtained from several different prefectures. Among the 50 SEB-producing isolates, 27 yielded three similar PFGE patterns that differed by only a few fragments, suggesting that they were closely related genetically. The three patterns were found in isolates of samples that retailed at 17 supermarkets in 11 prefectures, indicating that they may be disseminated among raw chicken meat in Japan.

A quantitative risk assessment model for Salmonella and whole chickens

Existing data and predictive models were used to define the input settings of a previously developed but modified quantitative risk assessment model (QRAM) for Salmonella and whole chickens. The QRAM was constructed in an Excel spreadsheet and was simulated using @Risk. The retail-to-table pathway was modeled as a series of unit operations and associated pathogen events that included initial contamination at retail, growth during consumer transport, thermal inactivation during cooking, cross-contamination during serving, and dose response after consumption. Published data as well as predictive models for growth and thermal inactivation of Salmonella were used to establish input settings. Noncontaminated chickens were simulated so that the QRAM could predict changes in the incidence of Salmonella contamination. The incidence of Salmonella contamination changed from 30% at retail to 0.16% after cooking to 4% at consumption. Salmonella growth on chickens during consumer transport was the only pathogen event that did not impact the risk of salmonellosis. For the scenario simulated, the QRAM predicted 0.44 cases of salmonellosis per 100,000 consumers, which was consistent with recent epidemiological data that indicate a rate of 0.66-0.88 cases of salmonellosis per 100,000 consumers of chicken. Although the QRAM was in agreement with the epidemiological data, surrogate data and models were used, assumptions were made, and potentially important unit operations and pathogen events were not included because of data gaps and thus, further refinement of the QRAM is needed.

Listeria spp. contamination in piggeries: comparison of three sites of environmental swabbing for detection and risk factor hypothesis

Listeria monocytogenes is a foodborne pathogen of major concern for public health in industrialized countries. Listeria carriage by pigs at the herd level could be a primary source for carcass contamination. Forty-seven finishing pig facilities were involved in the present study designed to compare three environmental swabbing sites in order to detect Listeria spp. in piggeries. Swabs were taken from the pen walls, the perianal regions of the pigs and the trough/feeder of the piggery premises. Listeria contamination of wet or dry feed given to the pigs was also investigated. The capacity of the various sampling sites for Listeria spp. detection were compared with a maximum likelihood estimation method. Listeria spp. were recovered in 74% of the pens studied and L. monocytogenes was detected in 15% of pens. With a specificity of 99%, sensitivity estimates (and 95% CI) of the Listeria spp. detection method were 93.4% (72.7-98.7) for pen walls, 73.1% (54.9-85.9) for pigs and 66.6% (48.6-80.7) for the trough/feeder. Listeria spp. were isolated from 84% of wet feed samples and 5% of dry feed samples. Listeria monocytogenes was found in 13% of wet feed samples. The type of feeding (wet versus dry) was associated (P < 0.001) with Listeria spp. contamination of both the pen and the feed. The results of this study confirm that Listeria spp., including L. monocytogenes, are present in pig facilities. Pen wall swabbing appears to be an effective way to assess Listeria spp. status of finishing pigs. The type of feeding (wet versus dry) could play a role in pig contamination.

Influence of poultry carcass skin sample site on the effectiveness of trisodium phosphate against Listeria monocytogenes

The aim of this study was to determine the influence of skin sample site on the efficacy of trisodium phosphate (TSP) solutions in reducing Listeria monocytogenes populations on chicken carcasses during refrigerated storage. Chicken skin samples from the legs, the breasts, and the dorsal area inoculated with L. monocytogenes (10(8) CFU/ml) were dipped for 15 min in sterile tap water (control) or in 8, 10, or 12% TSP. L. monocytogenes counts and surface pH values were determined after 0, 1, 3, and 5 days of storage at 2 degrees C. For all sampling times and TSP concentrations, the reductions in L. monocytogenes numbers in breast skin were significantly larger (P < 0.05) than those in leg skin or dorsal skin. No significant differences were found in pH values as an effect of skin site. Our results suggest that skin sampling site is an important factor that needs to be considered when decontamination protocols are developed for poultry carcasses with the TSP treatment.

Characterization of Staphylococcus aureus isolated from poultry meat in Spain

Ninety-six Staphylococcus aureus isolates from retail chicken carcasses in Spain were characterized using cultural and biochemical tests. The strains were phage typed with the international bacteriophage set for typing S. aureus of human origin. Eighty-eight (91.7%) strains were of the poultry ecovar. Strains of human ecovar were not found. These facts are congruent with findings of other authors. Ninety (93.7%) strains were phage typeable. Lysis by phages of Group III was the most frequent with 66 (68.7%) sensitive strains. Twenty-eight (29.2%) strains were sensitive at 100 routine test dilution (RTD) and only 16 (16.7%) at RTD. By using reversed phage typing, we managed to increase the number of phage typeable strains by 46 (47.9%). More than one S. aureus phage type was detected in 14 (35%) carcasses, which emphasizes the convenience of subtyping several S. aureus isolates from the same food sample in epidemiological studies. Two phage patterns (75/84 and 6/1030/ W57) were the most common. The S. aureus isolates were closely related, as 78 strains showed the most common or indistinguishable (<2 phage reaction differences) phage patterns.

Microsatellite markers linked to Salmonella enterica serovar enteritidis vaccine response in young F1 broiler-cross chicks

Reduction in Salmonella enteritidis (SE) contamination is of importance for poultry production as well as for food safety. The objectives of this study were to identify potential genetic markers of antibody response to SE vaccine in young broiler chicks and then to confirm this linkage in broiler-cross offspring, as well as to explore interactions of marker alleles with dam line and sex. The initial identification of suggestive quantitative trait loci (QTL) markers for antibody response to SE vaccine was conducted by using bulked segregant analysis (BSA) with 58 microsatellite markers in a broiler breeder male line. Four unlinked microsatellites that had allele frequency differences between the high and low antibody response DNA pools were selected for subsequent analysis in a linkage study. Antibody response was measured in an F1 population (n = 379) that was derived by crossing each of four males of the broiler line with several dams from four genetically distant, highly inbred lines (Spanish, Fayoumi, and MHC-congenic G-B1 and G-B2 Leghorn). These crosses enabled us to evaluate the broiler sire QTL-marker allele effects and to explore QTL interactions with the dam lines by individual genotyping. Each of the four microsatellites identified by BSA in the broiler population had a significant (P < 0.05) association with F1 population antibody response in one or more sire families. The effect of the interaction of microsatellite allele with dam line or sex on antibody response was frequently significant. Microsatellite markers linked to antibody response QTL were identified, and genetic interactions with dam line and sex were detected.

Salmonella enterica serovar enteritidis burden in broiler breeder chicks genetically associated with vaccine antibody response

The relationship between antibody response to Salmonella enteritidis vaccine and internal organ burden of S. enteritidis is not fully understood. The genetic relationship, therefore, between postchallenge S. enteritidis burden and antibody response to S. enteritidis vaccine was determined in broiler breeder chicks. Sibling chicks from a broiler breeder male line were either inoculated with a pathogenic S. enteritidis or vaccinated with a commercial S. enteritidis vaccine. Spleen, liver, cecal wall, and cecal content samples from S. enteritidis-challenged chicks (n = 120) were cultured for enumeration of bacteria. Unchallenged chicks (n = 314) were vaccinated at 11 days of age, and serum samples were taken at 10 days postvaccination. Antibody response to vaccination and number of S. enteritidis in cecal content cultures were negatively correlated (-0.772), demonstrating that genetic potential for greater antibody response to S. enteritidis vaccine is associated with lesser S. enteritidis bacterial burden in cecal content of broiler breeder chicks. The findings suggest that genetic selection for vaccine antibody responsiveness can lower bacterial burden in the gut lumenal content and, thus, potentially reduce contamination of poultry products at processing.

Microbiological quality of retail poultry carcasses in Spain

A total of 40 eviscerated and refrigerated chicken carcasses were collected from five retail outlets (three supermarkets and two poulterers' shops) in León (Spain). The level of microorganisms on chicken carcasses was assessed using the excised breast-skin technique. Mean counts (log10 CFU/g) of psychrotrophs, pseudomonads, fluorescent pseudomonads, enterococci, Micrococcaceae, Staphylococcus aureus, and yeasts and molds were 4.84, 4.11, 3.32, 2.72, 3.80, 3.67, and 2.99, respectively. A significant correlation coefficient was found between pseudomonads and fluorescent pseudomonad counts (r = 0.827; P < 0.001) and between Micrococcaceae and S. aureus counts (r = 0.915; P < 0.001). Levels of psychrotrophs, pseudomonads, fluorescent pseudomonads, and yeasts and molds were significantly (P < 0.05) higher in supermarkets than in poulterers' shops, possibly due to the longer period of time the carcasses spent in the supermarkets (between 1 and 2 days, as opposed to only 4 to 16 h in the case of poulterers' shops). Carcasses from poulterers' shops showed higher (P < 0.05) counts of enterococci. Micrococcaceae, and S. aureus, which suggests higher storage temperatures in these outlets. Only S. aureus counts (especially those from poulterers' shops) exceeded the established values in the microbiological criteria for poultry meat consulted.

Occurrence of Listeria species in retail poultry meat and comparison of a cultural/immunoassay for their detection

The prevalence of Listeria spp. on the skin of a hundred fresh chicken carcasses purchased from 20 retail stores in León was investigated using the routine test procedure recommended by the United States Department of Agriculture (USDA). PALCAM and Modified Oxford agar (MOX) were used for isolation. Listeria spp., Listeria monocytogenes, L. innocua, L. welshimeri, L. grayi and L. ivanovii were present in 95%, 32%, 66%, 7%, 4% and 2% of the samples, respectively. Next, an immunoassay test (Listeria Rapid Test; Oxoid, Unipath) and the routine test procedure (USDA) were compared for their ability to detect Listeria spp. on 40 chicken carcasses. When we used MOX for the isolations, the sensitivity of the immunoassay test was 100% and the specificity 85.7%. When we used PALCAM medium the sensitivity and specificity of the test was 94.29% and 80%, respectively.

Specificity of a conductance assay for enumeration of Escherichia coli from broiler carcass rinse samples containing genetically similar species

Experiments were conducted to evaluate the specificity of a rapid method for enumeration of Escherichia coli from fresh broiler chicken carcasses. In three separate trials, E. coli, Citrobacter freundii, Salmonella Enteritidis, and Shigella sonnei were serially diluted and then inoculated into identical broiler chicken carcass rinses. Inoculated rinses were mixed with double-strength Coliform Medium supplemented with 2% dextrose. This mixture was placed in a Bactometer module in duplicate, and conductance was measured at 44 degrees C. Results indicated that C. freundii did not grow to an appreciable degree in the selective medium at 44 degrees C. Salmonella Enteritidis grew similarly to E. coli; however, an initial level of 10(6) Salmonella in the food product would be required for Salmonella to interfere with enumeration of E. coli using this method. S. sonnei grew at a more rapid rate than E. coli; however, there was an interaction between the regression lines formed when serial dilutions (log10 CFU/ml) were compared to E. coli detection times for these two species of bacteria. Therefore, high levels of S. sonnei in a food sample may interfere with the enumeration of E. coli. In general, Salmonella and Shigella are not found at high enough levels on poultry products to interfere with enumeration of E. coli using this method and, if found at high levels, would be detected and rejected using this procedure. Hence, the presence of organisms that are genetically and phylogenetically similar to E. coli would not preclude enumeration of E. coli using conductance under these conditions.