Salmonella prevalence and persistence in industrialized poultry slaughterhouses

Phenotypic and genotypic characterization of antimicrobial resistance of non-typhoidal Salmonella from retail meat in California

Antimicrobial resistance (AMR) is a global emerging problem for food safety and public health. Retail meat is one of the vehicles that may transmit antimicrobial resistant bacteria to humans. Here we assessed the phenotypic and genotypic resistance of non-typhoidal Salmonella from retail meat collected in California in 2019 by the National Antimicrobial Resistance Monitoring System (NARMS) Retail Food Surveillance program. A total of 849 fresh meat samples were collected from randomly selected grocery stores in Northern and Southern California from January to December 2019. The overall prevalence of Salmonella was 15.31 %, with a significantly higher occurrence in Southern (28.38%) than in Northern (5.22 %) California. The prevalence of Salmonella in chicken (24.01 %) was higher (p < 0.001) compared to ground turkey (5.42 %) and pork (3.08 %) samples. No Salmonella were recovered from ground beef samples. The prevalence of Salmonella in meat with reduced antibiotic claim (20.35 %) was higher (p < 0.001) than that with conventional production (11.96 %). Salmonella isolates were classified into 25 serotypes with S. Kentucky (47.73 %), S. typhimurium (11.36 %), and S. Alachua (7.58 %) as predominant serotypes. Thirty-two out of 132 (24.24 %) Salmonella isolates were susceptible to all tested antimicrobial drugs, while 75.76 % were resistant to one or more drugs, 62.88 % to two or more drugs, and 9.85 % to three or more drugs. Antimicrobials that Salmonella exhibited high resistance to were tetracycline (82/132, 62.12 %) and streptomycin (79/132, 59.85 %). No significant difference was observed between reduced antibiotic claim and conventional production in the occurrence of single and multidrug resistance. A total of 23 resistant genes, a D87Y mutation of gyrA, and 23 plasmid replicons were identified from resistant Salmonella isolates. Genotypic and phenotypic results were well correlated with an overall sensitivity of 96.85 %. S. infantis was the most resistant serotype which also harbored the IncFIB (pN55391) plasmid replicon and gyrA (87) mutation. Data from Northern and Southern California in this study helps us to understand the AMR trends in Salmonella from retail meat sold in the highly populous and demographically diverse state of California.

16S amplicon-based microbiome biomapping of a commercial broiler hatchery

Hatcheries, where eggs from multiple breeder farms are incubated and hatched before being sent to different broiler farms, represent a nexus point in the commercial production of broilers in the United States. Considering all downstream microbial quality and safety aspects of broiler production (live production, processing, consumer use) can be potentially affected by the hatchery, a better understanding of microbial ecology within commercial hatcheries is essential. Therefore, a commercial broiler hatchery was biomapped using 16S rRNA amplicon-based microbiome analyses of four sample type categories (Air, Egg, Water, Facility) across five different places in the pre-hatch, hatch, and post-hatch areas. While distinct microbiota were found for each sample type category and hatchery area, microbial community analyses revealed that Egg microbiota trended towards clustering with the facility-related samples when moving from the prehatch to post-hatch areas, highlighting the potential effect of the hatchery environment in shaping the pre-harvest broiler-related microbiota. Prevalence analyses revealed 20 ASVs (Core20) present in the core microbiota of all sample types and areas, with each ASV possessing a unique distribution throughout the hatchery. Interestingly, three Enterobacteriaceae ASVs were in the Core20, including Salmonella. Subsequent analyses showed that Salmonella, while a minor prehatch and hatch Core20ASV, dominated the Enterobacteriaceae niche and total microbiota in the chick pad feces in the post-hatch area of the hatchery, and the presence of this Salmonella ASV in the post-hatch feces was associated with swabs of breakroom tables. These findings highlight the complexity of commercial hatchery microbiota, including identifying chick pad feces and breakroom tables as potentially important sampling or disinfection targets for hatchery managers to focus their Salmonella mitigation efforts to reduce loads entering live production farms.

High prevalence and genomic features of multidrug-resistant Salmonella enterica isolated from chilled broiler chicken on retail sale in the United Arab Emirates

Non-typhoidal Salmonella represents a significant global concern for food safety and One Health. Despite the United Arab Emirates (UAE) being a leading consumer of chicken meat globally, there is a lack of comprehensive understanding regarding the prevalence and genomic characteristics of Salmonella within the country. This study aims to address this gap by conducting a thorough analysis of Salmonella prevalence, antimicrobial resistance, and genomic profiles of isolates obtained from whole broiler carcasses retailed under chilled conditions in the UAE. Our findings reveal that Salmonella was detected in 41.2 % (130/315) of the sampled chilled broiler carcasses, with notable variability observed among samples sourced from six different companies. Phenotypic antimicrobial resistance (AMR) testing, among 105 isolates, highlighted high resistance rates to tetracycline (97.1 %), nalidixic acid (93.3 %), ampicillin (92.4 %), azithromycin (75.2 %), ciprofloxacin (63.8 %), and ceftriaxone (54.3 %). Furthermore, a concerning 99 % (104/105) of the isolates exhibited multidrug resistance. Whole-genome sequencing (WGS) of 60 isolates identified five serovars, with S. infantis/Sequence Type (ST) 32 (55 %) and S. Minnesota/ST-458 (28.3 %) being the most prevalent. WGS analysis unveiled 34 genes associated with antimicrobial resistance, including mcr-1.1 (only in two isolates), conferring resistance to colistin. The two major serovars, Infantis and Minnesota, exhibited significant variation (P-values <0.001) in the distribution of major AMR genes (aadA1, blaCMY-2, blaSHV-12, qnrB19, qnrS1, sul1, and sul2). Notably, the gene qacEdelta, conferring resistance to quaternary ammonium compounds commonly found in disinfectants, was universally present in all S. Infantis isolates (n = 33), compared to only one S. Minnesota isolate. Additionally, all S. Infantis isolates harbored the IncFIB (pN55391) plasmid replicon type. Major serovars exhibited distinct distributions of antimicrobial resistance genes, underscoring the importance of serovar-specific surveillance. These findings emphasize the critical need for continuous surveillance and intervention measures to address Salmonella contamination risks in poultry products, providing valuable insights for public health and regulatory strategies not only in the UAE but also globally.

Salmonella in Chicken and Pork Meat as a Likely Major Contributor to Foodborne Illness in Peru

Nontyphoidal Salmonella is one of the major causes of self-limiting diarrheal disease and the most common foodborne pathogen worldwide. It is an important contributor to the burden of foodborne illness in South America, including Peru, where chicken and pork are important vehicles for Salmonella infection. Salmonella infections are underreported, particularly in low- and middle-income countries where concerted action tackling Salmonella along the chicken and pork chains, from primary production to retail, is urgently needed. To support and inform the implementation of new strategies to reduce Salmonella contamination of chicken and pork, this study describes the frequency and distribution of foodborne outbreaks attributed to Salmonella in Peru and evaluates the level of Salmonella in chicken and pork meat sold in markets of three regions of Peru. To that end, we analyzed historical reports of foodborne outbreaks, levels of Salmonella in chicken and pork sold in markets, and the number of mesophiles in the collected meat samples. As a result, the microbiological analysis reveals a widespread contamination of chicken (77.1%) and pork (26.8%) with Salmonella. It also pinpoints Salmonella as the causative agent in nearly half of the outbreaks (47.0%) where the potential origin is identified over a 11-year period with chicken, mayonnaise, and pork being the most likely food vehicles. These results suggest that Salmonella is a major contributor to foodborne illness in Peru and that the monitoring of mesophiles could be a good strategy for surveillance, generating data to support source attribution studies and ultimately evidence-informed policies.

Development of a 1-step multiplex PCR assay for the detection of S. Enteritidis, S. Pullorum, S. Typhimurium, and S. Infantis associated with poultry production

Salmonellosis in poultry is detrimental to the advancement of the breeding industry and poses hazards to human health. Approximately 2,600 Salmonella varieties exist, among which S. Enteritidis, S. Pullorum, S. Typhimurium, and S. Infantis are prevalent serotypes in the poultry industry in recent years. They can also infect humans by contaminating poultry eggs and meat. Therefore, identifying these serotypes is crucial for successful preventive and control interventions. The White-Kauffmann-Le Minor scheme is time-consuming and requires expensive reagents. Whole-genome sequencing (WGS) and other molecular biology techniques require skilled technical staff. In comparison, the polymerase chain reaction (PCR) is more accurate, rapid, and inexpensive, thus proving suitable for widespread application in the poultry industry. Here, we selected 4 specific primers: lygD, mdh, ipaJ, and SIN_02055, which correspond to detecting S. Enteritidis, S. Typhimurium, S. Pullorum, and S. Infantis, respectively. They were integrated into a 1-step multiplex PCR method. We optimized the PCR method by utilizing specificity test results to determine the optimal annealing temperature (57°C). The PCR method exhibited excellent sensitivity for genomic DNA and bacterial cultures. We used the developed method to determine 157 clinical Salmonella isolates from various stages of the poultry production chain. The results aligned with serotype data generated via WGS analysis, demonstrating the method's excellent accuracy. In conclusion, this study developed a 1-step multiplex PCR method that simultaneously identifies S. Enteritidis, S. Typhimurium, S. Pullorum, and S. Infantis, allowing routine mass detection in the grass-root poultry industry.

Levels of Different Microbial Groups on Inert Surfaces of Poultry Slaughterhouses: Identification Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight and Detection of Extended-Spectrum Beta-Lactamase- and Carbapenemase-Producing Enterobacteria

Knowledge of the microbiota present in food processing environments is a significant advance that will allow for better evaluation of the risk of food contamination and a better design of the procedures for sanitization. The levels of microbial group indicators of hygienic quality were determined in different areas of the slaughter lines of two poultry slaughterhouses in the northwest of Spain (22 surfaces in each slaughterhouse were studied). The average microbial levels (cfu/cm2) were 2.15 × 102 ± 4.26 × 102 (total aerobic counts, TAC), 1.99 × 102 ± 5.00 × 102 (psychrotrophic microorganisms), 3.10 × 100 ± 1.37 × 101 (enterobacteria), 3.96 × 100 ± 2.55 × 101 (coliforms), 1.80 × 10-1 ± 7.79 × 10-1 (enterococci), and 1.12 × 10-1 ± 3.35 × 10-1 (vancomycin-resistant enterococci, VRE). TAC and psychrotrophic microorganisms were the most abundant groups in all samples (p < 0.05). The counts of both microbial groups were higher (p < 0.05) in samples of Slaughterhouse A than in those of Slaughterhouse B. Microbial loads for the rest of the bacteria were not influenced by the slaughterhouse sampled (p > 0.05). All 44 samples showed TAC and psychrotrophic microorganisms. Colonies of the rest of the microbial groups were only found in 26 samples (59.1% of the total). The isolates (one from each sample) were identified with MALDI-TOF and PCR. Gram-negative bacteria (all Enterobacteriaceae) were isolated in 23 samples, and Gram-positive bacteria were isolated in 16 (9 Enterococcus spp., 2 Enterococcus spp. and VRE, 3 VRE, 1 Enterococcus spp. and Listeria spp., and 1 Listeria spp.). The resistance of the strains to 11 (Enterococcus spp.) or 17 (Enterobacteriaceae) antibiotics was determined (disk diffusion, CLSI), finding an average of 2.05 ± 2.06 resistances per strain (3.46 ± 2.27 if reduced susceptibility reactions are included). A total of 37.3% of the Enterobacteriaceae isolates had a gene for resistance to beta-lactam antibiotics (blaTEM, blaCTX-M-15, blaKPC, blaCMY-2 or blaNDM). The high prevalence of resistant bacteria and resistance genes highlights the need to establish measures to control the spread of antibiotic resistance in poultry slaughterhouses. The findings of this work could contribute to the design of more effective sanitation procedures.

Prevalence, serovars, and risk factors associated with the presence of Salmonella in pork sold in public markets in Quito, Ecuador

Background

Salmonella enterica are bacteria that include more than 2,500 serovars. Most of these serovars have been linked to human foodborne illnesses, mainly related to poultry and pigs. Thus, these animals are considered the reservoirs of many Salmonella serovars and strains related to antibiotic resistance. This study aimed to determine the prevalence, serovars, β-lactam resistance genes, and the risk factors associated with Salmonella enterica in pork commercialized in open markets of Quito city.

Methods

For this, 165 pork meat samples were taken from municipal markets in three areas in the city. These samples were microbiologically processed following the ISO 6579-2014 standardized method. The polymerase chain reaction (PCR) test was used to identify Salmonella serotyping and resistance genes. Strains not identified by PCR were typed by the Kauffman White Le Minor scheme. A multivariate analysis was performed to identify risk factors associated with the presence of the microorganism.

Results

Salmonella prevalence in pork was 9.1%. Identified serovars were 4, [5], 12: i:- (53.3%), Infantis (33.3%), and Derby (13.4%). Furthermore, the β-lactam resistance genes bla CTX-M-65 could be identified in three S. infantis isolates. Multivariate analysis showed that temperature (above 8°C) and cutting surfaces (wood) presented significant association values.

Conclusions

In conclusion, pork in traditional markets of Quito is contaminated with Salmonella enterica, whose main serovars pose a public health concern, and shows beta-lactam resistance.

Characterization and pharmacokinetics of cinnamon and star anise compound essential oil pellets prepared via centrifugal granulation technology

Cinnamon and star anise essential oils are extracted from natural plants and provide a theoretical basis for the development and clinical application of compound essential oil pellets. However, cinnamon oil and star anise oil have the characteristics of a pungent taste, extreme volatility, poor palatability, and unstable physical and chemical properties, which limit their clinical use in veterinary medicine. In this study, the inhibitory effects of cinnamon oil and star anise oil on Escherichia coli and Salmonella were measured. Compound essential oil pellets were successfully prepared by centrifugal granulation technology. Subsequently, the in vitro dissolution of the pellets and their pharmacokinetics in pigs were investigated. The results showd that, cinnamon and star anise oils showed synergistic or additive inhibitiory effects on Escherichia coli and Salmonella. The oil pellets had enteric characteristics in vitro and high dissolution in vitro. The pharmacokinetic results showed that the pharmacokinetic parameters Cmax and AUC were directly correlated with the dosage and showed linear pharmacokinetic characteristics, which provided a theoretical basis for the development and clinical application of compound essential oil pellets.

Identification and classification of the genomes of novel microviruses in poultry slaughterhouse

Microviridae is a family of phages with circular ssDNA genomes and they are widely found in various environments and organisms. In this study, virome techniques were employed to explore potential members of Microviridae in a poultry slaughterhouse, leading to the identification of 98 novel and complete microvirus genomes. Using a similarity clustering network classification approach, these viruses were found to belong to at least 6 new subfamilies within Microviridae and 3 higher-level taxonomic units. Genome size, GC content and genome structure of these new taxa showed evident regularities, validating the rationality of our classification method. Our method can divide microviruses into about 45 additional detailed clusters, which may serve as a new standard for classifying Microviridae members. Furthermore, by addressing the scarcity of host information for microviruses, the current study significantly broadened their host range and discovered over 20 possible new hosts, including important pathogenic bacteria such as Helicobacter pylori and Vibrio cholerae, as well as different taxa demonstrated different host specificities. The findings of this study effectively expand the diversity of the Microviridae family, providing new insights for their classification and identification. Additionally, it offers a novel perspective for monitoring and controlling pathogenic microorganisms in poultry slaughterhouse environments.

Raw meat-based diet for pets: a neglected source of human exposure to Salmonella and pathogenic Escherichia coli clones carrying mcr, Portugal, September 2019 to January 2020

BackgroundThe pet industry is expanding worldwide, particularly raw meat-based diets (RMBDs). There are concerns regarding the safety of RMBDs, especially their potential to spread clinically relevant antibiotic-resistant bacteria or zoonotic pathogens.AimWe aimed to investigate whether dog food, including RMBD, commercially available in Portugal can be a source of Salmonella and/or other Enterobacteriaceae strains resistant to last-line antibiotics such as colistin.MethodsFifty-five samples from 25 brands (21 international ones) of various dog food types from 12 suppliers were screened by standard cultural methods between September 2019 and January 2020. Isolates were characterised by phenotypic and genotypic methods, including whole genome sequencing and comparative genomics.ResultsOnly RMBD batches were contaminated, with 10 of 14 containing polyclonal multidrug-resistant (MDR) Escherichia coli and one MDR Salmonella. One turkey-based sample contained MDR Salmonella serotype 1,4,[5],12:i:- ST34/cgST142761 with similarity to human clinical isolates occurring worldwide. This Salmonella exhibited typical antibiotic resistance (bla TEM + strA-strB + sul2 + tet(B)) and metal tolerance profiles (pco + sil + ars) associated with the European epidemic clone. Two samples (turkey/veal) carried globally dispersed MDR E. coli (ST3997-complexST10/cgST95899 and ST297/cgST138377) with colistin resistance (minimum inhibitory concentration: 4 mg/L) and mcr-1 gene on IncX4 plasmids, which were identical to other IncX4 circulating worldwide.ConclusionSome RMBDs from European brands available in Portugal can be a vehicle for clinically relevant MDR Salmonella and pathogenic E. coli clones carrying genes encoding resistance to the last-line antibiotic colistin. Proactive actions within the One Health context, spanning regulatory, pet-food industry and consumer levels, are needed to mitigate these public health risks.

Influence of a nanoscale coating on plucking fingers and stainless steel on attachment and detachment of Salmonella Enteritidis, Escherichia coli and Campylobacter jejuni

Gastroenteritis caused by Campylobacter represents the most common reported foodborne bacterial illness worldwide, followed by salmonellosis. Both diseases are often caused by the consumption of contaminated, insufficiently heated poultry meat. This can result from contamination of the meat during the slaughtering processes. Food contact surfaces like stainless steel or plucking fingers contribute significantly to cross-contamination of poultry carcasses. Modification of these surfaces could lead to a reduction of the bacterial burden, as already proven by successful application in various food industry sectors, such as packaging.In this study, nanoscale silica-coated and uncoated stainless-steel surfaces and plucking fingers were compared on a pilot scale regarding attachment and detachment of Campylobacter jejuni, Salmonella Enteritidis and Escherichia coli.The bacteria did not adhere less to the coated plucking fingers or stainless-steel sections than to the uncoated ones. The coating also did not lead to a significant difference in detachment of Campylobacter jejuni, Salmonella Enteritidis and Escherichia coli from the investigated surfaces compared to the uncoated ones.Our study did not reveal any differences between the coated and uncoated surfaces with regard to the investigated bacteria. In order to achieve a better adaptation of the coating to slaughterhouse conditions, future studies should focus on its further development based on the investigation of specific coating parameters.

Predictive modeling of Salmonella spp. growth behavior in cooked and raw chicken samples: Real-time PCR quantification approach and model assessment in different handling scenarios

The increasing prevalence of Salmonella contamination in poultry meat emphasizes the importance of suitable predictive microbiological models for estimating Salmonella growth behavior. This study was conducted to evaluate the potential of chicken juice as a model system to predict the behavior of Salmonella spp. in cooked and raw chicken products and to assess its ability to predict cross-contamination scenarios. A cocktail of four Salmonella serovars was inoculated into chicken juice, sliced chicken, ground chicken, and chicken patties, with subsequent incubation at 10, 15, 20, and 25°C for 39 h. The number of Salmonella spp. in each sample was determined using real-time polymerase chain reaction. Growth curves were fitted into the primary Baranyi and Roberts model to obtain growth parameters. Interactions between temperature and growth parameters were described using the secondary Ratkowsky's square root model. The predictive results generated by the chicken juice model were compared with those obtained from other chicken meat models. Furthermore, the parameters of the chicken juice model were used to predict Salmonella spp. numbers in six worst-case cross-contamination scenarios. Performance of the chicken juice model was evaluated using the acceptable prediction zone from -1.0 (fail-safe) to 0.5 (fail-dangerous) log. Chicken juice model accurately predicted all observed data points within the acceptable range, with the distribution of residuals being wider near the fail-safe zone (75%) than near the fail-dangerous zone (25%). This study offers valuable insights into a novel approach for modeling Salmonella growth in chicken meat products, with implications for food safety through the development of strategic interventions. PRACTICAL APPLICATION: The findings of this study have important implications in the food industry, as chicken juice could be a useful tool for predicting Salmonella behavior in different chicken products and thus reducing the risk of foodborne illnesses through the development of strategic interventions. However, it is important to recognize that some modifications to the chicken juice model will be necessary to accurately mimic all real-life conditions, as multiple factors particularly those related to food processing can vary between different products.

A bacteriophage cocktail can efficiently reduce five important Salmonella serotypes both on chicken skin and stainless steel

Salmonella is one of the most important zoonotic pathogens and is mostly transmitted through food of animal origin. Application of bacteriophages is a promising tool to biocontrol Salmonella on both food and food contact surfaces. In this study, we evaluated the effectiveness of a six-phage cocktail for the reduction of Salmonella Enteritidis and a mixture of five major Salmonella serotypes (S. Enteritidis, Salmonella Typhimurium, Salmonella Infantis, Salmonella Paratyphi B, and Salmonella Indiana) on chicken skin and stainless steel. A phage cocktail with a final concentration of 107 PFU/cm2 was sprayed on these surfaces. After adding the phage cocktail, the samples were incubated at RT (~23°C) for different periods of time. The phage cocktail caused a significant reduction of S. Enteritidis and the mixed culture on chicken skin 30 min after phage addition, with 1.8 log10 and 1 log10 units, respectively. Reduction rates (1.2-1.7 log10 units) on stainless steel after 30 min were similar. Four hours after addition, the phage cocktail caused a significant reduction on both surfaces up to 3 log10 units on chicken skin and 2.4 log10 units on stainless steel. In a further experiment, bacteria added to stainless steel were not allowed to dry to simulate a fresh bacterial contamination. In this case, the bacterial count of S. Enteritidis was reduced below the detection limit after 2 h. The results demonstrate that this phage cocktail has potential to be used in post-harvest applications to control Salmonella contaminations.

Persistence of microbiological hazards in food and feed production and processing environments

Listeria monocytogenes (in the meat, fish and seafood, dairy and fruit and vegetable sectors), Salmonella enterica (in the feed, meat, egg and low moisture food sectors) and Cronobacter sakazakii (in the low moisture food sector) were identified as the bacterial food safety hazards most relevant to public health that are associated with persistence in the food and feed processing environment (FFPE). There is a wide range of subtypes of these hazards involved in persistence in the FFPE. While some specific subtypes are more commonly reported as persistent, it is currently not possible to identify universal markers (i.e. genetic determinants) for this trait. Common risk factors for persistence in the FFPE are inadequate zoning and hygiene barriers; lack of hygienic design of equipment and machines; and inadequate cleaning and disinfection. A well-designed environmental sampling and testing programme is the most effective strategy to identify contamination sources and detect potentially persistent hazards. The establishment of hygienic barriers and measures within the food safety management system, during implementation of hazard analysis and critical control points, is key to prevent and/or control bacterial persistence in the FFPE. Once persistence is suspected in a plant, a 'seek-and-destroy' approach is frequently recommended, including intensified monitoring, the introduction of control measures and the continuation of the intensified monitoring. Successful actions triggered by persistence of L. monocytogenes are described, as well as interventions with direct bactericidal activity. These interventions could be efficient if properly validated, correctly applied and verified under industrial conditions. Perspectives are provided for performing a risk assessment for relevant combinations of hazard and food sector to assess the relative public health risk that can be associated with persistence, based on bottom-up and top-down approaches. Knowledge gaps related to bacterial food safety hazards associated with persistence in the FFPE and priorities for future research are provided.

Phage-Based Biosanitation Strategies for Minimizing Persistent Salmonella and Campylobacter Bacteria in Poultry

Control strategies to minimize pathogenic bacteria in food animal production are one of the key components in ensuring safer food for consumers. The most significant challenges confronting the food industry, particularly in the major poultry and swine sectors, are antibiotic resistance and resistance to cleaning and disinfection in zoonotic bacteria. In this context, bacteriophages have emerged as a promising tool for zoonotic bacteria control in the food industry, from animals and farm facilities to the final product. Phages are viruses that infect bacteria, with several advantages as a biocontrol agent such as high specificity, self-replication, self-limitation, continuous adaptation, low inherent toxicity and easy isolation. Their development as a biocontrol agent is of particular interest, as it would allow the application of a promising and even necessary "green" technology to combat pathogenic bacteria in the environment. However, bacteriophage applications have limitations, including selecting appropriate phages, legal restrictions, purification, dosage determination and bacterial resistance. Overcoming these limitations is crucial to enhance phage therapy's effectiveness against zoonotic bacteria in poultry. Thus, this review aims to provide a comprehensive view of the phage-biosanitation strategies for minimizing persistent Salmonella and Campylobacter bacteria in poultry.

Quantification of Salmonella transfer in cross-contamination scenarios found in chicken slaughterhouses

Chicken are among the main reservoirs of Salmonella, and slaughterhouses have been identified as key sites for cross-contamination of this pathogen. This study aimed to quantify the transfer rate of Salmonella in different cross-contamination scenarios found in chicken slaughterhouses. To this end, a pool of Salmonella spp. Was inoculated onto chicken carcasses and thighs, reaching out concentrations of 2-5 log10 CFU/g. After inoculation, carcasses and thighs were used to reproduce four cross-contamination scenarios based on industrial reality as follows: 1. Transfer of Salmonella from chicken carcasses to stainless steel and polyethylene surfaces; 2. Transfer of Salmonella between hanging chicken carcasses; 3. Transfer of Salmonella from stainless steel surfaces to chicken carcasses, and 4. Transfer of Salmonella from thighs to stainless steel and polyethylene surfaces. The results showed that the transfer rates (TR) of Salmonella on the chicken carcass to stainless steel and polyethylene were 25.77 ± 22.63% and 24.71 ± 13.93%, respectively, while the TR between hanged chicken carcasses was 5.11 ± 1.71%. When sliding carcasses through a stainless steel ramp, 41.47 ± 1.32% of the Salmonella present on the ramp adhered to the chicken carcasses, and the greater transfer seems to be linked to the wet surfaces. The transfer rates from the thighs to the stainless steel and polyethylene were 1.81 ± 0.66% and 9.0 ± 1.34%, respectively. Cross-contamination occurred regardless of the sample weight, time of contact, and amount of inoculum.

Synergistic Strategies of Heat and Peroxyacetic Acid Disinfection Treatments for Salmonella Control

The food industry has recognized a pressing need for highly effective disinfection protocols to decrease the risk of pathogen emergence and proliferation in food products. The integration of antimicrobial treatments in food production has occurred as a potential strategy to attain food items of superior quality with respect to microbiological safety and sensory attributes. This study aims to investigate the individual and synergistic effects of heat and peroxyacetic acid on the inactivation of bacterial cells, considering various contact times and environmental conditions. Four Salmonella serotypes, isolated from industrial meat production surfaces, were employed as model organisms. By systematically assessing the impacts of individual factors and synergistic outcomes, the effectiveness of bacterial cell inactivation and the efficiency of heat and peroxyacetic acid could be predicted. To better approximate real-world food processing conditions, this study also incorporated a bovine albumin-rich condition as a simulation of the presence of organic loads in processing steps. The findings revealed the essential need for a synergistic interplay of investigated parameters with the following optimized values: 1.5% concentration of peroxyacetic acid, temperature range of 60-65 °C, and contact time of 3 min for the complete effect regardless of the degree of contamination.

Genome analysis of third-generation cephalosporin-resistant Escherichia coli and Salmonella species recovered from healthy and diseased food-producing animals in Europe

The animal reservoir of Enterobacterales producing Extended-Spectrum-β-Lactamases (ESBL) and plasmid-borne cephalosporinases (pAmpC) is a global concern. Using genome data, we analyzed a population of Escherichia coli and Salmonella species resistant to third-generation cephalosporins (3GC-R) recovered from healthy food animals (HA) and diseased food animals (DA) across Europe. Among the isolates collected from HA (n = 4,498) and DA (n = 833) in up to twelve European countries, 62 (1.4%) and 45 (5.4%) were 3GC-R, respectively. The genomes of these 3GC-R 107 isolates were sequenced to identify blaESBL and blaAmpC, sequence types (STs), virulence-associated genes, and Salmonella serovars. We also assessed their population structure using core genome multilocus sequence typing. The 78 3GC-R Escherichia coli originated from poultry (n = 27), swine (n = 26), and cattle (n = 25). Almost all (n = 77; 98.7%) harbored at least one blaESBL or blaAmpC, with blaCTX-M-1 predominating. We identified 51 STs, with ST10 and ST101 being the most frequent. The population of 3GC-R E. coli was polyclonal. The 29 3GC-R Salmonella spp. were mostly retrieved from healthy broiler (96.5%). blaCMY-2 dominated in this population. We found two clusters of CMY-2-producing Salmonella spp. in Germany: one with 15 isolates of S. Heidelberg isolates and another with six S. Minnesota, all of them with blaCMY-2. Our results confirm the low prevalence of 3GC-R E. coli and Salmonella spp. in HA and DA. blaCTX-M-1 was dominating in a highly diverse population of E. coli. 3GC-R E.coli isolated from HA and DA were genetically unrelated, with high clonal diversity suggesting multiple origins of contamination. This contrasted with the clonal population of 3GC-R Salmonella spp. in which blaCMY-2 dominated through two dominant serovars in this collection.

Assessment of ATP-Bioluminescence and Dipslide Sampling to Determine the Efficacy of Slaughterhouse Cleaning and Disinfection Compared with Total Aerobic and Enterobacterales Counts

Inadequate cleaning and disinfection (C&D) in slaughterhouses can cause bacterial contamination of meat, resulting in foodborne disease and reduced meat quality. Different methods for monitoring the efficacy of C&D procedures are available, but few studies have assessed their reliability. This study examined C&D efficacy in slaughterhouses and evaluated the diagnostic performance of methods for measuring surface hygiene. One red meat and one poultry slaughterhouse in Sweden were each visited on six occasions before and six occasions after C&D. Sampling points were sampled with: swabbing and plating for total aerobic bacteria (TAB) and Enterobacterales (EB); dipslides for total viable count; and ATP-bioluminescence tests. To evaluate the diagnostic performance of the dipslide and ATP-bioluminescence methods, the results were compared with (TAB) as a reference. In total, 626 samples were collected. For the majority of samples, TAB was lower after than before C&D and EB were mainly detected before C&D, indicating C&D efficacy. Greater reductions in mean TAB were observed in processing areas (2.2 and 2.8 log CFU/100 cm2 in red meat and poultry slaughterhouse, respectively) than in slaughter areas (1.3 log CFU/100 cm2 in both slaughterhouses). Approximately half of all samples were assessed as non acceptably clean (52% for red meat and 46% for poultry slaughterhouse) according to previously published thresholds. Critical food contact surfaces that were insufficiently cleaned and disinfected were plucking fingers, shackles, and a post-dehairing table. Cleaning and disinfection of drains and floors were inadequate. The ATP-bioluminescence method showed low specificity compared with the reference (TAB) in both the red meat (0.30) and poultry slaughterhouses (0.64). The sensitivity of dipslides was low (0.26) in the red meat slaughterhouse compared with TAB. A combination of ATP-bioluminescence and dipslides could provide more accurate estimates of C&D efficacy.

Bio-Mapping of Microbial Indicators and Pathogen Quantitative Loads in Commercial Broiler Processing Facilities in South America

A bio-mapping study was conducted with the aim of creating a microbiological baseline on indicator organisms and pathogens in commercial broiler processing facilities located in a country in South America. Whole chicken carcass and wing rinses were collected from five stages of the poultry processing line: live receiving (LR), rehanger (R), post-evisceration (PE), post-chilling (PC), and wings (W). Rinses (n = 150) were enumerated using the MicroSnap™ system for total viable counts (TVC) and Enterobacteriaceae (EB), while the BAX®-System-SalQuant® and BAX®-System-CampyQuant™ were used for Salmonella and Campylobacter, respectively. TVC and EB were significantly different between stages at the processing line (p < 0.01). There was a significant reduction from LR to PC for both microbial indicators. TVC and EB counts increased significantly from PC to W. Salmonella counts at PC were significantly different from the other stages at the processing line (p = 0.03). Campylobacter counts were significantly higher than the other stages at PC (p < 0.01). The development of bio-mapping baselines with microbial indicators showed consistent reduction up to the post-chilling stage, followed by an increase at the wings sampling location. The quantification of pathogens demonstrates that prevalence analysis as a sole measurement of food safety is not sufficient to evaluate the performance of processing operations and sanitary dressing procedures in commercial processing facilities.

Genomic typing and virulence gene profile analysis of Salmonella Derby from different sources

Salmonella enterica serovar Derby (S. Derby) is one of the most common Salmonella serovars which can infect poultry, swine, and humans. With the reduction of the sequencing cost and the improvement of sequencing technology, whole genome sequencing (WGS) has become an important method for bacterial determination, molecular investigation, and pathogenic tracing analysis. In this study, we investigated S. Derby isolates from different sources in China using in-silico multilocus sequence typing (MLST), core genome MLST (cgMLST) and whole genome MLST (wgMLST) analysis based on WGS. The results showed that 21 S. Derby strains were divided into 3 STs using MLST analysis, including ST40 (n = 19, accounting for 90.48%), ST71 (n = 1, accounting for 4.76%) and ST8016 (n = 1, accounting for 4.76%). cgMLST and wgMLST analysis categorized the tested strains into 13 cgSTs and 21 wgSTs, respectively. The minimum spanning trees of cgMLST and wgMLST both divided these strains into 3 clusters and 4 singletons. In addition, virulence gene profiles of S. Derby isolates were also analyzed, and a total of 174 virulence genes belonged to 8 categories were identified. In summary, we studied genomic typing, phylogenetic relationship and virulence gene profiles of S. Derby strains from different sources in China. These findings were beneficial for the epidemiology and pathogenesis of Salmonella.

Survival persistence of the 3 common Salmonella enterica serotypes isolated from broilers' in different matrices

Broiler meat is the predominant source of Salmonella as a foodborne pathogen. Several control strategies have focused on the reduction of Salmonella spp. levels at different production stages. However, the persistence of Salmonella between consecutive flocks is still of great concern. This study was designed to understand the cause of reinfection in broiler flocks due to survival of Salmonella in feeding lines of related matrices. Salmonella (S.) Enteritidis, S. Infantis, and S. Typhimurium isolated from broiler farms in North-West Germany were used. Four types of matrices (phosphate buffer saline (PBS), dietary plant fat, fat with feed mixture, and feed) were applied to evaluate Salmonella survival (with the initial dose about 8.0 log10 CFU/mL) during a simulation of 4 production cycles. To evaluate the growth and survival status of Salmonella ISO 6579-1:2017 were performed (quantitatively by plate count method (PCM) and most probable number method (MPN)) and qualitatively) at 5 defined time points (-7, 0, 4, 7, and 35 d). In all matrices and for the 3 serovars, the Salmonella count decreased at the end of the fourth cycle in comparison to the beginning of the experimental infection, and was still cultivated except for fat matrix. The PBS matrices showed the highest survival level of Salmonella and did not decline drastically by the end of the fourth cycle (5.93 ± 0.00, 5.87 ± 0.02, 5.73 ± 0.05 log10 CFU/mL, respectively). However, the fat matrices showed the lowest survival level for the 3 isolates at d 35 since the first cycle (0 log10 CFU/mL using PCM). Regarding the fat-feed mixture, and feed matrices, there was a fluctuation in the survival rate of Salmonella (all serovars) within each cycle. For the qualitative method, the 3 serovars persisted in all matrices until the end of the fourth cycle except for fat matrices. The present study highlights the ability of Salmonella to survive for a long time in different temperatures and matrices despite efficient cleaning and disinfection processes in the feeding lines, which may influence reinfection with Salmonella in poultry houses.

Surveillance of antimicrobial resistance, phenotypic, and genotypic patterns of Salmonella enterica isolated from animal feedstuffs: Annual study

Background and Aim

Salmonellosis is a significant foodborne disease that causes serious illness in the gastrointestinal of humans and it is a public health problem worldwide. This study aimed to determine Salmonella spp. in animal feeds, its characteristic, serovar identification, genotyping, and drug sensitivity.

Materials and Methods

Salmonella spp. from animal feedstuffs was collected from January 1 to December 31, 2017, with 657 samples. Serogroup classification was performed by using the slide agglutination test. Then, the samples were analyzed for genotype patterns using pulsed-field gel electrophoresis (PFGE) for DNA fingerprint and antibiotic sensitivity by Vitek® 2 techniques.

Results

A total of 80 samples (12.17 %) were found to be Salmonella positive; commercial feed compounds of 60 samples (75%); soybean meal of 10 samples (12.5%); pork meal of 5 samples (6.25%); a fish meal of three samples (3.75%) and poultry meal of 2 samples (2.5%). Serogroups B, C, D, and E were found in this study; 8 samples (10%), 39 samples (48.75%), 8 samples (10%), and 13 samples (16.25%), respectively. A total of 12 samples (15%) were not determined by serogrouping. The most common serovars were Salmonella Rissen (10%), Salmonella Mbandaka (8.75%), and Salmonella Livingstone (6.25%), which belong to serogroup C. Nine of eleven pulsotypes were detected when analyzed by PFGE, showed similarity index between 40.8 and 100 %. Antimicrobial susceptibility tests by Vitek® 2 compact for 11 strains were classified into three groups: resistance to 4, 8, and 11 antibiotics, out of 20 antibiotics.

Conclusion

This study revealed annual variation of Salmonella spp. Serovar, genotype, and phenotype from commercial feed compounds and raw materials of which involved people must be aware.

Repeated cross-sectional study identifies differing risk factors associated with microbial contamination in common food products in the United Kingdom

All foods carry microbes, many of which are harmless, but foods can also carry pathogens and/or microbial indicators of contamination. Limited information exists on the co-occurrence of microbes of food safety concern and the factors associated with their presence. Here, a population-based repeated cross-sectional design was used to determine the prevalence and co-occurrence of Escherichia coli, Klebsiella spp., Salmonella spp. and Vibrio spp. in key food commodities - chicken, pork, prawns, salmon and leafy greens. Prevalence in 1,369 food samples for these four target bacterial genera/species varied, while 25.6% of all samples had at least two of the target bacteria and eight different combinations of bacteria were observed as co-occurrence profiles in raw prawns. Imported frozen chicken was 6.4 times more likely to contain Salmonella than domestic chicken, and imported salmon was 5.5 times more likely to be contaminated with E. coli. Seasonality was significantly associated with E. coli and Klebsiella spp. contamination in leafy greens, with higher detection in summer and autumn. Moreover, the odds of Klebsiella spp. contamination were higher in summer in chicken and pork samples. These results provide insight on the bacterial species present on foods at retail, and identify factors associated with the presence of individual bacteria, which are highly relevant for food safety risk assessments and the design of surveillance programmes.

Data-Mining Poultry Processing Bio-Mapping Counts of Pathogens and Indicator Organisms for Food Safety Management Decision Making

Bio-mapping studies play an important role, as the data collected can be managed and analyzed in multiple ways to look at process trends, find explanations about the effect of process changes, activate a root cause analysis for events, and even compile performance data to demonstrate to inspection authorities or auditors the effect of certain decisions made on a daily basis and their effects over time in commercial settings not only from the food safety perspective but also from the production side. This study presents an alternative analysis of bio-mapping data collected throughout several months in a commercial poultry processing operation as described in the article "Bio-Mapping Indicators and Pathogen Loads in a Commercial Broiler Processing Facility Operating with High and Low Antimicrobial Interventions". The conducted analysis identifies the processing shift effect on microbial loads, attempts to find correlation between microbial indicators data and pathogens loads, and identifies novel visualization approaches and conducts distribution analysis for microbial indicators and pathogens in a commercial poultry processing facility. From the data analyzed, a greater number of locations were statistically different between shifts under reduced levels of chemical interventions with higher means at the second shift for both indicators and pathogens levels. Minimal to negligible correlation was found when comparing aerobic counts and Enterobacteriaceae counts with Salmonella levels, with significant variability between sampling locations. Distribution analysis and visualization as a bio-map of the process resulted in a clear bimodality in reduced chemical conditions for multiple locations mostly explained by shift effect. The development and use of bio-mapping data, including proper data visualization, improves the tools needed for ongoing decision making in food safety systems.

Antimicrobial and Antibiofilm Effect of Commonly Used Disinfectants on Salmonella Infantis Isolates

Salmonella enterica subsp. enterica serovar Infantis is the most prevalent serovar in broilers and broiler meat in the European Union. The aim of our study was to test the biofilm formation and antimicrobial effect of disinfectants on genetically characterized S. Infantis isolates from poultry, food, and humans. For the biofilm formation under various temperature conditions (8 °C, 20 °C, and 28 °C) and incubation times (72 h and 168 h), the crystal violet staining method was used. The evaluation of the in vitro antimicrobial effect of Ecocid^® S, ethanol, and hydrogen peroxide was determined using the broth microdilution method. The antibiofilm effect of subinhibitory concentration (1/8 MIC) of disinfectants was then tested on S. Infantis 323/19 strain that had the highest biofilm formation potential. Our results showed that the biofilm formation was strain-specific; however, it was higher at 20 °C and prolonged incubation time. Moreover, strains carrying a pESI plasmid showed higher biofilm formation potential. The antibiofilm potential of disinfectants on S. Infantis 323/19 strain at 20 °C was effective after a shorter incubation time. As shown in our study, more effective precautionary measures should be implemented to ensure biofilm prevention and removal in order to control the S. Infantis occurrence.

Quantitative analysis of knowledge, attitude and practice of workers in chicken slaughter slabs toward food safety and hygiene in Ouagadougou, Burkina Faso

Introduction

In low- and middle-income countries, chicken serves as a cheap source of protein and an income source for many households. It is particularly important in the capital, Ouagadougou, Burkina Faso, where chicken is regularly consumed. However, hygiene standards are very low, posing a significant public health risk.

Methods

To better understand the food safety situation, we conducted a cross-sectional survey of the hygienic practices of 155 randomly selected chicken slaughter outlets and carcass shops with a semi-structured questionnaire.

Results and discussion

Of the outlets visited, 59% are not licensed, and 63% are not regularly inspected, operating in the dominant, largely unregulated informal sector. More than 80% of the chickens are sourced from village production systems, but around 6% of the birds die during transport. The monetary loss due to chicken death during transportation is around four million USD annually. Market hygiene is poor; 86% of the holding pens have no hard floor and are not washed regularly. Almost all (92%) chickens are slaughtered on bare earth floors; bleeding, plucking, and evisceration are done on a wooden table that is rarely washed. On average, the same scalding water is used for 33 birds, seven scalded at a time. Most respondents (49%) thought that plucking and evisceration were the major cause of contamination of carcasses with foodborne pathogens. Most operators only washed their hands and knives with tap water at the beginning of the slaughtering process. Some shops use refrigerators and freezers to store carcasses before selling. However, they store carcasses with other foods like fish, beef and vegetables, facilitating further cross-contamination. There were rats (26%), cats (39%) and dogs (30%) present at outlets, roaming for food, especially roadside outlets. Training schemes on hygienic food handling practices were favoured by outlets as an approach to improve matters; however, improvements in food safety will be limited without significant upgrades in infrastructure and facilities. Slaughter slabs need a standard house with stable energy, adequate airflow, clean water, toilets, detergents and freezers. Also, they need equipment like knives, tables and dishes made of high-quality, easy-to-clean materials.

Occurrence and distribution of Salmonella serovars in carcasses and foods in southern Italy: Eleven-year monitoring (2011–2021)

Salmonella is one of the most common agents of foodborne illness. The genus Salmonella includes two species (Salmonella bongori and S. enterica) and six subspecies (enterica I, salamae II, arizonae IIIa, diarizonae IIIb, houtenae IV, and indica VI), each of which contains multiple serotypes associated with animal and human infections. The aim of the study was to evaluate the presence of Salmonella spp. in carcasses of food-producing animals and foods in southern Italy and the serovar distribution among different sources. From 2011 to 2021, a total of 12,246 foods and 982 samples from animal carcasses were collected and analyzed. The overall percentage of positive samples was 5.84% (N = 773) and a significant increase in prevalence was observed by comparing the years 2011–2015 (257, 3.27%) and 2016–2021 (516, 9.61%; p &lt; 0.05). The highest percentage of positive food samples was observed in “Meat and Meat Products” (N = 327/2,438, 13.41%) followed by “Fish and fishery products” (N = 115/1,915, 6.01%). In carcasses, the highest percentage of positive samples was reported from broilers (N = 42/81, 51.85%) followed by buffalo (N = 50/101, 49.50%) and pork (N = 140/380, 36.84%). After typing, the isolates were assigned to the species S. enterica and to the subspecies: enterica (N = 760, 98.32%), diarizonae (N = 8, 1.03%), salamae (N = 3, 0.39%) and houtenae (N = 2, 0.26%). S. Infantis was the most frequently detected (N = 177, 24.76%), followed by S. Derby (N = 77, 10.77%), monophasic S. Typhimurium (N = 63, 8.81%), S. Typhimurium (N = 54, 7.55%), and S. Rissen (N = 47, 6.57%). By comparing the sampling period 2011–2015 with that of 2016–2021, an increase in the prevalence of S. Infantis and monophasic S. Typhimurium and a decrease of S. Typhimurium were recorded (p &lt; 0.05). Thus, present data suggest that, despite the implementation of national and European control strategies to protect against Salmonella, the prevalence of this pathogen in southern Italy is still increasing and a change of national control programs to protect against Salmonella are necessary.

Nontyphoidal Salmonella infections acquired from poultry

PURPOSE OF REVIEW

Nontyphoidal Salmonella is a major food safety concern in developed and developing countries. Table eggs are often linked to cases of foodborne gastrointestinal disease. This review is focused on the latest findings on foodborne Salmonella infections acquired from poultry products and their implications on food safety.

RECENT FINDINGS

Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST) are the predominant Salmonella serovars associated with human Salmonellosis. In Australia, ST is the predominant serovar but SE has been recently detected in some commercial free-range egg flocks. The Salmonella shedding in poultry flocks can be highly variable across different flocks and farms; as a result, the level of product contamination is largely attributed to the flock management. The microevolution in the ST genome after in-vivo passaging may have clinical significance. On farm use of Salmonella vaccines and/or interventions during the processing of the product can influence the bacterial load. The refrigeration of the product also influences the safety of the poultry product.

SUMMARY

Many interventions are in place for the control of Salmonella from farm to fork. However, given the biosecurity challenges because of the increase in public demand for free-range products, the emergence of Salmonella virulent types and expensive diagnostics, ongoing collaborative efforts from farmers, regulators and public health officials are required.

Transmission of antimicrobial resistance (AMR) during animal transport

The transmission of antimicrobial resistance (AMR) between food-producing animals (poultry, cattle and pigs) during short journeys (< 8 h) and long journeys (> 8 h) directed to other farms or to the slaughterhouse lairage (directly or with intermediate stops at assembly centres or control posts, mainly transported by road) was assessed. Among the identified risk factors contributing to the probability of transmission of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs), the ones considered more important are the resistance status (presence of ARB/ARGs) of the animals pre-transport, increased faecal shedding, hygiene of the areas and vehicles, exposure to other animals carrying and/or shedding ARB/ARGs (especially between animals of different AMR loads and/or ARB/ARG types), exposure to contaminated lairage areas and duration of transport. There are nevertheless no data whereby differences between journeys shorter or longer than 8 h can be assessed. Strategies that would reduce the probability of AMR transmission, for all animal categories include minimising the duration of transport, proper cleaning and disinfection, appropriate transport planning, organising the transport in relation to AMR criteria (transport logistics), improving animal health and welfare and/or biosecurity immediately prior to and during transport, ensuring the thermal comfort of the animals and animal segregation. Most of the aforementioned measures have similar validity if applied at lairage, assembly centres and control posts. Data gaps relating to the risk factors and the effectiveness of mitigation measures have been identified, with consequent research needs in both the short and longer term listed. Quantification of the impact of animal transportation compared to the contribution of other stages of the food-production chain, and the interplay of duration with all risk factors on the transmission of ARB/ARGs during transport and journey breaks, were identified as urgent research needs.

Infection dynamics of Salmonella Infantis vary considerably between chicken lines

AbstractSalmonella (S.) Infantis is the most common serovar in broilers and broiler meat in the European Union. In the field, fast-growing broilers are reported to be more affected than slow-growing and layer birds. The present study investigated the infection dynamics and immunological response of four chicken lines in the course of a S. Infantis infection. Two commercial chicken lines, Ross 308 and Hubbard ISA-JA-757, and two experimentally chicken lines, specific pathogen free (SPF) layers and broilers, were infected at 2 days of age. Investigations focused on faecal shedding, bacterial colonisation, humoral and cellular immune response in the blood. Ross and SPF broilers were mainly attributed as high shedders followed by Hubbard. SPF layers showed the least shedding. This is in agreement with the caecal colonisation, SPF layers harboured significant less bacteria. Systemic spread of S. Infantis to liver and spleen was highest in Ross being statistically significant at 7 days of age compared to the other lines. Spread of infection to in-contact birds, was noticed 5 days post infection in every line. Antibody response occurred in every chicken line from day 21 of age onwards. In contrast to the other chicken lines, significant differences in T cell subsets and monocytes/macrophages were found between infected and negative Hubbard birds at 7 days of age. Uninfected SPF birds had significant higher immune cell counts (T cell subsets, B cells and monocytes /macrophages) compared to uninfected commercial birds, a fact important for future experimental settings. The results illustrate that the infection dynamics of S. Infantis is influenced by the chicken line resulting in a higher risk of transmission to humans from fast-growing broilers.

Bacterial contamination of chicken meat in slaughterhouses and the associated risk factors: A nationwide study in Thailand

Slaughterhouses are a key source of bacterial contamination in poultry meat and products, which is a major health and economic concern for several public authorities. This study aimed to quantify the non-compliance of bacterial contamination on chicken meat sampled from slaughterhouses and identify risk factors associated with the contamination. A questionnaire survey of 569 chicken slaughterhouses was undertaken and 1,707 meat samples were collected to determine the level of bacterial contamination. The proportion of the non-compliance associated with aerobic plate count [APC] (24.6%), Staphylococcus aureus (6.3%), Enterococcus spp. (24.7%), coliforms (13.5%), Escherichia coli (33.3%), and Salmonella spp. (33.4%) based on the livestock authorities' criteria was determined. Our results highlighted that the scalding process without scalding water temperature control or improper scalding increased the risk of APC (odds ratio, OR = 4.84, 95% CI: 2.72-8.61), S. aureus (OR = 2.68, 95% CI: 1.29-5.55), Enterococcus spp. (OR = 3.38, 95% CI: 2.01-5.69), coliforms (OR = 3.01, 95% CI: 1.47-6.15), and E. coli (OR = 2.69, 95% CI: 1.58-4.56) contamination on meat samples. Meat from eviscerated carcasses was more likely to be non-compliance due to contamination by E. coli (OR = 1.96, 95% CI: 1.14-3.38). Furthermore, open or semi-closed system slaughterhouses (OR = 1.79, 95% CI: 1.23-2.60) and lack of equipment for specific slaughtering areas (OR = 1.65, 95% CI: 1.04-2.61) increased the likelihood of Salmonella spp. occurrence. This is the first study of factors influencing the non-compliance of meat samples across Thailand. Authorities can use the study findings to enhance food safety strategies at the national level.

Research Note: Persistent Salmonella problems in slaughterhouses related to clones linked to poultry companies

Salmonellosis remains one of the main foodborne zoonoses in Europe, with poultry products as the main source of human infections. The slaughterhouse has been identified as a potential source for Salmonella contamination of poultry meat. Despite the mandatory programme of the EU, there are companies with persistent Salmonella that are unable to remove the bacteria from their processing environment, compromising the entire production line. In this context, an intensive sampling study was conducted to investigate a slaughterhouse with persistent Salmonella problems, establishing the genetic relationship among Salmonella strains isolated during the slaughter process. A total of 36 broiler flocks were sampled during processing at the slaughterhouse. Salmonella was identified based on ISO 6579-1:2017 (Annex D), serotyped by Kauffman-White-Le-Minor technique, and the genetic relationship was assessed with ERIC-PCR followed by PFGE. The outcomes showed that 69.4% of the batches sampled carried Salmonella upon arrival at the slaughterhouse and that 46.3% of the different samples from carcasses were contaminated with Salmonella. The two serovars isolated at the different steps in the slaughterhouse were Enteritidis (98.2%) and Kentucky (1.8%). Pulsed-field gel electrophoresis analysis revealed a low genetic diversity, with all S. Enteritidis isolates showing a nearly identical pulsotype (similarity >85%) and S. Kentucky strains showed the same XbaI PFGE profile (95.0% genetic similarity). The results of this study showed a high genetic relationship among isolates recovered from carcasses and environmental samples in the slaughterhouse from both Salmonella-positive and Salmonella-free flocks. Salmonella strains re-circulated across to poultry flocks and re-entered the slaughterhouse to survive on the processing line. Thus, it is necessary to implement molecular diagnosis methods in time at the field level to determine the Salmonella epidemiology of the flock, to make rapid decisions for the control of Salmonella and prevent entry into the slaughterhouse environment.

Assessing Salmonella Prevalence and Complexity Through Processing Using Different Culture Methods

Conventional Salmonella surveillance requires a week for isolation, confirmation, and subsequent serotyping. We previously showed that this could be reduced by 24 h by combining the pre-enrichment and enrichment steps into a single selective pre-enrichment step and was tested on directly after picking. The goal of this study was 2-fold: 1) to evaluate the use of selective pre-enrichment through each step of processing, including postintervention when the Salmonella load is reduced, and 2) to assess any changes in serovar populations in Salmonella positive samples. Duplicate carcass drip samples, each representative of 500 broiler carcasses, were collected by catching processing water drip under moving carcass shackle lines in each of three commercial broiler slaughter plants. Samples were collected post-pick, post-inside-outside bird wash (IOBW), and post-chill; duplicate wing rinses were performed pre- and post-antimicrobial parts dip. Each processing plant was sampled 6 times for a total of 180 samples collected. The number of Salmonella positives identified with selective pre-enrichment conditions (48/180) was similar to traditional selective enrichment culture conditions (52/180), showed good concordance in recovery rate between the 2 culture methods (Fisher's exact test, P = 0.72). We also found that the incidence of Salmonella reduced dramatically after antimicrobial intervention (post-pick 66.7% vs. post chill 8.3%). When serovar populations were evaluated in Salmonella positive samples using CRISPR-SeroSeq, we detected four different Salmonella serovars, Kentucky, Infantis, Schwarzengrund, and Typhimurium, and their incidence rose between post-pick and post-IOBW. The relative abundance of Infantis within individual samples increased between post-pick and post-IOBW while the relative abundance of the other 3 serovars decreased. These results suggest that a selective pre-enrichment step reduces the time required for Salmonella isolation without negatively affecting detection and serovar profiles in culture positive samples were not altered between culture conditions used.

Detection of Sutterella spp. in Broiler Liver and Breast

Sutterella sp. is a gram-negative, microaerophilic bacterium that is particularly resistant to bile acids. It has recently been associated with several human pathologies such as inflammatory bowel disease, asthma, diabetes, and autism. Indeed, susceptibility patterns to ciprofloxacin and erythromycin, combined with resistance to metronidazole, indicate that Sutterella wadsworthensis patterns are closer to those of Campylobacter. The objective of this study is to identify, for the first time, Sutterella spp. in the liver and breast of broiler chickens by quantitative real-time PCR (qPCR). Liver, breast, and cecal content samples were taken from 25 birds and frozen at −20°C until analyzed. The main results showed that Sutterella sp. is part of the cecal microbiota of 48% of the birds and present in the liver and breast of, respectively 20 and 40% of the chicks with a variable Cq. We, therefore, conclude that Sutterella sp. exists in poultry and poultry meat and that foodstuffs of poultry origin might be considered as a potential source of contamination for humans.

Rapid and sensitive detection of Salmonella in milk based on hybridization chain reaction and graphene oxide fluorescence platform

Salmonella is a foodborne pathogen that has contributed to numerous food safety accidents worldwide, making it necessary to detect contamination at an early stage. A pair of specific primers based on the invA gene of Salmonella was designed for PCR. Target double-stranded DNA (dsDNA) from PCR was purified and denatured at high temperature to obtain target single-stranded DNA (ssDNA). Two carboxyfluorescein-labeled hairpin probes (H1-FAM and H2-FAM) were designed with complementary portions to the ssDNA sequence so that binding could trigger H1-FAM and H2-FAM hybridization chain reaction (HCR) to produce a long dsDNA complex. In this study, graphene oxide (GO) was used in the development of a homogeneous fluorescence detection platform for Salmonella. Using this HCR-GO assay platform, Salmonella detection was completed in 3.5 h. Salmonella was reliably and specifically detected with a limit of detection (LOD) of 4.2 × 10¹ cfu/mL in pure culture. Moreover, this new HCR-GO assay platform was successfully applied to the detection of Salmonella in artificially contaminated milk with a LOD of 4.2 × 10² cfu/mL.