Prioritization of Chicken Meat Processing Interventions on the Basis of Reducing the Salmonella Residual Relative Risk

Occurrence, virulence, and resistance genes in Salmonella enterica isolated from an integrated poultry company in Jordan

Salmonella is considered one of the most common foodborne pathogens worldwide. The annual number of hospitalizations and deaths related to zoonotic salmonellosis, which is transmitted from animals to humans and infects poultry and meat, is expected to be significant. Hence, the primary aims of this research were to isolate and characterize Salmonella species obtained from an integrated poultry company and identify some virulence, and antimicrobial resistance, with a specific concern about colistin resistance genes. A total of 635 samples collected from various sources in an integrated company in Jordan were screened for Salmonella species accompanying their virulence and antimicrobial resistance genes. Samples were collected from parent stock house drag swabs, broiler farms, premix, cecum at the slaughterhouse level, prechilling and postchilling stages, and the final product. Salmonella species were detected in 3% (6/200) of investigated parent stock house drag swabs, 13.8% (11/80) from cloacal swabs from broiler farms, 16.9% (11/65) from boiler farms premix, 24.4% (11/45) from the cecum at slaughterhouse level, 16.4% (9/55) from the prechilling stage, 37.8% (17/45) from the postchilling stage and 53.3% (24/45) from the final product stage. No isolates were detected in feed mills (0/20), parents' premix (0/40), or hatcheries (0/40). Salmonella isolates were resistant to ciprofloxacin (91.0%), nalidixic acid (86.5%), doxycycline (83.1%), tetracycline (83.1%), sulphamethoxazole-trimethoprim (79.8%) and ampicillin (76.4%). Serotyping shows that S. Infantis was the predominant serovar, with 56.2%. Based on the minimum inhibitory concentration (MIC) test, 39.3% (35/89) of the isolates were resistant to colistin; however, no mcr genes were detected. Among antimicrobial-resistant genes, blaTEM was the most prevalent (88.8%). Furthermore, the spvC, ompA, and ompF virulence genes showed the highest percentages (97.8%, 97.8%, and 96.6%, respectively). In conclusion, Salmonella isolates were found at various stages in the integrated company. S. Infantis was the most prevalent serotype. No mcr genes were detected. Cross-contamination between poultry production stages highlights the importance of good hygiene practices. Furthermore, the presence of virulence genes and the patterns of antimicrobial resistance present significant challenges for public health.

A machine learning approach to identifying Salmonella stress response genes in isolates from poultry processing

We explored the potential of machine learning to identify significant genes associated with Salmonella stress response during poultry processing using whole genome sequencing (WGS) data. The Salmonella isolates (n = 177) used in this study were obtained from various chicken sources (skin before chiller, chicken carcass before chiller, frozen chicken, and post-chill chicken carcass). Six machine learning algorithms (random forest, neural network, cost-sensitive learning, logit boost, and support vector machine linear and radial kernels) were trained on Salmonella WGS data, and model fit was assessed using standard evaluation metrics such as the area under the receiver operating characteristic (AUROC) curve and confusion matrix statistics. All models achieved high performances based on the AUROC metric, with logit boost showing the best performance with an AUROC score of 0.904, sensitivity of 0.889, and specificity of 0.920. The significant genes identified included ybtX, which encodes a Yersiniabactin-associated zinc transporter, and the transferase-encoding genes yccK and thiS. Additionally, genes coding for cold (cspA, cspD, and cspE) and heat shock (rpoH and rpoE) responses were identified. Other significant genes included those involved in lipopolysaccharide biosynthesis (irp1, waaD, rfc, and rfbX), DNA repair and replication (traI), biofilm formation (ccdA and fyuA), and cellular metabolism (irtA).

Modeling of interventions for reducing external Enterobacteriaceae contamination of broiler carcasses during processing

This article presents a mathematical model for the Enterobacteriaceae count on the surface of broiler chicken during slaughter and how it may be affected by different processing technologies. The model is based on a model originally developed for Campylobacter and has been adapted for Enterobacteriaceae using a Bayesian updating approach and hitherto unpublished data gathered from German abattoirs. The slaughter process in the model consists of five stages: input, scalding, defeathering, evisceration, washing, and chilling. The impact of various processing technologies along the broiler processing line on the Enterobacteriaceae count on the carcasses' surface has been determined from literature data. The model is implemented in the software R and equipped with a graphical user interface which allows interactively to choose among different processing technologies for each stage along the processing line. Based on the choice of processing technologies the model estimates the Enterobacteriaceae count on the surface of each broiler chicken at each stage of processing. This result is then compared to a so-called baseline model which simulates a processing line with a fixed set of processing technologies. The model calculations showed how even very effective removal of bacteria on the exterior of the carcass in a previous step will be undone by the cross-contamination with leaked feces, if feces contain high concentrations of bacteria.

Peroxyacetic Acid Effectiveness against Salmonella on Raw Poultry Parts Is Not Affected by Organic Matter

ABSTRACT

Organic matter (OM) accumulation is common in chill tanks used to decontaminate raw poultry parts during processing. OM negatively affects the antimicrobial activity of chlorine-based compounds, but its effect on the antimicrobial effectiveness of peroxyacetic acid (PAA) on poultry meat has not been described. Therefore, this study evaluated the effect of OM on the efficacy of PAA solutions in simulated postchill tanks to reduce Salmonella artificially inoculated onto chicken parts. Chicken thighs were inoculated with a five-strain cocktail of poultry-borne Salmonella enterica serovars at ca. 6 log CFU/mL. Then, the thighs were immersed for 30 or 45 s in PAA solutions (500 or 1,000 ppm) with chicken slurry to simulate OM accumulation (0, 15, or 30 g/L). The thighs were rinsed with neutralizing buffered peptone water (100 mL), and rinsates were plated onto xylose lysine desoxycholate agar. Experiments were performed in triplicate (three thighs per treatment per replicate). Chemical oxygen demand, total nitrogen, and pH were measured as the water quality parameters of the PAA solutions before and after use. Chemical oxygen demand ranged from 2,905 mg/L in unused 500-ppm solutions without added OM to 6,290 mg/L in used 1,000-ppm solutions with 30 g/L OM. Initial total nitrogen was 42.5 ± 2.0 and 60.9 ± 8.3 mg/L for 15 and 30 g/L OM, which increased by 27 ± 17 mg/L after use. The pH of solutions ranged from 3.16 ± 0.14 to 3.42 ± 0.09 for the 1,000-ppm solutions and from 3.59 ± 0.06 to 3.96 ± 0.06 for the 500-ppm solutions. Mean Salmonella reductions were 0.9 ± 0.1 log CFU/mL of rinsate for the 500-ppm PAA treatment and 1.1 ± 0.1 log CFU/mL of rinsate for 1,000-ppm PAA treatment. Exposure time did not have a significant effect on the logarithmic reductions. There was no significant effect of OM concentration (P > 0.05) on the reductions, indicating that the antimicrobial efficacy was not affected and that PAA solutions may continue to be reused as long as the PAA concentration is actively monitored.

HIGHLIGHTS

Essential Oil-Based Nanoparticles as Antimicrobial Agents in the Food Industry

The use of essential oils (EO) loaded with nanoparticles is the most promising alternative to increase food quality and safety. Interesting works describe the antimicrobial properties of EO for pathogen control in natural and processed foods for human health and animal production, also contributing to sustainability. Their association with different nanosystems allows novel developments in the micronutrition, health promotion, and pathogen control fields, preventing the aggravation of bacterial microevolution and combating antibiotic resistance. Benefits to the environment are also provided, as they are biodegradable and biocompatible. However, such compounds have some physicochemical properties that prevent commercial use. This review focuses on recent developments in antimicrobial EO-based nanoparticles and their application in different food matrices.

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.

Regional Salmonella Differences in United States Broiler Production from 2016 to 2020 and the Contribution of Multiserovar Populations to Salmonella Surveillance

Poultry remains a considerable source of foodborne salmonellosis despite significant reduction of Salmonella incidence during processing. There are multiple entry points for Salmonella during production that can lead to contamination during slaughter, and it is important to distinguish the serovars present between the different stages to enact appropriate controls. National Salmonella data from the U.S. Department of Agriculture-Food Safety Inspection Service (USDA-FSIS) monitoring of poultry processing was analyzed from 2016 to 2020. The overall Salmonella incidence at processing in broiler carcasses and intact parts (parts) decreased from 9.00 to 6.57% over this period. The incidence in parts was higher (11.15%) than in carcasses (4.78%). Regional differences include higher proportions of serovars Infantis and Typhimurium in the Atlantic and higher proportion of serovar Schwarzengrund in the Southeast. For Georgia, the largest broiler-producing state, USDA-FSIS data were compared to Salmonella monitoring data from breeder flocks over the same period, revealing serovar Kentucky as the major serovar in breeders (67.91%) during production but not at processing, suggesting that it is more effectively removed during antimicrobial interventions. CRISPR-SeroSeq was performed on breeder samples collected between 2020 and 2021 to explain the incongruence between pre- and postharvest and showed that 32% of samples contain multiple serovars, with up to 11 serovars found in a single flock. High-resolution sequencing identifies serovar patterns at the population level and can provide insight to develop targeted controls. The work presented may apply to other food production systems where Salmonella is a concern, since it overcomes limitations associated with conventional culture. IMPORTANCE Salmonella is a leading cause of bacterial foodborne illness in the United States, with poultry as a significant Salmonella reservoir. We show the relative decrease in Salmonella over a 5-year period from 2016 to 2020 in processed chicken parts and highlight regional differences with respect to the prevalence of clinically important Salmonella serovars. Our results show that the discrepancy between Salmonella serovars found in pre- and postharvest poultry during surveillance are due in part by the limited detection depth offered by traditional culture techniques. Despite the reduction of Salmonella at processing, the number of human salmonellosis cases has remained stable, which may be attributed to differences in virulence among serovars and their associated risk. When monitoring for Salmonella, it is imperative to identify all serovars present to appropriately assess public health risk and to implement the most effective Salmonella controls.

HPMCP-Coated Microcapsules Containing the Ctx(Ile21)-Ha Antimicrobial Peptide Reduce the Mortality Rate Caused by Resistant Salmonella Enteritidis in Laying Hens

The constant use of synthetic antibiotics as growth promoters can cause bacterial resistance in chicks. Consequently, the use of these drugs has been restricted in different countries. In recent years, antimicrobial peptides have gained relevance due to their minimal capacity for bacterial resistance and does not generate toxic residues that harm the environment and human health. In this study, a Ctx(Ile21)-Ha antimicrobial peptide was employed, due to its previously reported great antimicrobial potential, to evaluate its application effects in laying chicks challenged with Salmonella Enteritidis, resistant to nalidixic acid and spectinomycin. For this, Ctx(Ile21)-Ha was synthesized, microencapsulated and coated with hypromellose phthalate (HPMCP) to be released in the intestine. Two different doses (20 and 40 mg of Ctx(Ile21)-Ha per kg of isoproteic and isoenergetic poultry feed) were included in the chick's food and administered for 28 days. Antimicrobial activity, effect and response as treatment were evaluated. Statistical results were analyzed in detail and indicate that the formulated Ctx(Ile21)-Ha peptide had a positive and significant effect in relation to the reduction of chick mortality in the first days of life. However, there was moderate evidence (p = 0.07), not considered statistically significant, in the differences in laying chick weight between the control and microencapsulation treatment groups as a function of time. Therefore, the microencapsulated Ctx(Ile21)-Ha antimicrobial peptide can be an interesting and promising option in the substitution of conventional antibiotics.

Presence of Listeria monocytogenes and Salmonella spp. in lamb meat commercialized in Uruguaiana, Rio Grande do Sul, Brazil

The aim of this study was to evaluate the hygienic-sanitary quality of lamb meat sold in the city of Uruguaiana, Rio Grande do Sul (RS) by counting the indicator microorganisms and detecting pathogens such as Salmonella spp. and Listeria monocytogenes. Thirty-nine lamb meat samples were collected from 10 commercial establishments in Uruguaiana. The samples were subjected to counts of aerobic mesophilic microorganisms and enterobacteria, and to the detection of Salmonella spp. and L. monocytogenes, all following standard methods. The average counts of mesophilic microorganisms and enterobacteria were 6.08 log CFU/g (minimum 4.07 and max 6.87) and 4.73 log CFU/g (minimum 0 and max 5.88), respectively. For pathogens, L. monocytogenes was isolated from five samples (12.82%), with three samples in the same location. Only two samples (5.13%) were positive for Salmonella spp. The results demonstrated unsatisfactory hygienic-sanitary conditions because high counts of pathogens such as Salmonella spp. and L. monocytogenes. The counts of enterobacteria showed poor hygiene conditions during the various stages of production. The results also indicated fecal contamination, as Salmonella spp. and L. monocytogenes are present in the intestinal tract of both humans and animals. The high count of mesophilic microorganisms obtained could be owing to contaminated raw material or unsatisfactory processing, including unsanitary conditions and the inappropriate use of binomial time/temperature during storage.

The Effect of Sanitizers on Microbial Levels of Chicken Meat Collected from Commercial Processing Plants

Chicken meat can potentially become contaminated with bacteria at the processing plant. In Australia, there is currently a lack of knowledge on the parameters and indications of use of non-chlorine based treatments in the chicken meat processing plants. Chlorine is widely used as a sanitizer in Australian chicken meat processing plants but due to occupational health and safety concerns and consumer perception, there is a need to identify alternative sanitizers. This study aimed to assess the efficacy of four different sanitizers in reducing the microbial load from naturally contaminated chicken meat carcasses collected from the processing plants in South Australia. There was a significant variation in a load of Campylobacter and total viable count (TVC) between samples collected from two different processing plants and within carcass batches collected from the same plant that was tested during the study. All sanitizers generally reduced the load of Campylobacter on chicken meat carcasses. Treatment with acidified sodium chlorite significantly reduced the level of Salmonella enterica serovars at all temperatures tested during this study. These findings are helpful to the industry for selection of the appropriate sanitizers. Findings are also useful for the regulatory authorities in Australia for providing approval for the use of sanitizers.