Post-harvest interventions to reduce/eliminate pathogens in beef

Efficacy of Common Antimicrobial Interventions at and above Regulatory Allowable Pick-Up Levels on Pathogen Reduction

The objective of this study was to evaluate the food safety efficacy of common antimicrobial interventions at and above required uptake levels for processing aids on the reduction of Shiga-toxin producing E. coli (STEC) and Salmonella spp. through spray and dip applications. Beef trim was inoculated with specific isolates of STEC or Salmonella strains. Trim was intervened with peracetic or lactic acid through spray or dip application. Meat rinses were serially diluted and plated following the drop dilution method; an enumerable range of 2-30 colonies was used to report results before log transformation. The combination of all treatments exhibits an average reduction rate of 0.16 LogCFU/g for STEC and Salmonella spp., suggesting that for every 1% increase in uptake there is an increase of 0.16 LogCFU/g of reduction rate. There is a statistical significance in the reduction rate of Shiga-toxin producing Escherichia coli in relation to the uptake percentage (p < 0.01). The addition of explanatory variables increases the R2 of the regression for STEC, where all the additional explanatory variables are statistically significant for reduction (p < 0.01). The addition of explanatory variables increases the R2 of the regression for Salmonella spp., but only trim type is statistically significant for reduction rate (p < 0.01). An increase in uptake percentages showed a significant increase in reduction rate of pathogens on beef trimmings.

Distribution of Extremely Heat-Resistant Escherichia coli in the Beef Production and Processing Continuum

Understanding the dynamics of stress-resistant Escherichia coli (E. coli) across the meat production and processing continuum is important for tracking sources of such microbes and devising effective modes of control. The Locus of Heat Resistance (LHR) is a ∼14-19 Kb genetic element imparting extreme heat resistance (XHR) in Enterobacteriaceae. It has been hypothesized that thermal and antimicrobial interventions applied during meat processing may select for LHR⁺E. coli. Thus, our goal was to study the prevalence and molecular biology of LHR⁺E. coli among lots of beef cattle (n = 3) from production through processing. Two hundred thirty-two generic E. coli isolated from the same animals through seven stages of the beef processing continuum (cattle in feedyards to packaged strip loins) were examined. LHR⁺E. coli were rare (0.6%; 1 of 180) among the early stages of the beef continuum (feces and hides at feedlot, feces and hides at harvest, and preevisceration carcasses), whereas the prevalence of LHR⁺E. coli on final carcasses and strip loins was remarkably higher. Half (14 of 28) of the final carcass E. coli possessed the LHR, while 79.2% (19 of 24) of the strip loin E. coli did. Eighty-five percent (29 of 34) of the LHR⁺E. coli presented with the XHR phenotype. The selection or enrichment of LHR⁺E. coli from harvest steps to the final products appeared unlikely as the LHR⁺E. coli isolates were effectively controlled by antimicrobial interventions typically used during beef processing. Further, whole-genome sequencing of the isolates suggested LHR⁺E. coli are persisting in the chilled processing environment and that horizontal LHR transfer among E. coli isolates may take place.

The "Big Six": Hidden Emerging Foodborne Bacterial Pathogens

Non-O157 Shiga toxin-producing Escherichia coli (STEC) are emerging serogroups that often result in diseases ranging from diarrhea to severe hemorrhagic colitis in humans. The most common non-O157 STEC are O26, O45, O103, O111, O121, and O145. These serogroups are known by the name "big six" because they cause severe illness and death in humans and the United States Department of Agriculture declared these serogroups as food contaminants. The lack of fast and efficient diagnostic methods exacerbates the public impact of the disease caused by these serogroups. Numerous outbreaks have been reported globally and most of these outbreaks were caused by ingestion of contaminated food or water as well as direct contact with reservoirs. Livestock harbor a variety of non-O157 STEC serovars that can contaminate meat and dairy products, or water sources when used for irrigation. Hence, effective control and prevention approaches are required to safeguard the public from infections. This review addresses the disease characteristics, reservoirs, the source of infections, the transmission of the disease, and major outbreaks associated with the six serogroups ("big six") of non-O157 STEC encountered all over the globe.

Processing interventions for enhanced microbiological safety of beef carcasses and beef products: A review

Chilled beef is inevitably contaminated with microorganisms, starting from the very beginning of the slaughter line. A lot of studies have aimed to improve meat safety and extend the shelf life of chilled beef, of which some have focused on improving the decontamination effects using traditional decontamination interventions, and others have investigated newer technologies and methods, that offer greater energy efficiency, lower environmental impacts, and better assurances for the decontamination of beef carcasses and cuts. To inform industry, there is an urgent need to review these interventions, analyze the merits and demerits of each technology, and provide insight into 'best practice' to preserve microbial safety and beef quality. In this review, the strategies and procedures used to inhibit the growth of microorganisms on beef, from slaughter to storage, have been critiqued. Critical aspects, where there is a lack of data, have been highlighted to help guide future research. It is also acknowledge that different intervention programs for microbiological safety have different applications, dependent on the initial microbial load, the type of infrastructures, and different stages of beef processing.

A Comparative Study on Microbiological and Chemical Characteristics of Small Ruminant Carcasses from Abattoirs in Greece

Meat quality dictates consumer preferences with hygiene forming a key component, especially in meat types with declining popularity, such as sheep and goat meat. Aiming to increase the marketability of sheep and goat meat, we examined 370 sheep and goat carcasses from two abattoirs in Greece. Tests included enumeration of the total mesophilic viable count, total psychrophilic viable count and coliform count, and detection of Salmonella spp., Listeria monocytogenes and presumptive ESBL Escherichia coli. Moreover, designated samples of meat were used to measure pH, moisture, total fat and protein content. Goat carcasses had significantly higher microbial counts compared to sheep carcasses. Lamb and kid carcasses had larger TMVC, TPVC and coliform counts compared to carcasses from adult animals. One strain of L. monocytogenes (0.8%), typed as serovar 1/2a (3a), was isolated from one adult sheep carcass. Twelve strains of ESBL Escherichia coli (25%) were isolated; there were not any strains of Salmonella spp. The average values of pH, moisture, total fat and total protein were 5.83%, 67.76%, 7.21% and 21.31%, respectively, for sheep carcasses and 5.70%, 68.2%, 5.69% and 24.10%, respectively, for goat carcasses. The results showed a small deviation in assessed parameters, implying the uniformity of the conditions concerning rearing and slaughtering.

A Commentary on Salmonella From a Pre-Harvest Perspective

Salmonella occurs in all the major meat producing livestock species (ruminants, swine and poultry), most often residing within the gastrointestinal tract asymptomatically. While considerable success has been achieved post-harvest, the design of effective pre-harvest interventions to control Salmonella has lagged. A simplistic view of the extremely complex host/pathogen interaction suggests that the pathogen has a vested interest in not causing illness or death to the host. The former would initiate an immune response from the host and/or the application of therapeutic antibacterial agents, while the latter would require finding another suitable host. Due to the widespread prevalence of Salmonella within livestock and poultry, and the relatively few salmonellosis cases in comparison, it appears, and is supported by new research, that Salmonella has developed methods to avoid detection by the animal’s immune system and live essentially as a commensal organism within the gastrointestinal tract of the animal. Yet, for reasons that are not fully understood, this “commensal” Salmonella does on occasion become virulent, in young and mature animals alike. Indeed, these researchers have documented Salmonella carriage throughout the year in cattle, but only rarely, if at all, was salmonellosis observed. Further, evaluation of Salmonella isolates (serotype and antimicrobial resistance patterns) from sick and healthy cattle failed to explain that while Salmonella was present in the majority of cattle sampled on that farm, only a few developed salmonellosis. Virulence, as well as multi-drug resistance, in both livestock and humans appears to cluster within a few serotypes. As a result, petitions are circulating calling for the labeling of some Salmonella serotypes as adulterants, as was done with Escherichia coli O157:H7 and other enterohemorrhagic E. coli strains. Regulators are considering approaching the Salmonella problem by serotype, such as focusing specifically on the top 10 reported serotypes causing human illness. Herein, the authors will discuss the many challenges of controlling Salmonella pre-harvest, reflecting on the significant research portfolio that has been generated over the last 25 years, as well as challenging existing paradigms surrounding this pathogen and the experimental methods used to further our understanding of Salmonella and/or evaluate methods of control.

Rates of evolutionary change of resident Escherichia coli O157:H7 differ within the same ecological niche

Background

Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a pathogen known to reside in cattle feedlots. This retrospective study examined 181 STEC O157:H7 strains collected over 23 years from a closed-system feedlot. All strains were subjected to short-read sequencing, with a subset of 36 also subjected to long-read sequencing.

Results

Over 96% of the strains fell into four phylogenetically distinct clades. Clade membership was associated with multiple factors including stx composition and the alleles of a well-characterized polymorphism (tir 255 T > A). Small plasmids (2.7 to 40 kb) were found to be primarily clade specific. Within each clade, chromosomal rearrangements were observed along with a core phageome and clade specific phages. Across both core and mobile elements of the genome, multiple SNP alleles were in complete linkage disequilibrium across all strains within specific clades. Clade evolutionary rates varied between 0.9 and 2.8 SNP/genome/year with two tir A allele clades having the lowest evolutionary rates. Investigation into possible causes of the differing rates was not conclusive but revealed a synonymous based mutation in the DNA polymerase III of the fastest evolving clade. Phylogenetic trees generated through our bioinformatic pipeline versus the NCBI’s pathogen detection project were similar, with the two tir A allele clades matching individual NCBI SNP clusters, and the two tir T allele clades assigned to multiple closely-related SNP clusters.

Conclusions

In one ecological niche, a diverse STEC O157:H7 population exhibited different rates of evolution that associated with SNP alleles in linkage disequilibrium in the core genome and mobile elements, including tir 255 T > A.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08497-6.

Resistomes and microbiome of meat trimmings and colon content from culled cows raised in conventional and organic production systems

BACKGROUND

The potential to distribute bacteria resistant to antimicrobial drugs in the meat supply is a public health concern. Market cows make up a fifth of the U.S. beef produced but little is known about the entire population of bacteria (the microbiome) and entirety of all resistance genes (the resistome) that are found in this population. The objective of this study was to characterize and compare the resistomes and microbiome of beef, dairy, and organic dairy market cows at slaughter.

METHODS

Fifty-four (N = 54) composite samples of both colon content and meat trimmings rinsate samples were collected over six visits to two harvest facilities from cows raised in three different production systems: conventional beef, conventional dairy, and organic dairy (n = 3 samples per visit per production system). Metagenomic DNA obtained from samples were analyzed using target-enriched sequencing (resistome) and 16S rRNA gene sequencing (microbiome).

RESULTS

All colon content samples had at least one identifiable antimicrobial resistance gene (ARG), while 21 of the 54 meat trimmings samples harbored at least one identifiable ARGs. Tetracycline ARGs were the most abundant class in both colon content and carcass meat trimmings. The resistome found on carcass meat trimmings was not significantly different by production system (P = 0.84, R2 = 0.00) or harvest facility (P = 0.10, R2 = 0.09). However, the resistome of colon content differed (P = 0.01; R2 = 0.05) among production systems, but not among the harvest facilities (P = 0.41; R2 = 0.00). Amplicon sequencing revealed differences (P < 0.05) in microbial populations in both meat trimmings and colon content between harvest facilities but not production systems (P > 0.05).

CONCLUSIONS

These data provide a baseline characterization of an important segment of the beef industry and highlight the effect that the production system where cattle are raised and the harvest facilities where an animal is processed can impact associated microbiome and resistomes.

Rapid and multiplexed quantification of Salmonella, Escherichia coli O157:H7, and Shigella flexneri in ground beef using flow cytometry

Salmonella, Escherichia coli O157:H7 (E. coli O157:H7) and Shigella flexneri (S. flexneri) might contaminate similar types of meat products and cause deadly diseases in humans. In reality, ground beef samples may carry more than one pathogen and a rapid and accurate detection method for the simultaneous identification of multiple specific pathogenic strains in ground beef is crucial. In this study, a sample pretreatment protocol and a flow cytometry method were developed for rapid and multiplexed quantification of the three pathogens without cultural enrichment in ground beef. The whole process of sample pretreatment, staining, and instrument analysis can be accomplished within 1 h. The three bacteria upon sample pretreatment were demonstrated good recoveries (93.8%-101.2%). The quantitative detection range of the mothed was 10³ to 10⁸ cells/g for all three pathogens, and the detection limit for Salmonella, E. coli O157:H7 and S. flexneri in ground beef were 3.1 × 10³ cells/g, 2.1 × 10³ cells/g and 2.3 × 10³ cells/g, respectively. Therefore, the as-developed approach is a rapid and quantitative method for multiplexed detection of Salmonella, E. coli O157:H7, and S. flexneri in ground beef.

Beef abattoir interventions in a risk-based meat safety assurance system

In risk-based meat safety assurance system, the use of interventions is intended to accomplish the meat safety targets on chilled carcasses, particularly in situations when an abattoir is unable to sufficiently reduce risks arising from specific farms/animal batches by using process hygiene alone. Furthermore, interventions are considered whenever food safety authorities identify meat production processes associated with high risks for consumers. This paper overviews the role of beef interventions in a risk-based, meat safety assurance system. Cattle hide interventions (chemical hide washes and microbial immobilisation treatment with shellac) and beef carcass interventions (pasteurisation treatments with hot water and/or steam and organic (lactic) acid washes), show consistent reduction effects of aerobic bacteria and faecal indicators and reduced prevalences of naturally present VTEC and Salmonella. The review also identified interventions where there was a lack of data and further research was needed, and other contextual factors to inform the risk management decisions for further development of risk-based meat safety assurance system.

Locus of Heat Resistance (LHR) in Meat-Borne Escherichia coli: Screening and Genetic Characterization

Microbial resistance to processing treatments poses a food safety concern, as treatment tolerant pathogens can emerge. Occasional foodborne outbreaks caused by pathogenic Escherichia coli have led to human and economic losses. Therefore, this study screened for the extreme heat resistance (XHR) phenotype as well as one known genetic marker, the locus of heat resistance (LHR), in 4,123 E. coli isolates from diverse meat animals at different processing stages. The prevalences of XHR and LHR among the meat-borne E. coli were found to be 10.3% and 11.4%, respectively, with 19% agreement between the two. Finished meat products showed the highest LHR prevalence (24.3%) compared to other processing stages (0 to 0.6%). None of the LHR⁺ E. coli in this study would be considered pathogens based on screening for virulence genes. Four high-quality genomes were generated by whole-genome sequencing of representative LHR⁺ isolates. Nine horizontally acquired LHRs were identified and characterized, four plasmid-borne and five chromosomal. Nine newly identified LHRs belong to ClpK1 LHR or ClpK2 LHR variants sharing 61 to 68% nucleotide sequence identity, while one LHR appears to be a hybrid. Our observations suggest positive correlation between the number of LHR regions present in isolates and the extent of heat resistance. The isolate exhibiting the highest degree of heat resistance possessed four LHRs belonging to three different variant groups. Maintenance of as many as four LHRs in a single genome emphasizes the benefits of the LHR in bacterial physiology and stress response.IMPORTANCE Currently, a "multiple-hurdle" approach based on a combination of different antimicrobial interventions, including heat, is being utilized during meat processing to control the burden of spoilage and pathogenic bacteria. Our recent study (M. Guragain, G. E. Smith, D. A. King, and J. M. Bosilevac, J Food Prot 83:1438-1443, 2020, https://doi.org/10.4315/JFP-20-103) suggests that U.S. beef cattle harbor Escherichia coli that possess the locus of heat resistance (LHR). LHR seemingly contributes to the global stress tolerance in bacteria and hence poses a food safety concern. Therefore, it is important to understand the distribution of the LHRs among meat-borne bacteria identified at different stages of different meat processing systems. Complete genome sequencing and comparative analysis of selected heat-resistant bacteria provide a clearer understanding of stress and heat resistance mechanisms. Further, sequencing data may offer a platform to gain further insights into the genetic background that provides optimal bacterial tolerance against heat and other processing treatments.

Assessment of Hygienic Practices in Beef Cattle Slaughterhouses and Retail Shops in Bishoftu, Ethiopia: Implications for Public Health

Understanding the potential drivers of microbial meat contamination along the entire meat supply chain is needed to identify targets for interventions to reduce the number of meatborne bacterial outbreaks. We assessed the hygienic practices in cattle slaughterhouses (28 employees) and retail shops (127 employees) through face-to-face interviews and direct personal observations. At the slaughterhouses, stunning, de-hiding and evisceration in vertical position, carcass washing and separate storage of offal were the identified good practices. Lack of hot water baths, absence of a chilling room, infrequent hand washing, insufficiently trained staff and irregular medical check-up were practices that lead to unhygienic handling of carcasses. At the retail shops, cleaning equipment using soap and hot water (81%), storing unsold meat in refrigerators (92%), concrete floors and white painted walls and ceilings were good practices. Adjacently displaying offal and meat (39%), lack of a cold chain, wrapping meat with plastic bags and newspapers, using a plastic or wooden cutting board (57%), infrequent washing of equipment and floors, and inadequately trained employees were practices that could result in unhygienic handling of beef. Our study identified unhygienic practices both at the slaughterhouses and retail shops that can predispose the public to meatborne infections, which could be improved through training and implementation of quality control systems.

Chemistry, Safety, and Challenges of the Use of Organic Acids and Their Derivative Salts in Meat Preservation

Meat industries are constantly facing new waves of changes in the consumer’s nutritional trends, food safety, and quality requirements and legislations leading to an increase in interest for meat biopreservation to respond to all of these modern socioeconomic demands. Hence, to replace synthetic and/or expensive additives, new technologies in preserving meat products from microbial contamination have been established. In this context, organic acids and their salts have been considered as the most popular examples of preservatives that offer several advantages to be applied in meat industry. Here, characteristics of organic acids/salts commonly used in meat preservation were described based on the published literature. Moreover, after outlining the challenges and advantages of their use in meat industry, their current applications as meat preservatives on various meat type matrices such as beef, pork, sheep, and poultry were quite exposed based on previous and recent research works. Then, different application types were highlighted. Besides, some potent synergistic approaches based on several combinations of organic acids/salts with different existing preservative techniques are reported with an emphasised discussion of their application as possible solution tools to mainly overcome some problems linked to organic acids/salts when used solely, thus contributing to ensure the overall safety and improve the quality of meats. Finally, despite their usefulness in meat preservation, organic acids/salts may possess detrimental traits. In this context, a detailed discussion on their limits of use in meat products was provided in the last section of this paper.

Bacterial community analysis using 16S rRNA amplicon sequencing in the boning room of Australian beef export abattoirs

Microbial contamination associated with beef slaughter and boning has been investigated using traditional culture dependent approaches. However, conventional counting methods have disadvantages of detecting only cultivable bacterial groups that may be a small subset of the true microbial population. This study investigated the microbiology in the boning room of an integrated (abattoir A) and a fragmented (abattoir B) Australian beef export abattoirs using culture independent 16S rRNA gene amplicon sequencing coupled with total viable count (TVC). Transmission of microbial populations during processing of carcases onto beef trim was monitored and compared between the two abattoirs. The results showed that the abattoirs produced beef trim with a mean TVC of 2.64-2.70 log₁₀ CFU/cm². Initial counts of microbes on the chilled carcases entering the boning room were <1.5 log₁₀ CFU/cm² and the environmental surfaces had ≤2.0 log₁₀ CFU/cm² throughout the boning room. Profiling of 16S gene sequences demonstrated that the contamination of boned products (beef trim) may be a result of contamination accumulating from environmental surfaces that are regularly in contact with beef trim. The 16S data also showed that the bacterial communities on the carcases and trim shared similar community composition with microbiota on environmental surfaces at varying proportions depending on the day of processing. Bacteroidales, Clostridiales, Enterobacteriales, Lactobacillales and Pseudomonadales were predominantly present in the bacterial communities in both abattoirs. However, the changes in relative abundance of these bacteria through the boning process varied between the abattoirs. The findings from this study suggested that the transfer of bacterial contaminants in the beef cattle boning room can be dynamic, and a 16 s rRNA gene sequencing-based approach can improve our understanding of the sources of contamination in the boning environment.

Antimicrobial Efficacy of Acidified Peroxyacetic Acid Treatments Against Surrogates for Enteric Pathogens on Prerigor Beef

Two studies were conducted to evaluate the antimicrobial effects of pH-adjusted solutions of peroxyacetic acid (PAA) against nonpathogenic Escherichia coli surrogates for Shiga toxin–producing E. coli and Salmonella, inoculated on beef. In both studies, prerigor beef carcass surface tissue (10 × 10 cm pieces) was inoculated (6–7 log colony-forming units [CFU]/cm2) on the adipose side with a 5-strain mixture of E. coli biotype I. In the first study, samples were left untreated (control) or were immersed (10 s) in solutions of PAA (300 parts per million [ppm]) acidified with a sulfuric acid and sodium sulfate blend (SSS) (pH 1.2) or PAA (400 ppm) acidified with acetic acid (2%), citric acid (1%), lactic acid (3.5%), or SSS (pH 1.2 or pH 1.8). In the second study, samples were left untreated or were spray treated (10 s) using a spray cabinet, with water, PAA (350 ppm or 400 ppm), PAA (350 ppm or 400 ppm) acidified with SSS (pH 1.2), or PAA (400 ppm) acidified with acetic acid (2%). All immersion treatments effectively (P &lt; 0.05) reduced inoculated E. coli populations (6.2 log CFU/cm2) by 2.3 to 2.8 log CFU/cm2. When the test solutions were applied by spraying, the water and all PAA-containing treatments lowered inoculated populations (6.4 log CFU/cm2) by 0.4 (P ≥ 0.05) and 1.7–1.9 (P &lt; 0.05) log CFU/cm2, respectively. No (P ≥ 0.05) differences in decontamination efficacy were observed between the 5 PAA-containing spray treatments. Overall, the results showed that PAA and the pH-adjusted PAA treatments were effective in reducing levels of the surrogates for Shiga toxin–producing E. coli and Salmonella. Although no differences in antimicrobial efficacy were noted between the nonacidified and acidified PAA treatments immediately after treatment application, further studies are needed to evaluate how the acidified PAA treatments perform as part of a sequential multi-hurdle decontamination strategy to reduce pathogen contamination on beef carcasses.

Characterization and molecular subtyping of Shiga toxin-producing Escherichia coli strains in provincial abattoirs from the Province of Buenos Aires, Argentina, during 2016-2018

We characterized Shiga toxin-producing Escherichia coli (STEC) O157 (n = 20) and non-O157 (n = 68) isolated from carcasses (n = 54), the environment (n = 20), head meat (n = 3) and viscera washing and chilling water (n = 11) in provincial abattoirs before and after implementing improvement actions. The strains were tested for eae, saa, ehxA and fliC_H7 genes. Variants stx₁ and stx₂ were also determined. Pulsed-field gel electrophoresis (PFGE) was carried out with restriction enzymes XbaI and BlnI. All twenty O157 STEC strains [H7; H21; HNM] carried genes rfb_O157 and ehxA; 90.0 % were positive for eae and 15.0 % were negative for fliC_H7 and positive for saa. Results of PFGE showed 17 XbaI patterns, of which 14 were unique and three formed clusters. From the 68 non-O157 STEC strains, 66.2 %, 55.9 % and 2.9 % were positive for ehxA, saa and eae genes, respectively. Fifty-three XbaI patterns were obtained (49 unique and four forming clusters). Cross-contamination between products and between the environment and products was confirmed in all abattoirs. While the proposed improvements reduced the risk of contamination, Good Hygiene Practices and Good Manufacturing Practices should be implemented in provincial abattoirs, stressing the importance of having a uniform national food safety standard.

Anti-Escherichia coli O157:H7 as Natural Preservative to Control and Prevent Food Contamination in Meat and Fish Products

BACKGROUND AND OBJECTIVE

Shiga toxin-producing Escherichia coli O157:H7 is a troubled foodborne pathogen associated with contamination of meat, fish and poultry. The present work aimed to evaluate plant extracts as natural preservatives anti- Escherichia coli O157:H7 in meat and fish products.

MATERIALS AND METHODS

Antibacterial activity and minimum inhibitory concentrations (MICs) of seven herbal plants, clove, marjoram, sage, pomegranate peel, turmeric, Cassia fistula and black pepper and their different 6 mixes were examined against Escherichia coli O157:H7. Phytochemical qualitative analysis, phenolic compounds (HPLC), total phenolic, total flavonoid contents and antioxidant activities of individual extracts and their 6 mixes were evaluated. Combination Mix 5 extract was applied on meat and fish-fillet, then its antimicrobial effect against E. coli O157:H7 and sensory evaluation were assessed.

RESULTS

Five extracts exhibited good antibacterial activity against Escherichia coli O157:H7. The greatest inhibition zone was recorded by clove aqueous extract (25 mm). Mix 5 (clove, sage, pomegranate and Cassia fistula) showed the highest inhibition with MIC of 3.0 mg mL-1. This mix exhibited strong anti-bactericidal effect against E. coli O157:H7 in meat and fish-fillet products throughout 8 days of cold storage (4°C). The sensory evaluation revealed that Mix 5 was acceptable by panelists with concentration of 0.50% in beef burgers and 0.25% in fish-fillet.

CONCLUSION

This study suggests that the use of herbal extracts provide antibacterial potentials against food pathogens in meat and fish products.

Sustainability of safe foods: Joint environmental, economic and microbial load reduction assessment of antimicrobial systems in U.S. beef processing

Various antimicrobial interventions are applied sequentially in the beef processing industry to reduce microbial load on beef products by using intensive inputs (e.g., chemicals, energy), high strength wastewater, and potentially result in meat discoloration. This study serves as the first analysis to jointly evaluate environmental and economic assessment with its microbial load reduction of proposed antimicrobial systems in the U.S. beef processing industry to identify relatively sustainable systems that minimize environmental and economic impacts while providing microbial safe meat. Specifically, forty potential sequential antimicrobial systems were proposed and evaluated from three perspectives: microbial load reduction, environmental, and economic impacts, by meta-analysis, life cycle assessment, and operational cost analysis orderly. The results show that the antimicrobial systems applying steam pasteurization during the main intervention offer high microbial load reduction (>4.2 log CFU/cm² reduction from a hypothetical initial contamination at 5.0 log CFU/cm²). Human health impact (31.0 to 65.6%) and ecosystem toxicity (3.6 to 12.5%), eutrophication (11.9 to 15.5%) and global warming (6.4 to 22.2%) are the main contributors to the overall environmental single score among the forty antimicrobial systems. Antimicrobial chemicals (up to 82.8%), wastewater treatment (up to 12.7%), and natural gas (up to 10.7%) are the three major drivers of operational cost for sanitizing 1000 kg hot standard carcass weight (HSCW). Devalued (discolored) meat due to contact with heat from steam pasteurization or hot water wash has a considerable increase in economic ($4.5/1000 HSCW) and environmental (especially at farm stage) impacts. Certain antimicrobial systems (e.g., water wash followed by steam pasteurization) were found to be more promising with satisfactory effectiveness, better environmental and cost performance under uncertainty (1000 Monte Carlo simulations). Results from this study can guide the U.S. beef processing industry to advance sustainability while protecting human health from foodborne illness.

Microbiological Testing for the Proper Assessment of the Hygiene Status of Beef Carcasses

Microbiological testing is an important quality management tool in the food industry. In this study, the hygiene status of beef carcasses sampled in eight Brazilian slaughterhouses was assessed by enumeration of different hygiene indicator microorganisms, and a model to establish potential associations among these counts was proposed. The carcasses (n = 464) were surface sampled at four slaughtering steps (step 1: Hide after bleeding; step 2: Carcass after hide removal; step 3: Carcass after evisceration; step 4: Carcass after end washing) and subjected to a counting of mesophilic aerobes (MA), Enterobacteriaceae (EB), total coliforms (TC), and Escherichia coli (EC) using Petrifilm™ plates. Among the sampled beef carcasses (step 4), 32 (6.9%) and 71 (15.3%) presented counts above the microbiological criteria established by (EC) No. 1441/2007 for MA and EB, respectively. Thus, indicating that improvements in slaughter hygiene and a review of process controls are demanded in some of the studied slaughterhouses. The log count differences of EC, TC, and EB from MA were considered as response variables as a function of the slaughtering steps. Differential log counts changed consistently with the steps. The measurements, including the patterns in their inherently random variability, were fairly predictable from steps 1 and 4. The results indicated that differential log counts for TC and EC are not relevant, as their concentrations and random pattern can be inferred from counts of MA and EB. The proposed model can be used as a valuable tool for the design and adoption of feasible quality control programs in beef industries. The adoption of such a tool should have a positive contribution on consumers’ health and enhance product quality.

Detection, Prevalence, and Pathogenicity of Non-O157 Shiga Toxin-Producing Escherichia coli from Cattle Hides and Carcasses

Cattle are a major reservoir for Shiga toxin-producing Escherichia coli (STEC) and harbor these bacteria in the intestinal tract. The prevalence, concentration, and STEC serogroup isolated in cattle varies between individuals. Hide removal at slaughter serves as a major point of carcass contamination and ultimately beef products. Certain STEC serogroups, such as O26, O45, O103, O111, O121, O145, and O157, containing the intestinal adherence factor intimin, pose a large economic burden to food producers because of testing and recalls. Human infection with STEC can cause illnesses ranging from diarrhea to hemorrhagic colitis and hemolytic uremic syndrome, and is commonly acquired through ingestion of contaminated foods, often beef products. Previously, most studies focused on O157 STEC, but there is growing recognition of the importance of non-O157 STEC serogroups. This review summarizes detection methods, prevalence, and methods for prediction of pathogenicity of non-O157 STEC from cattle hides and carcasses. A synthesis of procedures is outlined for general non-O157 STEC and targeted detection of specific STEC serogroups. Standardization of sample collection and processing procedures would allow for more robust comparisons among studies. Presence of non-O157 STEC isolated from cattle hides and carcasses and specific factors, such as point of sample collection and season, are summarized. Also, factors that might influence STEC survival on these surfaces, such as the microbial population on hides and microbial adherence genes, are raised as topics for future investigation. Finally, this review gives an overview on studies that have used genetic and cell-based methods to identify specific phenotypes of non-O157 STEC strains isolated from cattle to assess their risk to human health.

Evaluation of intervention measures at different stages of the production chain in Argentinian exporting abattoirs

Antimicrobial treatments could help to decrease the transmission of microorganisms to beef carcasses and abattoir environments. The aim of this study was to evaluate the effectiveness of interventions in reducing Shiga toxin genes ( stx1 and stx2) presence in a commercial abattoir. Intervention measures included the application of electrolytically generated hypochlorous acid to steer pens (experiment 1), chlorinated water, electrolytically generated hypochlorous acid, and isoclor to steer pens (experiment 2), electrolytically generated hypochlorous acid to knocking pens (experiment 3), and aqueous ozone and electrolytically generated hypochlorous acid onto beef carcasses (experiment 4). Detection of stx in samples was performed with BAX® System Real-Time PCR Assay. Our results showed that treatment with pressurized electrolytically generated hypochlorous acid and isoclor were effective to reduce stx presence from hides on steer pens. Although there is no single strategy to ensure the reduction of stx presence in a commercial abattoir, the combined application of several antimicrobial interventions would be ideal.

Photohydroionization Reduces Shiga Toxin-Producing Escherichia coli and Salmonella on Fresh Beef with Minimal Effects on Meat Quality

The photohydroionization (PHI) technology utilizes a combination of UV light and low-level oxidizers to produce antimicrobial action, and thus, is a potential intervention to control pathogen contamination on surface of fresh beef. The objectives of the study were 1) to evaluate the effect of PHI on reduction of selected Escherichia coli (E. coli) O157:H7, non-O157 Shiga toxin-producing E. coli (STEC; O26, O45, O103, O111, O121, O145), antimicrobial resistant (AMR) and non-AMR Salmonella strains inoculated on beef flanks, and 2) to evaluate the effect of PHI treatment on the lean color and lipid oxidation of beef during refrigerated storage. Inoculated beef flanks were exposed to PHI treatment for 0 (control), 15, 30, or 60 s at 4°C. Exposure to PHI for 15 s reduced (P ≤ 0.05) pathogens on the surface of fresh beef ranging from 0.3 to 0.9 log CFU/cm2. Increasing the exposure time to 60 s did not improve (P > 0.05) reductions over 15 s for the majority of the selected pathogens, but yielded pathogen reductions ranging from 0.5 to 1.1 log CFU/cm2. Over all storage times when beef samples were exposed to PHI for 75 s, no difference (P > 0.05) was detected on lean a* value (24.67 versus 24.95), of treated and control fresh beef tissues, respectively. The highest TBARS values after storage for 14 d at 4°C was 0.33 mg MDA/kg of meat indicating that no oxidative rancidity occurred for treated beef samples. The PHI technology with 15 to 75 s exposure time was effective in controlling STEC and Salmonella contaminated on surface of fresh beef without causing adverse effects on fresh beef quality while reducing water and energy use. Further study of PHI treatment parameters under commercial plant conditions and ultimate validation of those parameters will be necessary for commercial implementation.

Validation of Antimicrobial Interventions for Reducing Shiga Toxin-Producing Escherichia coli Surrogate Populations during Goat Slaughter and Carcass Chilling

Demand and consumption of goat meat is increasing in the United States due to an increase in ethnic populations that prefer goat meat. As ruminant animals, goats are known reservoirs for Shiga toxin-producing Escherichia coli (STEC) and proper handling, especially during slaughter, is imperative to reduce the likelihood of carcass and meat contamination. However, the majority of antimicrobial intervention studies during the slaughter of ruminant species have focused on beef, highlighting the need for validation studies targeting small ruminants, such as goats, during slaughter and chilling procedures. The objective of this research was to evaluate 4.5% lactic acid (LA; pH 2.1), peroxyacetic acid (PAA; 400 ppm; pH 4.7), a hydrochloric and citric acid blend (Citrilow [CL]; pH 1.2), 5% levulinic acid plus 0.5% sodium dodecyl sulfate (LVA+SDS; pH 2.60), and a nontreated control (CON) for their efficacy in reducing STEC surrogates and their effect on carcass color from slaughter through 24-h chill. Fifteen goat carcasses across three replications were inoculated with a five-strain cocktail (ca. 5 log CFU/cm² attachment), containing rifampin-resistant surrogate E. coli (BAA-1427, BAA-1428, BAA-1429, BAA-1430, and BAA-1431) and were randomly assigned to an antimicrobial treatment. Antimicrobials were applied prechill and 24 h postchill. Mean log reductions achieved after prechill treatment with LA, PAA, CL, and LVA+SDS were 2.00, 1.86, 2.26, and 1.90 log CFU/cm², respectively. Antimicrobial treatment after the 24-h chilling, resulted in additional reductions of surrogate E. coli by 0.99, 1.03, 1.94, and 0.47 log CFU/cm² for LA, PAA, CL, and LVA+SDS, respectively. Antimicrobial treatments did not impact goat carcass objective color (L* and a*), except for b*. The antimicrobials tested in this study were able to effectively reduce surrogate STEC populations during slaughter and subsequent chilling without compromising carcass color.

Similar Levels of Antimicrobial Resistance in U.S. Food Service Ground Beef Products with and without a "Raised without Antibiotics" Claim

U.S. ground beef with "raised without antibiotics" (RWA) label claims are perceived as harboring fewer bacteria with antimicrobial resistance (AMR) than are found in conventional (CONV) ground beef with no such label claim. A total of 370 ground beef samples from CONV ( n = 191) and RWA ( n = 179) production systems were collected over 13 months from three food service suppliers. The following bacteria were cultured: Escherichia coli, tetracycline-resistant (TET^r) E. coli, third-generation cephalosporin-resistant (3GC^r) E. coli, Salmonella enterica, TET^r S. enterica, 3GC^r S. enterica, nalidixic acid-resistant S. enterica, Enterococcus spp., erythromycin-resistant Enterococcus spp., TET^r Enterococcus spp., Staphylococcus aureus, and methicillin-resistant S. aureus. TET^r E. coli was more frequently detected in CONV ground beef (CONV, 54.2%; RWA, 35.2%; P < 0.01), but supplier ( P < 0.01) and production system × suppler interaction ( P < 0.01) effects were also significant. Metagenomic DNA was isolated from each sample, and equal amounts of metagenomic DNA were pooled by supplier, month, and production system for 75 pooled samples (38 CONV, 37 RWA). The abundance of aac(6')-Ie-aph(2″)-Ia, aadA1, bla_CMY-2, bla_CTX-M, bla_KPC-2, erm(B), mecA, tet(A), tet(B), and tet(M) genes was assessed by quantitative PCR. The tet(A) (2.9-log₂-fold change, P = 0.04) and tet(B) (5.6-log₂-fold change) ( P = 0.03) genes were significantly more abundant in RWA ground beef. Phylogenetic analyses revealed that ground beef microbiomes differed more by supplier than by production system. These results were consistent with prior research suggesting antimicrobial use in U.S. beef cattle has minimal impact on the AMR of bacteria found in these products. These results should spur a reevaluation of assumptions regarding the impact of antimicrobial use during U.S. beef production on the AMR of bacteria in ground beef.

Detection and Quantification of Seven Major Serogroups of Shiga Toxin-Producing Escherichia coli on Hides of Cull Dairy, Cull Beef, and Fed Beef Cattle at Slaughter†

Dehiding during beef cattle processing can introduce fecal contaminants, including Shiga toxin-producing Escherichia coli (STEC), from hides onto carcass surfaces, creating the potential for contaminated beef. Fecal shedding of major STEC serogroups (O26, O45, O103, O111, O121, O145, and O157; STEC-7) may differ among cattle populations, yet no study has been conducted to isolate STEC-7 on hides of multiple cattle types on the same production days at the same processing plant. Our objective was to estimate and compare prevalence and concentrations of STEC-7 on hides of cull dairy, cull beef, and fed beef cattle from the same date and processing plant. Overall, 1,500 cattle hides were sponge sampled from cull dairy ( n = 500), cull beef ( n = 500) and fed beef cattle ( n = 500) over 10 processing days. To determine prevalence, samples were subjected to an immunomagnetic separation culture method, and presumptive STEC isolates were tested by PCR for serogroup and major virulence genes. A spiral plate method was used to enumerate STEC-7 from hide samples. Data were analyzed with linear mixed models. All STEC-7 serogroups except O121 were detected and quantified on cattle hides in this study population. Slightly more fed beef hides (77 of 500; 15.4%) and cull beef hides (76 of 500; 15.2%) were positive for at least one STEC-7 strain compared with cull dairy hides (57 of 500; 11.4%), but cattle type was not significantly associated ( P = 0.19) with STEC-7 prevalence. Fed beef hides had a significantly higher prevalence ( P < 0.05) of STEC O103, O145, and O157 serogroups than did either of the other cattle types. The highest proportions of quantifiable samples were for STEC O145 (32 of 1,500 samples; 2.1%) and O157 (31 of 1,500 samples; 2.1%) serogroups, with the majority of concentrations at 3 to 5 and 2 to 4 log CFU/100 cm² of hide, respectively. Results indicate that hide contamination with some major STEC serogroups differs significantly among cattle types at harvest, even within the same day and location.

Evaluation of Commercial Prototype Bacteriophage Intervention Designed for Reducing O157 and Non-O157 Shiga-Toxigenic Escherichia coli (STEC) on Beef Cattle Hide

Microbiological safety of beef products can be protected by application of antimicrobial interventions throughout the beef chain. This study evaluated a commercial prototype antimicrobial intervention comprised of lytic bacteriophages formulated to reduce O157 and non-O157 Shiga-toxigenic Escherichia coli (STEC) on beef cattle hide pieces, simulating commercial pre-harvest hide decontamination. STEC reduction in vitro by individual and cocktailed phages was determined by efficiency of plating (EOP). Following STEC inoculation onto hide pieces, the phage intervention was applied and hide pieces were analyzed to quantify reductions in STEC counts. Phage intervention treatment resulted in 0.4 to 0.7 log10 CFU/cm² (p < 0.01) E. coli O157, O121, and O103 reduction. Conversely, E. coli O111 and O45 did not show any significant reduction after application of bacteriophage intervention (p > 0.05). Multiplicity of infection (MOI) evaluation indicated E. coli O157 and O121 isolates required the fewest numbers of phages per host cell to produce host lysis. STEC-attacking phages may be applied to assist in preventing STEC transmission to beef products.

Frequency, characterization and genotypic analysis of Shiga toxin-producing Escherichia coli in beef slaughterhouses of Argentina

The objectives of this study were: (1) to estimate STEC frequency in hide and carcass samples taken from beef slaughterhouses supplying the domestic market in Argentina, (2) to establish the pheno-genotypic characteristics of STEC and non-toxigenic Escherichia coli of serogroups O26, O45, O103, O121, O111, O145 or O157 isolated from the analyzed samples and, (3) to study their clonal relatedness. Sixty hides and 60 carcasses were analyzed. At the screening step, 48% of hide and 80% of carcass samples tested positive for the stx gene by endpoint PCR. The STEC isolation rate was 5% for hides and 8% for carcasses. The isolation rate of STEC-positive for O26, O45, O103, O111, O145 or O157 serogroups was 0% for hides and 2% for carcasses. With the purpose of studying the clonal relatedness of isolates, macrorestriction fragment analysis by pulsed-field gel electrophoresis was performed. The results indicated cross-contamination between hides and between carcasses of animals in the same lot and, that the origin of carcass contamination was their own hide, or the hides of other animals in the same lot. The high detection rate at the screening step, especially in carcasses, and the evidence of cross-contamination show the need to apply additional in-plant intervention strategies aimed at preventing carcass contamination.

Establishing Statistical Equivalence of Data from Different Sampling Approaches for Assessment of Bacterial Phenotypic Antimicrobial Resistance

To assess phenotypic bacterial antimicrobial resistance (AMR) in different strata (e.g., host populations, environmental areas, manure, or sewage effluents) for epidemiological purposes, isolates of target bacteria can be obtained from a stratum using various sample types. Also, different sample processing methods can be applied. The MIC of each target antimicrobial drug for each isolate is measured. Statistical equivalence testing of the MIC data for the isolates allows evaluation of whether different sample types or sample processing methods yield equivalent estimates of the bacterial antimicrobial susceptibility in the stratum. We demonstrate this approach on the antimicrobial susceptibility estimates for (i) nontyphoidal Salmonella spp. from ground or trimmed meat versus cecal content samples of cattle in processing plants in 2013-2014 and (ii) nontyphoidal Salmonella spp. from urine, fecal, and blood human samples in 2015 (U.S. National Antimicrobial Resistance Monitoring System data). We found that the sample types for cattle yielded nonequivalent susceptibility estimates for several antimicrobial drug classes and thus may gauge distinct subpopulations of salmonellae. The quinolone and fluoroquinolone susceptibility estimates for nontyphoidal salmonellae from human blood are nonequivalent to those from urine or feces, conjecturally due to the fluoroquinolone (ciprofloxacin) use to treat infections caused by nontyphoidal salmonellae. We also demonstrate statistical equivalence testing for comparing sample processing methods for fecal samples (culturing one versus multiple aliquots per sample) to assess AMR in fecal Escherichia coli These methods yield equivalent results, except for tetracyclines. Importantly, statistical equivalence testing provides the MIC difference at which the data from two sample types or sample processing methods differ statistically. Data users (e.g., microbiologists and epidemiologists) may then interpret practical relevance of the difference.IMPORTANCE Bacterial antimicrobial resistance (AMR) needs to be assessed in different populations or strata for the purposes of surveillance and determination of the efficacy of interventions to halt AMR dissemination. To assess phenotypic antimicrobial susceptibility, isolates of target bacteria can be obtained from a stratum using different sample types or employing different sample processing methods in the laboratory. The MIC of each target antimicrobial drug for each of the isolates is measured, yielding the MIC distribution across the isolates from each sample type or sample processing method. We describe statistical equivalence testing for the MIC data for evaluating whether two sample types or sample processing methods yield equivalent estimates of the bacterial phenotypic antimicrobial susceptibility in the stratum. This includes estimating the MIC difference at which the data from the two approaches differ statistically. Data users (e.g., microbiologists, epidemiologists, and public health professionals) can then interpret whether that present difference is practically relevant.

Efficacy of a Blend of Sulfuric Acid and Sodium Sulfate against Shiga Toxin-Producing Escherichia coli, Salmonella, and Nonpathogenic Escherichia coli Biotype I on Inoculated Prerigor Beef Surface Tissue

A study was conducted to investigate the efficacy of a sulfuric acid-sodium sulfate blend (SSS) against Escherichia coli O157:H7, non-O157 Shiga toxin-producing E. coli (STEC), Salmonella, and nonpathogenic E. coli biotype I on prerigor beef surface tissue. The suitability of using the nonpathogenic E. coli as a surrogate for in-plant validation studies was also determined by comparing the data obtained for the nonpathogenic inoculum with those for the pathogenic inocula. Prerigor beef tissue samples (10 by 10 cm) were inoculated (ca. 6 log CFU/cm²) on the adipose side in a laboratory-scale spray cabinet with multistrain mixtures of E. coli O157:H7 (5 strains), non-O157 STEC (12 strains), Salmonella (6 strains), or E. coli biotype I (5 strains). Treatment parameters evaluated were two SSS pH values (1.5 and 1.0) and two spray application pressures (13 and 22 lb/in²). Untreated inoculated beef tissue samples served as controls for initial bacterial populations. Overall, the SSS treatments lowered inoculated (6.1 to 6.4 log CFU/cm²) bacterial populations by 0.6 to 1.5 log CFU/cm² (P < 0.05), depending on inoculum type and recovery medium. There were no main effects (P ≥ 0.05) of solution pH or spray application pressure when SSS was applied to samples inoculated with any of the tested E. coli inocula; however, solution pH did have a significant effect (P < 0.05) when SSS was applied to samples inoculated with Salmonella. Results indicated that the response of the nonpathogenic E. coli inoculum to the SSS treatments was similar (P ≥ 0.05) to that of the pathogenic inocula tested, making the E. coli biotype I strains viable surrogate organisms for in-plant validation of SSS efficacy on beef. The application of SSS at the tested parameters to prerigor beef surface tissue may be an effective intervention for controlling pathogens in a commercial beef harvest process.

Effect of a commercial steam-vacuuming treatment implemented after slaughtering for the decontamination of cattle carcasses

To assess the antimicrobial effect of a commercial steam-vacuuming system newly implemented after slaughtering, 105 cattle carcasses were examined for total viable counts (TVC) at four different areas. Before steam vacuuming, mean TVC of the excision samples were comparable at the perineal area and brisket (3.0-3.1 log CFU cm-2) or the hind leg and shoulder (2.6-2.7 log CFU cm-2). Steam vacuuming reduced mean TVC by 0.9, 0.7, 0.6, and 0.4 log CFU cm-2 at the perineal area, hind leg, shoulder, and brisket, respectively. With regard to the distribution of counts, steam vacuuming increased the proportion of TVC results <3.0 log CFU cm-2 from 74.8% (62.9-87.6% at carcass areas) to 86.7% (71.4-97.1% at carcass areas). Thus, steam vacuuming after slaughtering might be useful for the reduction of contamination in designated carcass areas, but the effect must not be overestimated and decontamination treatments always must be seen part of an integral food safety system.

Use of an Electrostatic Spraying System or the Sprayed Lethality in Container Method To Deliver Antimicrobial Agents onto the Surface of Beef Subprimals To Control Shiga Toxin-Producing Escherichia coli

The efficacy of an electrostatic spraying system (ESS) and/or the sprayed lethality in container (SLIC) method to deliver antimicrobial agents onto the surface of beef subprimals to reduce levels of Shiga toxin-producing Escherichia coli (STEC) was evaluated. Beef subprimals were surface inoculated (lean side; ca. 5.8 log CFU per subprimal) with 2 mL of an eight-strain cocktail comprising single strains of rifampin-resistant (100 μg/mL) STEC (O26:H11, O45:H2, O103:H2, O104:H4, O111:H^-, O121:H19, O145:NM, and O157:H7). Next, inoculated subprimals were surface treated with lauric arginate (LAE; 1%), peroxyacetic acid (PAA; 0.025%), or cetylpyridinium chloride (CPC; 0.4%) by passing each subprimal, with the inoculated lean side facing upward, through an ESS cabinet or via SLIC. Subprimals were then vacuum packaged and stored at 4°C. One set of subprimals was sampled after an additional 2 h, 3 days, or 7 days of refrigerated storage, whereas another set was retreated via SLIC after 3 days of storage with a different one of the three antimicrobial agents (e.g., a subprimal treated with LAE on day 0 was then treated with PAA or CPE on day 3). Retreated subprimals were sampled after 2 h or 4 days of additional storage at 4°C. A single initial application of LAE, PAA, or CPC via ESS or SLIC resulted in STEC reductions of ca. 0.3 to 1.3 log CFU per subprimal after 7 days of storage. However, when subprimals were initially treated with LAE, PAA, or CPC via ESS or SLIC and then separately retreated with a different one of these antimicrobial agents via SLIC on day 3, additional STEC reductions of 0.4 to 1.0 log CFU per subprimal were observed after an additional 4 days of storage. Application of LAE, PAA, or CPC, either alone or in combination, via ESS or SLIC is effective for reducing low levels (ca. 0.3 to 1.6 log CFU) of STEC that may be naturally present on the surface of beef subprimals.

Food Safety Practices in the U.S. Meat Slaughter and Processing Industry: Changes from 2005 to 2015

Meat slaughter establishments use a multipronged approach to ensure beef and pork products are safe for human consumption. To determine the approaches most commonly used, we conducted a national survey of federally inspected meat slaughter and processing establishments (376 completed surveys, 66% response rate) in 2015. We compared the results with a survey that was conducted in 2005, albeit of potentially different establishments, by using a similar questionnaire and similar data collection methods, thus allowing for an evaluation of trends in food safety practices over time. The use of some food safety practices has increased over the 10-yr time period, whereas others remained the same or decreased. For example, the use of chemical sanitizers or hot water for food contact surfaces and tools increased from 51 to 93%. As another example, microbiological testing of raw meat after fabrication, in addition to that required by regulation, increased from 50 to 72%. However, the use of organic acid rinse on carcasses in the slaughter area remained the same, at 66% of establishments. Written policies and procedures to control the use of hazardous chemicals decreased from 75 to 65% of establishments. The survey findings can be used to characterize food safety practices and technologies in the meat slaughter and processing industry and identify areas for improvement.

Preharvest Food Safety Challenges in Beef and Dairy Production

Foods of animal origin, including beef and dairy products, are nutritious and important to global food security. However, there are important risks to human health from hazards that are introduced to beef and dairy products on the farm. Food safety hazards may be chemical, biological, or physical in nature. Considerations about protecting the safety of beef and dairy products must begin prior to harvest because some potential food safety hazards introduced at the farm (e.g., chemical residues) cannot be mitigated by subsequent postharvest food processing steps. Also, some people have preferences for consuming food that has not been through postharvest processing even though those foods may be unsafe because of microbiological hazards originating from the farm. Because of human fallibility and complex microbial ecologies, many of the preharvest hazards associated with beef and dairy products cannot entirely be eliminated, but the risk for most can be reduced through systematic interventions taken on the farm. Beef and dairy farms differ widely in production practices because of differences in natural, human, and capital resources. Therefore, the actions necessary to minimize on-farm food safety hazards must be farm-specific and they must address scientific, political, economic, and practical aspects. Notable successes in controlling and preventing on-farm hazards to food safety have occurred through a combination of voluntary and regulatory efforts.

Effectiveness of a Commercial Lactic Acid Bacteria Intervention Applied to Inhibit Shiga Toxin-Producing Escherichia coli on Refrigerated Vacuum-Aged Beef

Because of their antagonistic activity towards pathogenic and spoilage bacteria, some members of the lactic acid bacteria (LAB) have been evaluated for use as food biopreservatives. The objectives of this study were to assess the antimicrobial utility of a commercial LAB intervention against O157 and non-O157 Shiga-toxigenic E. coli (STEC) on intact beef strip loins during refrigerated vacuum aging and determine intervention efficacy as a function of mode of intervention application. Prerigor strip loins were inoculated with a cocktail (8.9 ± 0.1 log₁₀ CFU/ml) of rifampicin-resistant (100.0 μg/ml; Rif^R) O157 and non-O157 STEC. Inoculated loins were chilled to ≤4°C and treated with 8.7 ± 0.1 log₁₀ CFU/ml LAB intervention using either a pressurized tank air sprayer (conventional application) or air-assisted electrostatic sprayer (ESS). Surviving STEC were enumerated on tryptic soy agar supplemented with 100.0 μg/ml rifampicin (TSAR) to determine STEC inhibition as a function of intervention application method (conventional, ESS) and refrigerated aging period (14, 28 days). Intervention application reduced STEC by 0.4 log₁₀ CFU/cm² (p < 0.05), although application method did not impact STEC reductions (p > 0.05). Data indicate that the LAB biopreservative may assist beef safety protection when utilized within a multi-intervention beef harvest, fabrication, and aging process.

Prevalence of Escherichia coli O157:H7 in beef cattle at slaughter and beef carcasses at retail shops in Ethiopia

Background

There is paucity of information regarding the epidemiology of Escherichia coli O157: H7 in developing countries. In this study, we investigated the occurrence of E. coli O157: H7 associated with beef cattle at processing plants and at retail shops in Ethiopia.

Methods

Various samples were collected from beef cattle at slaughter/processing plants, carcass at retail shops and humans at health centers. E. coli O157: H7 was isolated, identified and characterized for antimicrobial resistance, using standard microbiological methods.

Results

At the processing plants E. coli O157: H7 was detected in 1.89% of fecal, 0.81% of intestinal mucosal swab, 0.54% of skin swab and 0.54% of carcass internal swab samples. At retail shops it was detected in 0.8% of carcass and 0.8% of cutting board swab samples, while all samples from utensils, hands from workers, and fecal and stool samples were negative. All isolates were resistant to Amoxicillin, moderately resistant to Cefoxitine and Nitrofurantoins but susceptible to other antimicrobials tested.

Conclusions

E. coli O157: H7 occurs at low prevalence in beef cattle, and the current sanitary dressing procedures in the processing plants and storage conditions in the retail shops are effective against E. coli O157: H7.

National Beef Quality Audit-2016: Transportation, mobility, and harvest-floor assessments of targeted characteristics that affect quality and value of cattle, carcasses, and by-products

The National Beef Quality Audit-2016 (NBQA-2016) was conducted to assess current transportation, mobility, and quality characteristics of U.S. fed steers and heifers. Data were collected at 17 beef processing facilities between March and November 2016. About 8,000 live cattle were evaluated for transportation and mobility, and about 25,000 carcasses were evaluated on the slaughter floor. Cattle were in transit to the slaughter facility for a mean duration of 2.7 h from a mean distance of 218.5 km using trailers with dimensions ranging from 17.84 m² to 59.09 m². Area allotted per animal averaged 1.13 m² and ranged from 0.85 m² to 2.28 m². A total of 96.8% of cattle received a mobility score of 1 (walks easily, no apparent lameness). Identification types (35.1% had multiple) were lot visual tags (61.5%), individual tags (55.0%), electronic tags (16.9%), metal-clip tags (9.2%), bar-coded tags (0.05%), wattles (0.01%), and other (2.6%). Cattle were black-hided (57.8%), Holstein (20.4%), red-hided (10.5%), yellow-hided (4.8%), gray-hided (2.9%), brown-hided (1.3%), and white-hided (1.1%). Unbranded hides were observed on 74.3% of cattle; 18.6% had brands located on the butt, 6.3% on the side, and 1.3% on the shoulder (values exceed 100% due to multiple brands). For hide-on carcasses, 37.7% displayed no mud or manure; specific locations for mud or manure were legs (40.8%), belly (33.0%), tail region (15.5%), side (6.8%), and top-line (3.9%). Cattle without horns represented 83.3% of the sample, and cattle that did have horns measured: < 2.54 cm (5.5%), 2.54 to 12.7 cm (8.3%), and > 12.7 cm (2.9%). Carcasses without bruises represented 61.1% of those sampled, whereas 28.2% had 1, 8.2% had 2, 2.1% had 3, and 0.3% had 4 bruises. Of those carcasses with a bruise, the bruise was located on the loin (29.7%), round (27.8%), chuck (16.4%), rib (14.4%), and brisket/plate/flank (11.6%). Frequencies of offal condemnations were livers (30.8%), lungs (18.2%), viscera (16.3%), hearts (11.1%), heads (2.7%), and tongues (2.0%). Compared to NBQA-2011, fewer cattle were identified for traceability, fewer were black-hided, a greater number were Holstein cattle, more with no brand and no horns, fewer without bruises, more liver, lung, and viscera condemnations, and fewer heads and tongues were condemned. The NBQA remains an influential survey for the U.S. beef industry to provide benchmarks and strategic plans for continued improvement of beef quality and consistency.

Current Interventions for Controlling Pathogenic Escherichia coli

This review examined scientific reports and articles published from 2007 to 2016 regarding the major environmental sources of pathogenic Escherichia coli and the routes by which they enter the human gastrointestinal tract. The literature describes novel techniques used to combat pathogenic E. coli transmitted to humans from livestock and agricultural products, food-contact surfaces in processing environments, and food products themselves. Although prevention before contamination is always the best "intervention," many studies aim to identify novel chemical, physical, and biological techniques that inactivate or eliminate pathogenic E. coli cells from breeding livestock, growing crops, and manufactured food products. Such intervention strategies target each stage of the food chain from the perspective of "Farm to Table food safety" and aim to manage major reservoirs of pathogenic E. coli throughout the entire process. Issues related to, and recent trends in, food production must address not only the safety of the food itself but also the safety of those who consume it. Thus, research aims to discover new "natural" antimicrobial agents and to develop "multiple hurdle technology" or other novel technologies that preserve food quality. In addition, this review examines the practical application of recent technologies from the perspective of product quality and safety. It provides comprehensive insight into intervention measures used to ensure food safety, specifically those aimed at pathogenic E. coli.

Status, Antimicrobial Mechanism, and Regulation of Natural Preservatives in Livestock Food Systems

This review discusses the status, antimicrobial mechanisms, application, and regulation of natural preservatives in livestock food systems. Conventional preservatives are synthetic chemical substances including nitrates/nitrites, sulfites, sodium benzoate, propyl gallate, and potassium sorbate. The use of artificial preservatives is being reconsidered because of concerns relating to headache, allergies, and cancer. As the demand for biopreservation in food systems has increased, new natural antimicrobial compounds of various origins are being developed, including plant-derived products (polyphenolics, essential oils, plant antimicrobial peptides (pAMPs)), animal-derived products (lysozymes, lactoperoxidase, lactoferrin, ovotransferrin, antimicrobial peptide (AMP), chitosan and others), and microbial metabolites (nisin, natamycin, pullulan, ε-polylysine, organic acid, and others). These natural preservatives act by inhibiting microbial cell walls/membranes, DNA/RNA replication and transcription, protein synthesis, and metabolism. Natural preservatives have been recognized for their safety; however, these substances can influence color, smell, and toxicity in large amounts while being effective as a food preservative. Therefore, to evaluate the safety and toxicity of natural preservatives, various trials including combinations of other substances or different food preservation systems, and capsulation have been performed. Natamycin and nisin are currently the only natural preservatives being regulated, and other natural preservatives will have to be legally regulated before their widespread use.

Effect of Exposure Time and Organic Matter on Efficacy of Antimicrobial Compounds against Shiga Toxin-Producing Escherichia coli and Salmonella

Several antimicrobial compounds are in commercial meat processing plants for pathogen control on beef carcasses. However, the efficacy of the method used is influenced by a number of factors, such as spray pressure, temperature, type of chemical and concentration, exposure time, method of application, equipment design, and the stage in the process that the method is applied. The objective of this study was to evaluate effectiveness of time of exposure of various antimicrobial compounds against nine strains of Shiga toxin-producing Escherichia coli (STEC) and four strains of Salmonella in aqueous antimicrobial solutions with and without organic matter. Non-O157 STEC, STEC O157:H7, and Salmonella were exposed to the following aqueous antimicrobial solutions with or without beef purge for 15, 30, 60, 120, 300, 600, and 1,800 s: (i) 2.5% lactic acid, (ii) 4.0% lactic acid, (iii) 2.5% Beefxide, (iv) 1% Aftec 3000, (v) 200 ppm of peracetic acid, (vi) 300 ppm of hypobromous acid, and (vii) water as a control. In general, increasing exposure time to antimicrobial compounds significantly (P ≤ 0.05) increased the effectiveness against pathogens tested. In aqueous antimicrobial solutions without organic matter, both peracetic acid and hypobromous acid were the most effective in inactivating populations of STEC and Salmonella, providing at least 5.0-log reductions with exposure for 15 s. However, in antimicrobials containing organic matter, 4.0% lactic acid was the most effective compound in reducing levels of STEC and Salmonella, providing 2- to 3-log reductions with exposure for 15 s. The results of this study indicated that organic matter and exposure time influenced the efficacy of antimicrobial compounds against pathogens, especially with oxidizer compounds. These factors should be considered when choosing an antimicrobial compound for an intervention.