Occurrence, genotypes and antimicrobial susceptibility of Salmonella collected from the broiler production chain within an integrated poultry company

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.

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.

Prevalence and transmission of extensively drug-resistant Salmonella enterica serovar Kentucky ST198 based on whole-genome sequence in an intensive laying hen farm in Jiangsu, China

Salmonella, which is widely distributed in nature, is an important zoonotic pathogen affecting humans, livestock, and other animals. Salmonella infection not only hinders the development of livestock and poultry-related industries but also poses a great threat to human health. In this study, we collected 1,537 samples including weak chicks, dead embryos, fecal samples and environmental samples from 2020 to 2023 (for a period of 1 to 2 months per year) to keep a long-term monitor the prevalence of Salmonella in an intensive laying hen farm, 105 Salmonella strains were isolated with an isolation rate of 6.83% (105/1,537). It revealed a significant decrease in prevalence rates of Salmonella over time (P < 0.001). Before 2020, the predominant serotype was S. Enteritidis. S. Kentucky was first detected in November 2020 and its proportion was gradually found to exceed that of S. Enteritidis since then. S. Kentucky isolates were distributed in various links of the four regions in the poultry farm. A total of 55 S. Kentucky strains, were assigned to ST198 based on whole genome sequencing. Among them, 54 strains were resistant to 12 to 16 antibiotics, indicating that they were extensively drug-resistant (XDR). Seventeen antimicrobial resistance genes were detected in 55 S. Kentucky isolates. For most of these isolates, antibiotic resistance phenotypes were concordant with their genotypes. All S. Kentucky strains isolated from this farm in 2020 to 2023 showed a high similarity based on their core-genome SNP-based phylogeny. The traceability analysis revealed that S. Kentucky was introduced to the farm through newly purchased flocks. The long-term existence of XDR S. Kentucky ST198 poses a substantial risk because of the multiage management and circulation of workers in this poultry farm. Thus, this study is the first to report extensively drug-resistant S. Kentucky ST198 detected in this intensive poultry farm in China.

Prevalence and characterization of non-typhoidal Salmonella in egg from grading and packing plants in Korea

Egg washing guidelines vary across countries; however, since 2020, Korea has required that all eggs produced from farms with more than 10,000 laying hens must be washed through egg grading and packing (GP) plant. This study investigated the prevalence and characterization of non-typhoidal Salmonella in eggs after washing at GP plants. In total, 16,800 eggs were collected from 60 egg GP plants located inside commercial layer farms, and 840 pooled eggshell and egg contents were tested for Salmonella, respectively. Of the 60 GP plants tested, 11 (18.3%) and 12 (20.0%) plants were positive for Salmonella spp. In the eggshells and egg contents, respectively. In particular, High Salmonella prevalence in the eggshells and egg contents occurred most often in farms with laying hens older than 80 weeks (33.3% and 40.0%, respectively). However, among 840 pooled eggshells and egg content samples, only 19 (2.3%) of each sample type were positive only for non-typhoidal Salmonella spp. The most common Salmonella serovar in both eggshells and egg contents was S. Infantis, which was found in five (8.3%) of 60 GP plants for both samples types. The other Salmonella serovars detected in eggshells were S. Bareilly (5.0%), S. Agona (3.3%), S. Enteritidis (1.7%), and S. Montevideo (1.7%), whereas those detected in egg contents were S. Enteritidis (5.0%), S. Agona (3.3%), S. Newport (3.3%), S. Senftenberg (3.3%), and S. Derby (1.7%). Of the 19 virulence genes tested, 14 genes were detected in all Salmonella. Interestingly, the spvB gene was detected only in S. Enteritidis, and the sefC gene was detected only in S. Enteritidis and S. Senftenberg. Moreover, all S. Infantis isolates showed multidrug resistance (MDR) against five or more classes, and the other serovars only showed MDR against three to four classes or no MDR. These results suggest that comprehensive surveillance and advanced management approaches for egg GP plants are required to minimize egg contamination with non-typhoidal Salmonella.

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.

The Metabolic Pathway of Bile Secretion Is Vulnerable to Salmonella enterica Exposure in Porcine Intestinal Epithelial Cells

Pigs can be colonized with Salmonella enterica and become established carriers. However, the mechanisms of the host's response to Salmonella enterica infection are largely unclear. This study was constructed with the Salmonella enterica infection model in vitro using porcine intestinal epithelial cells (IPEC-J2). Transcriptome profiling of IPEC-J2 cells was carried out to characterize the effect of Salmonella enterica infection and lipopolysaccharide (LPS) treatment, in which LPS-induced inflammation was a positive control. At first, Salmonella enterica infection increased the cell apoptosis rate and induced an inflammation response in IPEC-J2. Then, the up-regulated genes were enriched in metabolic pathways, such as those for bile secretion and mineral absorption, while down-regulated genes were enriched in immune-related pathways, such as the Toll-like receptor signaling and p53 signaling pathways. Moreover, we found 368 up-regulated genes and 101 down-regulated genes in common. Then, an integrative analysis of the transcriptomic profile under Salmonella enterica infection and LPS treatment was conducted, and eight up-regulated genes and one down-regulated gene were detected. Among them, AQP8 is one critical gene of the bile secretion pathway, and its mRNA and protein expression were increased significantly under Salmonella enterica infection and LPS treatment. Thus, the AQP8 gene and bile secretion pathway may be important in IPEC-J2 cells under Salmonella enterica infection or LPS treatment.

Presence of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli in Food-Producing and Companion Animals and Wildlife on Small-Holder Farms of Floreana Island, Galápagos Islands

Background: Antimicrobial resistance (AR) has led to increasing human and animal morbidity and mortality and negative consequences for the environment. AR among Escherichia coli (EC) is on the rise, with serious concerns about extended-spectrum β-lactamase-producing E. coli (ESBL-EC). In the Galápagos Islands, where antimicrobials are available without a prescription, growing demands for food production can drive antimicrobial use. Food producing animals are at the interface of wildlife and environmental health on the smallest human-inhabited Galápagos Island, Floreana. We sought to determine if ESBL-EC were present in Floreana Island farm animal species and nearby wildlife and the relatedness of ESBL-EC isolates identified. Materials and Methods: During July 4-5, 2022, we visited 8 multispecies farms, representing 75% of food-producing animal production on Floreana, and collected 227 fecal samples from farm animals and wildlife. Each sample was plated on MacConkey agar supplemented with cefotaxime (4 μg/mL). Results: ESBL-EC was isolated from 20 (9%) fecal samples collected from pigs (N = 10), chickens (N = 6), wildlife (N = 3), and dog (N = 1). All ESBL-EC isolates were from samples taken at three (38%) of the eight farms. Fifteen (75%) of the ESBL-EC isolates were from a single farm. All ESBL-EC isolates were multidrug resistant. The most prevalent ESBL genes belonged to the blaCTX-M group. Among the typeable isolates from the farm with the largest proportion of ESBL-EC isolates (N = 14), we observed nine unique pulsed-field gel electrophoresis (PFGE) patterns, with identical patterns present across pig and chicken isolates. PFGE patterns in the three farms with ESBL-EC isolates were different. Conclusions: These results lend support for future routine AR monitoring activities at the livestock-wildlife interface in Galápagos to characterize potential interspecies transmission of AR bacteria and AR genes in this unique protected ecosystem, and the related human, animal, and environmental health impacts, and to formulate interventions to reduce AR spread in this setting.

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.

Chromatin Accessibility and Transcriptional Landscape during Inhibition of Salmonella enterica by Lactobacillus reuteri in IPEC-J2 Cells

Lactobacillus reuteri is a probiotic with bacteriostatic effects, which can effectively inhibit the activity of pathogens. However, the molecular mechanism underlying the inhibition of pathogens by L. reuteri in intestinal cells remains unclear. Using the porcine intestinal cell line IPEC-J2 as a model, we combined RNA-seq and ATAC-seq methods to delineate the porcine genome-wide changes in biological processes and chromatin accessibility in IPEC-J2 cells stimulated by Salmonella enterica BNCC186354, as well as L. reuteri ATCC 53608. Overall, we found that many porcine transcripts were altered after S. enterica BNCC186354 treatment, while L. reuteri ATCC 53608 treatment partially restored this alteration, such as salmonella infection and PI3K/AKT and MAPK pathways. Combined analysis of these two datasets revealed that 26 genes with similar trends overlapped between gene expression and chromatin accessibility. In addition, we identified potential host functional transcription factors (TFs), such as GATA1, TAL1, TBP, RUNX1, Gmeb1, Gfi1b, RARA, and RXRG, in IPEC-J2 cells that might play a critical role and are targeted by L. reuteri ATCC 53608. Moreover, we verified that PI3K/AKT, MAPK, and apoptosis pathways are potentially regulated by S. enterica BNCC186354 but restored by L. reuteri ATCC 53608. The PI3K/AKT pathway was activated by L. reuteri ATCC 53608, thereby potentially inhibiting S. enterica BNCC186354 infection. In conclusion, our data provide new insights into the expression pattern of functional genes and the epigenetic alterations in IPEC-J2 cells underlying the bacteriostatic action of L. reuteri ATCC 53608.

Mobile genetic elements drive the multidrug resistance and spread of Salmonella serotypes along a poultry meat production line

The presence of mobile genetic elements in Salmonella isolated from a chicken farm constitutes a potential risk for the appearance of emerging bacteria present in the food industry. These elements contribute to increased pathogenicity and antimicrobial resistance through genes that are related to the formation of biofilms and resistance genes contained in plasmids, integrons, and transposons. One hundred and thirty-three Salmonella isolates from different stages of the production line, such as feed manufacturing, hatchery, broiler farm, poultry farm, and slaughterhouse, were identified, serotyped and sequenced. The most predominant serotype was Salmonella Infantis. Phylogenetic analyses demonstrated that the diversity and spread of strains in the pipeline are serotype-independent, and that isolates belonging to the same serotype are very closely related genetically. On the other hand, Salmonella Infantis isolates carried the pESI IncFIB plasmid harboring a wide variety of resistance genes, all linked to mobile genetic elements, and among carriers of these plasmids, the antibiograms showed differences in resistance profiles and this linked to a variety in plasmid structure, similarly observed in the diversity of Salmonella Heidelberg isolates carrying the IncI1-Iα plasmid. Mobile genetic elements encoding resistance and virulence genes also contributed to the differences in gene content. Antibiotic resistance genotypes were matched closely by the resistance phenotypes, with high frequency of tetracycline, aminoglycosides, and cephalosporins resistance. In conclusion, the contamination in the poultry industry is described throughout the entire production line, with mobile genetic elements leading to multi-drug resistant bacteria, thus promoting survival when challenged with various antimicrobial compounds.

High levels of antimicrobial resistance in Escherichia coli and Salmonella from poultry in Ecuador

Objective

To describe antimicrobial resistance profiles of Escherichia coli and Salmonella spp. isolated from chicken carcasses and the antimicrobials commonly used in animals in Ecuador and provide information on antimicrobial resistance patterns for implementing evidence-based corrective measures.

Methods

Meat samples were collected from chicken carcasses in 199 slaughterhouses across Ecuador as part of a national pilot study for monitoring antimicrobial resistance in agricultural sources in 2019. Samples were tested for E. coli and Salmonella spp. Sensitivity to 10 critically important and three highly important antimicrobials (from a human health perspective) was assessed. The country report submitted to the World Organization for Animal Health was accessed to extract the quantity of antimicrobials produced or imported for use in animals.

Results

Of 383 samples, E. coli was isolated from 148 (39%) and Salmonella spp. from 20 (5%) samples. Ninety percent of the isolates were resistant to at least one critically important antimicrobial. Resistance was highest to erythromycin (E. coli 76%; Salmonella spp. 85%) and tetracycline (E. coli 71%; Salmonella spp. 90%). Critically or highly important antimicrobials (colistin, tetracycline, trimethoprim/sulfamethoxazole) formed the bulk (87%) of antimicrobials used in animals as per the World Organization for Animal Health report.

Conclusions

High prevalence of antimicrobial resistance in poultry in Ecuador calls for the development of guidelines and regulations on the use of antimicrobials and for engagement with livestock producers. The existing surveillance system needs to be strengthened to improve the monitoring of antimicrobial use and evolving resistance patterns.

Comprehensive profiling of serotypes, antimicrobial resistance and virulence of Salmonella isolates from food animals in China, 2015-2021

Introduction

Salmonella is a ubiquitous foodborne pathogen and mainly transmitted to human farm-to-fork chain through contaminated foods of animal origin.

Methods

In this study, we investigated the serotypes, antimicrobial resistance and virulence of Salmonella from China.

Results

A total of 617 Salmonella isolates were collected from 4 major food animal species across 23 provi nces in China from 2015-2021. Highest Salmonella prevalence were observed in Guangdong (44.4%) and Sandong (23.7%). Chickens (43.0%) was shown to be the major source of Salmonella contamination, followed by pigs (34.5%) and ducks (18.5%). The number of Salmonella increased significantly from 5.51% to 27.23% during 2015-2020. S. Derby (17.3%), S. Enteritidis (13.1%) and S. Typhimurium (11.4%) were the most common serotypes among 41 serotypes identifiedin this study. Antibiotic susceptibility testing showing that the majority of the Salmonella isolates were resistant to neomycin (99.7%), tetracycline (98.1%), ampicillin (97.4%), sulfadiazine/trimethoprim (97.1%), nalidixic acid (89.1%), doxycycline (83.1%), ceftria xone (70.3%), spectinomycin (67.7%), florfenicol (60.0%), cefotaxime (52.0%) and lomefloxacin (59.8%). The rates of resistance to multiple antibiotics in S. Derby and S.Typhimurium were higher than that in S. Enteritidis. However, the rate of resistance to fosfomycin were observed from higher to lower by S. Derby, S. Enteritidis, and S. Typhimurium. Biofilm formation ability analysis found that 88.49%of the Salmonella were able to produce biofilms, of which 236 Salmonella isolates were strong biofilm producer. Among the 26 types of antibiotics resistance genes (ARGs) were identified in this study, 4 ARGs (tetB,sul2,aadA2, and aph(3')-IIa) were highly prevalent. In addition, 5 β-lactam resistance genes (bla _TEM, bla _SHV, bla _CMY-2, bla _CTX-M, and bla _OXA) and 7 quinolone resistance genes (oqxA, oqxB, qnrB, qnrC, qnrD, qnrS, and qeqA) were detected among these isolates. 12 out of 17 virulence genes selected in this study were commonly presented in the chromosomes of tested isolate, with a detection rate of over 80%, including misL, spiA, stn, pagC, iroN, fim, msgA, sopB, prgH, sitC, ttrC, spaN.

Discussion

This study provided a systematical updating on surveillance on prevalence of Salmonella from food animals in China, shedding the light on continued vigilance for Salmonella in food animals.

Comprehensive Assessment of Subtyping Methods for Improved Surveillance of Foodborne Salmonella

High-resolution and efficient typing for the bacterial pathogen is essential for tracking the sources, detecting or diagnosing variants, and conducting a risk assessment. However, a systematic in-field investigation of Salmonella along the food chain has not been documented. This study assessed 12 typing methods, such as antimicrobial-resistance (AMR) gene profile typing, Core Genome Multilocus Sequence Typing (cgMLST), and CRISPR multi-virulence locus sequence typing (CRISPR-MVLST), to evaluate their effectiveness for use in routine monitoring of foodborne Salmonella transmission along the poultry production chain. During 2015-16, a total of 1,064 samples were collected from poultry production chain, starting from breeding farms and slaughterhouses to the markets of Zhejiang province in China. A total of 61 consecutive unique Salmonella isolates recovered from these samples were selected for genome sequencing and further comparative typing analysis. Traditional typing methods, including serotyping, AMR phenotype-based typing, as well as modern genotyping approaches, were evaluated and compared by their discrimination index (DI). The results showed that the serotyping method identified nine serovars. The gold standard cgMLST method indicated only 18 different types (DI = 0.8541), while the CRISPR-MVLST method detected 30 types (DI = 0.9628), with a higher DI than all examined medium-resolution WGS-based genotyping methods. We demonstrate that the CRISPR-MVLST might be used as a tool with high discriminatory power, comparable ease of use, ability of tracking the source of Salmonella strains along the food chain and indication of genetic features especially virulence genes. The available methods with different purposes and laboratory expertise were also illustrated to assist in rational implementation. IMPORTANCE In public health field, high-resolution and efficient typing of the bacterial pathogen is essential, considering source-tracking and risk assessment are fundamental issues. Currently, there are no recommendations for applying molecular characterization methods for Salmonella along the food chain, and a systematic in-field investigation comparing subtyping methods in the context of routine surveillance was partially addressed. Using 1,064 samples along a poultry production chain with a considerable level of Salmonella contamination, we collected representative isolates for genome sequencing and comparative analysis by using 12 typing techniques, particularly with whole-genome sequence (WGS) based methods and a recently invented CRISPR multi-virulence locus sequence typing (CRISPR-MVLST) method. CRISPR-MVLST is identified as a tool with higher discriminatory power compared with medium-resolution WGS-based typing methods, comparable ease of use and proven ability of tracking Salmonella isolates. Besides, we also offer recommendations for rational choice of subtyping methods to assist in better implementation schemes.

A PMAxxTM qPCR Assay Reveals That Dietary Administration of the Microalgae Tetraselmis chuii Does Not Affect Salmonella Infantis Caecal Content in Early-Treated Broiler Chickens

Salmonella enterica serovars cause infections in humans. S. enterica subsp. enterica serovar Infantis is considered relevant and is commonly reported in poultry products. Evaluating innovative approaches for resisting colonization in animals could contribute to the goal of reducing potential human infections. Microalgae represent a source of molecules associated with performance and health improvement in chickens. Tetraselmis chuii synthesizes fermentable polysaccharides as part of their cell wall content; these sugars are known for influencing caecal bacterial diversity. We hypothesized if its dietary administration could exert a positive effect on caecal microbiota in favor of a reduced S. Infantis load. A total of 72 one-day-old broiler chickens (COBB 500) were randomly allocated into three groups: a control, a group infected with bacteria (day 4), and a group challenged with S. Infantis but fed a microalgae-based diet. Caecal samples (n = 8) were collected two days post-infection. A PMAxxTM-based qPCR approach was developed to assess differences regarding bacterial viable load between groups. The inclusion of the microalga did not modify S. Infantis content, although the assay proved to be efficient, sensitive, and repeatable. The utilized scheme could serve as a foundation for developing novel PCR-based methodologies for estimating Salmonella colonization.

First report of multidrug-resistant Salmonella Infantis in broiler litter in Tolima, Colombia

Background and Aim:

Salmonella has been identified as one of the most widely distributed zoonotic pathogens in broiler litter. Multidrug-resistant strains have been isolated from salmonellosis outbreaks, compromising the success of their treatment. This study aimed to isolate and identify Salmonella spp. serovars in healthy broiler litter in Tolima (Colombia), determine their resistance to different antimicrobials, and detect genes associated with b-lactam resistance that could be useful to control Salmonella spp. in poultry.

Materials and Methods:

In total, 45 broiler litter samples were collected. Salmonella spp. was isolated and identified using selective and differential culture media and biochemical tests. Molecular confirmation of the pathogen was performed with the invA gene and serotyping by Kauffman–White scheme. Antimicrobial susceptibility to 15 antibiotics was determined by Kirby–Bauer method. In cefotaxime-resistant strains, blaCTX-M-F, blaCTX-M-1, blaCMY, and blaTEM genes were evaluated by polymerase chain reaction (PCR).

Results:

In total, 817 presumptive strains were obtained from xylose lysine deoxycholate and SalmonellaShigella agars and subcultured on xylose-lysine-tergitol 4 and MacConkey agars, from which 150 strains were isolated; 29 of these strains were presumptive for Salmonella spp. after performing biochemical tests and 16 were confirmed by PCR as Salmonella Infantis (15) and Gallinarum (1). All strains were found to be multiresistant to antibiotics, showing three different profiles and isolates resistant to cefotaxime, and the blaCTX-M gene was detected.

Conclusion:

This is the first study to isolate S. Infantis from broiler litter in Colombia. All isolates exhibited resistance to the evaluated antimicrobials, suggesting the misuse of antimicrobials in small- and medium-sized poultry farms. The presence of Salmonella enterica serovar Infantis is a public health problem. Thus, regular monitoring of poultry litter is recommended, as these bacteria can be transmitted to humans through animal products or contaminated environments.

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.

Investigating the dynamics of Salmonella contamination in integrated poultry companies using a whole genome sequencing approach

The study of non-typhoid Salmonella in broiler integrations has been limited by the resolution of typing techniques. Although serotyping of Salmonella isolates is used as a traditional approach, it is not of enough resolution to clearly understand the dynamics of this pathogen within poultry companies. The aim of this research was to investigate the epidemiology and population dynamics of Salmonella serotypes in 2 poultry integrations using a whole genome sequencing approach. Two hundred and forty-three Salmonella isolates recovered from the broiler production chain of 2 integrated poultry companies were whole genome sequenced and analyzed with dedicated databases and bioinformatic software. The analyses of sequences revealed that S. Infantis was the most frequent serotype (82.3%). Most isolates showed a potential for resistance against medically important antibiotics and disinfectants. Furthermore, 97.5% of isolates harbored the pESI-like mega plasmid, that plays an important role in the global dissemination of AMR. SNP tree analysis showed that there were clones that are niche-specific while other ones were distributed throughout the broiler production chains. In this study, we demonstrated the potential of whole genome sequencing analysis for a comprehensive understanding of Salmonella distribution in integrated poultry companies. Data obtained with these techniques allow determination of the presence of genetic factors that play an important role in the environmental fitness and pathogenicity of Salmonella.

Efficacy of Multivalent, Cochleate-Based Vaccine against Salmonella Infantis, S. Enteritidis and S. Typhimurium in Laying Hens

Salmonella enterica is an important foodborne pathogen. Commercial poultry are the main reservoirs of Salmonella enterica, leading to the contamination of food and outbreaks in humans. The vaccination of chickens is one of the most important strategies to reduce the number of Salmonella in poultry farms. Unfortunately, commercial vaccines have not been fully effective in controlling the spread and do not contain all the Salmonella serovars that circulate on farms. In this study, we evaluate a new, cochleate-based, trivalent injectable vaccine against S. Enteritidis, S. Typhimurium and S. Infantis, describing the vaccine security, capacity to induce specific anti-Salmonella serovar IgY and the gene expression of immune markers related to CD4 and CD8 T-cell-mediated immunity. Efficacy was evaluated through oral challenges performed separately for each Salmonella serotype. The efficacy and safety of the trivalent vaccine was proven under controlled conditions. The vaccine has no local or systemic reactions or adverse effects on poultry performance related to the vaccine. The vaccine provided significantly increased serum IgY titer levels, significantly reduced Salmonella CFU/g present in the cecum and an increased CD4+/CD8+ ratio in vaccinated animals when challenged with S. Infantis, S. Enteritidis and S. Typhimurium. These results indicate that this new trivalent vaccine does not generate adverse effects in poultry and produces an increase in neutralizing antibodies against the three Salmonella serovars.

Infection dynamics of Salmonella Infantis strains displaying different genetic backgrounds - with or without pESI-like plasmid - vary considerably

Food-borne infections with Salmonella are among the most common causes of human diseases worldwide, and infections with the serovar Infantis are becoming increasingly important. So far, diverse phenotypes and genotypes of S. Infantis have been reported. Therefore, the present study aimed to investigate the infection dynamics of two different S. Infantis strains in broilers. For this purpose, 15 birds were infected on day 2 of life with 108 CFU/ml of a pESI+ or a pESI- S. Infantis strain, respectively. Ten uninfected birds served as in-contact birds to monitor transmission. In both groups, an increase of infection was observed from 7 days of age onwards, reaching its peak at 28 days. However, the pESI+ strain proved significantly more virulent being re-isolated from most cloacal swabs and organs by direct plating. In contrast, the pESI- strain could be re-isolated from cloacal swabs and caeca only when enrichment was applied. Although the excretion of this strain was limited, the transmission level to in-contact birds was similar to the pESI+ strain. Differences in infection dynamics were also reflected in the antibody response: whereas the pESI+ strain provoked a significant increase in antibodies, antibody levels following infection with the pESI- strain remained in the range of negative control birds. The actual findings provide for the first time evidence of S. Infantis strain-specific infectivity in broilers and confirm previous observations in the field regarding differences in persistence on farms and resistance against disinfectants.

Multidrug-Resistant and Extended-Spectrum β-Lactamase-Producing Salmonella enterica Serotype Heidelberg Is Widespread in a Poultry Processing Facility in Southern Brazil

ABSTRACT

This study was conducted to characterize the distribution of Salmonella isolates in a poultry processing facility and to identify their antibiotic resistance profiles. Salmonella enterica was detected in 146 samples (66.7%), and 125 isolates were identified as Salmonella Heidelberg (n = 123), Salmonella Abony (n = 1), and Salmonella O:4,5 (n = 1). Salmonella Heidelberg isolates were subjected to XbaI macrorestriction analysis and pulsed-field gel electrophoresis. The 66 pulsotypes obtained were grouped into four major clusters, indicating cross-contamination and persistence of this serotype in the processing facility. Selected S. enterica isolates were characterized by their antibiotic resistance, and most (n = 122, 97.6%) were multidrug resistant. Resistance to third-generation cephalosporins ceftazidime (84 isolates, 67.2%) and cefotaxime and ceftriaxone (91 isolates, 72.8%) was particularly prevalent. Production of extended-spectrum β-lactamases (ESBL) was identified in 24 isolates (19.2%), and ESBL-producing isolates were resistant to at least eight antibiotics. This study revealed the high prevalence of Salmonella Heidelberg in the poultry chain, providing insight into the ecology of this pathogen in this facility. The high prevalence of multidrug-resistant S. enterica is a concern due to the potential consequences for public health.

HIGHLIGHTS

Molecular characterization of Salmonella spp. and Listeria monocytogenes strains from biofilms in cattle and poultry slaughterhouses located in the federal District and State of Goiás, Brazil

Listeria monocytogenes and Salmonella spp. are considered important foodborne pathogens that are commonly associated with foods of animal origin. The aim of this study was to perform molecular characterization of L. monocytogenes and Salmonella spp. isolated from biofilms of cattle and poultry slaughterhouses located in the Federal District and State of Goiás, Brazil. Fourteen L. monocytogenes isolates and one Salmonella sp. were detected in poultry slaughterhouses. No isolates were detected in cattle slaughterhouses. All L. monocytogenes isolates belonged to lineage II, and 11 different pulsotypes were detected. Pulsed-field gel electrophoresis analysis revealed the dissemination of two strains within one plant, in addition to the regional dissemination of one of them. The Salmonella isolate was identified via whole genome sequencing as Salmonella enterica serovar Minnesota ST548. In the sequence analysis, no premature stop codons were detected in the inlA gene of Listeria. All isolates demonstrated the ability to adhere to Caco-2 cells, while 50% were capable of invading them. Antimicrobial resistance was detected in 57.1% of the L. monocytogenes isolates, and resistance to sulfonamide was the most common feature. The tetC, ermB, and tetM genes were detected, and four isolates were classified as multidrug-resistant. Salmonella sp. was resistant to nine antimicrobials and was classified as multidrug-resistant. Resistance genes qnrB19, blaCMY-2, aac(6')-Iaa, sul2, and tetA, and a mutation in the parC gene were detected. The majority (78.5%) of the L. monocytogenes isolates were capable of forming biofilms after incubation at 37°C for 24 h, and 64.3% were capable of forming biofilms after incubation at 12°C for 168 h. There was no statistical difference in the biofilm-forming capacity under the different evaluated conditions. Salmonella sp. was capable of forming biofilms at both tested temperatures. Biofilm characterization was confirmed by collecting the samples consistently, at the same sampling points, and by assessing biofilm formation in vitro. These results highlight the potential risk of cross-contamination in poultry slaughterhouses and the importance of surveillance and pathogen control maintenance programs within the meat production industry.

Systematic Review: Nontyphoidal Salmonella in Food from Latin America

In Latin America, nontyphoidal Salmonella (NTS) is one of the most important etiological agents of foodborne infections; it can survive in soil, water, and food even after processing. Here, we aimed to perform a systematic review by collecting data on the prevalence, serotypes, and antimicrobial resistance (AMR) of NTS isolated from different food products in Latin America, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Out of 1766 studies screened, 244 reports from 13 Latin American countries were eligible. Among these, 182 reported NTS prevalence, 87 reported NTS serotypes, and 83 reported serotypes with AMR patterns. The NTS prevalence ranged from 0.005% to 93.3%, regardless of country and food. Meat showed the highest NTS prevalence. Enteritidis, Typhimurium, and Derby were the most frequently observed serotypes in different food products. The serotypes Enteritidis, Typhimurium, and Infantis, isolated from animal products, showed the highest AMR rate. The presence of NTS in fruits and vegetables, which are generally consumed raw or as ready-to-eat food, indicates a high risk of salmonellosis from consuming these foods. Thus, the reduction of this pathogen in the food chain requires a One Health approach, involving good agricultural and manufacturing practices, low antimicrobial use, and proper waste management.

Prevalence of Salmonella and Antimicrobial Resistance in Isolates from Food Animals - Six PLADs, China, 2019

What is already known about this topic?

Salmonella causes acute and chronic diseases in food animals, and infected food animals are one of the most important source of human infection.

What does this report contribute?

The prevalence of Salmonella was 10.5% in chicken samples, 24.4% in pig, 23.3% in duck, and 29.4% in milk. Salmonella isolates were highly resistant to ampicillin (59.60%).

What are the implications for public health practices?

Data on Salmonella infections among food animals in China could help identify sources and factors related to the spread of Salmonella in food animals and food production chains.

Whole-Genome Sequencing Reveals the Presence of the blaCTX-M-65 Gene in Extended-Spectrum β-Lactamase-Producing and Multi-Drug-Resistant Clones of Salmonella Serovar Infantis Isolated from Broiler Chicken Environments in the Galapagos Islands

Salmonella Infantis, a common contaminant of poultry products, is known to harbor mobile genetic elements that confer multi-drug resistance (MDR) and have been detected in many continents. Here, we report four MDR S. Infantis strains recovered from poultry house environments in Santa Cruz Island of the Galapagos showing extended-spectrum β-lactamase (ESBL) resistance and reduced fluoroquinolone susceptibility. Whole-genome sequencing (WGS) revealed the presence of the ESBL-conferring bla_CTX-M-65 gene in an IncFIB-like plasmid in three S. Infantis isolates. Multi-locus sequence typing (MLST) and single nucleotide variant/polymorphism (SNP) SNVPhyl analysis showed that the S. Infantis isolates belong to sequence type ST32, likely share a common ancestor, and are closely related (1–3 SNP difference) to bla_CTX-M-65-containing clinical and veterinary S. Infantis isolates from the United States and Latin America. Furthermore, phylogenetic analysis of SNPs following core-genome alignment (i.e., ParSNP) inferred close relatedness between the S. Infantis isolates from Galapagos and the United States. Prophage typing confirmed the close relationship among the Galapagos S. Infantis and was useful in distinguishing them from the United States isolates. This is the first report of MDR bla_CTX-M-65-containing S. Infantis in the Galapagos Islands and highlights the need for increased monitoring and surveillance programs to determine prevalence, sources, and reservoirs of MDR pathogens.

Salmonella prevalence and persistence in industrialized poultry slaughterhouses

Salmonella contamination sources and transmission routes were studied in 5 Belgian poultry slaughterhouses. Samples from the slaughter and cutting line after cleaning and disinfection were collected, as well as neck skin samples and thighs during slaughter of the first flock. In total, 680 swab and water samples were taken from the slaughter line before slaughter. In all slaughterhouses, Salmonella was notwithstanding cleaning and disinfection still isolated from the slaughter line before start of activities. The prevalence of Salmonella in the plucking area was 10.4% (38/365) (hanging area: 5.0%, scalding tank: 5.8%, plucking machine: 17.0%); in the evisceration room, 1.5% (2/138); and in the cutting area, 2.0% (3/149). No Salmonella (0/28) was found in samples from the chilling line. On neck skin samples taken from the various lines, Salmonella prevalence was 16.1% (48/299) after plucking, 16.0% (48/300) after evisceration, 23.3% (70/300) after chilling; on thighs, prevalence was 10.0% (24/240). Nine Salmonella serotypes were identified of which Salmonella Infantis was the most common serovar (53.8%), especially in slaughterhouse A. Two contamination causes were identified; first, although all flocks had an official Salmonella negative status, this was in one case incorrect and led to an enormous contamination of the neck skins of the flock and the slaughterline (i.e., cooling water). Second, molecular typing revealed cross-contamination from flocks slaughtered 1 d before sampling. Salmonella was apparently not always eliminated by the cleaning and disinfection process and able to contaminate the carcasses of the first slaughtered flock. In conclusion, the results of this study provided practical insights for poultry production to further improve their Salmonella control, for example, Salmonella status determination closer to the slaughter date, to adapt cleaning and disinfection protocols especially for critical machinery and better hygienic designed equipment.

Multidrug-Resistant Salmonella enterica Isolated in Paca (Cuniculus paca) Carcasses from the Belen Market, Iquitos, Perú

The consumption of wildlife meat is traditionally accepted in the Peruvian Amazon; however, little is known about the pathogens present in this type of food. One of the most frequently consumed species is a rodent, the paca (Cuniculus paca) or "majaz" in the Peruvian language. The objective of this study was to determine the presence of Salmonella enterica and its antimicrobial resistance profile in paca carcasses sold in the Belen Market of Iquitos-Peru. An observational, descriptive, cross-sectional study was carried out. Fresh and smoked paca carcasses (72 samples) were evaluated during the low-rain period (July 2019) in the traditional market of Iquitos, in the Amazonian Region. Meat samples were swabbed, and International Standards Organization (ISO) 6579-1: 2017 protocol was followed to Salmonella isolation. Antimicrobial susceptibility analysis was performed by the disk diffusion method. In addition, serotyping was performed by using the Kauffmann-White scheme. A total of 25 strains of S. enterica were isolated in the paca carcasses, mainly in fresh carcasses (48.6%). The serovars isolated were Agona (45.8%), Infantis (41.7%), Wangata (8.3%), and Javiana (4.2%). A considerable number of the isolated strains were multidrug resistant (40%). The highest prevalence of resistance corresponded to trimethoprim-sulfamethoxazole (64%) followed by nitrofurantoin (44%), chloramphenicol (40%), cefotaxime (40%), and nalidixic acid (40%). Ten strains isolated (40%) were identified as producers of extended spectrum beta lactamases, all in S. enterica serovar Infantis. This study describes the presence of Salmonella Infantis with multidrug resistance profiles in wildlife meat carcasses, making the consumption of this type of products a risk factor for the development of foodborne diseases in the Amazon region. Institutional Review Board: Approval Resolution of Thesis Project: N° 024-DACMVZ-DAFCVB-U.CIENTÍFICA-2019.

Genomic Epidemiology of Salmonella Infantis in Ecuador: From Poultry Farms to Human Infections

Salmonella enterica is one of the most important foodborne pathogens around the world. In the last years, S. enterica serovar Infantis has become an important emerging pathogen in many countries, often as multidrug resistant clones. To understand the importance of S. enterica in the broiler industry in Ecuador, we performed a study based on phenotypic and WGS data of isolates from poultry farms, chicken carcasses and humans. We showed a high prevalence of S. enterica in poultry farms (41.4%) and chicken carcasses (55.5%), but a low prevalence (1.98%) in human samples. S. Infantis was shown to be the most prevalent serovar with a 98.2, 97.8, and 50% in farms, foods, and humans, respectively, presenting multidrug resistant patterns. All sequenced S. Infantis isolates belonged to ST32. For the first time, a pESI-related megaplasmid was identified in Ecuadorian samples. This plasmid contains genes of antimicrobial resistance, virulence factors, and environmental stress tolerance. Genomic analysis showed a low divergence of S. Infantis strains in the three analyzed components. The results from this study provide important information about genetic elements that may help understand the molecular epidemiology of S. Infantis in Ecuador.

Phenotypic and Genotypic Characterization of Virulence Factors and Susceptibility to Antibiotics in Salmonella Infantis Strains Isolated from Chicken Meat: First Findings in Chile

Simple Summary

Salmonella Infantis (S. Infantis) is a zoonotic pathogen that causes gastroenteritis in humans and animals, with poultry being its main reservoir. This pathogen has emerged over the last few decades in different countries, causing outbreaks in humans subsequent to foodborne transmission. It is important to be able to characterize this pathogen in order to establish control measures in the poultry industry. In this study, we investigated the presence of virulence genes, biofilm formation abilities, antibiotic resistance genes, and antibiotic susceptibility in S. Infantis. The results showed that the S. Infantis strains isolated from chicken meat for sale in supermarkets in Santiago, Chile are multidrug-resistant (MDR) and contain virulence genes, making them pathogenic. Thus, Salmonella Infantis should be under surveillance in the poultry food production chain with the aim of protecting public health.

Abstract

Salmonella Infantis is a zoonotic pathogen that causes gastroenteritis in humans and animals, with poultry being its main reservoir. In Chile, there are no data to characterize S. Infantis strains in poultry production. In this study, 87 S. Infantis strains were isolated from chicken meat for sale in supermarkets in Santiago, Chile, and characterized according to their virulence genes, biofilm formation abilities, antibiotic susceptibility, and resistance genes. Through polymerase chain reaction or PCR, the strains were analyzed to detect the presence of 11 virulence genes, 12 antibiotic resistance genes, and integrase genes. Moreover, disc diffusion susceptibility to 18 antimicrobials and the ability to form biofilm in vitro were evaluated. Results demonstrated six different virulence gene profiles. Ninety-four percent of the strains were multi-resistant to antibiotics with weak biofilm formation abilities, 63.2% of the strains were broad spectrum β- lactam resistant, and the bla_CTX-M-65 gene was amplified in 13 strains. Only 3.4% of the strains were fluoroquinolone resistant, and the qnrB gene was amplified in two strains. Colistin resistance was exhibited in 28.7% of the strains, but mrc genes were not amplified in any strain under study. The isolated S. Infantis strains are pathogenic and antibiotic multi-resistant, and thus, this Salmonella serotype should be under surveillance in the poultry food production chain with the aim of protecting public health.

Comparative analysis of multidrug resistance plasmids and genetic background of CTX-M-producing Escherichia coli recovered from captive wild animals

Multiple interlinked factors are associated with the global resistome, whereas multidrug-resistant (MDR) pathogens have been related to increased mortality rates in humans and animals. CTX-M-type is the most prevalent extended-spectrum β-lactamase (ESBL) among Enterobacteriaceae, which raises concern worldwide. Zoological gardens have a high density of animals that live very close to each other and to humans. Therefore, this study aimed to investigate through the whole-genome sequencing (WGS) MDR Escherichia coli lineages obtained from captivity wild animals in a zoo. Genetic background showed a wide resistome for antimicrobials (e.g., bla_CTX-M-65, bla_CTX-M-8, bla_CMY-2, qnrB19), metals (e.g., pcoABCDERS, silABCEP, merACDEPRT), and antibacterial biocides (e.g., sugE, mdfA) among MDR CTX-M-producing E. coli belonging to CC155 and CC156. Mobilome analysis revealed several plasmids, and eight of them were completely characterized, which showed different backbone-encoding genes. Comparative analysis of plasmids bla_CTX-M-65/IncHI2-ST3, bla_CTX-M-8/IncI1-ST113, and IncQ1 showed a high identity among plasmids obtained from humans and animals worldwide distributed. Besides, several virulence genes, CRISPR, and prophage-related sequences were also detected. The occurrence of MDR E. coli belonging to CCs closely related to humans and food-producing animals and the high similarity among the plasmids from MDR E. coli carrying clinically significant antimicrobial resistance genes may indicate intercontinental dissemination of these lineages and plasmids. Therefore, these findings contribute to the monitoring of antimicrobial resistance and the human-animal-environment interface worldwide. Key Points • Wide resistome for antimicrobials, metals, and antibacterial biocides. • Multidrug resistance plasmids (bla_CTX-M-65/IncHI2-ST3, bla_CTX-M-8/IncI1-ST113). • Co-occurrence of plasmid-mediated resistance and virulence genes.

Study of the antibiotic residues in poultry meat in some of the EU countries and selection of the best compositions of lactic acid bacteria and essential oils against Salmonella enterica

In this study, the presence of antibiotics (ANB) residues was evaluated in poultry meat purchased from German and Lithuanian markets. In addition, the antimicrobial activity of 13 lactic acid bacteria (LAB) strains, 2 essential oils (EO) (Thymus vulgaris and Origanum vulgare L.), and their compositions were tested for the purpose of inhibiting antibiotic-resistant Salmonella spp. ANB residues were found in 3 out of the 20 analyzed poultry meat samples: sample no. 8 contained enrofloxacin (0.46 μg/kg), sample no. 14 contained both enrofloxacin and doxycycline (0.05 and 16.8 μg/kg, respectively), and sample no. 18 contained enrofloxacin (2.06 μg/kg). The maximum residue limits (MRLs) for the sum of enrofloxacin and ciprofloxacin and for doxycycline in the poultry muscle are 100 μg/kg. Finally, none of the tested poultry meat samples exceeded the suggested MRLs; however, the issue of ANB residues still requires monitoring of the poultry industry in Germany, Poland, and Lithuania, despite the currently established low ANB concentrations. These findings can be explained by the increased use of alternatives to ANB in the poultry industry. Our results showed that an effective alternative to ANB, which can help to reduce the occurrence of antibiotic-resistant salmonella, is a composition containing 1.0% of thyme EO and the following LAB strains: Lactobacillus plantrum LUHS122, Enteroccocus pseudoavium LUHS242, Lactobacillus casei LUHS210, Lactobacillus paracasei LUHS244, Lactobacillus plantarum LUHS135, Lactobacillus coryniformins LUHS71, and Lactobacillus uvarum LUHS245, which can be recommended for poultry industry as components of feed or for the treatment of surfaces, to control the contamination with Salmonella strains. However, it should be mentioned that most of the tested LAB strains were inhibited by thyme EO at the concentrations of 0.5 and 1.0%, except for LUHS122, LUHS210, and LUHS245. Finally, it can be noted that the agents responsible for the inhibitory effect on Salmonella are not the viable LAB strains but rather their metabolites, and further studies are needed to identify which metabolites are the most important.

Molecular epidemiology of Salmonella Infantis in Europe: insights into the success of the bacterial host and its parasitic pESI-like megaplasmid

Salmonella Infantis is one of the five serovars most frequently causing human salmonellosis in Europe, mainly associated with poultry. A clone harbouring a conjugative plasmid of emerging S. Infantis (pESI)-like megaplasmid, carrying multidrug resistant (MDR) and extended-spectrum beta-lactamases (ESBL) genes, has spread in the Italian broiler chicken industry also causing human illness. This work is aimed at elucidating the molecular epidemiology of S. Infantis and pESI-like in Europe using whole-genome sequencing and bioinformatics analysis, and to investigate the genetic relatedness of S. Infantis clones and pESI-like from animals, meat, feed and humans provided by institutions of nine European countries. Two genotyping approaches were used: chromosome or plasmid SNP-based analysis and the minimum spanning tree (MST) algorithm based on core-genome multilocus sequence typing (cgMLST). The European S. Infantis population appeared heterogeneous, with different genetic clusters defined at core-genome level. However, pESI-like variants present in 64.1 % of the isolates were more genetically homogeneous and capable of infecting different clonal lineages in most of the countries. Two different pESI-like with ESBL genes (n=82) were observed: bla_CTX-M-1-positive in European isolates and bla_CTX-M-65-positive in American isolates (study outgroup). Both variants had toxin-antitoxin systems, resistance genes towards tetracyclines, trimethoprim, sulphonamides and aminoglycosides, heavy metals (merA) and disinfectants (qacEΔ). Worryingly, 66 % of the total isolates studied presented different gyrA chromosomal point mutations associated with (fluoro)quinolone resistance (MIC range 0.125–0.5 mg/L), while 18 % displayed transferable macrolide resistance mediated by mph, mef and erm(B) genes. Proper intervention strategies are needed to prevent further dissemination/transmission of MDR S. Infantis and pESI-like along the food chain in Europe.

Presence of Bacterial Pathogens and Levels of Indicator Bacteria Associated with Duck Carcasses in a Commercial Processing Facility

ABSTRACT

Little information has been published on the microbiological aspects of U.S. commercial duck processing. The objective of this study was to measure prevalence and/or levels of bacteria in duck samples representing the live bird and partially or fully processed oven-ready duck meat. At 12 monthly sampling times, samples were collected at six sites along the processing line in a commercial duck slaughter plant. Crop and cecum samples were collected at the point of evisceration. Whole carcass rinse samples were collected before and after carcass immersion chilling plus application of an antimicrobial spray. Leg quarters were collected from the cut-up line before and after application of an antimicrobial dip treatment. All samples (five from each site per monthly replication) were directly plated and/or enriched for Salmonella and Campylobacter. For the last 10 replications, carcass and leg quarter rinse samples were also evaluated for enumeration of total aerobic bacteria, Escherichia coli, and coliforms. Most cecum, crop, and prechill carcass rinse samples were positive for Campylobacter (80, 72, and 67%, respectively). Carcass chilling and chlorinated spray significantly lowered Campylobacter prevalence (P < 0.01), and even fewer leg quarters were positive for Campylobacter (P < 0.01). Passage through a chlorinated dip did not further reduce Campylobacter prevalence on leg quarters. Salmonella was infrequently found in any of the samples examined (≤10%). Total aerobic bacteria, coliforms, and E. coli levels were reduced (P < 0.01) on whole carcasses by chilling but were not different after cut-up or leg quarter dip treatment. Overall, current commercial duck processing techniques as applied in the tested plant were effective for reducing the prevalence and levels of Campylobacter on duck meat products.

HIGHLIGHTS

Prevalence, Antimicrobial Resistance, Virulence Genes and Genetic Diversity of Salmonella Isolated from Retail Duck Meat in Southern China

Salmonella is an important cause of foodborne diseases. This study was undertaken to investigate the prevalence, serotype distribution, antimicrobial resistance, virulence genes, and genetic diversity of Salmonella isolates recovered from fresh duck meat obtained from retail markets in Southern China. In total, 365 samples of fresh duck meat were collected from retail markets in six different cities of Guangdong Province between May 2017 and April 2019. High levels of Salmonella contamination were detected in duck meat (151/365, 41.4%). Twenty-six different Salmonella serotypes were identified: S. Corvallis (n = 25, 16.6%), S. Kentucky (n = 22, 14.6%) and S. Agona (n = 20, 13.3%) were the most prevalent serotypes. All isolates were resistant to at least one antibiotic and 133 (88.1%) isolates exhibited multidrug resistance (MDR). Most (86.1%) Salmonella isolates carried seven classes of virulence-associated genes. This study showed the diversity of Salmonella serotypes and genotypes and the high prevalence of MDR isolates carrying multiple virulence-associated genes among isolates from duck meat obtained from retail markets in Southern China. Isolates from different districts had similar pulsed-field gel electrophoresis (PFGE) patterns indicating that circulating foodborne Salmonella constitutes a potential public health issue across different districts.

Antibiotic resistance of Salmonella strains from layer poultry farms in central Ecuador

AIMS

This study evaluated the antimicrobial resistance of Salmonella enterica strains from layer poultry farms in central Ecuador isolated during 2017. This geographical area is responsible for around 60% of total domestic egg production, yet, as of 2019, no reports had been published on the phenotypic and genotypic antibiotic resistance patterns of Salmonella in the layer poultry farms of this area.

METHODS AND RESULTS

Thirty-one isolates from layer poultry farms in central Ecuador obtained during 2017 were evaluated. The resistance profiles exhibited considerable differences in serovar and sample origin, grouping into nine clades by phenotype. S. Infantis strains were of the MDR phenotype in 94·4% of isolates. S. Typhimurium strains were of a reduced antimicrobial resistance phenotype and 50% showed resistance to one antimicrobial compound. One of the S. enterica nontyped strains had an MDR profile to 11 of the 20 antibiotics evaluated (eight groups). And the two remaining S. enterica nontyped strains showed resistance to two and three antibiotics respectively. The ESBL phenotype, which is resistant to clinically notable antibiotics such as ceftriaxone, ampicillin and cefepime, was observed only in S. Infantis (15/18). These strains harbour the emerging bla_CTX-M-65 gene, and co-harbour tetA and sul1 resistance genes in four strains. Additional β-lactamase genes, carbapenemase-producing genes (bla_IMP, bla_VIM , bla_OXA48 , bla_KPC , bla_NDM ) and colistin-mobile resistance gene mcr-1 were not detected.

CONCLUSIONS

The findings highlight the potential role of layer poultry farm environments in central Ecuador as reservoirs of MDR Salmonella strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results suggest the necessity of reinforcing biosecurity practices to reduce the probability of transmission of MDR Salmonella across the food chain.

Environmental persistence and virulence of Salmonella spp. Isolated from a poultry slaughterhouse

Salmonella spp. is responsible for severe foodborne disease, and is one of the main agents involved in foodborne outbreaks worldwide. Contamination occurs mainly as a result of poultry and egg consumption since they can carry some serotypes pathogenic to humans. The aim of the study was to evaluate the persistence and pathogenic potential of Salmonella spp. (n = 40) isolated from poultry slaughterhouse mats, using adhesion and invasion assays, antimicrobial susceptibility by disc diffusion, and biofilm production as phenotypic tests and genotypic analyses. Polystyrene mats presented 3.2 times greater chance of isolating Salmonella than canvas mats. Besides, we observed resistance to tetracycline (17.5%), ampicillin (10%), cefotaxime (7.5%), trimethoprim-sulfamethoxazole (5%), and chloramphenicol (2.5%). All strains possessed the invA, sipB, sipD, ssaR, sifA, sitC, iroN, tolC, flgK, fljB, and flgL genes. The genes sopB and sipA were both present in 92.5% of the isolates, while sopD and spvB were observed in 90% and 32.5% of strains, respectively. All strains adhered to and invaded HeLa cells. Regarding biofilm production, 31 (77.5%) strains were able to produce biofilm on polystyrene microplates. Using PFGE, we detected the persistence of clones in the environment for up to 18 fromthe 20 weeks. The ability of these strains to produce a biofilm and thus persist in the environment and disperse through contact surfaces in the processing plant favors the contamination of food, aggravated by the pathogenic potential of these isolates demonstrated by their adhesion capacity, invasion and resistance to various antibiotic agents.