Phenotypic and molecular characterisation of Salmonella spp. isolates in healthy poultry.

1. Epidemiological surveillance of Salmonella spp. serves as a primary tool for maintaining the health of poultry flocks. Characterising circulating serotypes is crucial for implementing control and prevention measures. This study conducted phenotypic and molecular characterisation of S. enterica Pullorum, S. enterica Heidelberg, and S. enterica Corvalis isolated from broiler chickens during slaughtering.2. All strains were susceptible to gentamicin, neomycin and norfloxacin. However, resistance rates exceeded 50% for ciprofloxacin and tiamulin, irrespective of the serotype. Approximately 64% of strains were classified as multidrug-resistant, with S. enterica Heidelberg strains exhibiting significantly higher overall resistance. The isolates demonstrated the ability to adhere and produce biofilm at a minimum of three temperatures, with S. enterica Pullorum capable of biofilm production at all temperatures encountered during poultry rearing.3. Each strain possessed between two and seven different virulence-associated genes. Genetic similarity, as indicated by pulsed field gel electrophoresis, exceeded 90% for all three serotypes and strains were classified in the R5 ribotype by PCR, regardless of serotype. Sequencing revealed high similarity among all strains, with homology ranging from 99.61 to 100% and all were classified to a single cluster.4. The results suggested a clonal relationship among the strains, indicating the possible circulation of a unique clonal group of S. enterica Pullorum in the southern region of Brazil.

Molecular characterization of Escherichia coli isolates recovered from broilers with cellulitis.

Avian cellulitis in broilers, caused by avian pathogenic Escherichia coli, is a major cause for carcass rejections during meat inspection, resulting in significant economic losses. In this study, we analysed E. coli isolates obtained from broiler chickens affected by cellulitis for their genetic relatedness and antimicrobial resistance phenotype and genotype. The objective was to determine whether there is a clonal spread or whether these clinical isolates differ. For this purpose, E. coli was isolated from swab samples collected from diseased broilers across 77 poultry farms in Germany, resulting in 107 isolates. These isolates were subjected to serotyping, PCR-based phylotyping and macrorestriction analysis with subsequent pulsed-field gel-electrophoresis for typing purposes. In addition, the presence of virulence genes associated with avian pathogenic E. coli (APEC) was investigated by PCR. Antimicrobial susceptibility of the isolates was examined by the disk diffusion method according to CLSI guidelines and subsequently, the presence of corresponding resistance genes was investigated by PCR. Typing results revealed that a significant proportion of the isolates belonged to serotype O78:K80, which is one of the major APEC serotypes. Phylogenetic grouping showed that phylogenetic group D was most commonly represented (n = 49). Macrorestriction analysis showed overall heterogenous results, however, some clustering of closely related isolates was observed. The level of antimicrobial resistance was high, with 83.8% of isolates non-susceptible to at least one class of antimicrobial agents and 40% of isolates showing resistance to at least three classes. The most frequently observed resistance was to ampicillin, mediated by blaTEM (n = 56). However, few isolates were non-susceptible to ciprofloxacin (n = 8) and none of the isolates was resistant to 3rd generation cephalosporins or carbapenems. Overall, the results show that genetically diverse APEC associated with avian cellulitis can be found among and within German poultry farms. While most isolates were antimicrobial resistant, resistance levels to high(est) priority critically important antimicrobials were low.

Antimicrobial resistance in E. Coli of animal origin and discovery of a novel ICE mobile element in Northeast China.

BACKGROUND: Multidrug resistance in Enterobacteriaceae including resistance to quinolones is rising worldwide. The development of resistance may lead to the emergence of new transmission mechanisms. In this study, the collection of different E. coli was performed from animals and subjected to subsequent procedures including pulsed-field gel electrophoresis, micro-broth dilution method, polymerase chain reaction. Whole genome sequencing of E. coli C3 was performed to detect the affinity, antimicrobial resistance and major carriers of the isolates. RESULTS: A total of 66 E. coli were isolated and their antibiotic resistance genes, frequency of horizontal transfer and genetic environment of E. coli C3 were determined. The results showed there were both different and same types in PFGE typing, indicating clonal transmission of E. coli among different animals. The detection of antimicrobial resistance and major antibiotic resistance genes and the plasmid transfer results showed that strains from different sources had high levels of resistance to commonly used clinical antibiotics and could be spread horizontally. Whole-genome sequencing discovered a novel ICE mobile element. CONCLUSION: In summary, the antimicrobial resistance of E. coli in northeast China is a serious issue and there is a risk of antimicrobial resistance transmission. Meanwhile, a novel ICE mobile element appeared in the process of antimicrobial resistance formation.

Impact of genetic diversity and antibiotic-resistance of Salmonella isolated from feral cats: One Health approach.

Free-living cats usually live in colonies in urban areas, especially close to parks and neighbourhoods where people feed them without any sanitary control. This can pose a human, animal and environmental health concern due to the close contact between uncontrolled colonies, the population and other domestic and/or wild animals. Thus, this study aimed to assess the genetic diversity and antimicrobial resistance (AMR) among Salmonella enterica subsp. enterica strains isolated from feral cats in a previous epidemiological study in the Gran Canaria island (Spain). A total of nineteen Salmonella isolates were obtained from November 2018 to January 2019 in a Salmonella epidemiological study in feral cats. All isolates obtained were genotyped by pulsed-field gel electrophoresis (PGFE) and were tested for antimicrobial susceptibility, in accordance with Decision 2013/652/EU. PFGE analysis revealed isolates clustering by serovar, with identical clones for serovars Bredeney and Grancanaria, while differing pulsotypes were observed for serovars Florida (88.89 % similarity) and Nima (83.23 % similarity). All but two isolates were resistant to at least one antimicrobial. The results obtained demonstrate that feral cats in the region investigated are a reservoir of Salmonella strains resistant to gentamicin (94.1 %) and of the critically important antimicrobial tigecycline (23.5 %). Hence, they could excrete AMR strains through their faeces and contaminate the environment, favoring the spread of such bacteria to cohabiting pets. Moreover, this widespread presence of AMR Salmonella clones across various serovars highlights the urgent need to implement efficient antimicrobial stewardship and control programs by the local governments due to the ongoing need to protect human and animal health under a One Health concept.

Genotypic and phenotypic analysis of Elizabethkingia meningoseptica in bullfrog Rana catesbeiana isolated in Taiwan.

Elizabethkingia meningoseptica is a hazardous bacterium for agriculture production and human health. The present study identified E. meningoseptica from the bullfrog, human and reference strain BCRC 10677 by API 20NE, 50S ribosome protein L27 sequencing and pulse field gel electrophoresis to differentiate isolates of E. meningoseptica from aquatic animals and humans. All isolates from bullfrogs and humans were identified as E. meningoseptica by DNA sequencing with 98.8%-100% sequence identity. E. meningoseptica displayed significant genetic diversity when analysed using pulsed-field gel electrophoresis (PFGE). There were six distinct pulsotypes, including one pulsotype found in bullfrog isolates and five pulsotypes found in human isolates. However, E. meningoseptica from bullfrog exhibited one genotype only by PFGE. Overall, molecular epidemiological analysis of PFGE results indicated that the frog E. meningoseptica outbreaks in Taiwan were produced by genetically identical clones. The bullfrog isolates were not genetically related to other E. meningoseptica from human and reference isolates. This research provided the first comparisons of biochemical characteristics and genetic differences of E. meningoseptica from human and bullfrog isolates.

Phenotypic and genotypic characterization of Listeria monocytogenes in clinical ruminant cases in Korea.

Listeria monocytogenes, a foodborne human and veterinary pathogen, is associated with high mortality rates in ruminants. However, no studies have investigated the antimicrobial resistance of L. monocytogenes isolates from clinical ruminant cases. This study aimed to determine the phenotypic and genotypic characteristics of L. monocytogenes isolates from clinical cases of Korean ruminants. We collected 24 L. monocytogenes isolates from aborted bovine fetuses and goats presenting with listeriosis-related symptoms. The isolates were subjected to PCR serogrouping, conventional serotyping, virulence gene detection, and antimicrobial susceptibility testing. Furthermore, pulsed-field gel electrophoresis and multilocus sequence typing were used to classify and compare genetic diversity among the isolates, including human L. monocytogenes isolates. The most prevalent L. monocytogenes serotypes were 4b (Ⅳb), 1/2a (Ⅱa; Ⅱc), and 1/2b (Ⅱb). All isolates harbored the virulence genes; however, llsX-encoding listeriolysin were identified only in serotypes 4b and 1/2b. All isolates, including two found in humans, formed three genetically diverse pulsed-field gel electrophoresis clusters according to serotype, lineage, and sequence type. The most prevalent sequence type was ST1, followed by ST365 and ST91. The isolates from ruminants with listeriosis were resistant to oxacillin and ceftriaxone and showed diverse lineage, serotype (serogroup), and sequence type characteristics. Considering that the atypical sequence types exhibited clinical manifestations and histopathological lesions, further study is needed to elucidate the pathogenicity of genetically diverse ruminant L. monocytogenes isolates. Furthermore, continuous monitoring of antimicrobial resistance is required to prevent the emergence of L. monocytogenes strains resistant to common antimicrobials.

Zoonotic pathogens linked with hedgehog diphtheric disease.

Hedgehog diphtheric disease (HDD), an ulcerative skin disease with a high fatality rate, is an emerging threat to European hedgehogs (Erinaceus europaeus). We explored the potential role of a panel of zoonotic pathogens in the presumed multifactorial nature of HDD in 188 hedgehogs from 3 wildlife rescue centres in Belgium. As expected, and with a prevalence of 67% in 57 hedgehogs with skin lesions, characteristic of HDD, the occurrence of Corynebacterium ulcerans was strongly associated with the disease. Remarkably, with a prevalence of 42% in affected animals, infections with Borrelia burgdorferi sensu lato were 3.92 times more likely to be detected in HDD (95% confidence interval: 1.650-9.880; p = .0024). Overall, 40 hedgehogs tested positive for the B. burgdorferi sensu lato complex, including Borrelia afzelii (n = 30), Borrelia bavariensis (n = 7) and Borrelia spielmanii (n = 7). Other widely occurring pathogens included Salmonella (prevalence of 19%, with three pulsed-field gel electrophoresis profiles) and Leptospira sp. (prevalence of 11%, including Leptospira interrogans and Leptospira borgpetersenii), but these were not associated with the occurrence of HDD. These findings show that hedgehogs in Belgium represent a significant reservoir of multiple zoonotic bacteria, of which toxigenic C. ulcerans and B. burgdorferi sensu lato are associated with widespread hedgehog skin pathology and mortality.

Characterisation and epidemiological subtyping of Shiga toxin-producing Escherichia coli isolated from the beef production chain in Gauteng, South Africa.

In South Africa, there is a shortage of epidemiologic data on Shiga toxin-producing Escherichia coli (STEC) in the beef production chain. This study was conducted to characterise STEC isolates originating from three studies conducted in a cattle feedlot, beef abattoirs and retail outlets in Gauteng province, South Africa. Polymerase chain reaction was used to detect virulence genes, the Epsilometer test to assess antimicrobial susceptibility, pulsed-field gel electrophoresis (PFGE) to investigate genetic relatedness of isolates, and conventional serotyping for phenotypic identification. Amongst the 86 STEC isolates, the eaeA gene was detected in 20 (23%), and 26 different serogroups were identified, including the clinically important O8, O174, O2, 020 and O117. The majority of the isolates (95%; 82/86) exhibited resistance to one or more antimicrobial agents, and 30 of the isolates (35%) exhibited multi-drug resistance (MDR), being resistant to at least three antimicrobial classes. The PFGE patterns showed a highly diverse but related STEC population, with 45 distinct patterns and evidence of horizontal transmission along the beef production chain. This is significant because it demonstrates continual environmental contamination and risk of contamination along the beef production chain and the food chain. To our knowledge, this is the first study that provides evidence of horizontal transmission of STEC along the beef production chain in South Africa. This epidemiological information could facilitate the development of a proactive strategy for reducing potential foodborne outbreaks and transmission of antimicrobial resistant pathogens in the food chain.

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

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

Genotyping and phenotyping of Lactococcus garvieae isolates from fish by pulse-field gel electrophoresis (PFGE) and electron microscopy indicate geographical and capsular variations.

Lactococcus garvieae is the etiological agent of Lactococcosis, an evolving disease affecting many fish species and causing significant economic losses worldwide. Assessing pathogen relatedness and bacterial population structure is critical for determining the epidemiology of L. garvieae infections and in establishing effective pathogen management methods. The previously published morphological and genetic studies point to a clonal population structure, as seen in other fish bacteria. In the present study, the pulsed-field gel electrophoresis (PFGE) method was utilized to define a population of 41 Taiwanese isolates from outbreaks with comparisons to four well-characterized non-Taiwanese isolates previously published. Two restriction enzymes (ApaI and SmaI) were utilized individually for PFGE analysis (cut-off value = 90.0%), revealing genetic heterogeneity across L. garvieae isolates, with ApaI and SmaI yielding 12 and seven distinct PFGE band patterns, respectively. The phylogenic analysis using internal transcribed spacer region clustered all L. garvieae isolates in the same clad. Furthermore, the electron microscopic results confirmed the absence of capsular gene cluster (CGC) in previously characterized Taiwanese vaccine strain (S3) from grey mullet. Overall, our findings emphasize the importance of analysing the morphological and genetic diversity in L. garvieae being correlated for proper taxonomic classification in vaccine strain selection and epidemiological studies.

A national study through a 'Farm-to-fork' Approach to determine Salmonella dissemination along with the Lebanese poultry production chain.

This cross-sectional study was conducted to determine the prevalence of Salmonella at different stages of the broiler production chain and layer flocks in addition to their antibiotic resistance profile and molecular patterns. Over a period of 3 years, different sample matrices were collected from Lebanese farms, slaughterhouses and retail markets. Out of 672 Salmonella serotyped, 514 were analysed for antimicrobial resistance and 214 for clonality using Pulsed-field gel electrophoresis (PFGE). The results highlighted an important prevalence of Salmonella, 30% in farms, 35.8% in slaughterhouses and 22.4% at retail level. A large diversity of serotypes was identified with predominance among Salmonella Infantis (32.9%), Salmonella Enteritidis (28.4%) and Salmonella Kentucky (21.4%). High resistance to nalidixic acid was revealed in all the isolates. The most prominent resistance was exhibited in S. Kentucky and S. Infantis. The latter was resistant to tetracycline (99%), streptomycin (88.2%) and remarkable multi-drug resistance (MDR) (89.7%). All S. Kentucky isolates were resistant to ciprofloxacin, MDR (62.4%) and 6% were resistant to extended-spectrum cephalosporin (ESCs). One persistent clone of S. Enteritidis was found common between poultry and humans. Similar genomic profiles were detected between farms, slaughterhouses and retail suggesting the dissemination of identical clones throughout the food chain possibly due to weak barriers preventing such transmission.

Isolation and characterization of Salmonella spp. from food and food contact surfaces in a chicken processing factory.

The presence of Salmonella serotypes is a major safety concern of the food industry and poultry farmers. This study aimed to isolate and identify Salmonella spp. from a chicken processing facility by PCR and pulsed-field gel electrophoresis (PFGE). In addition, the biofilm-forming abilities of the isolated bacteria on stainless steel, silicone rubber, plastic, and chicken skin were also investigated. PCR was used for the confirmation of Salmonella serotypes, and then gene similarity within the same serotype was analyzed by PFGE. As a result, 26 S. Enteritidis isolates were detected at a high rate from both food contact surfaces and chicken products during processing. All of them were 100% genetically identical to the same bacteria. The results indicated that the virulence factors and effective biofilm-forming ability of S. Enteritidis isolates could affect human health and economic revenue. It was also suggested that the visual observation of food and food contact surfaces could be a great concern in the future. The continuous monitoring of S. Enteritidis molecular and biofilm characteristics is needed to increase food safety.

Salmonella spp. profiles isolated from seabird samples from the Brazilian coast.

In view of growing concerns, in a One Health context, regarding the transport and dissemination of pathogenic microorganisms among seabirds and other vertebrate animals, including humans, the aim of this study was to identify Salmonella spp. in stranded and non-stranded resident and migratory wild seabirds from the Brazilian coast. Antimicrobial susceptibility and molecular profiles, quinolone resistance genes and antigenic characterization of the isolates were also carried out. Fresh faeces and cloacal swabs were obtained totaling 122 seabirds sampled throughout different Brazilian coast regions. At the laboratory, sample culturing, Salmonella spp. isolation and biochemical identification were performed, followed by antigenic profile identification by serum agglutination, susceptibility profile characterization by the agar disc diffusion technique, detection of quinolone resistance genes (qnrA, qnrB, qnrS) using the multiplex polymerase chain reaction technique (multiplex PCR) and, finally, isolates profiles identification by pulsed field gel electrophoresis (PFGE). Salmonella enterica subsp. enterica was identified in 7% of the studied birds, comprising three different serovars: Panama (63 %), Typhimurium (25 %) and Newport (13 %). The most important findings reported herein are the first description of Salmonella panama in seabirds and the totality of isolates being resistant (or intermediate) to at least one tested antimicrobial, with emphasis on quinolone resistance. The molecular results suggest that the observed resistance cannot be explained by the presence of plasmid-mediated quinolone resistance genes. The PFGE suggests that the Panama and Newport profiles detected herein are not yet widespread in Brazil, unlike Typhimurium, which is already well distributed throughout the country. Considering this finding, we suggest that seabirds are an important link in the epidemiological chain of this serovar. The monitoring of these bacteria in seabirds, as well as of their susceptibility profiles to antimicrobials, must be continuous, strengthening the role of these animals as environmental health indicators and sentinels.

The diversity of Campylobacter spp. throughout the poultry processing plant.

Campylobacteriosis is the leading food-borne disease in developed countries, and poultry are a major source for human infection. The diversity of Campylobacter on chicken carcasses during processing may lead to isolates that are able to survive abattoir processing. This has important implications for public health and adds a further layer to the complexity of the epidemiology of campylobacteriosis. The diversity of the Campylobacter spp. populations on broiler carcasses was studied at three different stages of processing (post-bleed, post-scald and post-chill) in three UK processing plants, using the pulsed-field gel electrophoresis (PFGE) KpnI enzyme. One hundred and sixty Campylobacter strains from 3 processing plants were identified as C. jejuni (92.3%) with 27 PFGE subtype profiles recovered from carcasses at the post-bleed point. Change in populations was identified when carcasses move towards the end of poultry processing. Seven C. jejuni genotypes were able to survive the scalding tank stage process, and 5 genotypes surviving the entire poultry process. Confirmation by PFGE gives information on the genotypic profiles of C. jejuni on chicken carcasses and how they change according to the temperatures exposed to during processing. Diversity within C. jejuni populations produces genotypes that adapt to tolerate the processing environment, and these may be capable of causing human disease. Understanding more about the genotypes that survive the processing will have important implications for public health.

Contamination of chicken carcasses and the abattoir environment with Listeria monocytogenes in Taiwan.

1. The following study provides the first data on the detection and types of Listeria monocytogenes isolated from broiler chickens during processing and from six Taiwanese abattoir environments.2. Listeria monocytogenes was not detected in any cloacal (n = 120) or environmental (n = 256) samples collected before and during processing, indicating that faecal material and the environment of abattoirs were not important sources of L. monocytogenes for poultry carcases. However, 28 of 246 (11.4%; 95% CI: 7.7-16.0) rinse samples collected from carcases post-evisceration from three abattoirs were positive for L. monocytogenes.3. The only serotypes detected were 1/2a (82.1%; 95% CI: 63.1-93.9) and 1/2b (14.3%; 95% CI: 4.0-32.7), with 3.6% (95% CI: 0.1-18.3) non-typable isolates.4. Characterisation by Pulsed Field Gel Electrophoresis (PFGE) identified five PFGE types, confirming cross-contamination with L. monocytogenes during evisceration, chilling and post-chilling.5. These findings highlight the potential for cross-contamination to occur through direct contact between carcases, especially whilst in chilling tanks.

Identification of the Pseudomonas fluorescens group as being responsible for blue pigment on fresh cheese.

New cases of blue cheese discoloration has led to recent research to identify the causal agent and factors that favor blue pigment appearing. Nonetheless, very few reports have described the source of contamination and the measurements to eradicate the microbiological source on cheese farms by determining the relation between blue discoloration on fresh cheese and the Pseudomonas fluorescens group. Thus, 60 samples from a cheese farm (cheese, equipment surfaces, tap water, and raw and pasteurized milk) were analyzed by phenotypical, MALDI-TOF, 16S rRNA sequencing and pulsed-field gel electrophoresis tests to determine the causal agent. The results obtained by pulsed-field gel electrophoresis with restriction enzymes XbaI and SpeI confirmed tap water as the initial contaminated source. The above-mentioned result was essential to avoid Pseudomonas contamination due to the most residual microorganisms being inactivated through a new disinfection program.

Isolation and characterization of Escherichia albertii in poultry at the pre-harvest level.

Escherichia albertii, often misidentified as Escherichia coli, has become an emerging foodborne human enteric pathogen. However, the prevalence and major animal reservoirs of this significant pathogen are still not clear. Here, we performed comprehensive microbiological, molecular, comparative genomics and animal studies to understand the status and features of E. albertii in the US domestic and food animals. Although no E. albertii was identified in a total of 1,022 diverse E. coli strains isolated from pets and food animals in a retrospective screening, in a pilot study, E. albertii was successfully isolated from a broiler farm (6 out of 20 chickens). The chicken E. albertii isolates showed clonal relationship as indicated by both pulsed-field gel electrophoresis (PFGE) and whole-genome sequence analysis. The isolated chicken E. albertii displayed multidrug resistance; all the resistance determinants including the extended-spectrum beta-lactamase gene, carried by plasmids, could be conjugatively transferred to E. coli, which was further confirmed by S1-PFGE and Southern hybridization. Whole-genome sequence-based phylogenetic analysis showed the chicken E. albertii strains were phylogenetically close to those of human origins. Challenge experiment demonstrated that the E. albertii strains isolated from human and wild bird could successfully colonize in the chicken intestine. Together, this study, for the first time, reported the isolation of E. albertii in poultry at the pre-hrvest level. The findings from multi-tier characterization of the chicken E. albertii strains indicated the importance of chickens as a reservoir for E. albertii. A large scale of E. albertii survey in poultry production at the pre-harvest level is highly warranted in the future.

The effect of partial depopulation on Campylobacter introduction in broiler houses.

Poultry is seen as the main reservoir for Campylobacter. Control of this zoonotic pathogen in primary production could potentially reduce the colonization in broiler flocks and consequently reduce the number of human infections. In the present study, 20 broiler flocks from 10 farms, were sampled immediately before and 5 to 7 d after partial depopulation (thinning) for the presence of Campylobacter using cecal droppings and overshoes. At the time of thinning, the catching crew, transportation vehicles, forklift, and transport containers were sampled for the presence of Campylobacter. Samples were cultivated; presumed positive isolates were confirmed by PCR. The isolates were molecularly typed by flaA restriction analysis and pulsed field gel electrophoresis. Results show that all flocks were thinned using Campylobacter-contaminated equipment and materials. One-third of the broiler flocks became colonized after thinning. In 67% of the colonization cases, identical strains were found matching those of container systems, transport trucks, and/or forklifts. This identifies thinning as an important risk factor for Campylobacter introduction into broiler houses. Setup and compliance with biosecurity practices during thinning is essential to prevent Campylobacter colonization of broiler flocks.

Research Note: Identification and characterization of Salmonella spp. in mechanically deboned chickens using pulsed-field gel electrophoresis.

Salmonella is one of the common foodborne bacteria, causing 80.3 million illnesses every year worldwide. This study was conducted to isolate and identify Salmonella enterica serovars from poultry samples responsible for causing foodborne poisoning in the Mississippi area, United States. A total of 55 S. enterica serovars-Enteritidis (6), Oranienburg (1), Schwarzengrund (8), Heidelberg (4), Kentucky (22), 4, [5], 12:i:- (1), Montevideo (2), Infantis (9), and multi serotypes (2)-were isolated from approximately 110 poultry samples. Through pulsed-field gel electrophoresis (PFGE) analysis, 8 to 13 bands were obtained. The profiles showed >90% similarity in strains within the same type. Consequently, PFGE could be a useful tool to determine chromosomal similarity (clonality of strains) that can be used to trace down epidemiologic sources and geographical origins of Salmonella.

High genetic similarity of Salmonella Enteritidis as a predominant serovar by an independent survey in 3 large-scale chicken farms in China.

Salmonella Enteritidis (SE) are important zoonotic pathogens, and can be easily transferred to humans by contaminated animal products. Epidemic surveys of SE are necessary in current modern large-scale chicken farms. In this study, Salmonella strains were isolated from possibly infected samples collected at 3 independent farms, and their serotype, drug resistances, virulence genes, and genetic similarity were analyzed by molecular genetic analysis technologies including multilocus sequence typing (MLST), clustered regularly interspaced short palindromic repeats (CRISPR), pulsed-field gel electrophoresis (PFGE), and whole-genome sequencing (WGS). A total of 346 Salmonella strains were isolated from 3,598 samples (9.61%); 329 isolates were identified as SE (95.09%) and 308 isolates were multidrug resistant (93.62%). Virulotyping based on 6 virulence genes showed high similarity in SE isolates of each farm, with the exception of 2 isolates. All SE isolates were found to be the same ST11 type by MLST, and 22 strains of 150 SE isolates selected at random were found to belong to 1 cluster by PFGE and the same SET1 type by CRISPR. WGS results further revealed that these isolates belonged to the same clonal cluster, with high genetic similarity of 99.80 to 100.00%. All these results indicated that these SE isolates were overwhelmingly dominant and demonstrated high genetic similarity, which revealed that the same SE clone might be transmitted in these farms.