Human and avian extraintestinal pathogenic Escherichia coli: infections, zoonotic risks, and antibiotic resistance trends

Distribution of papA and papG Variants among Escherichia coli Genotypes: Association with Major Extraintestinal Pathogenic Lineages

The pyelonephritis-associated fimbria (P fimbria) is one of the most recognized adhesion determinants of extraintestinal pathogenic Escherichia coli strains (ExPECs). Twelve variants have been described for the gene encoding the P fimbria major structural subunit PapA and three variants for the gene encoding the adhesin subunit PapG. However, their distribution among the ExPEC diversity has not been comprehensively addressed. A complete landscape of that distribution might be valuable for delineating basic studies about the pathogenicity mechanisms of ExPECs and following up on the evolution of ExPEC lineages, particularly those most epidemiologically relevant. Therefore, we performed a massive descriptive study to detect the papA and papG variants along different E. coli genotypes represented by genomic sequences contained in the NCBI Assembly Refseq database. The most common papA variants were F11, F10, F48, F16, F12, and F7-2, which were found in significant association with the most relevant ExPEC genotypes, the phylogroups B2 and D, and the sequence types ST95, ST131, ST127, ST69, ST12, and ST73. On the other hand, the papGII variant was by far the most common followed by papGIII, and both were also found to have a significant association with common ExPEC genotypes. We noticed the presence of genomes, mainly belonging to the sequence type ST12, harboring two or three papA variants and two papG variants. Furthermore, the most common papA and papG variants were also detected in records representing strains isolated from humans and animals such as poultry, bovine, and dogs, supporting previous hypotheses of potential cross-transmission. Finally, we characterized a set of 17 genomes from Chilean uropathogenic E. coli strains and found that ST12 and ST73 were the predominant sequence types. Variants F7-1, F7-2, F8, F9, F11, F13, F14, F16, and F48 were detected for papA, and papGII and papGIII variants were detected for papG. Significant associations with the sequence types observed in the analysis of genomes contained in the NCBI Assembly Refseq database were also found in this collection in 16 of 19 cases for papA variants and 7 of 9 cases for the papG variants. This comprehensive characterization might support future basic studies about P fimbria-mediated ExPEC adherence and future typing or epidemiological studies to monitor the evolution of ExPECs producing P fimbria.

Short-chain fatty acids inhibit bacterial plasmid transfer through conjugation in vitro and in ex vivo chicken tissue explants

The animal gut acts as a potent reservoir for spreading and maintaining conjugative plasmids that confer antimicrobial resistance (AMR), fitness, and virulence attributes. Interventions that inhibit the continued emergence and expansion of AMR and virulent strains in agricultural and clinical environments are greatly desired. This study aims to determine the presence and efficacy of short-chain fatty acids (SCFA) inhibitory effects on the conjugal transfer of AMR plasmids. In vitro broth conjugations were conducted between donor Escherichia coli strains carrying AMP plasmids and the plasmid-less Escherichia coli HS-4 recipient strain. Conjugations were supplemented with ddH2O or SCFAs at 1, 0.1, 0.01, or 0.001 molar final concentration. The addition of SCFAs completely inhibited plasmid transfer at 1 and 0.1 molar and significantly (p < 0.05) reduced transfer at 0.01 molar, regardless of SCFA tested. In explant models for the chicken ceca, either ddH2O or a final concentration of 0.025 M SCFAs were supplemented to the explants infected with donor and recipient E. coli. In every SCFA tested, significant decreases in transconjugant populations compared to ddH2O-treated control samples were observed with minimal effects on donor and recipient populations. Finally, significant reductions in transconjugants for plasmids of each incompatibility type (IncP1ε, IncFIβ, and IncI1) tested were detected. This study demonstrates for the first time the broad inhibition ability of SCFAs on bacterial plasmid transfer and eliminates AMR with minimal effect on bacteria. Implementing interventions that increase the concentrations of SCFAs in the gut may be a viable method to reduce the risk, incidence, and rate of AMR emergence in agricultural and human environments.

Fecal Shedding of Clostridioides difficile in Calves in Sao Paulo State, Brazil

OBJECTIVE

This study aimed to evaluate the fecal shedding of C. difficile in calves on farms in Sao Paulo State, Brazil.

MATERIALS AND METHODS

Fecal samples (n=300) were collected from diarrheic (n=78) and nondiarrheic (n=222) calves less than 60 days of age from 20 farms. Fecal samples were inoculated into enrichment broth supplemented with taurocholate and cultured under anaerobic conditions. Colonies suspected to be C. difficile were harvested for DNA extraction and then multiplex PCR for the detection of genes encoding toxins A and B and binary toxins. All toxigenic isolates were ribotyped and tested for antimicrobial susceptibility, and five selected strains were subjected to whole-genome sequencing to determine their sequence type.

RESULTS AND DISCUSSION

C. difficile was isolated from 29.3% (88/300) of the samples. All toxigenic isolates (17/88, 19.3%) were classified as ribotypes RT046 (13/17 -79.47%, A+B+ CDT-) and RT126 (4/17=20.53%, A+B+ CDT+). The sequenced strains from RT046 were classified as ST35 (Clade 1), while those from RT126 were classified as ST11 (Clade 5). No associations between the epidemiological factors in any of the groups and C. difficile isolation were observed. Most of the toxigenic isolates (16/17=94.41%) were classified as multidrug-resistant. Calves can be an important source of toxigenic C. difficile strains, including multidrug-resistant isolates from ribotypes commonly observed in humans.

From "resistance genes expression" to "horizontal migration" as well as over secretion of Extracellular Polymeric Substances: Sludge microorganism's response to the increasing of long-term disinfectant stress

Glutaraldehyde-Didecyldimethylammonium bromides (GDs) has been frequently and widely employed in livestock and poultry breeding farms to avoid epidemics such as African swine fever, but its long-term effect on the active sludge microorganisms of the receiving wastewater treatment plant was keep unclear. Four simulation systems were built here to explore the performance of aerobic activated sludge with the long-term exposure of GDs and its mechanism by analyzing water qualities, resistance genes, extracellular polymeric substances and microbial community structure. The results showed that the removal rates of CODCr and ammonia nitrogen decreased with the exposure concentration of GDs increasing. It is worth noting that long-term exposure to GDs can induce the horizontal transfer and coordinated expression of a large number of resistance genes, such as qacE, sul1, tetx, and int1, in drug-resistant microorganisms. Additionally, it promotes the secretion of more extracellular proteins, including arginine, forming a "barrier-like" protection. Therefore, long-term exposure to disinfectants can alter the treatment capacity of activated sludge receiving systems, and the abundance of resistance genes generated through horizontal transfer and coordinated expression by drug-resistant microorganisms does pose a significant threat to ecosystems and health. It is recommended to develop effective pretreatment methods to eliminate disinfectants.

Baicalin Weakens the Virulence of Porcine Extraintestinal Pathogenic Escherichia coli by Inhibiting the LuxS/AI-2 Quorum-Sensing System

Porcine extraintestinal pathogenic Escherichia coli (ExPEC) is a pathogenic bacterium that causes huge economic losses to the pig farming industry and considerably threatens human health. The quorum sensing (QS) system plays a crucial role in the survival and pathogenesis of pathogenic bacteria. Hence, it is a viable approach to prevent ExPEC infection by compromising the QS system, particularly the LuxS/AI-2 system. In this study, we investigated the effects of baicalin on the LuxS/AI-2 system of ExPEC. Baicalin at concentrations of 25, 50, and 100 μg/mL significantly diminished the survival ability of ExPEC in hostile environments and could inhibit the biofilm formation and autoagglutination ability in ExPEC. Moreover, baicalin dose-dependently decreased the production of AI-2 and down-regulated the expression level of luxS in PCN033. These results suggest that baicalin can weaken the virulence of PCN033 by inhibiting the LuxS/AI-2 system. After the gene luxS was deleted, AI-2 production in PCN033 was almost completely eliminated, similar to the effect of baicalin on the production of AI-2 in PCN033. This indicates that baicalin reduced the production of AI-2 by inhibiting the expression level of luxS in ExPEC. In addition, the animal experiment further showed the potential of baicalin as a LuxS/AI-2 system inhibitor to prevent ExPEC infection. This study highlights the potential of baicalin as a natural quorum-sensing inhibitor for therapeutic applications in preventing ExPEC infection by targeting the LuxS/AI-2 system.

A comprehensive study of colisepticaemia progression in layer chickens applying novel tools elucidates pathogenesis and transmission of Escherichia coli into eggs

Colisepticaemia caused by avian pathogenic Escherichia coli (APEC) is a challenging disease due to its high economic importance in poultry, dubious pathogenesis and potential link with zoonosis and food safety. The existing in vitro studies can't define hallmark traits of APEC isolates, suggesting a paradigm shift towards host response to understand pathogenesis. This study investigated the comprehensive pathological and microbial progression of colisepticaemia, and transmission of E. coli into eggs using novel tools. In total 48 hens were allocated into three groups and were inoculated intratracheally with ilux2-E. coli PA14/17480/5-/ovary (bioluminescent strain), E. coli PA14/17480/5-/ovary or phosphate buffered saline. Infection with both strains led to typical clinical signs and lesions of colibacillosis as in field outbreaks. Based on lung histopathology, colisepticaemia progression was divided into four disease stages as: stage I (1-3 days post infection (dpi)), stage II (6 dpi), stage III (9 dpi) and stage IV (16 dpi) that were histologically characterized by predominance of heterophils, mixed cells, pyogranuloma, and convalescence, respectively. As disease progressed, bacterial colonization in host organs also decreased, revealed by the quantification of bacterial bioluminescence, bacteriology, and quantitative immunohistochemistry. Furthermore, immunofluorescence, immunohistochemistry, and bacteria re-isolation showed that E. coli colonized the reproductive tract of infected hens and reached to egg yolk and albumen. In conclusion, the study provides novel insights into the pathogenesis of colisepticemia by characterizing microbial and pathological changes at different disease stages, and of the bacteria transmission to table eggs, which have serious consequences on poultry health and food safety.

UV-Triggered Drug Release from Mesoporous Titanium Nanoparticles Loaded with Berberine Hydrochloride: Enhanced Antibacterial Activity

Mesoporous titanium nanoparticles (MTN) have always been a concern and are considered to have great potential for overcoming antibiotic-resistant bacteria. In our study, MTN modified with functionalized UV-responsive ethylene imine polymer (PEI) was synthesized. The characterization of all products was performed by different analyses, including SEM, TEM, FT-IR, TGA, XRD, XPS, and N2 adsorption-desorption isotherms. The typical antibacterial drug berberine hydrochloride (BH) was encapsulated in MTN-PEI. The process exhibited a high drug loading capacity (22.71 ± 1.12%) and encapsulation rate (46.56 ± 0.52%) due to its high specific surface area of 238.43 m2/g. Moreover, UV-controlled drug release was achieved by utilizing the photocatalytic performance of MTN. The antibacterial effect of BH@MTN-PEI was investigated, which showed that it could be controlled to release BH and achieve a corresponding antibacterial effect by UV illumination for different lengths of time, with bacterial lethality reaching 37.76% after only 8 min of irradiation. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the nanoparticles have also been studied. The MIC of BH@MTN-PEI was confirmed as 1 mg/mL against Escherichia coli (E. coli), at which the growth of bacteria was completely inhibited during 24 h and the concentration of 5 mg/mL for BH@MTN-PEI was regarded as MBC against E. coli. Although this proof-of-concept study is far from a real-life application, it provides a possible route to the discovery and application of antimicrobial drugs.

A spatial analysis of urban gulls contribution to the potential spread of zoonotic and antibiotic-resistant bacteria

Wildlife human interactions within cities are becoming more common with consequences for pathogen transmission and human health. Large gulls are opportunistic feeders, adapted to coexist with humans in urban environments, and are potential vectors for spread and transmission of pathogens, including antimicrobial-resistant bacteria. We investigated the potential role that urban gulls play in the spread and dispersal of these bacteria. We analysed 129 faecal swabs from yellow-legged gulls (Larus michahellis) of different ages (56 adults and 73 immatures) during the breeding period from three years in the highly populated city of Barcelona (northeastern Spain). Thirteen individuals tested positive for the pathogenic bacteria (Escherichia coli, Listeria monocytogenes, Campylobacter jejuni), including antibiotic-resistant strains. We modelled the potential spatial spread of pathogens using the GPS trajectories of 58 yellow-legged gulls (23 adults, 35 immature individuals), which included the thirteen individuals that tested positive for pathogenic bacteria. By overlapping the spatially explicit pathogen dispersal maps with the distribution of urban installations sensitive at risk of possible pathogen spillover (e.g. elder and medical centres, markets, food industries, kindergartens, or public water sources), we identified potential areas at risk of pathogen spillover. Pathogens may be potentially spread to municipalities beyond Barcelona city borders. The results revealed that immature gulls dispersed pathogens over larger areas than adults (maximum dispersal distances of 167 km versus 53.2 km, respectively). Recreational urban water sources were the most sensitive habitats visited by GPS-tagged gulls that tested positive, followed by schools. Combining GPS movement data with pathogen analytics allows spatially explicit maps to be generated using a One Health approach that can help urban and public health management within large cities, such as Barcelona, and identify areas used by humans that are sensitive to pathogen spillover from gulls.

Phenotypic and genotypic characterizations of bacteria isolated from the respiratory microbiota of healthy turkeys with potential for probiotic composition

Desirable characteristics of Staphylococcus sp., Streptococcus sp., Bacillus sp., Klebsiella sp., Escherichia coli, and Pseudomonas pseudoalcaligenes isolated from the trachea of healthy turkeys were evaluated as probiotic candidates in the search for new alternatives to solve antimicrobial resistance issues in poultry. In current study phenotypic and genotypic capacity to produce bacteriocin-like substances, efficacy to inhibit the growth of avian pathogens, susceptibility to antimicrobials of bacteria isolated from the respiratory microbiota of healthy turkeys, and the presence of virulence-associated genes (VAGs) predictors of Avian Pathogenic Escherichia coli (APEC) were evaluated. Nine E. coli and one Klebsiella sp. strains produced bacteriocin-like substances, and all harbored the cvaA gene. Some strains also showed antagonistic activity against APEC. Multidrug-resistant profile was found in 54% of the strains. Six strains of bacteriocin-like substances producing E. coli also harbored 3-5 VAGs. The study showed that two bacterial genuses (Klebsiella sp. and E. coli) present desirable probiotic characteristics. Our results identified strains with potential for poultry's respiratory probiotic.

Backyard poultry: exploring non-intensive production systems

The concept of backyard poultry historically encompassed "food-producing animals." Nevertheless, a recent shift in livestock production paradigms within developed countries is evident, as backyard poultry owners now raise their birds for purposes beyond self-consumption, raising animals in a familiar way, and fostering emotional bonds with them. Because backyard animals are frequently privately owned, and the resulting products are typically not marketed, very little information is available about the demographic profile of backyard owners and information on flocks' characteristics, husbandry, and welfare. Thus, this review aims to clarify the characteristics of backyard poultry, highlighting the prevalent infectious diseases and the zoonotic risk to which farmers are exposed. According to the FAO, there are different types of poultry production systems: intensive, sub-intensive, and extensive. The system conditions, requirements, and the resulting performance differ extensively due to the type of breed, feeding practices, prevalence of disease, prevention and control of diseases, flock management, and the interactions among all these factors. The presence and transmission of infectious diseases in avian species is a problem that affects both the animals themselves and public health. Bacterial (Escherichia coli, Salmonella, Campylobacter, and Mycoplasma), parasitic (helminths, louses, and mites), and viral (Avian influenza, Newcastle, Marek, Infectious Bronchitis, Gumboro, Infectious Laringotracheitis, and Fowlpox) are the most important pathogens involved in backyard poultry health. In addition, Avian influenza, Salmonella, Campylobacter, and E. coli, could be a risk for backyard farmers and/or backyard-derived products consumers. Thus, proper biosecurity implementation measures are mandatory to control them. While the principles and practices of on-farm biosecurity may be well-versed among commercial farmers, hobbyists, and backyard farmers might not be familiar with the necessary steps to protect their flocks from infectious diseases and curb their transmission. This sector represents the fourth category of poultry farming, characterized by the lowest biosecurity standards. Consequently, it is imperative to address the legal status of backyard poultry, educate owners about biosecurity measures, and promote proper veterinary care and disease control.

Synthesis and antibacterial activity of FST and its effects on inflammatory response and intestinal barrier function in mice infected with Escherichia coli O78

Pathogenic Escherichia coli (E. coli) can cause intestinal diseases in humans and livestock, damage the intestinal barrier, increase systemic inflammation, and seriously threaten human health and the development of animal husbandry. In this study, we designed and synthesized a novel conjugate florfenicol sulfathiazole (FST) based on drug combination principles, and investigated its antibacterial activity in vitro and its protective effect on inflammatory response and intestinal barrier function in E. coli O78-infected mice in vivo. The results showed that FST had superior antibacterial properties and minimal cytotoxicity compared with its prodrugs as florfenicol and sulfathiazole. FST protected mice from lethal E. coli infection, reduced clinical signs of inflammation, reduced weight loss, alleviated intestinal structural damage. FST decreased the expression of inflammatory cytokines IL-1β, IL-6, TNF-α, and increased the expression of claudin-1, Occludin, and ZO-1 in the jejunum, improved the intestinal barrier function, and promoted the absorption of nutrients. FST also inhibited the expression of TLR4, MyD88, p-p65, and p-p38 in the jejunum. The study may lay the foundation for the development of FST as new drugs for intestinal inflammation and injury in enteric pathogen infection.

Association Between Escherichia coli Load in the Gut and Body Weight Gain in Broiler Chickens: A Systematic Review and Meta-Analysis

Escherichia coli is one of the first commensal bacteria to colonize the chicken gut, where it predominates at an early stage of broiler chick life. Escherichia coli can potentially cause colibacillosis in chickens, spreading to extraintestinal systemic organs, which results in high economic losses in poultry industry, as well as a potential risk to public health. Many studies conducted to investigate the effectiveness of natural products as alternatives to antibiotics and to enhance the production performance in broiler chickens have assessed E. coli load in the chicken gut, but it is still unknown how the E. coli count is linked to broiler growth performance. A systematic search of published research articles, including key terms of interest such as broiler chickens, growth performance, and E. coli count, was conducted using two main databases (PubMed and the Web of Science). A random effects metaregression model was built to evaluate the association between E. coli count and weight gain in untreated groups of broilers (negative controls) from eligible studies. Of 2108 articles in the initial screening, 60 were included in the final meta-analysis. After data extraction, records from the ileum and cecum at 21, 35, and 42 days of age were considered for the meta-analysis. The meta-analysis showed that the average E. coli count in both the ileum and cecum at 21 days of age was positively associated with the average weight gain in the studied broiler chickens, while no statistically significant associations were found at 35 and 42 days of age. In conclusion, the positive association between E. coli load and body weight gain in young broiler chickens may be attributed to the relative dominance of E. coli in the gut of this age group when the microbial population is less diverse. The dynamic association between the production performance and the load of E. coli that has dubious pathogenic potential suggests the importance of careful assessment of commensal E. coli to develop strategies to enhance production, particularly in young broiler chickens.

Characterization of ESBL/AmpC-producing extraintestinal Escherichia coli (ExPEC) in dogs treated at a veterinary hospital in Brazil

The clinical aspects and lineages involved in Extraintestinal pathogenic Escherichia coli (ExPEC) infections in dogs remain largely unknown. In this study, we investigated the antimicrobial resistance and molecular structures of ExPECs isolated from infected dogs in Brazil. Samples were obtained from dogs (n = 42) with suspected extraintestinal bacterial infections. Phylogroup B2 was predominant (65.1%). No association was observed between the site of infection, phylogroups, or virulence factors. Almost half of the isolates (44.2%) were MDR, and 20.9% were extended-spectrum β-lactamase (ESBL)-positive. E. coli isolates that were resistant to fluoroquinolones (27.9%) were more likely to be MDR. The CTX-M-15 enzyme was predominant among the ESBL-producing strains, and seven sequence types were identified, including the high-risk clones ST44 and ST131. Single SNPs analysis confirmed the presence of two clonal transmissions. The present study showed a high frequency of ExPECs from phylogroup B2 infecting various sites and a high frequency of ESBL-producing strains that included STs frequently associated with human infection. This study also confirmed the nosocomial transmission of ESBL-producing E. coli, highlighting the need for further studies on the prevention and diagnosis of nosocomial infections in veterinary settings.

Surveillance of Escherichia coli in different types of chicken and duck hatcheries: one health outlook

Escherichia coli is an important zoonotic bacterium that significantly impacts one health concept. E. coli is normally detected in the gut of warm-blooded animals, but some serotypes can cause diseases in humans and animals. Moreover, it can continue for a long time in different environments, replicate in water, and survive outside different hosts. In this study, 171 samples collected from 10 different types of poultry hatcheries (automatic, semiautomatic, and manual "traditional" types) were examined for the prevalence of E. coli. PCR was applied to verify the E. coli isolates via 16S rRNA gene-specific primers. From the gathered samples, 62 E. coli isolates were recovered (36.3%). The highest prevalence was met with the manual "traditional" hatcheries (57.1%) with no significance difference (P = 0.243) in the 3 types of hatcheries. The incidence of E. coli varied significantly in different tested avian types and breeds. The prevalence was 35.7% in duck hatcheries and 37% in chicken hatcheries, with significant differences between breeds of both species (P = 0.024 and 0.001, respectively). The identification of zoonotic E. coli serotypes in this study is concerning, highlighting the need for collaborative efforts across various sectors, including social, environmental, and governance, to promote the adoption of the one health principle in the chicken business. Periodical surveillance, biosecurity measures at the hatcheries and farm levels, and boosting the immunity of birds were recommended to limit the risk of E. coli spread from avian sources to humans.

ProQ binding to small RNA RyfA promotes virulence and biofilm formation in avian pathogenic Escherichia coli

Avian pathogenic Escherichia coli (APEC) is a notable subpathotype of the nonhuman extraintestinal pathogenic E. coli (ExPEC). Recognized as an extraintestinal foodborne pathogen, the zoonotic potential of APEC/ExPEC allows for cross-host transmission via APEC-contaminated poultry meat and eggs. ProQ, an RNA binding protein, is evolutionarily conserved in E. coli. However, its regulatory roles in the biofilm formation and virulence of APEC/ExPEC have not been explored. In this study, proQ deletion in the APEC strain FY26 significantly compromised its biofilm-forming ability. Furthermore, animal tests and cellular infection experiments showed that ProQ depletion significantly attenuated APEC virulence, thereby diminishing its capacity for bloodstream infection and effective adherence to and persistence within host cells. Transcriptome analysis revealed a decrease in the transcription level of the small RNA (sRNA) RyfA in the mutant FY26ΔproQ, suggesting a direct interaction between the sRNA RyfA and ProQ. This interaction might indicate that sRNA RyfA is a novel ProQ-associated sRNA. Moreover, the direct binding of ProQ to the sRNA RyfA was crucial for APEC biofilm formation, pathogenicity, adhesion, and intracellular survival. In conclusion, our findings provide detailed insight into the interaction between ProQ and sRNA RyfA and deepen our understanding of the regulatory elements that dictate APEC virulence and biofilm development. Such insights are instrumental in developing strategies to counteract APEC colonization within hosts and impede APEC biofilm establishment on food surfaces.

NhaA facilitates the maintenance of bacterial envelope integrity and the evasion of complement attack contributing to extraintestinal pathogenic Escherichia coli virulence

Extraintestinal pathogenic Escherichia coli (ExPEC) is responsible for severe bloodstream infections in humans and animals. However, the mechanisms underlying ExPEC's serum resistance remain incompletely understood. Through the transposon-directed insertion-site sequencing approach, our previous study identified nhaA, the gene encoding a Na+/H+ antiporter, as a crucial factor for infection in vivo. In this study, we investigated the role of NhaA in ExPEC virulence utilizing both in vitro models and systemic infection models involving avian and mammalian animals. Genetic mutagenesis analysis revealed that nhaA deletion resulted in filamentous bacterial morphology and rendered the bacteria more susceptible to sodium dodecyl sulfate, suggesting the role of nhaA in maintaining cell envelope integrity. The nhaA mutant also displayed heightened sensitivity to complement-mediated killing compared to the wild-type strain, attributed to augmented deposition of complement components (C3b and C9). Remarkably, NhaA played a more crucial role in virulence compared to several well-known factors, including Iss, Prc, NlpI, and OmpA. Our findings revealed that NhaA significantly enhanced virulence across diverse human ExPEC prototype strains within B2 phylogroups, suggesting widespread involvement in virulence. Given its pivotal role, NhaA could serve as a potential drug target for tackling ExPEC infections.

Genome-Wide Analysis of Escherichia coli Isolated from Dairy Animals Identifies Virulence Factors and Genes Enriched in Multidrug-Resistant Strains

The gastrointestinal tracts of dairy calves and cows are reservoirs of antimicrobial-resistant bacteria (ARB), which are present regardless of previous antimicrobial therapy. Young calves harbor a greater abundance of resistant bacteria than older cows, but the factors driving this high abundance are unknown. Here, we aimed to fully characterize the genomes of multidrug-resistant (MDR) and antimicrobial-susceptible Escherichia coli strains isolated from pre-weaned calves, post-weaned calves, dry cows, and lactating cows and to identify the accessory genes that are associated with the MDR genotype to discover genetic targets that can be exploited to mitigate antimicrobial resistance in dairy farms. Results indicated that both susceptible and resistant E. coli isolates recovered from animals on commercial dairy operations were highly diverse and encoded a large pool of virulence factors. In total, 838 transferrable antimicrobial resistance genes (ARGs) were detected, with genes conferring resistance to aminoglycosides being the most common. Multiple sequence types (STs) associated with mild to severe human gastrointestinal and extraintestinal infections were identified. A Fisher's Exact Test identified 619 genes (ARGs and non-ARGs) that were significantly enriched in MDR isolates and 147 genes that were significantly enriched in susceptible isolates. Significantly enriched genes in MDR isolates included the iron scavenging aerobactin synthesis and receptor genes (iucABCD-iutA) and the sitABCD system, as well as the P fimbriae pap genes, myo-inositol catabolism (iolABCDEG-iatA), and ascorbate transport genes (ulaABC). The results of this study demonstrate a highly diverse population of E. coli in commercial dairy operations, some of which encode virulence genes responsible for severe human infections and resistance to antibiotics of human health significance. Further, the enriched accessory genes in MDR isolates (aerobactin, sit, P fimbriae, and myo-inositol catabolism and ascorbate transport genes) represent potential targets for reducing colonization of antimicrobial-resistant bacteria in the calf gut.

Complete closed genome sequences of three multidrug-resistant uropathogenic Escherichia coli

Infection by antibiotic-resistant extraintestinal pathogenic Escherichia coli may result in treatment failure and thus pose a serious public health threat. Here we report the complete closed genome sequence of three multidrug-resistant (MDR) human uropathogenic E. coli isolates using long-read sequencing technology and de novo assembly.

Emergence and Genomic Features of a mcr-1 Escherichia coli from Duck in Hungary

Plasmids carrying high-risk resistance mechanisms in pathogenic E. coli have gained particular attention in veterinary medicine, especially since the discovery of the colistin resistance gene, mcr-1. Here, we provide the first evidence of its emergence and describe the complete mcr-1 plasmid sequence of a multi-resistant avian pathogenic E. coli (APEC) strain from waterfowl in Hungary. Whole-genome sequencing analysis and core-genome MLST were performed to characterize the genome structure of the mcr-1 plasmid and to reveal the phylogenetic relation between the Hungarian duck strain Ec45-2020 and the internationally circulating mcr-1-positive E. coli strains from poultry and humans. Results showed that plasmid pEc45-2020-33kb displayed a high level of genome identity with mcr-1 plasmids of IncX4 type widespread among human, animal and food reservoirs of enteric bacteria of public health. The mcr-1-positive E. coli strain Ec45-2020 belongs to the ST162 genotype, considered as one of the globally disseminated zoonotic genotypes of MDR E. coli. In accordance with international findings, our results underline the importance of continuous surveillance of enteric bacteria with high-risk antimicrobial resistance genotypes, including neglected animals, such as waterfowls, as possible reservoirs for the colistin resistance gene mcr-1.

A lytic phage to control multidrug-resistant avian pathogenic Escherichia coli (APEC) infection

The inappropriate use of antibiotics has led to the emergence of multidrug-resistant strains. Bacteriophages (phages) have gained renewed attention as promising alternatives or supplements to antibiotics. In this study, a lytic avian pathogenic Escherichia coli (APEC) phage designated as PEC9 was isolated and purified from chicken farm feces samples. The morphology, genomic information, optimal multiplicity of infection (MOI), one-step growth curve, thermal stability, pH stability, in vitro antibacterial ability and biofilm formation inhibition ability of the phage were determined. Subsequently, the therapeutic effects of the phages were investigated in the mice model. The results showed that PEC9 was a member of the siphovirus-like by electron microscopy observation. Biological characterization revealed that it could lyse two serotypes of E. coli, including O1 (9/20) and O2 (6/20). The optimal multiplicity of infection (MOI) of phage PEC9 was 0.1. Phage PEC9 had a latent period of 20 min and a burst period of 40 min, with an average burst size of 68 plaque-forming units (PFUs)/cell. It maintained good lytic activity at pH 3-11 and 4-50°C and could efficiently inhibit the bacterial planktonic cell growth and biofilm formation, and reduce bacterial counts within the biofilm, when the MOI was 0.01, 0.1, and 1, respectively. Whole-genome sequencing showed that PEC9 was a dsDNA virus with a genome of 44379 bp and GC content of 54.39%. The genome contains 56 putative ORFs and no toxin, virulence, or resistance-related genes were detected. Phylogenetic tree analysis showed that PEC9 is closely related to E. coli phages vB_EcoS_Zar3M, vB_EcoS_PTXU06, SECphi18, ZCEC10, and ZCEC11, but most of these phages exhibit different gene arrangement. The phage PEC9 could successfully protect mice against APEC infection, including improved survival rate, reduced bacterial loads, and organ lesions. To conclude, our results suggest that phage PEC9 may be a promising candidate that can be used as an alternative to antibiotics in the control of APEC infection.

Antimicrobial Resistance in Escherichia coli and Its Correlation with Antimicrobial Use on Commercial Poultry Farms in Bangladesh

Antimicrobial resistance is a global concern, posing risks to human and animal health. This research quantified antimicrobial resistance (AMR) in E. coli isolates from poultry fecal and environmental samples in Bangladesh and explored their association with antimicrobial use (AMU). We screened 725 fecal and 250 environmental samples from 94 conventional broilers and 51 Sonali farms for E. coli presence using MALDI-TOF mass spectrometry. AMU data were collected at flock levels, expressed as treatment incidence (TI), while minimum inhibitory concentrations (MIC) for 14 antibiotics were determined on five fecal E. coli isolates per farm and on all environmental isolates. MIC results were interpreted using human clinical breakpoints and EUCAST epidemiological cut-off values (ECOFFs). Acquired resistance against commonly used antimicrobial agents such as ciprofloxacin, tetracycline and ampicillin, was extremely high and predominantly clinically relevant. There was a moderate correlation between fecal and environmental antibiotic resistance index (ARI), but there was no significant correlation between AMU and AMR, suggesting that the observed AMR prevalence is unrelated to current AMU in poultry, but may be due to high historical AMU. A high level of multidrug resistance, including against critically important antimicrobials, was found in both farm types. Therefore, an AMR/AMU surveillance program is urgently needed in the poultry production sector of Bangladesh.

Baicalin Weakens the Porcine ExPEC-Induced Inflammatory Response in 3D4/21 Cells by Inhibiting the Expression of NF-κB/MAPK Signaling Pathways and Reducing NLRP3 Inflammasome Activation

Porcine extraintestinal pathogenic Escherichia coli (ExPEC) is a leading cause of death in pigs and has led to considerable economic losses for the pig industry. Porcine ExPEC infections often cause systemic inflammatory responses in pigs, characterized by meningitis, arthritis, pneumonia, and septicemia. Baicalin has been reported to possess potent anti-inflammatory activity, but its function in porcine ExPEC remains unknown. The aim of this study was to explore the protective effect and mechanism of baicalin against the porcine ExPEC-induced inflammatory responses in 3D4/21 cells. After treatment with baicalin, the effects on cell damage, the level of pro-inflammatory cytokines, the expression of nuclear factor-κB (NF-κB)/mitogen-activated protein kinase (MAPK) signaling pathways, and the activation of NOD-like receptor protein 3 (NLRP3) inflammasomes were examined. Our results show that baicalin significantly reduced the damage to 3D4/21 cells infected with porcine ExPEC PCN033. Further study showed that baicalin significantly reduced the transcription and expression of pro-inflammatory cytokines such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and interleukin-8 (IL-8). Furthermore, baicalin inhibited the phosphorylation of proteins such as P65, nuclear factor κB inhibitor α (IκBα), extracellular regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and P38 and reduced the expression levels of proteins such as NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), and caspase-1. These results reveal that baicalin reduced the damage to 3D4/21 cells by inhibiting the expression of NF-κB/MAPK signaling pathways and blocking NLRP3 inflammasome activation in 3D4/21 cells infected with porcine ExPEC. Taken together, these results suggest that baicalin may have potential as a medicine for the treatment of porcine ExPEC-infected pigs by regulating inflammatory responses. This study provides a novel potential pharmaco-therapeutic approach to preventing porcine ExPEC infection.

Antimicrobial Efficacy of Cinnamon Essential Oil against Avian Pathogenic Escherichia coli from Poultry

Colibacillosis, caused by E. coli, is responsible for economic losses in the poultry industry due to mortality, decreased production, and the cost of antibiotic treatments. Prevention of colibacillosis is based on improved biosecurity measures and the use of the vaccine performed with O78 E. coli strains, which is responsible for most cases of colibacillosis. Recently, there has been increased interest in other infection control methods, such as the use of natural compounds. The aim of this study was to evaluate the antimicrobial efficacy of cinnamon essential oil (CEO) against E. coli strains isolated from poultry. The MIC50 and MIC90 of CEO were determined by testing 117 strains belonging to serogroups O78, O2, O128, O139, isolated from laying hens (91 strains), broilers (10 strains), and turkeys (16 strains). The bacterial strains were tested at cell densities of 108 and 106 CFU/mL. At the cell density of 108 CFU/mL, MIC50 and MIC90 were 0.4 and 0.5 µL/mL for most of the tested strains, while they corresponded to 0.5 µL/mL for all strains isolated from broilers and for strains belonging to serogroup O139. At the cell density of 106 CFU/mL, MIC50 and MIC90 were 0.3 and 0.4 µL/mL, regardless of bird species of origin and for strains belonging to serogroups O78 and O2. In addition, a concentration of 0.04 µL/mL of CEO corresponded both to MIC50 and MIC90 for strains belonging to serogroups O139 and O128. Based on these results, cinnamon essential oil showed an effective antibacterial activity against E. coli strains from poultry and could find field application for the prevention of colibacillosis.

Characterization of two novel lytic bacteriophages having lysis potential against MDR avian pathogenic Escherichia coli strains of zoonotic potential

Avian pathogenic E. coli (APEC) is associated with local and systemic infections in poultry, ducks, turkeys, and many other avian species, leading to heavy economical losses. These APEC strains are presumed to possess zoonotic potential due to common virulence markers that can cause urinary tract infections in humans. The prophylactic use of antibiotics in the poultry sector has led to the rapid emergence of Multiple Drug Resistant (MDR) APEC strains that act as reservoirs and put human populations at risk. This calls for consideration of alternative strategies to decrease the bacterial load. Here, we report isolation, preliminary characterization, and genome analysis of two novel lytic phage species (Escherichia phage SKA49 and Escherichia phage SKA64) against MDR strain of APEC, QZJM25. Both phages were able to keep QZJM25 growth significantly less than the untreated bacterial control for approximately 18 h. The host range was tested against Escherichia coli strains of poultry and human UTI infections. SKA49 had a broader host range in contrast to SKA64. Both phages were stable at 37 °C only. Their genome analysis indicated their safety as no recombination, integration and host virulence genes were identified. Both these phages can be good candidates for control of APEC strains based on their lysis potential.

High resistance of fluoroquinolone and macrolide reported in avian pathogenic Escherichia coli isolates from the humid subtropical regions of Pakistan

OBJECTIVES

This study aimed to assess the antimicrobial resistance profile, virulence potential, and genetic characterization of avian pathogenic Escherichia coli (APEC) that cause colibacillosis in poultry.

METHODS

Antibiotic susceptibility testing (AST) was measured via the Kirby-Bauer disc diffusion method against 27 commonly used antibiotics. Phylogrouping, virulence-associated gene detection, and hybrid strain detection via multiplex polymerase chain reaction (PCR) and genetic diversity were analysed via ERIC-PCR fingertyping method.

RESULTS

AST analysis showed 100% of isolates were multidrug-resistant (MDR) and highest resistance was against penicillin, tetracycline, and macrolide classes of antibiotics. The mcr-1 gene was present in 40% of the isolates, though only 4% of isolates were showing phenotypic resistance. Despite the scarce use of fluoroquinolone, carbapenem, and cephalosporin in the poultry sector, resistance was evident because of the high prevalence of extended-spectrum β-lactamase (ESBL) (53.7%) and other β-lactamases in APEC isolates. β-lactamase genotyping of APEC isolates revealed that 85.7% of isolates contained either blaCTX or blaTEM and around 38% of isolates were complement resistant. Growth in human urine was evident in 67.3% of isolates. Phylogroup B1 (51%) was the most prevalent group followed by phylogroups A (30.6%), D (13.61%), and B2 (4.76%). The most prevalent virulence-associated genes were fimH, iss, and tatT. Results showed that 26 isolates (17.69%) can be termed hybrid strains and APEC/EHEC (enterohemorrhagic E. coli) was the most prevalent hybrid E. coli pathotype. ERIC-PCR fingerprinting genotype analysis clustered APEC isolates in 40 groups (E1-E40). This study provides insights into the antibiotic resistance and virulence profiling of the APEC isolates in Pakistan.

CONCLUSIONS

The findings of this study provide insights into that the antibiotic resistance and virulence profiling of the APEC isolates in Pakistan. This data can inform future studies designed to better estimate the severity of the colibacillosis in poultry farms.

First report of mobile colistin resistance gene mcr-1 in avian pathogenic Escherichia coli isolated from turkeys in the Gaza Strip, Palestine

Background and Aim

Colistin is used to treat avian pathogenic Escherichia coli (APEC), a microorganism that affects turkey meat production in the Gaza Strip and worldwide. However, the recent emergence of plasmid-borne mobile colistin resistance (mcr) genes in pathogenic E. coli strains is a serious antimicrobial resistance (AMR) challenge for both human and animal health. In December 2018, colistin was banned as a veterinary antimicrobial in the Gaza Strip. This study aimed to detect and track the prevalence of colistin-resistant APEC isolated from turkey flocks in the Gaza Strip.

Materials and Methods

This study investigated 239 APEC isolates from turkey flocks in the Gaza Strip between October 2018 and December 2021 (at 6-month intervals). The colistin-resistant APEC strains were detected using the broth microdilution method. The mcr-1 gene was identified using a polymerase chain reaction.

Results

The overall colistin resistance among the isolated APECs was 32.2% during the study period. The average resistance in the first interval was 37.5%, which significantly decreased to 9.3% in the last interval. Among the 77 phenotypically resistant isolates, 32.4% were positive for mcr-1. The average abundance of mcr-1 in the first interval was 66.6%, which decreased to 25% in the last interval.

Conclusion

To the best of our knowledge, this is the first study reporting the presence of the mcr-1 gene among the APEC isolates from turkeys in the Gaza Strip. Banned veterinary use of colistin significantly decreased the percentage of resistant APEC isolates from turkeys in Gaza Strip. Further studies are needed to investigate other colistin resistance genes and track the emergence of AMR.

Antimicrobial resistance profiles of Escherichia coli isolated from laying hens in Zambia: implications and significance on one health

Background

Antimicrobial resistance (AMR) has been deepening in the layer poultry sector in Zambia partly due to the inappropriate use of antimicrobials. Escherichia coli (E. coli), a commensal and zoonotic bacterium, can potentially be a source of AMR.

Objectives

This study assessed the phenotypic AMR profiles of E. coli isolated from the apparent health-laying hens in Lusaka and Copperbelt provinces of Zambia.

Methods

A cross-sectional study was conducted between September 2020 and April 2021 in which 365 cloacal swabs were collected from 77-layer farms based in Lusaka and Copperbelt provinces of Zambia. E. coli isolation and identification were done using cultural and biochemical properties and confirmed using the 16S rRNA gene sequencing. Antimicrobial susceptibility testing (AST) was done using the Kirby-Bauer disc-diffusion method. Data analysis was done using WHONET 2020 and Stata v.16.1.

Results

Of the 365 samples, E. coli was isolated from 92.9% (n = 339). The AMR was detected in 96.5% (n = 327) of the isolates, of which 64.6% (n = 219) were multidrug-resistant (MDR). E. coli was highly resistant to tetracycline (54.6%) and ampicillin (54%) but showed low resistance to meropenem (0.9%), ceftazidime (6.2%) and chloramphenicol (8.8%).

Conclusion

This study found a high prevalence of E. coli resistant to some commonly used antibiotics in poultry, which is a public health concern because of the potential contamination of eggs and layers of chicken meat that enter the food chain. Urgent attention is needed, including strengthening antimicrobial stewardship and surveillance programmes in layer poultry production in Zambia.

Long noncoding RNAs expression profile of RIP2 knockdown in chicken HD11 macrophages associated with avian pathogenic E. coli (APEC) infection

Avian pathogenic E. coli (APEC) has been detected to cause many acute and chronic diseases, resulting in huge economic losses to the poultry industry. Previous experiments have identified the effect of receptor interacting serine/threonine kinase 2 (RIP2) gene in APEC infection. Moreover, increasing evidence indicates that long noncoding RNAs (lncRNAs) play important roles in the anti-bacteria responses. However, little is known about the functions of lncRNAs, especially related to RIP2, in response to APEC. Therefore, we tried to reveal lncRNAs potentially involved in the immune and inflammatory response against APEC infection, with a particular focus on those possibly correlated with RIP2. A total of 1856 and 1373 differentially expressed (DE) lncRNAs were identified in knockdown of RIP2 cells following APEC infection (shRIP2+APEC) vs. APEC and shRIP2 vs. wild type cells (WT), respectively, which were mainly enriched in lysosome, phagosome, NOD-like receptor signaling pathway, TGF-beta signaling pathway. Significantly, TCONS_00009695 regulated by RIP2 could directly alter the expression of target BIRC3 to modulate cytokines and to participate in immune and inflammatory response against APEC infection. Our findings aid to a better understanding of host responses to APEC infection and provide new directions for understanding the potential association between lncRNAs and APEC pathogenesis.

Integrated analysis of mRNA and microRNA expression pattern reveals differential transcriptome signatures in RIPK2 over-expressing chicken macrophages infected with avian pathogenic E. coli

1. As RIPK2 (receptor interacting serine/threonine kinase 2) has been shown to to alleviate excessive inflammatory responses, the following study conducted a systematic and in-depth analysis of the mRNA-seq and miRNA-seq data from chicken macrophages with/without over-expression of RIPK2 (oeRIPK2) combined with/without avian pathogenic E. coli (APEC) infection to identify the miRNA-mRNA interaction network and potential signalling pathways involved.2. A total of 9,201 differentially expressed (DE) mRNAs and 300 DE miRNA were identified in both oeRIPK2+APEC vs. APEC and oeRIPK2 vs. the wild-type (WT). Moreover, 4,269 instances of co-expression between miRNAs and mRNAs were seen involving 1,652 DE mRNAs and 164 DE miRNAs.3. Functional analysis of the DE mRNAs in the miRNA-mRNA interaction network showed that 223 biological processes and five KEGG pathways were significantly enriched in the two comparisons. In total, 128 pairs of miRNA-mRNA interactions were involved in the identified MAPK signalling pathway and focal adhesion immune related pathways.4. Significantly, these screened miRNAs (gga-miR-222b-5p and gga-miR-214) and their target genes were highly correlated with APEC infection and RIPK2. These recognised key genes, miRNA and the overall miRNA-mRNA regulatory network, enables better understanding of the molecular mechanism of host response to APEC infection, especially related to RIPK2.

Characterization of unconventional pathogenic Escherichia coli isolated from bloodstream infection: virulence beyond the opportunism

Extraintestinal pathogenic Escherichia coli (ExPEC) is the leading cause of urinary tract infection worldwide and a critical bloodstream infection agent. There are more than 50 virulence factors (VFs) related to ExPEC pathogenesis; however, many strains isolated from extraintestinal infections are devoid of these factors. Since opportunistic infections may occur in immunocompromised patients, E. coli strains that lack recognized VFs are considered opportunist, and their virulence potential is neglected. We assessed eleven E. coli strains isolated from bloodstream infections and devoid of the most common ExPEC VFs to understand their pathogenic potential. The strains were evaluated according to their capacity to interact in vitro with human eukaryotic cell lineages (Caco-2, T24, HEK293T, and A549 cells), produce type 1 fimbriae and biofilm in diverse media, resist to human sera, and be lethal to Galleria mellonella. One strain displaying all phenotypic traits was sequenced and evaluated. Ten strains adhered to Caco-2 (colon), eight to T24 (bladder), five to HEK-293 T (kidney), and four to A549 (lung) cells. Eight strains produced type 1 fimbriae, ten adhered to abiotic surfaces, nine were serum resistant, and seven were virulent in the G. mellonella model. Six of the eleven E. coli strains displayed traits compatible with pathogens, five of which were isolated from an immune-competent host. The genome of the EC175 strain, isolated from a patient with urosepsis, reveals that the strain belonged to ST504-A, and serotype O11:H11; harbors thirteen VFs genes, including genes encoding UpaG and yersiniabactin as the only ExPEC VFs identified. Together, our results suggest that the ExPEC pathotype includes pathogens from phylogroups A and B1, which harbor VFs that remain to be uncovered.

Chicken Production and Human Clinical Escherichia coli Isolates Differ in Their Carriage of Antimicrobial Resistance and Virulence Factors

Contamination of food animal products by Escherichia coli is a leading cause of foodborne disease outbreaks, hospitalizations, and deaths in humans. Chicken is the most consumed meat both in the United States and across the globe according to the U.S. Department of Agriculture. Although E. coli is a ubiquitous commensal bacterium of the guts of humans and animals, its ability to acquire antimicrobial resistance (AMR) genes and virulence factors (VFs) can lead to the emergence of pathogenic strains that are resistant to critically important antibiotics. Thus, it is important to identify the genetic factors that contribute to the virulence and AMR of E. coli. In this study, we performed in-depth genomic evaluation of AMR genes and VFs of E. coli genomes available through the National Antimicrobial Resistance Monitoring System GenomeTrackr database. Our objective was to determine the genetic relatedness of chicken production isolates and human clinical isolates. To achieve this aim, we first developed a massively parallel analytical pipeline (Reads2Resistome) to accurately characterize the resistome of each E. coli genome, including the AMR genes and VFs harbored. We used random forests and hierarchical clustering to show that AMR genes and VFs are sufficient to classify isolates into different pathogenic phylogroups and host origin. We found that the presence of key type III secretion system and AMR genes differentiated human clinical isolates from chicken production isolates. These results further improve our understanding of the interconnected role AMR genes and VFs play in shaping the evolution of pathogenic E. coli strains. IMPORTANCE Pathogenic Escherichia coli causes disease in both humans and food-producing animals. E. coli pathogenesis is dependent on a repertoire of virulence factors and antimicrobial resistance genes. Food-borne outbreaks are highly associated with the consumption of undercooked and contaminated food products. This association highlights the need to understand the genetic factors that make E. coli virulent and pathogenic in humans and poultry. This research shows that E. coli isolates originating from human clinical settings and chicken production harbor different antimicrobial resistance genes and virulence factors that can be used to classify them into phylogroups and host origins. In addition, to aid in the repeatability and reproducibility of the results presented in this study, we have made a public repository of the Reads2Resistome pipeline and have provided the accession numbers associated with the E. coli genomes analyzed.

Caracterización fenotípica y molecular de colifagos de granjas de pollos de engorde con Colibacilosis y plantas beneficiadoras de aves en Azuay, Ecuador

La Escherichia coli patógena extraintestinal, denominada E. coli patógena aviar, posee atributos de virulencia específicos que causan infecciones invasivas en aves de corral, responsables de la Colibacilosis aviar. Los veterinarios tienen opciones restringidas de agentes antimicrobianos para su tratamiento, debido a problemas de resistencia bacteriana de la E. coli, que incide indirectamente en la salud humana. Como alternativa se plantea el uso de bacteriófagos con poder bacteriolítico específico contra bacterias enteropatógenas. El objetivo de este estudio fue el de caracterizar bacteriófagos líticos específicos para E. coli (colifagos) como una alternativa de biocontrol contra la colibacilosis aviar, determinando su especificidad frente a E. coli enteropatógenas aisladas de la zona, su capacidad lítica, fenotipo y genotipo. Para ello se recolectaron muestras ambientales de plantas beneficiadoras avícolas y de aguas residuales en granjas de producción con problemas de colibacilosis. Se procedió al aislamiento de bacteriófagos con actividad lítica aparente frente a E. coli TOP10F´ y sobre los aislados de E. coli patógenas previamente caracterizadas de la zona. Un total de 36 aislados de colifagos líticos fueron enfrentados a 10 cepas patógenas de E. coli. De éstos, 22 fagos afectaron entre el 10–50 % de las cepas evaluadas, 5 fagos infectaron entre el 60 y 70 % y solo 9 fagos no mostraron capacidad lítica frente a las cepas patógenas de E. coli. Los fagos con capacidad lítica más alta fueron seleccionados y caracterizados genotípicamente mediante la técnica de fragmentos de restricción de longitud polimórfica (RFLP), posterior a su tratamiento con enzimas de restricción: BamHI, EcoRI, EcoRV y Hind III. Como resultado se obtuvieron 4 colifagos con diferentes patrones de banda. Se concluye que, en muestras ambientales de granjas avícolas diagnosticadas de colibacilosis, se pueden aislar una gran variedad de colifagos con potencial lítico para el biocontrol de E. coli patógena.

The shared NDM-positive strains in the hospital and connecting aquatic environments

The spread of antibiotic-resistant priority pathogens outside hospital settings is, both, a significant public health concern and an environmental problem. In recent years, New Delhi Metallo-β-lactamase (NDM)-positive strains have caused nosocomial infections with high mortality and poor prognosis worldwide. Our study investigated the links of NDM-positive strains between the hospital and the connecting river system in Jinan city, Eastern China by using NDM-producing Escherichia coli (NDM-EC) as an indicator via whole genome sequencing. Thirteen NDM-EC isolates were detected from 187 river water and sediment samples, while 9 isolates were identified from patients at the local hospital. All NDM-EC isolates were resistant to imipenem, meropenem, cefotaxime, cefoxitin, ampicillin, tetracycline, fosfomycin, piperacillin-tazobactam. The bla_NDM-5 (n = 20) and bla_NDM-9 (n = 2) genes were identified, which were predominantly on IncX3 plasmids (n = 13), followed by IncFII plasmids (n = 5) and IncFIA plasmids (n = 2). Conjugation experiments showed that 21 isolates could transfer NDM-harboring plasmids. The well-conserved bla_NDM-5 genetic environment (ISAba125-bla_NDM-5/9-ble_MBL-trpF-dsbD-IS26) of these plasmids suggested a common genetic origin. Nine sequence types (STs) were detected, including three international high-risk clones ST167 (n = 8), ST410 (n = 1), and ST617 (n = 1). Phylogenetic analysis showed ST167 E. coli from the river was genotypically related to clinical isolates recovered from patients. Furthermore, ST167 isolates showed high genetic similarities with other clinical strains from geographically distinct regions. The genetic concordance between isolates from different sampling sites in the same river (ST218 clone), and different rivers (ST448 clone) raises concerns regarding the rapid dissemination of NDM-EC in the aquatic environment. The emergence and spread of the clinically relevant NDM-positive strains, especially for E. coli ST167 clone, an international high-risk clone associated with multi-resistance and virulence capacity, within and between the hospital and aquatic environments were elucidated, highlighting the need for attention and action.

Dramatic increase in slaughter condemnations due to Escherichia coli ST23 and ST101 within the Danish broiler production

Escherichia coli constitutes a major challenge to poultry even when the prevalence of colibacillosis is low. Additionally, specific E. coli strains can severely enhance the detrimental effects on productivity, animal welfare and antimicrobial use. In 2019-2020, a dramatic increase in colibacillosis occurred among Danish broilers causing late-onset mortality and high slaughter condemnations. In the present study, the pathology and causative E. coli-types were characterised. Furthermore, the outbreak-related strains were compared to isolates from concurrent "background" colibacillosis. During the study, 1039 birds were subjected to a comprehensive post-mortem examination, and a total of 349 E. coli isolates were sequenced and characterised by multi-locus sequence typing, virulence and resistance gene presence, plasmid replicon content and phylogenetic analysis. Productivity data from outbreak flocks revealed a mortality of 6.34% ± 3.74 and a condemnation of 5.04% ± 3.67. Contrary, the numbers were 3.18% ± 1.57% and 1.02% ± 0.4 among non-outbreak flocks, respectively. Major lesions were cellulitis (46.82%), airsacculitis (67.63%), pericarditis (55.49%), perihepatitis (41.04%) and femoral head necrosis with physeal/metaphyseal involvement (44.51%). Among non-outbreak broilers, the prevalence was 4.46%, 7.64%, 7.01%, 3.82% and 8.28%, respectively. ST23 and ST101 dominated heavily in outbreak flocks, whereas non-outbreak related isolates consisted of various other STs. A low level of resistance markers was evident, except in few multidrug-resistant isolates. Within ST23 and ST101, 13 and 12 virulence genes were significantly over-represented compared to non-outbreak isolates. In conclusion, clonal lineages were documented as the cause of a devastating outbreak of colibacillosis with great prospects for future interventions.

In vitro digestion of ESC-resistant Escherichia coli from poultry meat and evaluation of human health risk

Introduction

The spread of antimicrobial resistance (AMR) has become a threat against human and animal health. Third and fourth generation cephalosporins have been defined as critically important antimicrobials by The World Health Organization. Exposure to Extended spectrum cephalosporin-resistant E. coli may result in consumers becoming carriers if these bacteria colonize the human gut or their resistance genes spread to other bacteria in the gut microbiota. In the case that these resistant bacteria at later occasions cause disease, their resistance characteristics may lead to failure of treatment and increased mortality. We hypothesized that ESC-resistant E. coli from poultry can survive digestion and thereby cause infections and/or spread their respective resistance traits within the gastro-intestinal tract.

Methods

In this study, a selection of 31 ESC-resistant E. coli isolates from retail chicken meat was exposed to a static in vitro digestion model (INFOGEST). Their survival, alteration of colonizing characteristics in addition to conjugational abilities were investigated before and after digestion. Whole genome data from all isolates were screened through a custom-made virulence database of over 1100 genes for virulence- and colonizing factors.

Results and discussion

All isolates were able to survive digestion. Most of the isolates (24/31) were able to transfer their bla _CMY2-containing plasmid to E. coli DH5-á, with a general decline in conjugation frequency of digested isolates compared to non-digested. Overall, the isolates showed a higher degree of cell adhesion than cell invasion, with a slight increase after digestion compared non-digested, except for three isolates that displayed a major increase of invasion. These isolates also harbored genes facilitating invasion. In the virulence-associated gene analysis two isolates were categorized as UPEC, and one isolate was considered a hybrid pathogen. Altogether the pathogenic potential of these isolates is highly dependent on the individual isolate and its characteristics. Poultry meat may represent a reservoir and be a vehicle for dissemination of potential human pathogens and resistance determinants, and the ESC-resistance may complicate treatment in the case of an infection.

Common viral and bacterial avian respiratory infections: an updated review

Many pathogens that cause chronic diseases in birds use the respiratory tract as a primary route of infection, and respiratory disorders are the main leading source of financial losses in the poultry business. Respiratory infections are a serious problem facing the poultry sector, causing severe economic losses. Avian influenza virus, Newcastle disease virus, infectious bronchitis virus, and avian pneumovirus are particularly serious viral respiratory pathogens. Mycoplasma gallisepticum, Staphylococcus, Bordetella avium, Pasteurella multocida, Riemerella anatipestifer, Chlamydophila psittaci, and Escherichia coli have been identified as the most serious bacterial respiratory pathogens in poultry. This review gives an updated summary, incorporating the latest data, about the evidence for the circulation of widespread, economically important poultry respiratory pathogens, with special reference to possible methods for the control and prevention of these pathogens.

Efficacy of quorum sensing and growth inhibitors alone and in combination against avian pathogenic Escherichia coli infection in chickens

Avian pathogenic E. coli (APEC), a causative agent of colibacillosis, is associated with high mortality and morbidity which results in severe economic losses to the poultry industry worldwide. APEC can be transmitted to humans through the consumption of contaminated poultry products. The limited effect of the current vaccines and the advent of drug-resistant strains have necessitated the development of alternative therapies. Previously, we identified 2 small molecules (SMs; [quorum sensing inhibitor; QSI-5] and [growth inhibitor; GI-7]) with high efficacy in vitro and in chickens subcutaneously challenged with APEC O78. Here, we optimized the oral challenge dose of APEC O78 in chickens to mimic the infection in the natural settings, evaluated the efficacy of the GI-7, QSI-5, and combination of GI-7 and QSI-5 (GI7+ QSI-5) in chickens orally infected with APEC, and compared their efficacy to sulfadimethoxine (SDM), an antibiotic currently used to treat APEC. Using the optimized dose of each SM in drinking water, GI-7, QSI-5, GI7+ QSI-5, and SDM were evaluated in chickens challenged with the optimized dose of APEC O78 (1 × 10⁹ CFU/chicken; orally; d 2 of age) and grown on built-up floor litter. Reduction in mortality was 90, 80, 80, and 70% in QSI-5, GI-7+QSI-5, GI-7, and SDM treated groups compared to the positive control (PC), respectively. GI-7, QSI-5, GI-7+QSI-5, and SDM reduced the APEC load in the cecum by 2.2, 2.3, 1.6, and 0.6 logs and in the internal organs by 1.3, 1.2, 1.4, and 0.4 logs compared to PC (P < 0.05), respectively. The cumulative pathological lesions scores were 0.51, 0.24, 0.0, 0.53, and 1.53 in GI-7, QSI-5, GI-7+QSI-5, SDM, and PC groups, respectively. Overall, GI-7 and QSI-5 individually have promising effects as a potential antibiotic-independent approach to control APEC infections in chickens.

Molecular and Antimicrobial Susceptibility Characterization of Escherichia coli Isolates from Bovine Slaughterhouse Process

Antimicrobials are routinely used in human and veterinary medicine. With repeated exposure, antimicrobials promote antibiotic resistance, which poses a threat to public health. In this study, we aimed to determine the susceptibility patterns, virulence factors, and phylogroups of E. coli isolates during the killing process in a bovine slaughterhouse. We analyzed 336 samples (from water, surfaces, carcasses, and feces), and 83.3% (280/336) were positive for E. coli. The most common phenotypic resistances that we detected were 50.7% (142/280) for tetracycline, 44.2% (124/280) for cephalothin, 34.6% (97/280) for streptomycin, and 36.7% (103/280) for ampicillin. A total of 82.4% of the isolates had resistance for at least one antimicrobial, and 37.5% presented multiresistance. We detected a total of 69 different phenotypic resistance patterns. We detected six other resistance-related genes, the most prevalent being tetA (22.5%) and strB (15.7%). The prevalence values of the virulence genes were 5.4% in hlyA, 1.4% in stx1, and 0.7% in stx2. The frequencies of the pathogenic strains (B2 and D) were 32.8% (92/280) and 67.1% (188/280) as commensals A and B1, respectively. E. coli isolates with pathogenic potential and multiresistance may represent an important source of dissemination and a risk to consumers.

Prevalence, Characterization, and Antimicrobial Resistance of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli from Domestic Free-Range Poultry in Agogo, Ghana

Poultry has been suggested as an important source for extended-spectrum beta-lactamase (ESBL)-producing bacteria that can lead to difficult-to treat infections in humans. Therefore, this study aims to determine the frequency, the genetics, and antimicrobial resistance profiles of ESBL-producing Escherichia coli in domestic free-range poultry in Agogo, Ghana. The study was set up and piloted from January 2019 until June 2019. Between June and December 2019, fecal samples (N = 144) were collected from free-roaming chickens from domestic farms in the regions of Sukuumu, Bontodiase, and Freetown and cultured on ESBL screening agar. Strain identification and antibiotic susceptibility were performed using the VITEK 2 compact system. ESBL-producing E. coli were confirmed using the double disk synergy test. Molecular characterization of ESBL-associated genes (bla_TEM, bla_SHV, and bla_CTX-M) were performed using conventional polymerase chain reaction (PCR) and further sequencing of obtained PCR amplicons. The result showed that 56.2% (n/N = 81/144) of collected fecal samples were positive for ESBL-producing E. coli. Majority of the isolates showed resistance to tetracycline (93.8%, n/N = 76/81) and trimethoprim-sulfamethoxazole (66.7, n/N = 54/81), whereas resistance to carbapenems was not found. The majority of ESBL-producing E. coli carried the bla_CTX-M genes, with bla_CTX-M-15 being the dominant (95.1%, n/N = 77/81) genotype. In this study, we report high frequencies of ESBL-producing E. coli in smallholder free-range poultry representing a potential source of infection, highlighting the need for control of antibiotic use and animal hygiene/sanitation measures, both important from a One Health perspective.

Evaluation of immunogenicity and efficacy of the enterobactin conjugate vaccine in protecting chickens from colibacillosis

Colibacillosis is one of the most common and economically devastating infectious diseases in poultry production worldwide. Innovative universal vaccines are urgently needed to protect chickens from the infections caused by genetically diverse avian pathogenic Escherichia coli (APEC). Enterobactin (Ent) is a highly conserved siderophore required for E. coli iron acquisition and pathogenesis. The Ent-specific antibodies induced by a novel Ent conjugate vaccine significantly inhibited the in vitro growth of diverse APEC strains. In this study, White Leghorn chickens were immunized with the Ent conjugate vaccine using a crossed design with two variables, vaccination (with or without) and APEC challenge (O1, O78, or PBS control), resulting in six study groups (9 to 10 birds/group). The chickens were subcutaneously injected with the vaccine (100 μg per bird) at 7 days of age, followed by booster immunization at 21 days of age. The chickens were intratracheally challenged with an APEC strain (10⁸ CFU/bird) or PBS at 28 days of age. At 5 days post infection, all chickens were euthanized to examine lesions and APEC colonization of the major organs. Immunization of chickens with the Ent vaccine elicited a strong immune response with a 64-fold increase in the level of Ent-specific IgY in serum. The hypervirulent strain O78 caused extensive lesions in lung, air sac, heart, liver, and spleen with significantly reduced lesion scores observed in the vaccinated chickens. Interestingly, the vaccination did not significantly reduce APEC levels in the examined organs. The APEC O1 with low virulence only caused sporadic lesions in the organs in both vaccination and control groups. The Ent conjugate vaccine altered the bacterial community of the ileum and cecum. Taken together, the findings from this study showed the Ent conjugate vaccine could trigger a strong specific immune response and was promising to confer protection against APEC infection.

The Two-Component System CpxRA Affects Antibiotic Susceptibility and Biofilm Formation in Avian Pathogenic Escherichia coli

Avian pathogenic Escherichia coli (APEC) is one of the common extraintestinal infectious disease pathogens in chickens, geese, and other birds. It can cause a variety of infections, and even the death of poultry, causing enormous economic losses. However, the misuse and abuse of antibiotics in the poultry industry have led to the development of drug resistance in the gut microbes, posing a challenge for the treatment of APEC infections. It has been reported that the CpxRA two-component system has an effect on bacterial drug resistance, but the specific regulatory mechanism remains unclear. In this study, the regulatory mechanism of CpxRA on APEC biofilm formation and EmrKY efflux pump was investigated. The cpxRA knockout strain of E. coli APEC40 was constructed, and the molecular regulatory mechanism of CpxR on biofilms and efflux pump-coding genes were identified by biofilm formation assays, drug susceptibility test, real-time reverse transcription quantitative PCR, and electrophoretic mobility shift assay (EMSA). The results indicated that CpxR can directly bind to the promoter region of emrKY and negatively regulate the sensitivity of bacteria to ofloxacin and erythromycin. These results confirm the important regulatory role of the CpxRA two-component system under antibiotic stress in APEC.

Genomic diversity, pathogenicity and antimicrobial resistance of Escherichia coli isolated from poultry in the southern United States

Escherichia coli (E. coli) are typically present as commensal bacteria in the gastro-intestinal tract of most animals including poultry species, but some avian pathogenic E. coli (APEC) strains can cause localized and even systematic infections in domestic poultry. Emergence and re-emergence of antimicrobial resistant isolates (AMR) constrain antibiotics usage in poultry production, and development of an effective vaccination program remains one of the primary options in E. coli disease prevention and control for domestic poultry. Thus, understanding genetic and pathogenic diversity of the enzootic E. coli isolates, particularly APEC, in poultry farms is the key to designing an optimal vaccine candidate and to developing an effective vaccination program. This study explored the genomic and pathogenic diversity among E. coli isolates in southern United States poultry. A total of nine isolates were recovered from sick broilers from Mississippi, and one from Georgia, with epidemiological variations among clinical signs, type of housing, and bird age. The genomes of these isolates were sequenced by using both Illumina short-reads and Oxford Nanopore long-reads, and our comparative analyses suggested data from both platforms were highly consistent. The 16 s rRNA based phylogenetic analyses showed that the 10 bacteria strains are genetically closer to each other than those in the public database. However, whole genome analyses showed that these 10 isolates encoded a diverse set of reported virulence and AMR genes, belonging to at least nine O:H serotypes, and are genetically clustered with at least five different groups of E. coli isolates reported by other states in the United States. Despite the small sample size, this study suggested that there was a large extent of genomic and serological diversity among E. coli isolates in southern United States poultry. A large-scale comprehensive study is needed to understand the overall genomic diversity and the associated virulence, and such a study will be important to develop a broadly protective E. coli vaccine.

Virulence potential of antimicrobial-resistant extraintestinal pathogenic Escherichia coli from retail poultry meat in a Caenorhabditis elegans model

Healthy poultry can be a reservoir for extraintestinal pathogenic Escherichia coli (ExPEC), some of which could be multidrug resistant to antimicrobials. These ExPEC strains could contaminate the environment and/or food chain representing thus, food safety and human health risk. However, few studies have shown the virulence of poultry-source antimicrobial-resistant (AMR) ExPEC in humans. This study characterized AMR ExPEC and investigated the virulence potential of some of their isolates in a Caenorhabditis elegans infection model. A total of 46 E. coli isolates from poultry (chicken, n = 29; turkey, n = 12) retail meats and chicken feces (n = 4), or humans (n = 1) were sequenced and identified as ExPEC. Except eight, all remaining 38 ExPEC isolates were resistant to at least one antibiotic and carried corresponding antimicrobial resistance genes (ARGs). About 27 of the 46 ExPEC isolates were multidrug-resistant (≥3 antibiotic classes). Seven ExPEC isolates from chicken or turkey meats were of serotype O25:H4 and sequence type (ST) 131 which clustered with an isolate from a human urinary tract infection (UTI) case having the same serotype and ST. The C. elegans challenge model using eight of studied ExPEC isolates harboring various ARGs and virulence genes (VGs) showed that regardless of their ARG or VG numbers in tested poultry meat and feces, ExPEC significantly reduced the life span of the nematode (P < 0.05) similarly to a human UTI isolate. This study indicated the pathogenic potential of AMR ExPEC from retail poultry meat or feces, but more studies are warranted to establish their virulence in poultry and human. Furthermore, relationships between specific resistance profiles and/or VGs in these E. coli isolates for their pathogenicity deserve investigations.

Characteristics, pathogenic mechanism, zoonotic potential, drug resistance, and prevention of avian pathogenic Escherichia coli (APEC)

Although most Escherichia coli (E. coli) strains are commensal and abundant, certain pathogenic strains cause severe diseases from gastroenteritis to extraintestinal infections. Extraintestinal pathogenic E. coli (ExPEC) contains newborn meningitis E. coli (NMEC), uropathogenic E. coli (UPEC), avian pathogenic E. coli (APEC), and septicemic E. coli (SEPEC) based on their original host and clinical symptom. APEC is a heterogeneous group derived from human ExPEC. APEC causes severe respiratory and systemic diseases in a variety of avians, threatening the poultry industries, food security, and avian welfare worldwide. APEC has many serotypes, and it is a widespread pathogenic bacterium in poultry. In addition, ExPEC strains share significant genetic similarities and similar pathogenic mechanisms, indicating that APEC potentially serves as a reservoir of virulence and resistance genes for human ExPEC, and the virulence and resistance genes can be transferred to humans through food animals. Due to economic losses, drug resistance, and zoonotic potential, APEC has attracted heightened awareness. Various virulence factors and resistance genes involved in APEC pathogenesis and drug resistance have been identified. Here, we review the characteristics, epidemiology, pathogenic mechanism zoonotic potential, and drug resistance of APEC, and summarize the current status of diagnosis, alternative control measures, and vaccine development, which may help to have a better understanding of the pathogenesis and resistance of APEC, thereby reducing economic losses and preventing the spread of multidrug-resistant APEC to humans.

In Vitro and In Vivo Evaluation of Lacticaseibacillus rhamnosus GG and Bifidobacterium lactis Bb12 Against Avian Pathogenic Escherichia coli and Identification of Novel Probiotic-Derived Bioactive Peptides

Avian pathogenic E. coli (APEC), an extra-intestinal pathogenic E. coli (ExPEC), causes colibacillosis in poultry and is also a potential foodborne zoonotic pathogen. Currently, APEC infections in poultry are controlled by antibiotic medication; however, the emergence of multi-drug-resistant APEC strains and increased restrictions on the use of antibiotics in food-producing animals necessitate the development of new antibiotic alternative therapies. Here, we tested the anti-APEC activity of multiple commensal and probiotic bacteria in an agar-well diffusion assay and identified Lacticaseibacillus rhamnosus GG and Bifidobacterium lactis Bb12 producing strong zone of inhibition against APEC. In co-culture assay, L. rhamnosus GG and B. lactis Bb12 completely inhibited the APEC growth by 24 h. Further investigation revealed that antibacterial product(s) in the culture supernatants of L. rhamnosus GG and B. lactis Bb12 were responsible for the anti-APEC activity. The analysis of culture supernatants using LC-MS/MS identified multiple novel bioactive peptides (VQAAQAGDTKPIEV, AFDNTDTSLDSTFKSA, VTDTSGKAGTTKISNV, and AESSDTNLVNAKAA) in addition to the production of lactic acid. The oral administration (10⁸ CFU/chicken) of L. rhamnosus GG significantly (P < 0.001) reduced the colonization (~ 1.6 logs) of APEC in the cecum of chickens. Cecal microbiota analysis revealed that L. rhamnosus GG moderated the APEC-induced alterations of the microbial community in the cecum of chickens. Further, L. rhamnosus GG decreased (P < 0.05) the abundance of phylum Proteobacteria, particularly those belonging to Enterobacteriaceae (Escherichia-Shigella) family. These studies indicate that L. rhamnosus GG is a promising probiotic to control APEC infections in chickens. Further studies are needed to optimize the delivery of L. rhamnosus GG in feed or water and in conditions simulating the field to facilitate its development for commercial applications.

Genetic characterization of third- or fourth-generation cephalosporin-resistant avian pathogenic Escherichia coli isolated from broilers

The third- or fourth-generation cephalosporins (3GC or 4 GC) are classified as "critically important antimicrobials for human medicine" by WHO, but resistance to these drugs is increasing rapidly in avian pathogenic E. coli (APEC). This study investigated the distribution and genetic characteristics of 3GC- or 4 GC-resistant APEC isolates from five major integrated broiler operations in Korea. The prevalence of 3GC- or 4GC-resistant APEC isolates in 1-week-old broilers was the highest in farms of operation C (53.3%); however, the highest prevalence of these isolates in 4-week-old broilers was the highest on the farms of operation A (60.0%), followed by operations E (50.0%) and C (35.7%). All 49 3GC- or 4GC-resistant APEC isolates had at least one β-lactamase-encoding gene. The most common β-lactamase-encoding genes was extended-spectrum β-lactamase gene, bla _CTX-M-15, detected in 24 isolates (49.0%), followed by bla _TEM-1 (32.7%). Sixteen isolates (32.7%) harbored class 1 integrons, and four isolates (8.2%) showed different gene cassette-arrangements. However, only 1 of 26 isolates harboring class 2 integrons carried a gene cassette. Furthermore, both CRISPR 1 and 2 arrays were detected in most isolates (36 isolates; 73.5%), followed by CRISPR 2 (18.4%) and CRISPR 1 (4.1%). Interestingly, CRISPR 2 was significantly more prevalent in multidrug resistant (MDR)-APEC isolates than in non-MDR APEC isolates, whereas CRISPR 3 and 4 were significantly more prevalent in non-MDR APEC isolates (each 11.1%; p < 0.05). None of the protospacers of CRISPR arrays were directly associated with antimicrobial resistance. Our findings indicate that the distribution and characteristics of 3GC or 4GC-resistant APEC isolates differed among the integrated broiler operations; moreover, improved management protocols are needed to control the horizontal transmission of 3GC or 4GC-resistant APEC isolates.

Impact of Lactobacillus-originated metabolites on enterohemorrhagic E. coli in rumen fluid

Rumen is one of the richest microbial ecosystems naturally harboring many zoonotic pathogens. Controlling the colonization of cattle originated zoonotic pathogens in rumen, particularly enterohemorrhagic Escherichia coli (EHEC), is critical in reducing foodborne enteric diseases in humans. In this study, we aimed to inhibit the growth of EHEC in a simulated rumen system with collected rumen fluids (RFs) using live probiotics, synbiotics, and their metabolites. EHEC inoculated RF was treated with live wild type Lactobacillus casei (LCwt), LCwt with 0.5% peanut flour (LCwt+PF), an engineered LC capable of overexpressing linoleate isomerase (LCCLA), and their metabolites collected in cell-free culture supernatants (CFCSwt, CFCSwt+PF, and CFCSCLA) at various time points. A growth stimulatory effect toward Lactobacillus spp. was exerted by all CFCS, while the EHEC was suppressed. Among other treatments only LCwt+PF reduced EHEC by 2.68 logs after 72 h. This observation was also supported by metataxonomic analysis. A reduction in Bacteroidetes and Proteobacteria while increase in Firmicutes was observed at 48 h by the presence of CFCSs as compared to the control. Our observation implies probiotic-originated metabolites modulate rumen microbiota positively which can be deployed to control the transmission of cattle-borne pathogens specifically EHEC.

Effect of Ultraviolet Radiation on Reducing Airborne Escherichia coli Carried by Poultry Litter Particles

Airborne Escherichia coli (E. coli) originating in poultry houses can be transmitted outside poultry farms through the air, posing risks of barn-to-barn infection through airborne transmission. The objective of this study is to examine the effect of ultraviolet (UV) light on the inactivation of airborne E. coli carried by poultry dust particles under laboratory conditions. A system containing two chambers that were connected by a UV scrubber was designed in the study. In the upstream chamber of the system, airborne E. coli attached to dust particles were aerosolized by a dry aerosolization-based system. Two sets of air samplers were placed in the two chambers to collect the viable airborne E. coli. By comparing the concentration of airborne E. coli in the two chambers, the inactivation rates were calculated. The airborne E. coli inactivation rates were tested at different contact times with the aid of a vacuum pump (from 5.62 to 0.23 s of contact time) and different UV irradiance levels (of 1707 µW cm^-2 and 3422 µW cm^-2). The inactivation rates varied from over 99.87% and 99.95% at 5.62 s of contact time with 1707 µW cm^-2 and 3422 µW cm^-2 of UV irradiance to 72.90% and 86.60% at 0.23 s of contact time with 1707 µW cm^-2 and 3422 µW cm^-2 of UV irradiance. The designed system was able to create the average UV irradiation of 1707 µW cm^-2 and 3422 µW cm^-2 for one UV lamp and two UV lamps, respectively. The findings of this study may provide an understanding of the effect of UV light on the inactivation of airborne E. coli carried by dust particles and help to design an affordable mitigation system for poultry houses.

ESBLs-producing Escherichia coli from sheep-origin: Genome-wide virulence genes identification and in vivo virulence assessment in mice and Galleria mellonella

The worldwide spread of pathogenic Escherichia coli, together with the multidrug resistant linked with extended-spectrum β-lactamases (blaCTX-M , blaTEM and blaOXA ), not only affect the health of animals and humans but also bring huge economic losses to animal husbandry. Despite the high levels of virulence present in many extended-spectrum beta-lactamases (ESBLs)-producing E. coli isolates, however, few studies have comprehensively assessed the pathogenicity of ESBLs-producing E. coli isolates. Thus, the aim of the present study was to investigate the presence of virulence genes in third-generation cephalosporin-resistant E. coli and to assess their pathogenicity and zoonotic potential. Previously, we identified 67 ESBLs-producing E. coli strains from sheep anal swabs in northwest China. In this study, we genotypically and phenotypically characterized isolates of E. coli that produce ESBLs. According to the VirulenceFinder and virulence factors database, all ESBLs-producing E. coli strains harboured a wide range of virulence genes. The ColV plasmid-related genes (hlyF, ompT, iss, iutA and cvaC) were present in 52 (77.6%) ESBLs-producing E. coli isolates. Surprisingly, quite a number of extraintestinal pathogenic E. coli virulence-related genes were detected in 62 (92.5%) of 67 isolates. A total of 33 serotypes and 37 sequence types (STs) were found in 67 ESBLs-producing isolates. ST10 is the most prevalent ST, which is represented by five strains. The cluster analysis showed that CC10 and CC23 were the common clonal complexes (CCs). Predominant serotypes were O8 (10%) and O9 (9%) followed by 6% each of O89, O101 and O185. Most sheep-origin ESBLs-producing E. coli held the highly pathogenic to human and displayed moderate-to-vigorous-intensity motor capacity. The ESBLs-producing E. coli isolates with numerous virulence-related genes were able to cause multiple infectious diseases in animal models (mice, neonatal rats and Galleria mellonella). To our knowledge, this study represents an important first step for a comprehensive characterization of pathogenicity and zoonotic potential of sheep-origin ESBLs-producing E. coli isolates. These findings may be of significant value for the identification of pathogenicity and zoonotic potential risks associated with sheep-origin ESBLs-producing E. coli.