Search Results (106)

In veterinary hospitals, the risk of C. difficile nosocomial acquired infections remains largely unknown, and only a few studies surveyed the environmental prevalence of C. difficile in these facilities. The aim of this study was to determine the prevalence of C. difficile in the Ontario Veterinary College large animal hospital environment and to characterize the recovered isolates. Methods. The environment of the large animal clinic of a university veterinary hospital was tested for the presence of C. difficile. Samples were collected from 157 surface sites and cultured using selective enriched broth and selective agar media. Multiplex PCR method for the detection of C. difficile toxin A (tcdA), toxin B (tcdB) binary toxin (cdtA⁄cdtB) genes; high-resolution capillary gel-based electrophoresis PCR-Ribotyping; multilocus sequence typing (MLST) and antimicrobial resistance predictions from sequenced genome were performed. Results. Thirteen isolates were recovered from 157 (8.3%) of multiple sampled sites of the main hospital. Ten distinct ribotypes, of which 7 were positive for toxin genes A and B, and all were negative for binary toxin genes. The two most common PCR ribotypes were 014 and 010. Isolates belong to the MLST Clade 1 and were further divided into 5 different sequence types. A high prevalence of AMR genes was observed in some isolates. Conclusions. C. difficile is present in different areas of the large animal hospital environment, particularly areas of high traffic and surfaces difficult to clean. Active surveillance and biosecurity measures should be in place to maintain a low environmental contamination and prevent nosocomial infections. Full article

The unarmored dinoflagellate Akashiwo sanguinea is a cosmopolitan harmful algal species known for forming intense blooms leading to mass mortality of fish, shellfish, and seabirds. Globally distributed populations of A. sanguinea have been classified into four ribotypes based on their characteristic sequences in LSU rRNA gene and primary geographic distributions. In this study, we compared the bacterial communities co-existing with the six strains of A. sanguinea from China and the USA (belonging to two ribotypes) using high-throughput sequencing of 16S rRNA gene amplicons. Generally, a bacterial microbiome with high diversity was found to be associated with laboratory-cultured A. sanguinea strains from different geographic origins. Based on ribotype classification, the six samples were divided into two groups (ribotype A: AsCHINA; ribotype C: AsUSA) for subsequent comparative analyses of their bacterial communities. Beta diversity analysis revealed a clear separation between the two groups, reflecting significant differences in bacterial community composition between the two ribotypes. Significantly higher abundance of nitrogen-fixing bacteria was found in the AsUSA group, suggesting that ribotype C may benefit from external nitrogen sources provided by their bacterial associates. If this also holds true in natural environments, this nitrogen-fixing partnership likely confers a competitive advantage to ribotype C in oligotrophic offshore waters, and potentially extends bloom duration when environmental nitrogen is depleted. Our study raised the possibility that different ribotypes of A. sanguinea may harbor distinct prokaryotic microbiomes in their phycospheres under stable cultivation conditions. Further comprehensive comparison among more isolates across all four ribotypes is highly necessary to validate this hypothesis. Full article

The emergence of antimicrobial resistance (AMR) in Clostridium difficile (C. difficile), particularly to last-line antibiotics such as linezolid, represents a critical challenge in clinical settings. This study investigates the genomic epidemiology of linezolid-resistant C. difficile, focusing on the distribution and mutational patterns of the chloramphenicol–florfenicol resistance (cfr) gene and its association with multidrug resistance. We analyzed 514 clinical isolates (354 from NCBI Pathogen Detection, 160 from EnteroBase), revealing distinct prevalence patterns among cfr subtypes: cfr(C) was dominant (156/354 NCBI strains; 101/160 EnteroBase strains), whereas cfr(B) frequently harbored missense mutations (p.R247K, p.V294I, and less commonly p.A334T). The cfr(E) subtype was exclusively identified in ribotype 027 (RT027) strains. Notably, cfr(C) exhibited a strong association with RT017, correlating with a conserved 99 bp genomic deletion. Phylogenetic analysis linked cfr-carriage to predominant sequence types (ST1 in NCBI strains, ST37 in EnteroBase isolates). Furthermore, the co-occurrence of cfr with additional AMR genes conferred resistance to macrolides (erythromycin, azithromycin) and tetracyclines, indicating a convergent evolution toward multidrug resistance. These findings underscore the interplay between cfr mutations, hypervirulent ribotypes, and AMR dissemination, necessitating enhanced surveillance to mitigate the spread of resistant C. difficile lineages. Full article

The possible origin of four cultivated species of the genus Avena of different ploidy and different subgenome composition (A. strigosa, A. abyssinica, A. byzantina, and A. sativa) from possible wild species was investigated. The region of the internal transcribed spacer ITS1 and the 5.8S rRNA gene in the cultivated species was studied with next-generation sequencing (NGS), and the patterns of occurrence and distribution of the ribotypes were compared among them and with those of the wild species. According to these data diploid, A. strigosa is more closely related to the diploid A. hirtula than to polyploid oats, and it could have evolved independently of polyploid cultivated species. The tetraploid Avena abyssinica could be a cultivated derivative of A. vaviloviana. Two hexaploid cultivated species, A. byzantina and A. sativa, could have a different origin; A. sativa could be the cultivated form of A. fatua, whereas A. byzantina could originate independently. It was found that the oat species with the A and C subgenomes, even with strong morphological and karyological differences, could intercross and pass the further stages of introgression producing a new stable combination of genomes. Our data show that almost all species of Avena could form an introgressive interspecies complex. Full article

In recent decades, ships’ ballast water and associated sediments have been recognized globally as significant vectors for the dissemination of non-indigenous species, which has attracted extensive attention due to its ecological and economic impacts. The characteristics of production of resting cysts in the dinoflagellate life cycle further increases the risk of biological invasions through ballast tank sediments. Despite extensive research which has characterized the species diversity of dinoflagellate cysts within ballast tank sediments, the possibility and importance of invasions caused by different ribosomal types of the same species have been paid little attention. In this study, two cultures of dinoflagellates were established through cyst germination from the ballast tank sediments collected from two ships (“THETIS” and “WARIYANAREE”) arriving at the Jiangyin Port (China) and identified as Wangodinium sinense Z. Luo, Zhangxi Hu, Yingzhong Tang and H.F. Gu by comprehensive phylogenetic analysis of rDNA sequences (including LSU, SSU, and ITS1-5.8S-ITS2). Despite the rDNA sequences of the isolates showing a generally high similarity to reference sequences, the LSU D1-D6 sequences contained up to 11 stable single nucleotide polymorphisms (SNPs), while SSU and ITS1-5.8S-ITS2 sequences exhibited up to five and two divergence sites, respectively. Moreover, phylogenetic analyses based on partial LSU and SSU rDNA sequences further indicated that strains germinated from ships’ ballast tank sediments formed a strongly supported sister clade to the strains previously isolated from Chinese and Korean waters, representing a novel ribo-type distinct from Chinese and Korean strains. Detailed morphological observations using light microscopy (LM) and scanning electron microscopy (SEM) did not find differences between our isolates and the holotype of the species in key diagnostic characteristics including the position and shape of the nucleus and chloroplasts, as well as the ASC structure, which suggested that no significant morphological divergence has occurred among these ribo-types. Acute toxicity exposure assays indicated that this ribo-type of W. sinense posed no lethal effect on rotifers at concentrations ≤ 10⁴ cells/mL, yet it remains necessary to maintain vigilance regarding the potential risk of algal blooms resulting from higher cell density or environmental changes in the invaded ecosystems. This study reports the first successful germination of W. sinense cysts from ballast tank sediments, indicating that its cysts may be widely transferred through ballast tank sediments, and presents a potential risk of bio-invasions of new genotypes of species to a region where other genotypes of the same species have been present as indigenous species. Full article

Moricandia moricandiodes is an endemic species found in the south and east of the Iberian Peninsula. Five subspecies have been recognized, and all exist as fragmented populations on limestones and marls with salt and gypsum intrusions under a continental Mediterranean climate, except for one of the subspecies, which inhabits semi-arid and hotter environments. In this study, we sampled populations covering the distribution area of the species and performed a population and phylogeographic study to assess the evolutionary history of populations and the taxonomic relationships of subspecies. ISSR markers, nrITS, and plastid sequences were used in the analyses. The results revealed that, in general, southern populations showed higher genetic diversity than northern populations, suggesting that the former are located in glacial refugia. Furthermore, we did not find clear differences between subspecies, except for M. moricandioides subsp. pseudofoetida, which showed exclusive haplotypes and an exclusive ribotype. Isolation and rapid divergence are discussed as the probable causes of differentiation, whereas bottlenecks and secondary contact between populations would explain the absence of differentiation among the other subspecies. Finally, we propose a few guidelines for the conservation of M. moricandioides. Full article

Clostridioides difficile Infection (CDI) continues to be a major cause of antibiotic-associated diarrhea and pseudomembranous colitis, fueled in large measure by virulence factors TcdA and TcdB. These giant glucosyltransferase toxins interfere with host cytoskeletal integrity and inflammatory signaling by inhibiting Rho GTPase; however, the detailed structural dynamics, receptor selectivity, and subcellular trafficking mechanisms remain in part unspecified. This review integrates recent insights from cryo-electron microscopy (cryo-EM) and X-ray crystallography to describe the quaternary architecture of TcdA/B, emphasizing conformational changes key to pore formation and endosomal escape. We also examine the genomic heterogeneity of hypervirulent C. difficile strains (e.g., ribotype 027), correlating toxin gene polymorphisms (e.g., tcdC mutations) with increased toxin production and virulence. Mechanistic explanations of toxin-driven inflammasome activation and epithelial barrier dysfunction are situated within host immune evasion mechanisms, including microbiota-derived bile acid regulation of toxin stability. Subsequent innovative therapeutic strategies, encompassing the utilization of engineered neutralizing antibodies that specifically target the autoprocessing domain alongside structure-guided small-molecule inhibitors, are subjected to a rigorous evaluation. By integrating structural biology, systems-level omics, and clinical epidemiology, this review establishes a comprehensive framework for understanding C. difficile toxin pathogenesis and guiding next-generation precision antimicrobials. Full article

Background: Clostridioides difficile infection (CDI) remains a significant public health challenge in the United States, with limited treatment options currently available. Objectives: This study investigated the antimicrobial efficacy of a fungal-based fermentate derived from Aspergillus oryzae, cultivated in a proprietary food-grade medium, against toxigenic strains of C. difficile. Methods and Results: The ethyl acetate extract of A. oryzae fermentate (fungal extract) exhibited potent bactericidal activity, producing a significant zone of inhibition across all tested C. difficile strains, including hypervirulent Ribotype 027. Notably, 80% of the tested strains (four out of five) exhibited greater susceptibility to the fungal extract than to 5 µg vancomycin discs. Inner colony formation within the zone of inhibition was observed for all strains treated with vancomycin but only one strain was exposed to fungal extract. Time kill assays further confirmed the rapid bactericidal effect of the fungal extract, achieving complete C. difficile eradication within six hours. Mechanistic studies using scanning electron microscopy (SEM) and flow cytometry revealed that the fungal extract induced severe membrane disruption, leading to intracellular leakage and complete lysis. Flow cytometry analysis confirmed membrane depolarization and permeability loss on C. difficile cells. Conclusions: These findings highlight that the fungal extract of A. oryzae exhibits a promising antimicrobial activity against C. difficile. Future studies will focus on identifying its active components, evaluating its efficacy in vivo, and assessing its impact on gut microbiota to establish its potential clinical application in managing CDI. Full article

Background/Objectives: Clostridioides difficile infection (CDI) represents a significant public health challenge globally, driven by its increasing prevalence, hypervirulent strains like ribotype 027 (RT027), and growing antibiotic resistance. This study aimed to evaluate the prevalence of RT027 and analyze molecular markers of vancomycin and metronidazole resistance in stool samples from CDI patients hospitalized in Poland between 2017 and 2019. Methods: A total of 200 stool samples from confirmed CDI cases were analyzed for the presence of RT027, vanA (vancomycin resistance), and nim (metronidazole resistance) genes. DNA was extracted, and a polymerase chain reaction (PCR) was conducted using specific primers. Statistical associations between RT027 and resistance genes were evaluated using chi-square tests and logistic regression. Results: RT027 was detected in 14% of samples. The vanA gene, indicative of vancomycin resistance, was found in 52.5% of samples, while the nim gene, associated with metronidazole resistance, was present in 1.5% of cases. Co-occurrence of RT027 with vanA was not statistically significant. The study revealed no significant association between RT027 and vanA. Also, no significant association was observed between RT027 and nim due to the latter’s low prevalence. Conclusions: This study highlights a concerning prevalence of vanA among CDI cases, indicating widespread vancomycin resistance and challenging current treatment guidelines. While RT027 prevalence was moderate, no significant associations with vancomycin or metronidazole resistance were observed. These findings emphasize the need for molecular surveillance and improved antimicrobial stewardship to manage CDI effectively. Full article

Clostridioides difficile is the leading cause of antibiotic-associated diarrhea in hospitalized patients. In recent years, the incidence of C. difficile infection (CDI) has increased globally, with a notable rise in community-associated CDI (CA-CDI). The presence of the microorganism in animals, the environment, and food suggests that these sources may contribute to the spread of the infection in the community. This review applies a One Health approach, integrating human, animal, and environmental health, to provide a comprehensive strategy for understanding and managing this pathogen. Findings reveal the widespread dissemination of C. difficile in animals, the environment, and food. The predominant PCR ribotypes identified were RTs 078 and 014/020, followed by RTs 126, 001, 002, 009, 010, and 033. C. difficile strains exhibited resistance to multiple antimicrobial agents, including clindamycin, erythromycin, fluoroquinolones, cephalosporins, and tetracyclines. Discriminative typing methods, such as whole-genome sequencing, revealed clonal relationships between C. difficile strains from humans and animals, indicating either direct transmission or a common environmental source of infection. The high genetic similarity between isolates from the environment and humans indicates potential environmental contamination. Additionally, clusters of C. difficile strains found in food and humans indicate a possible foodborne transmission route. This review summarizes the current knowledge on the role of Clostridioides difficile within the One Health framework. Full article

Clostridioides difficile (C. difficile), once considered a predominantly nosocomial pathogen, is increasingly implicated in community-acquired infections (CA-CDIs). This study investigates the prevalence, ribotypes, and antimicrobial susceptibility of C. difficile in Irish pork products and abattoirs, with a focus on the potential public health implications. A total of 180 retail pork products and 150 pig carcase swabs from three abattoirs were examined, alongside 30 environmental lairage samples. The C. difficile isolates were characterised through ribotyping and tested in terms of antimicrobial susceptibility. No C. difficile was isolated from the retail pork, while the carcase swabs yielded a low recovery rate (0.66%). However, the lairage areas were contaminated with C. difficile (33%), and six different ribotypes were identified, including the clinically relevant RT078. The ribotypes exhibited susceptibility to the antibiotics used to treat C. difficile infection (CDI) (fidaxomicin, vancomycin, and metronidazole) but showed resistance to tetracycline (9%) and ciprofloxacin (100%). These findings align with the international findings on antimicrobial resistance in C. difficile and suggest that strict EU food safety standards could mitigate retail pork contamination risks. Nevertheless, the environmental exposure during slaughtering and handling processes presents potential transmission risks for workers. Full article

Background/Objectives: Clostridioides difficile is a Gram-positive, spore-forming enteric pathogen that causes intestinal disorders, including inflammation and diarrhea, primarily through toxin production. Standard treatment options for C. difficile infection (CDI) involve a limited selection of antibiotics that are not fully effective, leading to high recurrence rates. Vaccination presents a promising strategy for preventing both CDI and its recurrence. Cell wall protein 2 (Cwp2), a highly immunogenic and abundant surface-exposed C. difficile cell wall protein, plays an important role in the bacterium’s adherence in vitro. In this study, we aimed to analyze the homology and immunogenicity of Cwp2 and its protection efficacy as a vaccine candidate against CDI in mice. Methods: we conducted in silico analyses to assess the homology and immunogenicity of Cwp2, and we evaluated its potential as a vaccine candidate against CDI using a mouse model of immunization and infection. Results: Our in silico analyses predicted the immunogenic region (functional domain) of Cwp2 and revealed its high homology among various toxinotypes and ribotypes (R.T.s) or sequence types (S.T.s). Immunizations of mice with the Cwp2 functional domain (Cwp2_A) induced potent IgG/A antibody responses against Cwp2_A, protected mice from CDI, and reduced C. difficile spore and toxin levels in feces post-infection. Additionally, anti-Cwp2_A sera inhibited the binding of C. difficile vegetative cells to HCT8 cells. Conclusions: Our report demonstrates for the first time the potential of Cwp2_A as an effective vaccine candidate against CDI in mice. Full article

The dinoflagellate genus Heterocapsa includes several widely distributed and potentially toxic species associated with Harmful Algal Blooms (HABs), particularly affecting the Western Pacific Ocean. To reveal the biodiversity of Heterocapsa in Beibu Gulf, six strains were morphologically characterized using light and scanning electron microscopy, while large subunit rDNA (LSU rDNA) and internal transcribed spacer (ITS) were sequenced for phylogenetic analysis through maximum likelihood and Bayesian inferences. Two strains (BGERL169, BGERL170) were identified as Heterocapsa philippinensis ribotype I, three (BGERL171-BGERL173) as a new Heterocapsa philippinensis ribotype II, and one strain (BGERL174) as Heterocapsa pseudotriquetra. Cells of H. philippinensis were ovoid to spherical, yellowish-brown, with reticulate chloroplasts, and had a sausage-shaped nucleus positioned longitudinally along the dorsal side of the cell, and the theca was arranged in Po, cp, X, 5′, 3a, 7″, 6c, 5s, 5‴, 2⁗. Additionally, BGERL169 and BGERL171 showed no hemolytic toxicity in rabbit erythrocyte lysis assays. To the best of our knowledge, this research provides the first morphological and phylogenetic analysis of H. philippinensis, including the identification of a new ribotype, as well as the discovery of H. pseudotriquetra in Chinese waters. The findings contribute to the understanding of Heterocapsa species biogeography and toxicity in Chinese waters, offering valuable data for future HAB monitoring in Beibu Gulf. Full article

×Leymotrigia bergrothii is a presumed hybrid of Leymus arenarius and Elytrigia repens. This article investigates the hybrid origin and genome composition of this species. These plants are sterile, do not undergo pollination, and do not produce seeds; occasionally, underdeveloped stamens containing abortive pollen grains form in individual spikelets. The karyotype analysis of root meristem cells revealed a diploid chromosome number of 49 in ×L. bergrothii, reported here for the first time. Subsequently, we examined the intragenomic polymorphism of the transcribed spacer ITS1 in several species of Elytrigia, Elymus, Leymus, Hordeum, and Psathyrostachys, and compared the ribotype patterns of these species with those of ×L. bergrothii. It is shown that the St-ribotype variants found in Elytrigia repens and Elytrigia pseudocaesia, as well as the ribotypes of the La family, which dominate in the genome of Leymus arenarius, correspond to major ribotypes in ×L. bergrothii. The ribotypes of the St and La families are present in the nuclear genome of ×L. bergrothii in almost equal proportions. A comparison of intron and exon sequences of the trnL gene in the chloroplast DNA of Leymus arenarius, Elytrigia repens, and ×L. bergrothii showed that this region in ×L. bergrothii is identical or very close to that of Elytrigia repens, suggesting that Elytrigia repens was the cytoplasmic donor to ×L. bergrothii. Thus, our study confirms the hypothesis that this species represents a sterile first-generation hybrid of Leymus arenarius and Elytrigia repens, reproducing vegetatively. Full article

Clostridioides difficile is widely recognised as one of the most common causes of healthcare-associated C. difficile infections due to the ability of spores to survive for prolonged periods in the hospital environment. This study aimed to evaluate the efficacy of UV-C 254 nm light in the inactivation of the spores of different C. difficile ribotypes on brain heart infusion (BHI) agar plates or in phosphate-buffered saline (PBS) with varying spore densities. Furthermore, the effectiveness of a sporicidal surface disinfectant against C. difficile spores was determined on different surfaces. Spore suspensions of different C. difficile strains in the range of 10⁵–10⁷ colony-forming units (CFUs) mL⁻¹ were inoculated on BHI agar plates or in PBS and exposed to UV-C light for up to 30 min. Additionally, a spore suspension of 10³–10⁵ CFUs was spread over a 1 cm² test area on different surfaces, and sporicidal surface wipes were used according to the manufacturer’s instructions. The findings demonstrated that spores of C. difficile ribotypes exhibited a complete reduction in log₁₀ CFU on BHI agar plates and PBS following 20 min of exposure to a UV-C dose of 2208 mJ cm⁻². The surface wipes with sporicidal properties demonstrated efficacy in reducing the number of C. difficile spores on the Formica, stainless steel, and plastic surfaces by 2.03–3.53 log₁₀. The present study demonstrates that moist surfaces or liquids can enhance the efficacy of UV-C treatment in reducing C. difficile spores. This approach may be applicable to the surfaces of healthcare facilities and to water disinfection systems. Full article