Biofilm-like structures and pathogenicity of Escherichia hermannii YS-11, a clinical isolate from a persistent apical periodontitis lesion

Catheter-Related Bloodstream Infection in Hemodialysis Patient due to Atlantibacter hermannii

Atlantibacter hermannii, previously known as Escherichia hermannii, is a rare causative agent of human infections. Several reports testify that the most frequently infected patients are immunosuppressed, especially those undergoing hemodialysis. A 34-year-old man with an end-stage renal disease complained of chills, fever, and general fatigue at the end of a regular hemodialysis session. The echocardiographic examination showed vegetation located on the dialysis catheter in the right atrium. Empirical therapy was initiated with intravenous gentamicin, and after the isolation of the agent, the treatment was continued with intravenous imipenem/cilastatin. The blood cultures and the tip of the replaced catheter were positive for A. hermannii, identified by Vitek 2 Compact. Verification of the automated identification was performed using 16S sequencing. The 16S sequence product was used to query the NCBI bacterial database and revealed 99.75% identity to that of A. hermannii strain CIP 103176 16S ribosomal RNA in the NCBI GenBank database. The antimicrobial susceptibility results revealed resistance to aminopenicillins and susceptibility to all other tested antimicrobials. To our knowledge, this is the first report of catheter-related vegetation with echocardiographic confirmation and the successful eradication of A. hermannii infection in a patient undergoing hemodialysis with imipenem/cilastatin.

Metagenomic Analysis Reveals a Mitigating Role for Lactobacillus paracasei and Bifidobacterium animalis in Experimental Periodontitis

Probiotics have aroused increasing concern as an intervention strategy for periodontitis (PD), but their underlying mechanism of action remains poorly characterized. Regarding the significance of oral microbiota dysbiosis related to PD, we predicted that the preventive activity of probiotics may be influenced by suppressing the bacterial pathogenicity. Herein, we investigated the effects of Lactobacillus paracasei L9 (L9) and Bifidobacterium animalis A6 (A6) on PD using a rat model, and demonstrated a regulatory effect of probiotics on oral flora from a metagenomics perspective. Oral administration of A6 or L9 effectively relieved gingival bleeding, periodontal inflammatory infiltration, and alveolar bone resorption. In addition, A6 or L9 treatment reduced the inflammatory response and increased the expression of anti-inflammatory cytokines, which we expected to ameliorate alveolar bone resorption as mediated by the receptor activator of the nuclear factor-κB ligand/OPG signaling pathway. More importantly, using metagenomic sequencing, we showed that probiotics significantly altered the taxonomic composition of the subgingival microbiome, and reduced the relative proportions of pathogenic bacterial genera such as Streptococcus, Fusobacterium, Veillonella, and Escherichia. Both probiotics significantly inhibited levels of bacterial virulence factors related to adherence, invasion, exoenzyme, and complement protease functions that are strongly correlated with the pathogenesis of PD. Our overall results suggest that A6 and L9 may constitute promising prophylactic agents for PD, and should thus be further explored in the future.

Metagenomic Analysis Reveals a Mitigating Role for Lactobacillus paracasei and Bifidobacterium animalis in Experimental Periodontitis

Probiotics have aroused increasing concern as an intervention strategy for periodontitis (PD), but their underlying mechanism of action remains poorly characterized. Regarding the significance of oral microbiota dysbiosis related to PD, we predicted that the preventive activity of probiotics may be influenced by suppressing the bacterial pathogenicity. Herein, we investigated the effects of Lactobacillus paracasei L9 (L9) and Bifidobacterium animalis A6 (A6) on PD using a rat model, and demonstrated a regulatory effect of probiotics on oral flora from a metagenomics perspective. Oral administration of A6 or L9 effectively relieved gingival bleeding, periodontal inflammatory infiltration, and alveolar bone resorption. In addition, A6 or L9 treatment reduced the inflammatory response and increased the expression of anti-inflammatory cytokines, which we expected to ameliorate alveolar bone resorption as mediated by the receptor activator of the nuclear factor-κB ligand/OPG signaling pathway. More importantly, using metagenomic sequencing, we showed that probiotics significantly altered the taxonomic composition of the subgingival microbiome, and reduced the relative proportions of pathogenic bacterial genera such as Streptococcus, Fusobacterium, Veillonella, and Escherichia. Both probiotics significantly inhibited levels of bacterial virulence factors related to adherence, invasion, exoenzyme, and complement protease functions that are strongly correlated with the pathogenesis of PD. Our overall results suggest that A6 and L9 may constitute promising prophylactic agents for PD, and should thus be further explored in the future.

Metagenomic Analysis Reveals a Mitigating Role for Lactobacillus paracasei and Bifidobacterium animalis in Experimental Periodontitis

Probiotics have aroused increasing concern as an intervention strategy for periodontitis (PD), but their underlying mechanism of action remains poorly characterized. Regarding the significance of oral microbiota dysbiosis related to PD, we predicted that the preventive activity of probiotics may be influenced by suppressing the bacterial pathogenicity. Herein, we investigated the effects of Lactobacillus paracasei L9 (L9) and Bifidobacterium animalis A6 (A6) on PD using a rat model, and demonstrated a regulatory effect of probiotics on oral flora from a metagenomics perspective. Oral administration of A6 or L9 effectively relieved gingival bleeding, periodontal inflammatory infiltration, and alveolar bone resorption. In addition, A6 or L9 treatment reduced the inflammatory response and increased the expression of anti-inflammatory cytokines, which we expected to ameliorate alveolar bone resorption as mediated by the receptor activator of the nuclear factor-κB ligand/OPG signaling pathway. More importantly, using metagenomic sequencing, we showed that probiotics significantly altered the taxonomic composition of the subgingival microbiome, and reduced the relative proportions of pathogenic bacterial genera such as Streptococcus, Fusobacterium, Veillonella, and Escherichia. Both probiotics significantly inhibited levels of bacterial virulence factors related to adherence, invasion, exoenzyme, and complement protease functions that are strongly correlated with the pathogenesis of PD. Our overall results suggest that A6 and L9 may constitute promising prophylactic agents for PD, and should thus be further explored in the future.

Facile Synthesis of Sugar Nucleotides from Common Sugars by the Cascade Conversion Strategy

Sugar nucleotides are essential glycosylation donors in the carbohydrate metabolism. Naturally, most sugar nucleotides are derived from a limited number of common sugar nucleotides by de novo biosynthetic pathways, undergoing single or multiple reactions such as dehydration, epimerization, isomerization, oxidation, reduction, amination, and acetylation reactions. However, it is widely believed that such complex bioconversions are not practical for synthetic use due to the high preparation cost and great difficulties in product isolation. Therefore, most of the discovered sugar nucleotides are not readily available. Here, based on de novo biosynthesis mainly, 13 difficult-to-access sugar nucleotides were successfully prepared from two common sugars D-Man and sucrose in high yields, at a multigram scale, and without the need for tedious purification manipulations. This work demonstrated that de novo biosynthesis, although undergoing complex reactions, is also practical and cost-effective for synthetic use by employing a cascade conversion strategy.

Examples of potato epidermis endophytes and rhizosphere microbes that may be human pathogens contributing to potato peel colic

Potato tubers defend themselves against herbivores with endogenous secondary compounds such as solanine and scopolamine. They also recruit endophytes and members of the tuberosphere to repel herbivores. Many of these endophyte defence features are overcome by cooking, with some notable exceptions that have been identified by rDNA analysis of potato peel samples and may account for some previously unrecognised features of potato peel colic. This is relevant regarding the rather modern way of cooking, where the potato peel is left intact in food and consumed.

PICC-associated infection with Escherichia hermannii: A case report and review of the literature

Since its identification as a unique species in 1982, Escherichia hermannii has been implicated as a pathogenic organism in very few cases of human disease. Our report discusses a case of bacteremia with Escherichia hermannii identified by Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and RapID^™ ONE analysis in a patient getting TPN through a peripherally-inserted CVC (PICC). The PICC was removed. The bloodstream infection was successfully treated with empiric piperacillin-tazobactam, which was then narrowed to trimethoprim-sulfamethoxazole based on sensitivity data for a 14 day course of antimicrobial therapy. E. hermannii’s association with bloodstream infection in patients with central venous catheters supports data implicating biofilm formation as a key pathogenic feature of E. hermannii. Of the 9 previous cases of E. hermannii infection reviewed in the literature, 4 cases occurred in immunocompromised hosts, 2 were associated with trauma or injection, 2 were associated with central lines, and only one case had no identifiable risk factor. E. hermannii appears to act as an opportunistic pathogen, causing disease in an immunocompromised host or through a central access catheter, injection, or trauma. E. hermannii likely causes catheter-related bloodstream infections in these hosts through biofilm formation, demonstrating the importance of catheter removal in addition to antimicrobial therapy in the treatment of these infections.

Catheter Related Escherichia hermannii Sepsis in a Haemodialysis Patient

Escherichia hermannii is an extremely rare etiological agent of invasive infection, and thus, the bacterium was initially considered non-pathogenic. However, in five previously reported case reports E. hermannii has been implicated as the sole pathogen. Our case report describes blood stream infection with E.hermannii in a haemodialysis patient with persisting symptoms, high fever and inflammatory markers despite appropriate antibiotic treatment until replacement of the dialysis catheter. We suspect biofilm formation to be a crucial pathogenic feature for E. hermannii in the maintenance of an infection, which stresses the necessity of antibiotic treatment along with catheter replacement in bloodstream- and catheter-related infection with E. hermannii.

Pathogenicity of exopolysaccharide-producing Actinomyces oris isolated from an apical abscess lesion

Aim

To demonstrate a capacity for producing exopolysaccharides (EPSs) and an ability to form biofilm on abiotic materials of Actinomyces oris strain K20.

Methodology

The productivity of EPSs and the ability to form biofilm of strain K20 were evaluated by measuring viscosity of spent culture media and by scanning electron microscopy (SEM) and the biofilm assay on microtitre plates, respectively. High-performance liquid chromatography was used to determine the chemical composition of the viscous materials. To examine the role of the viscous materials attributable to the pathogenicity in this organism, the ability of strain K20 to induce abscess formation was compared in mice to that of ATCC 27044.

Results

The viscosity of the spent culture media of K20 was significantly higher than that of ATCC 27044. Strain K20 showed dense meshwork structures around the cells and formed biofilms on microtitre plates, whereas ATCC 27044 did not. Chemical analysis of the viscous materials revealed that they were mainly composed of neutral sugars with mannose constituting 77.5% of the polysaccharides. Strain K20 induced persistent abscesses in mice lasting at least 5 days at a concentration of 10⁸ cells mL⁻¹, whereas abscesses induced by ATCC 27044 healed and disappeared or decreased in size at day 5.

Conclusions

Strain K20 produced EPSs, mainly consisting of mannose, and formed biofilms. This phenotype might play an important role for A. oris to express virulence through the progression of apical periodontitis.

Comparison of the virulence of exopolysaccharide-producing Prevotella intermedia to exopolysaccharide non-producing periodontopathic organisms

BACKGROUND

Evidence in the literature suggests that exopolysaccharides (EPS) produced by bacterial cells are essential for the expression of virulence in these organisms. Secreted EPSs form the framework in which microbial biofilms are built.

METHODS

This study evaluates the role of EPS in Prevotella intermedia for the expression of virulence. This evaluation was accomplished by comparing EPS-producing P. intermedia strains 17 and OD1-16 with non-producing P. intermedia ATCC 25611 and Porphyromonas gingivalis strains ATCC 33277, 381 and W83 for their ability to induce abscess formation in mice and evade phagocytosis.

RESULTS

EPS-producing P. intermedia strains 17 and OD1-16 induced highly noticeable abscess lesions in mice at 107 colony-forming units (CFU). In comparison, P. intermedia ATCC 25611 and P. gingivalis ATCC 33277, 381 and W83, which all lacked the ability to produce viscous materials, required 100-fold more bacteria (109 CFU) in order to induce detectable abscess lesions in mice. Regarding antiphagocytic activity, P. intermedia strains 17 and OD1-16 were rarely internalized by human polymorphonuclear leukocytes, but other strains were readily engulfed and detected in the phagosomes of these phagocytes.

CONCLUSIONS

These results demonstrate that the production of EPS by P. intermedia strains 17 and OD1-16 could contribute to the pathogenicity of this organism by conferring their ability to evade the host's innate defence response.

Complete Genome Sequence of Rothia mucilaginosa DY-18: A Clinical Isolate with Dense Meshwork-Like Structures from a Persistent Apical Periodontitis Lesion

Rothia mucilaginosa is an opportunistic pathogen in the human oral cavity and pharynx. We found that R. mucilaginosa DY-18, a clinical isolate from a persistent apical periodontitis lesion, had biofilm-like structures. Similar structures were also observed on R. mucilaginosa ATCC25296. To further study these structures, we determined the complete genome sequence of DY-18 and found it a 2.26-Mb chromosome. Regarding stress responsive systems known to affect biofilm formation in many bacteria, DY-18 genome possessed only two sigma factor genes. One of these encoded an additional sigma factor whose promoter-binding activity may be regulated in response to environmental stimuli. Additionally, several genes assigned to two-component signal transduction systems were presented in this genome. To the best of our knowledge, this is the first complete genome of R. mucilaginosa species and our data raise the possibility that this organism regulates the biofilm phenotype through these stress responsive systems.