Search

Bovine parasitic otitis poses challenges in diagnosis, treatment and involves various agents, such as bacteria, fungi, mites, and nematodes. This study focused on the nematodes and bacteria isolated from the auditory canals of dairy cattle. A total of twenty samples were collected from dairy cattle in two states of Brazil. The results showed that Metarhabditis freitasi and M. costai nematodes were identified in 75% of samples. Bacterial species from the ear, identified via mass spectrometry, revealed that different strains were present in 65% of the cattle. Mycoplasma spp. were identified in 45% of samples through molecular techniques. Gram-negative bacteria and Mycoplasma spp. were exclusively found in nematode-infected cattle. Furthermore, the bacteria exhibited resistance to multiple antimicrobial classes, and demonstrating multiresistance. Electron microscopy revealed biofilm aggregates on the cuticle of Metarhabditis spp., suggesting a potential role of these nematodes in bacterial migration and interaction with nervous tissue. Thirteen bacterial strains demonstrated biofilm formation ability, indicating their potential pathogenic role. This research highlights the persistent and complex nature of parasitic otitis, emphasizing the significant role of nematode-bacteria associations in its pathogenicity. The presence of resistant strains and biofilm formation underscores the challenges in managing the diagnosis and treatment of bovine parasitic otitis.

Background: Clinicians are often faced with changes in socket anatomy after tooth extraction. Extraction socket management can be challenging, particularly in the aesthetic zone. Before an implant-based treatment can be proposed, a detailed diagnosis of the defect type must be made and a treatment plan developed accordingly to ensure the long-term stability of peri-implant tissues., Materials and Methods: The present authors developed a new extraction socket classification and associated recommendations for planning and execution of immediate dentoalveolar restoration., Results: The classification is based on six criteria: the bony anatomy of the 360-degree socket, socket health, facial gingival recession, periodontal biotype, bone density and apical height of the remaining bone. These criteria guide immediate dentoalveolar restoration planning so an optimal peri-implant tissue structure and aesthetic outcome can be achieved, and enabled long-term resolution in a complex clinical case., Conclusions: When planning post-extraction treatment that is effective and predictable in the long term, 360-degree anatomical classification of the extraction socket must be performed to ensure that the treatment is proportional to the socket and surrounding soft tissue damage., Conflict-Of-Interest Statement: The authors declare there are no conflicts of interest relating to this study.

The recently proposed nonadditive stochastic model (NSM) offers a coherent physical interpretation for diffusive phenomena in glass-forming systems. This model presents nonexponential relationships between viscosity, activation energy, and temperature, characterizing the non-Arrhenius behavior observed in supercooled liquids. In this work, we fit the NSM viscosity equation to experimental temperature-dependent viscosity data corresponding to 25 glass-forming liquids and compare the fit parameters with those obtained using the Vogel-Fulcher-Tammann (VFT), Avramov-Milchev (AM), and Mauro-Yue-Ellison-Gupta-Allan (MYEGA) models. The results demonstrate that the NSM provides an effective fitting equation for modeling viscosity experimental data in comparison with other established models (VFT, AM, and MYEGA), characterizing the activation energy in fragile liquids, presenting a reliable indicator of the degree of fragility of the glass-forming liquids.

The etiological agent for infective endocarditis (IE), a life-threatening disease, is usually gram-positive bacteria. However, gram-negative bacteria can rarely cause IE and 4% of cases are associated with morbidity and mortality. This study aimed to characterize Escherichia coli and Klebsiella pneumoniae isolates from the blood of patients with IE. The characteristics of blood isolates were compared with those of urinary isolates from patients with urinary tract infections (UTIs). The results of this study revealed that K. pneumoniae isolates from patients with IE were phylogenetically related to those from patients with UTI. Additionally, the resistance phenotype, resistance gene, virulence gene, and plasmid profiles were similar between the blood and urinary isolates. The isolates belonging to the sequence types (STs) 76, 36, 101 (K. pneumoniae), and 69 (E. coli) are reported to be associated with drug resistance. The Enterobacteriaceae isolates from patients with IE did not produce extended-spectrum β-lactamase or carbapenemase. Additionally, this study investigated the virulence phenotype, biofilm formation ability, and the ability to adhere to the epithelial cells in vitro of the isolates. The isolates from patients with IE exhibited weaker biofilm formation ability than the urinary isolates. All isolates from patients with IE could adhere to the renal epithelial cells. However, three isolates from patients with UTIs could not adhere to the epithelial cells. The closely related K. pneumoniae isolates (648, KP1, KP2, KP3, and KP4) could not form biofilms or adhere to the epithelial cells. In summary, the molecular analysis revealed that the genetic characteristics of IE-causing K. pneumoniae and E. coli were similar to those of UTI-causing isolates. These isolates belonged to the STs that are considered treatable. Genetically similar isolates did not exhibit the same virulence phenotype. Thus, these non-hypervirulent clones must be monitored as they can cause complex infections in susceptible hosts., (© 2021. The Author(s).)

Background: Enteroaggregative Escherichia coli (EAEC) is an E. coli pathotype that presents aggregative adhesion patterns on in vitro cultivated cells, mainly related to persistent diarrhea cases in children. EAEC virulence factors are important for host colonization and pathogeni-city. Intestinal epithelial cells (IECs) recognize pathogen-associated molecular patterns (PAMPs) and initiate an immune response. Several studies using in vivo and in vitro models emphasize the probiotic activity and immunomodulatory capacity of Lactobacillus and Bifidobacterium species., Objective: To evaluate the modulation of cytokine production by probiotics Bifidobacterium animalis and Lactobacillus casei in human intestinal Caco-2 cells exposed to different strains of EAEC., Methods: Caco-2 cells were incubated with EAEC strains in the presence or absence of probiotics. The production of cytokines IL-8, TNF-α, IL-1β and IL-10 was evaluated in the supernatants by a sandwich enzyme-linked immunosorbent assay (ELISA)., Results: Cytokine production did not change when uninfected and EAEC-infected Caco-2 cells were exposed to probiotics separately. All EAEC induced a significant increase in IL-8 production by Caco-2 cells, but the probiotics, even together, could not reduce its production. On the other hand, the synergic activity of probiotic strains significantly increased TNF-α production but decreased the basal production of IL-1ß. Also, probiotics induced a significant increase in the production of the anti-inflammatory cytokine IL-10 during EAEC infection., Conclusion: Our results reinforce the synergistic immunomodulatory activity of probiotics during EAEC infection.

Objectives: Urinary tract infections (UTIs) caused by multidrug-resistant Escherichia coli have become a major medical concern. Old antibiotics such as fosfomycin have become an alternative therapeutic option due to their effectiveness and, as a result, fosfomycin is now used as a first-line drug for the treatment of UTIs in many countries. Despite low resistance rates, fosfomycin heteroresistance, defined as a phenomenon where subpopulations of bacteria are resistant to high antibiotic concentrations whereas most of the bacteria are susceptible, is an underestimated problem., Methods: The frequency of heteroresistance in E. coli isolated from hospitalized patients in Brazil and its effect on susceptibility of E. coli in biofilms was studied and the isolates were molecularly characterized to reveal the mechanisms behind their fosfomycin heteroresistance using whole-genome sequencing., Results: A higher frequency of fosfomycin heteroresistance compared with other studies was found. In biofilms, most heteroresistant isolates were less sensitive to fosfomycin than control isolates and showed overexpression of metabolic genes thereby increasing their survival rate. Molecular characterization showed that some resistant subpopulations derived from heteroresistant isolates had a defect in their fosfomycin uptake system caused by mutations in transporter and regulatory genes, whereas others overexpressed the murA gene. None to minor effects on bacterial fitness were observed. Oxidative stress protection, virulence and metabolic genes were differentially expressed in resistant subpopulations and heteroresistant isolates., Conclusion: Frequent detection of heteroresistance in UTIs may play a role in the failure of antibiotic treatments and should therefore be more carefully diagnosed., (Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Characterization of the non-Arrhenius behavior of glass-forming liquids is a broad avenue for research toward the understanding of the formation mechanisms of noncrystalline materials. In this context, this paper explores the main properties of the viscosity of glass-forming systems, considering super-Arrhenius diffusive processes. We establish the viscous activation energy as a function of the temperature, measure the degree of fragility of the system, and characterize the fragile-to-strong transition through the standard Angell's plot. Our results show that the non-Arrhenius behavior observed in fragile liquids can be understood through the non-Markovian dynamics that characterize the diffusive processes of these systems. Moreover, the fragile-to-strong transition corresponds to a change in the spatiotemporal range of correlations during the glass transition process.

Background: The competence of enteroaggregative Escherichia coli (EAEC) to adhere to the intestinal epithelium of the host is a key role to the colonization and disease development. The virulence genes are crucial for EAEC pathogenicity during adherence, internalization and persistence in the host. The overwhelming majority of antigen encounters in a host occurs on the intestine surface, which is considered a part of innate mucosal immunity. Intestinal epithelial cells (IECs) can be activated by microorganisms and induce an immune response., Objective: The present study investigated the interaction of invasive EAEC strains with T84 intestinal epithelial cell line in respect to bacterial invasiveness, persistence and cytokines production., Methods: We evaluated intracellular persistence of invasive EAEC strains (H92/3, I49/3 and the prototype 042) and production of cytokines by sandwich ELISA in T84 cells upon 24 hours of infection., Results: The survival rates of the prototype 042 was 0.5x103 CFU/mL while survival of I49/3 and H92/3 reached 3.2x103 CFU/mL and 1.4x103 CFU/mL, respectively. Infection with all EAEC strains tested induced significant amounts of IL-8, IL-6 and TNF-α compared to uninfected T84 cells., Conclusion: These data showed that infection by invasive EAEC induce a proinflammatory immune response in intestinal epithelial T84 cells.

Urinary tract infections (UTIs) are often caused by Escherichia coli . Their increasing resistance to broad-spectrum antibiotics challenges the treatment of UTIs. Whereas, E. coli ST131 is often multidrug resistant (MDR), ST69 remains susceptible to antibiotics such as cephalosporins. Both STs are commonly linked to community and nosocomial infections. E. coli phylogenetic groups B2 and D are associated with virulence and resistance profiles making them more pathogenic. Little is known about the population structure of E. coli isolates obtained from urine samples of hospitalized patients in Brazil. Therefore, we characterized E. coli isolated from urine samples of patients hospitalized at the university and three private hospitals in Rio de Janeiro, using whole genome sequencing. A high prevalence of E. coli ST131 and ST69 was found, but other lineages, namely ST73, ST648, ST405, and ST10 were also detected. Interestingly, isolates could be divided into two groups based on their antibiotic susceptibility. Isolates belonging to ST131, ST648, and ST405 showed a high resistance rate to all antibiotic classes tested, whereas isolates belonging to ST10, ST73, ST69 were in general susceptible to the antibiotics tested. Additionally, most ST69 isolates, normally resistant to aminoglycosides, were susceptible to this antibiotic in our population. The majority of ST131 isolates were ESBL-producing and belonged to serotype O25:H4 and the H30-R subclone. Previous studies showed that this subclone is often associated with more complicated UTIs, most likely due to their high resistance rate to different antibiotic classes. Sequenced isolates could be classified into five phylogenetic groups of which B2, D, and F showed higher resistance rates than groups A and B1. No significant difference for the predicted virulence genes scores was found for isolates belonging to ST131, ST648, ST405, and ST69. In contrast, the phylogenetic groups B2, D and F showed a higher predictive virulence score compared to phylogenetic groups A and B1. In conclusion, despite the diversity of E. coli isolates causing UTIs, clonal groups O25:H4-B2-ST131 H30-R, O1:H6-B2-ST648, and O102:H6-D-ST405 were the most prevalent. The emergence of highly virulent and MDR E. coli in Brazil is of high concern and requires more attention from the health authorities.

Background: The diarrheal syndrome is considered a serious public health problem all over the world and is considered a major cause of morbidity and mortality in developing countries. The high incidence of enteroaggregative Escherichia coli in diarrheal syndromes classified as an emerging pathogen of gastrointestinal infections. After decades of study, your pathogenesis remains uncertain and has been investigated mainly using in vitro models of adhesion in cellular lines., Objective: The present study investigated the interaction of enteroaggregative Escherichia coli strains isolated from childhood diarrhea with rabbit ileal and colonic mucosa ex vivo, using the in vitro organ culture model., Methods: The in vitro adhesion assays using cultured tissue were performed with the strains co-incubated with intestinal fragments of ileum and colon over a period of 6 hours. Each strain was tested with three intestinal fragments for each region. The fragments were analysed by scanning electron microscopy., Results: Through scanning electron microscopy we observed that all strains adhered to rabbit ileal and colonic mucosa, with the typical aggregative adherence pattern of "stacked bricks" on the epithelium. However, the highest degree of adherence was observed on colonic mucosa. Threadlike structures were found in greater numbers in the ileum compared to the colon., Conclusion: These data showed that enteroaggregative Escherichia coli may have a high tropism for the human colon, which was ratified by the higher degree of adherence on the rabbit colonic mucosa. Finally, data indicated that in vitro organ culture of intestinal mucosa from rabbit may be used to elucidate the enteroaggregative Escherichia coli pathogenesis.

Purpose: This article describes the use of rapid prototyping (RP) for diagnosis, planning, and execution of the reconstruction of hard and soft tissue in socket defects using immediate dentoalveolar restoration (IDR)., Summary: In cases of tissue loss in anterior dental areas, esthetic rehabilitation poses a major challenge with respect to treatment planning with the goal of long-term tissue maintenance. The IDR technique consists of immediate reconstruction in a single procedure of bone and soft tissue around implants placed immediately after extraction, and prosthetic rehabilitation. As this procedure is immediate and flapless, the correct diagnosis of tissue loss and correct graft adaptation are mandatory. RP can increase the precision of the procedure, as demonstrated using a clinical case characterized by total loss of the buccal bone wall and gingival recession. The results were evaluated by clinical assessment, photography, radiography, cone beam computed tomography (CBCT), and prototyping., Conclusion: The application of RP facilitated the execution of IDR as it enabled more accurate diagnosis of the socket defect and more precise adaptation of the tissue graft. A clinical study should be conducted to evaluate the effects of RP on the clinical results of the IDR technique.

During the colonization of surfaces, Escherichia coli bacteria often encounter DNA-damaging agents and these agents can induce several defence mechanisms. Base excision repair (BER) is dedicated to the repair of oxidative DNA damage caused by reactive oxygen species (ROS) generated by chemical and physical agents or by metabolism. In this work, we have evaluated whether the interaction with an abiotic surface by mutants derived from E. coli K-12 deficient in some enzymes that are part of BER causes DNA damage and associated filamentation. Moreover, we studied the role of endonuclease V (nfi gene; 1506 mutant strain) in biofilm formation. Endonuclease V is an enzyme that is involved in DNA repair of nitrosative lesions. We verified that endonuclease V is involved in biofilm formation. Our results showed more filamentation in the xthA mutant (BW9091) and triple xthA nfo nth mutant (BW535) than in the wild-type strain (AB1157). By contrast, the mutant nfi did not present filamentation in biofilm, although its wild-type strain (1466) showed rare filaments in biofilm. The filamentation of bacterial cells attaching to a surface was a consequence of SOS induction measured by the SOS chromotest. However, biofilm formation depended on the ability of the bacteria to induce the SOS response since the mutant lexA Ind(-) did not induce the SOS response and did not form any biofilm. Oxygen tension was an important factor for the interaction of the BER mutants, since these mutants exhibited decreased quantitative adherence under anaerobic conditions. However, our results showed that the presence or absence of oxygen did not affect the viability of BW9091 and BW535 strains. The nfi mutant and its wild-type did not exhibit decreased biofilm formation under anaerobic conditions. Scanning electron microscopy was also performed on the E. coli K-12 strains that had adhered to the glass, and we observed the presence of a structure similar to an extracellular matrix that depended on the oxygen tension. In conclusion, it was proven that bacterial interaction with abiotic surfaces can lead to SOS induction and associated filamentation. Moreover, we verified that endonuclease V is involved in biofilm formation., (© 2014 The Authors.)

Corynebacterium diphtheriae still represents a global medical challenge, particularly due to the significant number of individuals susceptible to diphtheria and the emergence of non-toxigenic strains as the causative agents of invasive infections. In this study, we characterized the clinical and microbiological features of what we believe to be the first case of C. diphtheriae infection of a percutaneous nephrostomy catheter insertion site in an elderly patient with a fatal bladder cancer. Moreover, we demonstrated the potential role of adherence, biofilm formation and fibrin deposition traits in C. diphtheriae from the catheter-related infection. Non-toxigenic C. diphtheriae isolated from the purulent discharge (named strain BR-CAT5003748) was identified by the API Coryne system (code 1 010 324) and a multiplex PCR for detection of dtxR and tox genes. Strain BR-CAT5003748 showed resistance to oxacillin, ceftazidime and ciprofloxacin. In experiments performed in vitro, the catheter isolate was classified as moderately hydrophobic and as moderately adherent to polystyrene surfaces. Glass provided a more effective surface for biofilm formation than polystyrene. Micro-organisms adhered to (>1.5 x 10(6) c.f.u.) and multiplied on surfaces of polyurethane catheters. Microcolony formation (a hallmark of biofilm formation) and amorphous accretions were observed by scanning electron microscopy on both external and luminal catheter surfaces. Micro-organisms yielded simultaneous expression of localized adherence-like and aggregative-like (LAL/AAL) adherence patterns to HEp-2 cells. Interestingly, the coagulase tube test resulted in the formation of a thin layer of fibrin embedded in rabbit plasma by the non-toxigenic BR-CAT5003748 strain. In conclusion, C. diphtheriae should be recognized as a potential cause of catheter-related infections in at-risk populations such as elderly and cancer patients. LAL/AAL strains may be associated with virulence traits that enable C. diphtheriae to effectively produce biofilms on catheter surfaces. Biofilm formation and fibrin deposition could have contributed to the persistence of C. diphtheriae at the infected insertion site and the obstruction of the nephrostomy catheter.