Influence of Kidney Environment Parameters on Antibiotic Efficacy Against Uropathogenic Escherichia coli.

BACKGROUND AND OBJECTIVE: Urinary tract infections (UTIs) are common infections affecting the urinary system, predominantly caused by bacterial pathogens, with Escherichia coli being the most frequent pathogen. Infections of the kidney (eg, pyelonephritis) are severe and challenging to treat, due to the specific tissue microenvironment. In this study, the influence of different parameters mimicking the kidney environment on the effectiveness of antibiotics prescribed for pyelonephritis on the growth of uropathogenic strains was analyzed. METHODS: To investigate the influence of different factors mimicking the kidney environment, we tested the effect of different kidney-representative concentrations of sodium chloride and urea, and different pH values on the efficacy of ertapenem, levofloxacin, and ceftriaxone. The effectiveness was assessed by determining the minimal inhibitory concentrations (MICs) against various E. coli strains. KEY FINDINGS AND LIMITATIONS: The study revealed that pH significantly influences the MIC values of levofloxacin. Acidification of the pH led to an increase of the MIC values, while an alkaline pH had the opposite effect. The influence of sodium chloride and urea concentrations was strain and antibiotic specific. Since three different antibiotics were tested in this study, further research with additional antibiotics is warranted. CONCLUSIONS AND CLINICAL IMPLICATIONS: These results suggest that the physicochemical conditions within the kidney can substantially influence the success of antibiotic therapy for pyelonephritis. Therefore, it is crucial for clinicians to consider these factors when selecting and dosing antibiotics. Further research is needed to evaluate a broader range of antibiotics and additional environmental parameters, to develop a more comprehensive understanding of how the kidney environment affects antimicrobial activity. This knowledge will be vital in optimizing treatment strategies for pyelonephritis, ultimately improving patient outcomes. PATIENT SUMMARY: The physicochemical conditions within the kidney influence the success of antibiotic therapy for pyelonephritis. Our findings are vital in optimizing treatment strategies and will ultimately improve patient outcomes.

Bisphosphonate-Related Osteonecrosis of the Jaw and Oral Microbiome: Clinical Risk Factors, Pathophysiology and Treatment Options.

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) represents a serious health condition, impacting the lives of many patients worldwide. The condition challenges clinical care due to its complex etiology and limited therapeutic options. A thorough understanding of the pathophysiological and patient-related factors that promote disease development is essential. Recently, the oral microbiome has been implicated as a potential driver and modulating factor of BRONJ by several studies. Modern genomic sequencing methods have provided a wealth of data on the microbial composition of BRONJ lesions; however, the role of individual species in the process of disease development remains elusive. A comprehensive PubMed search was conducted to identify relevant studies on the microbiome of BRONJ patients using the terms "microbiome", "osteonecrosis of the jaws", and "bisphosphonates". Studies focusing on symptoms, epidemiology, pathophysiology, risk factors, and treatment options were included. The principal risk factors for BRONJ are tooth extraction, surgical procedures, and the administration of high doses of bisphosphonates. Importantly, the oral microbiome plays a significant role in the progression of the disease. Several studies have identified alterations of microbial composition in BRONJ lesions. However, there is no consensus regarding bacterial species that are associated with BRONJ across studies. The bacterial genera typically found include Actinomyces, Fusobacterium, and Streptococcus. It is postulated that these microbes contribute to the pathogenesis of BRONJ by promoting inflammation and disrupting normal bone remodeling processes. Current therapeutic approaches are disease-stage-specific and the necessity for more effective treatment strategies remains. This review examines the potential causes of and therapeutic approaches to BRONJ, highlighting the link between microbial colonization and BRONJ development. Future research should seek to more thoroughly investigate the interactions between bisphosphonates, the oral microbiome, and the immune system in order to develop targeted therapies.

Nucleocapsids of the Rift Valley fever virus ambisense S segment contain an exposed RNA element in the center that overlaps with the intergenic region.

Rift Valley fever virus (RVFV) is a mosquito-borne zoonotic pathogen. Its RNA genome consists of two negative-sense segments (L and M) with one gene each, and one ambisense segment (S) with two opposing genes separated by the noncoding "intergenic region" (IGR). These vRNAs and the complementary cRNAs are encapsidated by nucleoprotein (N). Using iCLIP2 (individual-nucleotide resolution UV crosslinking and immunoprecipitation) to map all N-vRNA and N-cRNA interactions, we detect N coverage along the L and M segments. However, the S segment vRNA and cRNA each contain approximately 100 non-encapsidated nucleotides stretching from the IGR into the 5'-adjacent reading frame. These exposed regions are RNase-sensitive and predicted to form stem-loop structures with the mRNA transcription termination motif positioned near the top. Moreover, optimal S segment transcription and replication requires the entire exposed region rather than only the IGR. Thus, the RVFV S segment contains a central, non-encapsidated RNA region with a functional role.

Pneumococcal hydrogen peroxide regulates host cell kinase activity.

Introduction: Protein kinases are indispensable reversible molecular switches that adapt and control protein functions during cellular processes requiring rapid responses to internal and external events. Bacterial infections can affect kinase-mediated phosphorylation events, with consequences for both innate and adaptive immunity, through regulation of antigen presentation, pathogen recognition, cell invasiveness and phagocytosis. Streptococcus pneumoniae (Spn), a human respiratory tract pathogen and a major cause of community-acquired pneumoniae, affects phosphorylation-based signalling of several kinases, but the pneumococcal mediator(s) involved in this process remain elusive. In this study, we investigated the influence of pneumococcal H2O2 on the protein kinase activity of the human lung epithelial H441 cell line, a generally accepted model of alveolar epithelial cells. Methods: We performed kinome analysis using PamGene microarray chips and protein analysis in Western blotting in H441 lung cells infected with Spn wild type (SpnWT) or with SpnΔlctOΔspxB -a deletion mutant strongly attenuated in H2O2 production- to assess the impact of pneumococcal hydrogen peroxide (H2O2) on global protein kinase activity profiles. Results: Our kinome analysis provides direct evidence that kinase activity profiles in infected H441 cells significantly vary according to the levels of pneumococcal H2O2. A large number of kinases in H441 cells infected with SpnWT are significantly downregulated, whereas this no longer occurs in cells infected with the mutant SpnΔlctOΔspxB strain, which lacks H2O2. In particular, we describe for the first time H2O2-mediated downregulation of Protein kinase B (Akt1) and activation of lymphocyte-specific tyrosine protein kinase (Lck) via H2O2-mediated phosphorylation.

The Bacterial Oral Microbiome in Children with Congenital Heart Disease: An Extensive Review.

Children with congenital heart disease have poorer oral health compared with healthy children. Oral diseases, such as dental caries and gingivitis, are associated with the oral microbiome. The objective of this review was to find evidence of differences in the bacterial colonization of the oral cavity of children with congenital heart disease (CHD) versus healthy children. A literature review was conducted according to predetermined criteria, including the need for controlled clinical trials. Half of the 14 studies that met the inclusion criteria reported significant differences in bacterial colonization in children with congenital heart disease. A variety of influencing factors were discussed. There is some evidence for alterations in the oral microflora as a result of physiopathological and treatment-related factors in children with CHD, but additional research is required to validate these findings.

Impact of Endogenous Pneumococcal Hydrogen Peroxide on the Activity and Release of Pneumolysin.

Streptococcus pneumoniae is the leading cause of community-acquired pneumonia. The pore-forming cholesterol-dependent cytolysin (CDC) pneumolysin (PLY) and the physiological metabolite hydrogen peroxide (H2O2) can greatly increase the virulence of pneumococci. Although most studies have focused on the contribution of both virulence factors to the course of pneumococcal infection, it is unknown whether or how H2O2 can affect PLY activity. Of note, S. pneumoniae exploits endogenous H2O2 as an intracellular signalling molecule to modulate the activity of several proteins. Here, we demonstrate that H2O2 negatively affects the haemolytic activity of PLY in a concentration-dependent manner. Prevention of cysteine-dependent sulfenylation upon substitution of the unique and highly conserved cysteine residue to serine in PLY significantly reduces the toxin's susceptibility to H2O2 treatment and completely abolishes the ability of DTT to activate PLY. We also detect a clear gradual correlation between endogenous H2O2 generation and PLY release, with decreased H2O2 production causing a decline in the release of PLY. Comparative transcriptome sequencing analysis of the wild-type S. pneumoniae strain and three mutants impaired in H2O2 production indicates enhanced expression of several genes involved in peptidoglycan (PG) synthesis and in the production of choline-binding proteins (CPBs). One explanation for the impact of H2O2 on PLY release is the observed upregulation of the PG bridge formation alanyltransferases MurM and MurN, which evidentially negatively affect the PLY release. Our findings shed light on the significance of endogenous pneumococcal H2O2 in controlling PLY activity and release.

Faecalibacterium prausnitzii, Bacteroides faecis and Roseburia intestinalis attenuate clinical symptoms of experimental colitis by regulating Treg/Th17 cell balance and intestinal barrier integrity.

Ulcerative colitis (UC) is a severe inflammatory bowel disease (IBD) characterized by multifactorial complex disorders triggered by environmental factors, genetic susceptibility, and also gut microbial dysbiosis. Faecalibacterium prausnitzii, Bacteroides faecis, and Roseburia intestinalis are underrepresented species in UC patients, leading to the hypothesis that therapeutic application of those bacteria could ameliorate clinical symptoms and disease severity. Acute colitis was induced in mice by 3.5% DSS, and the commensal bacterial species were administered by oral gavage simultaneously with DSS treatment for up to 7 days. The signs of colonic inflammation, the intestinal barrier integrity, the proportion of regulatory T cells (Tregs), and the expression of pro-inflammatory and anti-inflammatory cytokines were quantified. The concentrations of SCFAs in feces were measured using Gas-liquid chromatography. The gut microbiome was analyzed in all treatment groups at the endpoint of the experiment. Results were benchmarked against a contemporary mesalazine treatment regime. We show that commensal species alone and in combination reduced disease activity index scores, inhibited colon shortening, strengthened the colonic epithelial barrier, and positively modulated tight junction protein expression. The expression level of pro-inflammatory cytokines was significantly reduced. Immune modulation occurred via inhibition of the loss of CD4 +CD25 +Treg cells in the spleen. Our study proofed that therapeutic application of F. prausnitzii, B. faecis, and R. intestinalis significantly ameliorated DSS-induced colitis at the level of clinical symptoms, histological inflammation, and immune status. Our data suggest that these positive effects are mediated by immune-modulatory pathways and influence on Treg/Th17 balance.

The microbiome landscape in pediatric Crohn's disease and therapeutic implications.

Dysbiosis of the gut microbiome and a pathological immune response in intestinal tissues form the basis of Crohn's disease (CD), which is a debilitating disease with relevant morbidity and mortality. It is increasing in childhood and adolescents, due to western life-style and nutrition and a large set of predisposing genetic factors. Crohn's disease-associated genetic mutations play an essential role in killing pathogens, altering mucosal barrier function, and protecting the host microbiome, suggesting an important pathogenic link. The intestinal microbiome is highly variable and can be influenced by environmental factors. Changes in microbial composition and a reduction in species diversity have been shown to be central features of disease progression and are therefore the target of therapeutic approaches. In this review, we summarize the current literature on the role of the gut microbiome in childhood, adolescent, and adult CD, current therapeutic options, and their impact on the microbiome.

Phenotypic and genomic assessment of the potential threat of human spaceflight-relevant Staphylococcus capitis isolates under stress conditions.

Previous studies have reported that spaceflight specific conditions such as microgravity lead to changes in bacterial physiology and resistance behavior including increased expression of virulence factors, enhanced biofilm formation and decreased susceptibility to antibiotics. To assess if spaceflight induced physiological changes can manifest in human-associated bacteria, we compared three spaceflight relevant Staphylococcus capitis isolates (DSM 111179, ISS; DSM 31028, clean room; DSM 113836; artificial gravity bedrest study) with the type strain (DSM 20326T). We tested the three strains regarding growth, colony morphology, metabolism, fatty acid and polar lipid pattern, biofilm formation, susceptibility to antibiotics and survival in different stress conditions such as treatment with hydrogen peroxide, exposure to desiccation, and irradiation with X-rays and UV-C. Moreover, we sequenced, assembled, and analyzed the genomes of all four strains. Potential genetic determinants for phenotypic differences were investigated by comparative genomics. We found that all four strains show similar metabolic patterns and the same susceptibility to antibiotics. All four strains were considered resistant to fosfomycin. Physiological differences were mainly observed compared to the type strain and minor differences among the other three strains. The ISS isolate and the bedrest study isolate exhibit a strong delayed yellow pigmentation, which is absent in the other two strains. Pigments were extracted and analyzed by UV/Vis spectroscopy showing characteristic carotenoid spectra. The ISS isolate showed the highest growth rate as well as weighted average melting temperature (WAMT) of fatty acids (41.8°C) of all strains. The clean room isolate showed strongest biofilm formation and a high tolerance to desiccation. In general, all strains survived desiccation better in absence of oxygen. There were no differences among the strains regarding radiation tolerance. Phenotypic and genomic differences among the strains observed in this study are not inevitably indicating an increased virulence of the spaceflight isolate. However, the increased growth rate, higher WAMT and colony pigmentation of the spaceflight isolate are relevant phenotypes that require further research within the human spaceflight context. We conclude that combining genetic analysis with classical microbiological methods allows the detailed assessment of the potential threat of bacteria in highly regulated and extreme environments such as spaceflight environments.

Different Involvement of Vimentin during Invasion by Listeria monocytogenes at the Blood-Brain and the Blood-Cerebrospinal Fluid Barriers In Vitro.

The human central nervous system (CNS) is separated from the blood by distinct cellular barriers, including the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CFS) barrier (BCSFB). Whereas at the center of the BBB are the endothelial cells of the brain capillaries, the BCSFB is formed by the epithelium of the choroid plexus. Invasion of cells of either the BBB or the BCSFB is a potential first step during CNS entry by the Gram-positive bacterium Listeria monocytogenes (Lm). Lm possesses several virulence factors mediating host cell entry, such as the internalin protein family-including internalin (InlA), which binds E-cadherin (Ecad) on the surface of target cells, and internalin B (InlB)-interacting with the host cell receptor tyrosine kinase Met. A further family member is internalin (InlF), which targets the intermediate filament protein vimentin. Whereas InlF has been shown to play a role during brain invasion at the BBB, its function during infection at the BCSFB is not known. We use human brain microvascular endothelial cells (HBMEC) and human choroid plexus epithelial papilloma (HIBCPP) cells to investigate the roles of InlF and vimentin during CNS invasion by Lm. Whereas HBMEC present intracellular and surface vimentin (besides Met), HIBCPP cells do not express vimentin (except Met and Ecad). Treatment with the surface vimentin modulator withaferin A (WitA) inhibited invasion of Lm into HBMEC, but not HIBCPP cells. Invasion of Lm into HBMEC and HIBCPP cells is, however, independent of InlF, since a deletion mutant of Lm lacking InlF did not display reduced invasion rates.