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Bacterial pathogenesis

Jennifer H Madenspacher, Michael B Fessler
Although community-acquired pneumonia remains a major public health problem, murine models of bacterial pneumonia have recently facilitated significant preclinical advances in our understanding of the underlying cellular and molecular pathogenesis. In vivo mouse models capture the integrated physiology and resilience of the host defense response in a manner not revealed by alternative, simplified ex vivo approaches. Several methods have been described in the literature for intrapulmonary inoculation of bacteria in mice, including aerosolization, intranasal delivery, peroral endotracheal cannulation under 'blind' and visualized conditions, and transcutaneous endotracheal cannulation...
September 28, 2016: Journal of Visualized Experiments: JoVE
Emily L Clark, Madhu Emmadi, Katharine L Krupp, Ananda R Podilapu, Jennifer D Helble, Suvarn S Kulkarni, Danielle H Dube
Bacterial glycans contain rare, exclusively bacterial monosaccharides that are frequently linked to pathogenesis and essentially absent from human cells. Therefore, bacterial glycans are intriguing molecular targets. However, systematic discovery of bacterial glycoproteins is hampered by the presence of rare deoxy amino sugars, which are refractory to traditional glycan-binding reagents. Thus, the development of chemical tools that label bacterial glycans is a crucial step toward discovering and targeting these biomolecules...
October 21, 2016: ACS Chemical Biology
Kazuhiko Umazume, Jun Suzuki, Yoshihiko Usui, Yoshihiro Wakabayashi, Hiroshi Goto
Purpose. Endogenous endophthalmitis (EE) is a rare ocular disease caused by bacterial or fungal infection of intraocular spaces by hematogenous spread of pathogens from distant infectious loci in the body. We investigated the clinical characteristics and management of eyes with EE in ten consecutive patients. Methods. Ten patients (10 eyes) with EE treated at Tokyo Medical University Hospital in 2014 were reviewed. We retrospectively studied the causative organisms, systemic complications, pre/postoperative mean best-corrected visual acuity (BCVA), and status of posterior vitreous detachment (PVD)...
2016: Journal of Ophthalmology
Yaohong Wang, Sudeep P George, Swati Roy, Eric Pham, Amin Esmaeilniakooshkghazi, Seema Khurana
In the small intestine, epithelial cells are derived from stem cells in the crypts, migrate up the villus as they differentiate and are ultimately shed from the villus tips. This process of proliferation and shedding is tightly regulated to maintain the intestinal architecture and tissue homeostasis. Apoptosis regulates both the number of stem cells in the crypts as well as the sloughing of cells from the villus tips. Previously, we have shown that villin, an epithelial cell-specific actin-binding protein functions as an anti-apoptotic protein in the gastrointestinal epithelium...
October 21, 2016: Scientific Reports
Shivanand Hegde, Martina Zimmermann, Martina Flöck, Rene Brunthaler, Joachim Spergser, Renate Rosengarten, Rohini Chopra-Dewasthaly
Mycoplasmas are amongst the most successful pathogens of both humans and animals yet the molecular basis of mycoplasma pathogenesis is poorly understood. This is partly due to the lack of classical virulence factors and little similarity to common bacterial pathogenic determinants. Using Mycoplasma agalactiae as a model we initiated research in this direction by screening a transposon mutant library in the natural sheep host using a negative selection method. Having successfully identified putative factors involved in the colonization of local infection and lymphogenic sites, the current study assessed mutants unable to spread systemically in sheep after experimental intramammary infection...
October 20, 2016: Veterinary Research
Ya-Qin Tan, Jing Zhang, Gang Zhou
Macroautophagy/autophagy is a conserved lysosomal degradation process essential for cell physiology and human health. By regulating apoptosis, inflammation, pathogen clearance, immune response and other cellular processes, autophagy acts as a modulator of pathogenesis and is a potential therapeutic target in diverse diseases. With regard to oral disease, autophagy can be problematic either when it is activated or impaired, because this process is involved in diverse functions, depending on the specific disease and its level of progression...
October 20, 2016: Autophagy
Racquel Domingo-Gonzalez, Oliver Prince, Andrea Cooper, Shabaana A Khader
Chemokines and cytokines are critical for initiating and coordinating the organized and sequential recruitment and activation of cells into Mycobacterium tuberculosis-infected lungs. Correct mononuclear cellular recruitment and localization are essential to ensure control of bacterial growth without the development of diffuse and damaging granulocytic inflammation. An important block to our understanding of TB pathogenesis lies in dissecting the critical aspects of the cytokine/chemokine interplay in light of the conditional role these molecules play throughout infection and disease development...
October 2016: Microbiology Spectrum
Oscar Almarza, Katherine Valderrama, Manuel Ayala, Cristopher Segovia, Javier Santander
Piscirickettsia salmonis, a Gram-negative fastidious facultative intracellular pathogen, is the causative agent of the salmonid rickettsial septicemia (SRS). The P. salmonis iron acquisition mechanisms and its molecular regulation are unknown. Iron is an essential element for bacterial pathogenesis. Typically, genes that encode for the iron acquisition machinery are regulated by the ferric uptake regulator (Fur) protein. P. salmonis fur sequence database reveals a diversity of fur genes without functional verification...
March 2016: International Microbiology: the Official Journal of the Spanish Society for Microbiology
Seonghoon Kim, Dhilon S Patel, Soohyung Park, Joanna Slusky, Jeffery B Klauda, Göran Widmalm, Wonpil Im
Lipid A is the lipid anchor of a lipopolysaccharide in the outer leaflet of the outer membrane of Gram-negative bacteria. In general, lipid A consists of two phosphorylated N-acetyl glucosamine and several acyl chains that are directly linked to the two sugars. Depending on the bacterial species and environments, the acyl chain number and length vary, and lipid A can be chemically modified with phosphoethanolamine, aminoarabinose, or glycine residues, which are key to bacterial pathogenesis. In this work, homogeneous lipid bilayers of 21 distinct lipid A types from 12 bacterial species are modeled and simulated to investigate the differences and similarities of their membrane properties...
October 18, 2016: Biophysical Journal
Haley Echlin, Matthew W Frank, Amy Iverson, Ti-Cheng Chang, Michael D L Johnson, Charles O Rock, Jason W Rosch
The pneumococcus is one of the most prodigious producers of hydrogen peroxide amongst bacterial pathogens. Hydrogen peroxide production by the pneumococcus has been implicated in antibiotic synergism, competition between other bacterial colonizers of the nasopharynx, and damage to epithelial cells. However, the role during invasive disease has been less clear with mutants defective in hydrogen peroxide production demonstrating both attenuation and heightened invasive disease capacity depending upon strain and serotype background...
October 2016: PLoS Pathogens
C H Dai, L N Gan, W U Qin, C Zi, G Q Zhu, S L Wu, W B Bao
An efficient and accurate method to test Escherichia coli (E. coli) adhesion to intestinal epithelial cells will contribute to the study of bacterial pathogenesis and the function of genes that encode receptors related to adhesion. This study used the quantitative real-time polymerase chain reaction (qPCR) method. qPCR primers were designed from the PILIN gene of E. coli F18ab, F18ac, and K88ac, and the pig β-ACTIN gene. Total deoxyribonucleic acid (DNA) from E. coli and intestinal epithelial cells (IPEC-J2 cells) were used as templates for qPCR...
September 1, 2016: Polish Journal of Veterinary Sciences
Abdul Arif Khan, Zakir Khan, Mohd Abul Kalam, Azmat Ali Khan
Microbial pathogenesis involves several aspects of host-pathogen interactions, including microbial proteins targeting host subcellular compartments and subsequent effects on host physiology. Such studies are supported by experimental data, but recent detection of bacterial proteins localization through computational eukaryotic subcellular protein targeting prediction tools has also come into practice. We evaluated inter-kingdom prediction certainty of these tools. The bacterial proteins experimentally known to target host subcellular compartments were predicted with eukaryotic subcellular targeting prediction tools, and prediction certainty was assessed...
October 6, 2016: Briefings in Bioinformatics
Alejandro Romero, Paolo R Saraceni, Susana Merino, Antonio Figueras, Juan M Tomás, Beatriz Novoa
The selection of an experimental animal model is of great importance in the study of bacterial virulence factors. Here, a bath infection of zebrafish larvae is proposed as an alternative model to study the virulence factors of Aeromonas hydrophila. Intraperitoneal infections in mice and trout were compared with bath infections in zebrafish larvae using specific mutants. The great advantage of this model is that bath immersion mimics the natural route of infection, and injury to the tail also provides a natural portal of entry for the bacteria...
2016: Frontiers in Microbiology
Deepti Varshney, Akanksha Jaiswar, Alok Adholeya, Pushplata Prasad
BACKGROUND: Subtilisin-like serine proteases or Subtilases in fungi are important for penetration and colonization of host. In Hypocreales, these proteins share several properties with other fungal, bacterial, plant and mammalian homologs. However, adoption of specific roles in entomopathogenesis may be governed by attainment of unique biochemical and structural features during the evolutionary course. Due to such functional shifts Subtilases coded by different family members of Hypocreales acquire distinct features according to respective hosts and lifestyle...
October 19, 2016: BMC Evolutionary Biology
Erica L Heipertz, Jourdan Harper, Wendy E Walker
IFN regulatory factor (IRF)3 plays a detrimental role in the cecal ligation and puncture (CLP) mouse model of sepsis. However, it is unclear which pathway activates IRF3 in this context. In this report we investigate two pathways that activate IRF3: the Stimulator of Interferon Genes (STING) pathway (which senses cytosolic DNA) and the TIR-domain-containing adapter-inducing interferon-β (TRIF) pathway (which sense dsRNA and LPS via Toll-like receptor (TLR) 3 and 4). Initially, we examine the impact of these pathways using a severe CLP model (∼90% mortality)...
October 17, 2016: Shock
Aran Singanayagam, Andrew I Ritchie, Sebastian L Johnston
PURPOSE OF REVIEW: The emergence of next-generation 16S rRNA sequencing techniques has facilitated a more detailed study of the body's microbiota and led to renewed interest in the association between microbial exposure and asthma inception. In this review, we evaluate the evidence that the respiratory tract and intestinal microbiota contribute to asthma pathogenesis and progression. RECENT FINDINGS: Human studies have revealed associations between the presence of potentially pathogenic bacteria in the respiratory tract in early life and subsequent risk of allergic sensitization and asthma...
October 15, 2016: Current Opinion in Pulmonary Medicine
Fatemeh Nooshabadi, Hee-Jeong Yang, Yunfeng Cheng, Madeleine S Durkee, Hexin Xie, Jianghong Rao, Jeffrey D Cirillo, Kristen C Maitland
Tuberculosis is a pulmonary disease with an especially high mortality rate in immuno-compromised populations, specifically children and HIV positive individuals. The causative agent, Mycobacterium tuberculosis (Mtb), is a very slow growing and difficult organism to work with, making both diagnosis and development of effective treatments cumbersome. We utilize a fiber-optic fluorescence microendoscope integrated with a whole-body imaging system for in vivo Mtb detection. The system exploits an endogenous enzyme of Mtb (β-lactamase, or BlaC) using a BlaC-specific NIR fluorogenic substrate...
October 18, 2016: Journal of Biophotonics
Hirohiko Nakae, Ayumi Tsuda, Takashi Matsuoka, Tetsuya Mine, Yasuhiro Koga
OBJECTIVE: To investigate the structure of the gastric microbiota in functional dyspepsia (FD) and its role in the pathophysiology. DESIGN: We compared the basic physiological properties of the gastric fluid (GF) and the structure of the microbiota in the GF of 44 healthy control (HC) participants and 44 patients with FD. We then treated the patients with FD with a yogurt containing a probiotic strain of Lactobacillus gasseri OLL2716 (LG21 yogurt) and investigated the effects on the bacteriological parameters and symptoms to examine the relationship between them...
2016: BMJ Open Gastroenterology
Shuai-Yin Chen, Rong-Guang Zhang, Guang-Cai Duan
Infection with Helicobacter pylori is the strongest risk factor for the development of chronic gastritis, gastric ulcer and gastric carcinoma. The majority of the H. pylori-infected population remains asymptomatic, and only 1% of individuals may progress to gastric cancer. The clinical outcomes caused by H. pylori infection are considered to be associated with bacterial virulence, genetic polymorphism of hosts as well as environmental factors. Most H. pylori strains possess a cytotoxin-associated gene (cag) pathogenicity island (cagPAI), encoding a 120-140 kDa CagA protein, which is the most important bacterial oncoprotein...
October 4, 2016: Oncology Reports
Maria Letizia Di Martino, Maurizio Falconi, Gioacchino Micheli, Bianca Colonna, Gianni Prosseda
Shigella is a highly adapted human pathogen, mainly found in the developing world and causing a severe enteric syndrome. The highly sophisticated infectious strategy of Shigella banks on the capacity to invade the intestinal epithelial barrier and cause its inflammatory destruction. The cellular pathogenesis and clinical presentation of shigellosis are the sum of the complex action of a large number of bacterial virulence factors mainly located on a large virulence plasmid (pINV). The expression of pINV genes is controlled by multiple environmental stimuli through a regulatory cascade involving proteins and sRNAs encoded by both the pINV and the chromosome...
2016: Frontiers in Molecular Biosciences
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