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Microbiology Spectrum

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https://read.qxmd.com/read/30767846/group-a-streptococcus-mediated-host-cell-signaling
#1
Vijay Pancholi
In the past decade, the field of the cellular microbiology of group A Streptococcus ( S. pyogenes ) infection has made tremendous advances and touched upon several important aspects of pathogenesis, including receptor biology, invasive and evasive phenomena, inflammasome activation, strain-specific autophagic bacterial killing, and virulence factor-mediated programmed cell death. The noteworthy aspect of S. pyogenes -mediated cell signaling is the recognition of the role of M protein in a variety of signaling events, starting with the targeting of specific receptors on the cell surface and on through the induction and evasion of NETosis, inflammasome, and autophagy/xenophagy to pyroptosis and apoptosis...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30767845/-bacteroidetes-gliding-motility-and-the-type-ix-secretion-system
#2
Mark J McBride
Members of the phylum Bacteroidetes have many unique features, including gliding motility and the type IX protein secretion system (T9SS). Bacteroidetes gliding and T9SSs are common in, but apparently confined to, this phylum. Most, but not all, members of the phylum secrete proteins using the T9SS, and most also exhibit gliding motility. T9SSs secrete cell surface components of the gliding motility machinery and also secrete many extracellular or cell surface enzymes, adhesins, and virulence factors. The components of the T9SS are novel and are unrelated to those of other bacterial secretion systems...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30761982/the-conserved-role-of-yidc-in-membrane-protein-biogenesis
#3
Sri Karthika Shanmugam, Ross E Dalbey
YidC insertase plays a pivotal role in the membrane integration, folding, and assembly of a number of proteins, including energy-transducing respiratory complexes, both autonomously and in concert with the SecYEG channel in bacteria. The YidC family of proteins is widely conserved in all domains of life, with new members recently identified in the eukaryotic endoplasmic reticulum membrane. Bacterial and organellar members share the conserved 5-transmembrane core, which forms a unique hydrophilic cavity in the inner leaflet of the bilayer accessible from the cytoplasm and the lipid phase...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30737916/phase-variation-of-streptococcus-pneumoniae
#4
Jing Li, Jing-Ren Zhang
Streptococcus pneumoniae undergoes phase variation or spontaneous, reversible phenotypic variation in colony opacity, encapsulation, and pilus expression. The variation in colony opacity appears to occur in all strains, whereas the switches in the production of the capsule and pilus have been observed in several strains. This chapter elaborates on the variation in colony opacity since this phenomenon has been extensively characterized. S. pneumoniae produces opaque and transparent colonies on the translucent agar medium...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30737915/platforms-and-analytical-tools-used-in-nucleic-acid-sequence-based-microbial-genotyping-procedures
#5
Duncan MacCannell
In the decade and a half since the introduction of next-generation sequencing (NGS), the technical feasibility, cost, and overall utility of sequencing have changed dramatically, including applications for infectious disease epidemiology. Massively parallel sequencing technologies have decreased the cost of sequencing by more than 6 orders or magnitude over this time, with a corresponding increase in data generation and complexity. This review provides an overview of the basic principles, chemistry, and operational mechanics of current sequencing technologies, including both conventional Sanger and NGS approaches...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30737914/gram-positive-type-iv-pili-and-competence
#6
Sandra Muschiol, Marie-Stephanie Aschtgen, Priyanka Nannapaneni, Birgitta Henriques-Normark
Type IV pili (T4P) are remarkable bacterial surface appendages that carry out a range of functions. Various types of T4P have been identified in bacteria and archaea, making them almost universal structures in prokaryotes. T4P are best characterized in Gram-negative bacteria, in which pilus biogenesis and T4P-mediated functions have been studied for decades. Recent advances in microbial whole-genome sequencing have provided ample evidence for the existence of T4P also in many Gram-positive species. However, comparatively little is known, and T4P in Gram-positive bacteria are just beginning to be dissected...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30737913/sortases-surface-proteins-and-their-roles-in-staphylococcus-aureus-disease-and-vaccine-development
#7
Olaf Schneewind, Dominique Missiakas
Sortases cleave short peptide motif sequences at the C-terminal end of secreted surface protein precursors and either attach these polypeptides to the peptidoglycan of Gram-positive bacteria or promote their assembly into pilus structures that are also attached to peptidoglycan. Sortase A, the enzyme first identified in the human pathogen Staphylococcus aureus , binds LPXTG motif sorting signals, cleaves between threonine (T) and glycine (G) residues, and forms an acyl enzyme between its active-site cysteine thiol and the carboxyl group of threonine (T)...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30737912/toxins-and-superantigens-of-group-a-streptococci
#8
Blake A Shannon, John K McCormick, Patrick M Schlievert
Streptococcus pyogenes (i.e., the group A Streptococcus ) is a human-restricted and versatile bacterial pathogen that produces an impressive arsenal of both surface-expressed and secreted virulence factors. Although surface-expressed virulence factors are clearly vital for colonization, establishing infection, and the development of disease, the secreted virulence factors are likely the major mediators of tissue damage and toxicity seen during active infection. The collective exotoxin arsenal of S. pyogenes is rivaled by few bacterial pathogens and includes extracellular enzymes, membrane active proteins, and a variety of toxins that specifically target both the innate and adaptive arms of the immune system, including the superantigens; however, despite their role in S...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30681070/a-hybrid-secretion-system-facilitates-bacterial-sporulation-a-structural-perspective
#9
Natalie Zeytuni, Natalie C J Strynadka
Bacteria employ a number of dedicated secretion systems to export proteins to the extracellular environment. Several of these comprise large complexes that assemble in and around the bacterial membrane(s) to form specialized channels through which only selected proteins are actively delivered. Although typically associated with bacterial pathogenicity, a specialized variant of these secretion systems has been proposed to play a central part in bacterial sporulation, a primitive protective process that allows starving cells to form spores that survive in extreme environments...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30681069/genetics-of-sanguinis-group-streptococci-in-health-and-disease
#10
Angela Nobbs, Jens Kreth
With the application of increasingly advanced "omics" technologies to the study of our resident oral microbiota, the presence of a defined, health-associated microbial community has been recognized. Within this community, sanguinis -group streptococci, comprising the closely related Streptococcus sanguinis and Streptococcus gordonii , together with Streptococcus parasanguinis , often predominate. Their ubiquitous and abundant nature reflects the evolution of these bacteria as highly effective colonizers of the oral cavity...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30681068/the-remarkable-biomechanical-properties-of-the-type-1-chaperone-usher-pilus-a-structural-and-molecular-perspective
#11
Manuela K Hospenthal, Gabriel Waksman
Chaperone-usher (CU) pili are long, supramolecular protein fibers tethered to the surface of numerous bacterial pathogens. These virulence factors function primarily in bacterial adhesion to host tissues, but they also mediate biofilm formation. Type 1 and P pili of uropathogenic Escherichia coli (UPEC) are the two best-studied CU pilus examples, and here we primarily focus on the former. UPEC can be transmitted to the urinary tract by fecal shedding. It can then ascend up the urinary tract and cause disease by invading and colonizing host tissues of the bladder, causing cystitis, and the kidneys, causing pyelonephritis...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30681067/outer-membrane-vesicle-host-cell-interactions
#12
Jessica D Cecil, Natalie Sirisaengtaksin, Neil M O'Brien-Simpson, Anne Marie Krachler
Outer membrane vesicles (OMVs) are nanosized proteoliposomes derived from the outer membrane of Gram-negative bacteria. They are ubiquitously produced both in culture and during infection and are now recognized to play crucial roles during host-microbe interactions. OMVs can transport a broad range of chemically diverse cargoes, including lipids and lipopolysaccharides, membrane-embedded and associated proteins and small molecules, peptidoglycan, and nucleic acids. Particularly, virulence factors such as adhesins and toxins are often enriched in OMVs...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30659556/biology-of-hand-to-hand-bacterial-transmission
#13
Rosa Del Campo, Laura Martínez-García, Ana María Sánchez-Díaz, Fernando Baquero
Numerous studies have demonstrated that adequate hand hygiene among hospital staff is the best measure to prevent hand-to-hand bacterial transmission. The skin microbiome is conditioned by the individual physiological characteristics and anatomical microenvironments. Furthermore, it is important to separate the autochthonous resident microbiota from the transitory microbiota that we can acquire after interactions with contaminated surfaces. Two players participate in the hand-to-hand bacterial transmission process: the bacteria and the person...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30657107/the-biology-of-streptococcus-mutans
#14
J A Lemos, S R Palmer, L Zeng, Z T Wen, J K Kajfasz, I A Freires, J Abranches, L J Brady
As a major etiological agent of human dental caries, Streptococcus mutans resides primarily in biofilms that form on the tooth surfaces, also known as dental plaque. In addition to caries, S. mutans is responsible for cases of infective endocarditis with a subset of strains being indirectly implicated with the onset of additional extraoral pathologies. During the past 4 decades, functional studies of S. mutans have focused on understanding the molecular mechanisms the organism employs to form robust biofilms on tooth surfaces, to rapidly metabolize a wide variety of carbohydrates obtained from the host diet, and to survive numerous (and frequent) environmental challenges encountered in oral biofilms...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30632480/capsular-polysaccharide-of-group-a-streptococcus
#15
Michael R Wessels
Most clinical isolates of Streptococcus pyogenes elaborate a capsular polysaccharide, which is composed of hyaluronic acid, a high-molecular-mass polymer of alternating residues of N -acetyl glucosamine and glucuronic acid. Certain strains, particularly those of the M18 serotype, produce abundant amounts of capsule, resulting in formation of large, wet-appearing, translucent or "mucoid" colonies on solid media, whereas strains of M-types 4 and 22 produce none. Studies of acapsular mutant strains have provided evidence that the capsule enhances virulence in animal models of infection, an effect attributable, at least in part, to resistance to complement-mediated opsonophagocytic killing by leukocytes...
January 2019: Microbiology Spectrum
https://read.qxmd.com/read/30547858/nonconventional-therapeutics-against-staphylococcus-aureus
#16
Caroline M Grunenwald, Monique R Bennett, Eric P Skaar
Staphylococcus aureus is one of the most important human pathogens that is responsible for a variety of diseases ranging from skin and soft tissue infections to endocarditis and sepsis. In recent decades, the treatment of staphylococcal infections has become increasingly difficult as the prevalence of multi-drug resistant strains continues to rise. With increasing mortality rates and medical costs associated with drug resistant strains, there is an urgent need for alternative therapeutic options. Many innovative strategies for alternative drug development are being pursued, including disruption of biofilms, inhibition of virulence factor production, bacteriophage-derived antimicrobials, anti-staphylococcal vaccines, and light-based therapies...
November 2018: Microbiology Spectrum
https://read.qxmd.com/read/30547857/staphylococcal-plasmids-transposable-and-integrative-elements
#17
Neville Firth, Slade O Jensen, Stephen M Kwong, Ronald A Skurray, Joshua P Ramsay
Strains of Staphylococcus aureus , and to a lesser extent other staphylococcal species, are a significant cause of morbidity and mortality. An important factor in the notoriety of these organisms stems from their frequent resistance to many antimicrobial agents used for chemotherapy. This review catalogues the variety of mobile genetic elements that have been identified in staphylococci, with a primary focus on those associated with the recruitment and spread of antimicrobial resistance genes. These include plasmids, transposable elements such as insertion sequences and transposons, and integrative elements including ICE and SCC elements...
November 2018: Microbiology Spectrum
https://read.qxmd.com/read/30523778/-listeria-monocytogenes-cell-biology-of-invasion-and-intracellular-growth
#18
Javier Pizarro-Cerdá, Pascale Cossart
The Gram-positive pathogen Listeria monocytogenes is able to promote its entry into a diverse range of mammalian host cells by triggering plasma membrane remodeling, leading to bacterial engulfment. Upon cell invasion, L. monocytogenes disrupts its internalization vacuole and translocates to the cytoplasm, where bacterial replication takes place. Subsequently, L. monocytogenes uses an actin-based motility system that allows bacterial cytoplasmic movement and cell-to-cell spread. L. monocytogenes therefore subverts host cell receptors, organelles and the cytoskeleton at different infection steps, manipulating diverse cellular functions that include ion transport, membrane trafficking, post-translational modifications, phosphoinositide production, innate immune responses as well as gene expression and DNA stability...
November 2018: Microbiology Spectrum
https://read.qxmd.com/read/30387415/laboratory-methods-in-molecular-epidemiology-bacterial-infections
#19
Lee W Riley
In infectious disease epidemiology, the laboratory plays a critical role in diagnosis, outbreak investigations, surveillance, and characterizing biologic properties of microbes associated with their transmissibility, resistance to anti-infectives, and pathogenesis. The laboratory can inform and refine epidemiologic study design and data analyses. In public health, the laboratory functions to assess effect of an intervention. In addition to research laboratories, the new-generation molecular microbiology technology has been adapted into clinical and public health laboratories to simplify, accelerate, and make precise detection and identification of infectious disease pathogens...
November 2018: Microbiology Spectrum
https://read.qxmd.com/read/30387414/population-genetics-and-molecular-epidemiology-of-eukaryotes
#20
Ronald E Blanton
Molecular epidemiology uses the distribution and organization of a pathogen's DNA to understand the distribution and determinants of disease. Since the biology of DNA for eukaryotic pathogens differs substantially from that of bacteria, the analytic approach to their molecular epidemiology can also differ. While many of the genotyping techniques presented earlier in this series, "Advances in Molecular Epidemiology of Infectious Diseases," can be applied to eukaryotes, the output must be interpreted in the light of how DNA is distributed from one generation to the next...
November 2018: Microbiology Spectrum
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