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Streptococcus is a genus of gram-positive coccus or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales, in the phylum Bacillota. Cell division in streptococci occurs along a single axis, thus when growing they tend to form pairs or chains, which may appear bent or twisted. This differs from staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells. Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes.
Streptococcus pneumoniae, or pneumococcus, is a Gram-positive, spherical bacteria, alpha-hemolytic member of the genus Streptococcus. S. pneumoniae cells are usually found in pairs (diplococci) and do not form spores and are non motile. As a significant human pathogenic bacterium S. pneumoniae was recognized as a major cause of pneumonia in the late 19th century, and is the subject of many humoral immunity studies.
The bacterial capsule is a large structure common to many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell. It is a well-organized layer, not easily washed off, and it can be the cause of various diseases.
Pneumococcal pneumonia is a type of bacterial pneumonia that is caused by Streptococcus pneumoniae (pneumococcus). It is the most common bacterial pneumonia found in adults, the most common type of community-acquired pneumonia, and one of the common types of pneumococcal infection. The estimated number of Americans with pneumococcal pneumonia is 900,000 annually, with almost 400,000 cases hospitalized and fatalities accounting for 5-7% of these cases.
The quellung reaction, also called the Neufeld reaction, is a biochemical reaction in which antibodies bind to the bacterial capsule of Streptococcus pneumoniae, Klebsiella pneumoniae, Neisseria meningitidis, Bacillus anthracis, Haemophilus influenzae, Escherichia coli, and Salmonella. The antibody reaction allows these species to be visualized under a microscope. If the reaction is positive, the capsule becomes opaque and appears to enlarge.
Pneumococcal infection is an infection caused by the bacterium Streptococcus pneumoniae.
Pneumolysin is a virulence factor of the Gram-positive bacteria Streptococcus pneumoniae.
Bacterial cellular morphologies are the shapes that are characteristic of various types of bacteria and often key to their identification. Their direct examination under a light microscope enables the classification of these bacteria.
Sortase refers to a group of prokaryotic enzymes that modify surface proteins by recognizing and cleaving a carboxyl-terminal sorting signal. For most substrates of sortase enzymes, the recognition signal consists of the motif LPXTG (Leu-Pro-any-Thr-Gly), then a highly hydrophobic transmembrane sequence, followed by a cluster of basic residues such as arginine. Cleavage occurs between the Thr and Gly, with transient attachment through the Thr residue to the active site Cys residue, followed by transpeptidation that attaches the protein covalently to cell wall components. Sortases occur in almost all Gram-positive bacteria and the occasional Gram-negative bacterium or Archaea, where cell wall LPXTG-mediated decoration has not been reported. Although sortase A, the "housekeeping" sortase, typically acts on many protein targets, other forms of sortase recognize variant forms of the cleavage motif, or catalyze the assembly of pilins into pili.
In biology, a pathogen, in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ.
Enzybiotics are an experimental antibacterial therapy. The term is derived from a combination of the words “enzyme” and “antibiotics.” Enzymes have been extensively utilized for their antibacterial and antimicrobial properties. Proteolytic enzymes called endolysins have demonstrated particular effectiveness in combating a range of bacteria and are the basis for enzybiotic research. Endolysins are derived from bacteriophages and are highly efficient at lysing bacterial cells. Enzybiotics are being researched largely to address the issue of antibiotic resistance, which has allowed for the proliferation of drug-resistant pathogens posing great risk to animal and human health across the globe.
Elaine I. Tuomanen is an American pediatrician and chair of the Department of Infectious Diseases at St. Jude Children's Research Hospital. She is noted for her research on Molecular pathogenesis of Streptococcus pneumoniae.
Samir Kumar Saha is an eminent Bangladeshi microbiologist and public health expert. He is the professor, senior consultant and head of the department of Diagnostic Division of Microbiology at the Dhaka Shishu Hospital for children and also the executive director of The Child Health Research Foundation (CHRF) at the Bangladesh Institute of Child Health.
In microbiology, colonial morphology refers to the visual appearance of bacterial or fungal colonies on an agar plate. Examining colonial morphology is the first step in the identification of an unknown microbe. The systematic assessment of the colonies' appearance, focusing on aspects like size, shape, colour, opacity, and consistency, provides clues to the identity of the organism, allowing microbiologists to select appropriate tests to provide a definitive identification.
Jessica A. Scoffield is an American microbiologist and an assistant professor in the Department of Microbiology at the University of Alabama at Birmingham School of Medicine. Scoffield studies the mechanisms by which oral commensal bacteria interfere with pathogenic bacterial growth in order to inform the development of active therapeutic tools to prevent drug resistant pathogen infection. In 2019, Scoffield became the inaugural recipient of the American Association for Dental Research Procter and Gamble Underrepresented Faculty Research Fellowship.
Necrotizing pneumonia (NP), also known as cavitary pneumonia or cavitatory necrosis, is a rare but severe complication of lung parenchymal infection. In necrotizing pneumonia, there is a substantial liquefaction following death of the lung tissue, which may lead to gangrene formation in the lung. In most cases patients with NP have fever, cough and bad breath, and those with more indolent infections have weight loss. Often patients clinically present with acute respiratory failure. The most common pathogens responsible for NP are Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae. Diagnosis is usually done by chest imaging, e.g. chest X-ray, CT scan. Among these CT scan is the most sensitive test which shows loss of lung architecture and multiple small thin walled cavities. Often cultures from bronchoalveolar lavage and blood may be done for identification of the causative organism(s). It is primarily managed by supportive care along with appropriate antibiotics. However, if patient develops severe complications like sepsis or fails to medical therapy, surgical resection is a reasonable option for saving life.
Daniela M. Ferreira is a Brazilian British immunologist. She is a specialist in bacterial infection, respiratory co-infection, mucosal immunology and vaccine responses. She is currently Professor of Respiratory Infection and Vaccinology at the Oxford Vaccine Group in the Department of Paediatrics at the University of Oxford and the Director of the Liverpool Vaccine Group at the Liverpool School of Tropical Medicine. She leads a team of scientists studying protective immune responses against pneumococcus and other respiratory pathogens such as SARS-CoV2. Her team has established a novel method of inducing pneumococcal carriage in human volunteers. They use this model to:
Competence stimulating peptide (CSP), a chemical messenger assisting quorum sensing initiation, exists in many bacterial genera. Bacterial transformation of deoxyribonucleic acids (DNA) is driven by CSP coupled quorum sensing.
Regulator gene glucosyltransferases are a family of cell signaling proteins in bacteria. Rgg proteins are part of the RRNPP superfamily of transcriptional regulators and are found in multiple Gram-positive Firmicutes bacteria, such as Streptococcus, Lactobacillus, and Listeria species. The Rgg family of proteins are quorum sensing systems that alter transcription levels by binding to DNA when the Rgg is bound to a cognate signaling Short Hydrophobic Peptide (SHP). The SHP acts as a pheromone and is generally secreted by peptidase-containing ABC transporters such as PptAB. It is thought that associated peptidases cleave the SHP into its active form upon secretion. This truncated SHP is then internalized by bacterial cells through a conserved oligopeptidase permease family. The internalized, active SHP then associates with Rgg to form a complex that binds to the promoter region of multiple genes and alters transcription. There can be several different Rgg/SHP paralogs present in a single bacterial strain, usually each with their own specific regulon. While it is theorized that each SHP can only bind to its associated Rgg, there is evidence in some species for crosstalk between different SHPs and Rggs.
Lipoprotein rotamase A (SlrA), also known as peptidyl prolyl isomerase A (PpiA), functions as a molecular chaperone that operates within the Streptococcus pneumoniae cell membrane-cell wall interface as well as outside the bacteria. SlrA shares homology with the cyclophilin-type peptidyl-prolyl isomerases (PPIases). PPIases accelerate the folding of proteins by catalyzing the cis-trans isomer conversions of peptide bonds in the amino acid proline.
References
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- ↑ Land, Adrian D.; Hogan, Patrick; Fritz, Stephanie; Levin, Petra Anne (2015-06-22). "Phenotypic Variation Is Almost Entirely Independent of the Host-Pathogen Relationship in Clinical Isolates of S. aureus". PLOS ONE. 10 (6): e0129670. Bibcode:2015PLoSO..1029670L. doi: 10.1371/journal.pone.0129670 . ISSN 1932-6203. PMC 4476556 . PMID 26098551.
- ↑ Land, Adrian D.; Winkler, Malcolm E. (August 2011). "The requirement for pneumococcal MreC and MreD is relieved by inactivation of the gene encoding PBP1a". Journal of Bacteriology. 193 (16): 4166–4179. doi:10.1128/JB.05245-11. ISSN 1098-5530. PMC 3147673 . PMID 21685290.
- ↑ Land, Adrian D.; Tsui, Ho-Ching T.; Kocaoglu, Ozden; Vella, Stephen A.; Shaw, Sidney L.; Keen, Susan K.; Sham, Lok-To; Carlson, Erin E.; Winkler, Malcolm E. (Dec 2013). "Requirement of essential Pbp2x and GpsB for septal ring closure in Streptococcus pneumoniae D39: Essential role of GpsB in pneumococcal division". Molecular Microbiology. 90 (5): 939–955. doi:10.1111/mmi.12408. PMC 4120849 . PMID 24118410.
- ↑ "1,000 inspiring Black scientists in America". Cell Mentor. Cell Press & Cell Signaling Technology. 28 Dec 2020. Retrieved 2023-06-30.