VO 5 microbiology

• The human body acts as a host and, together with the microbes associated with it, represents a host-microbiome supraorganism.
• The microbiome is the entity of all microorganisms that naturally colonize a multicellular organism without triggering disease symptoms.
• Helicobacter surrounds itself with ammonia, which protects it against stomach acid.
• Lean mice have more Bacteroidetes, while obese mice have more firmicutes and methanogens.
• Methanogens produce more H2, which facilitates fermentation and the amount of nutrients acquired by the host.
• Mouse offspring of mothers with maternal immune activation (MIA) show autism-like behavior, which can be cured by feeding them with the human commensal bacterium Bacteroides fragilis.
• The tetanus toxin prevents the release of glycine from vesicles, resulting in continuous release of acetylcholine and muscle contraction
• Vibrio cholerae is a Gram-negative bacterium that causes cholera
• Clostridium tetani is a rod-shaped, Gram-positive bacterium that can form spores and is the causative agent of tetanus
• Tetanus infection can cause spasm in the extensor muscles of the back (opisthotonus)
• Cholera is treated by compensating for the loss of ions and water through administration of fluids
• The cholera toxin produced by Vibrio cholerae disrupts normal sodium ion influx, leading to severe diarrhea
• Some intestinal bacteria can increase the levels of indole-pyruvate and 4-ethylphenylsulfate, the neuroactive substance believed to trigger autism-like behaviors.
• Extravasation is the process in which cells migrate from blood capillaries to lymphatic capillaries and back.
• Pathogens are destroyed by three different mechanisms: innate immunity, antibody-mediated immunity, and cell-mediated immunity.
• Pathogen-associated molecular patterns (PAMPs) are macromolecules in pathogens or on their surface that exhibit repeating subunits and can be polysaccharides, proteins, nucleic acids, or lipids.
• Phagocytes are characterized by pathogen-associated molecular patterns (PAMPs) and pattern recognition receptors (PRRs), which activate the phagocytes to ingest and destroy pathogens.
• Phagocytes recognize pathogens through the interaction between pathogen-associated molecular patterns (PAMPs) and pattern-recognizing molecules on phagocyte receptors.
• Hematopoietic stem cells in the bone marrow differentiate into myeloid or lymphoid progenitor cells, which then differentiate into mature cells that perform different functions in the immune response.
• Lymph nodes are secondary lymphoid organs.
• Bacterial adherence is the first step of infection, and it can be facilitated by structures such as capsules, fimbriae, pili, and flagella.
• Some pathogenic bacteria form capsules, such as Bacillus anthracis, which consists of a polypeptide containing only the amino acid D-glutamate.
• Hyaluronidase and streptokinase occur particularly in virulent strains of Streptococcus pyogenes and coagulase in virulent strains of Staphylococcus aureus.
• Salmonella species encode a large number of virulence factors including type I fimbriae, antiphagocytic proteins, siderophores, exotoxins, and endotoxins.
• The botulinum toxin excreted by Clostridium botulinum prevents the release of acetylcholine, resulting in irreversible muscle relaxation and paralysis.
• The diphtheria toxin excreted by Corynebacterium diphtheriae catalyzes the ADP-ribosylation of elongation factor 2 (EF-2), leading to the cessation of protein biosynthesis and cell death.
• Virulence factors in Salmonella are encoded by genes located on mobile DNA and not on the chromosome, specifically in Salmonella pathogenicity islands (SPI).
• The tetanus toxin excreted by Clostridium tetani blocks the release of glycine, leading to increased muscle stimulation and the release of acetylcholine.
• There are 3 classes of exotoxins: AB toxins, cytotoxins, and superantigen toxins.
• Lipopolysaccharide (LPS) released by Gram-negative bacteria binds to the LPS-binding protein (LBP) and the LPS/CD14 complex triggers a signal transduction that leads to the activation of the transcription factor NF-kB, resulting in the production of inflammatory cytokines and chemokines.
• The CTX φ bacteriophage is a lysogenic, filamentous, single-stranded DNA phage that turns Vibrio cholerae into a highly pathogenic microbe causing cholera in humans.
• The main lymphoid organs are the bone marrow, thymus, lymph nodes, spleen, and MALT.
• The Staphylococcal α-Toxin is a pore-forming cytotoxin produced by Staphylococcus cells that oligomerizes in the cytoplasmic membrane of target cells, forming a pore and causing cell lysis.
• Innate immunity is the basic ability of the immune system to attack pathogens in general, while adaptive immunity is triggered by exposure to specific pathogens and is directed against a specific type of invading pathogen.
• Blood flows through the veins to the heart, lungs, and then through the arteries to the tissues, while lymph flows through the thoracic lymphatic duct into the left subclavian vein of the circulatory system.
• Pseudomonas aeruginosa, an opportunistic pathogen, forms biofilms in the lungs of cystic fibrosis patients.
• Enzymes like hyaluronidase, coagulase, and streptokinase can act as virulence factors in gram-positive bacterial pathogens.
• The membrane-spanning TLR2 interacts with peptidoglycan of gram-positive bacteria
• The LPS-CD14 complex then binds to the transmembrane receptor TLR-4
• Most phagocytes contain lysosomes, which are cytoplasmic vacuoles that contain bactericidal substances