Pathogenesis Flashcards
Define pathogenesis. What are the three main steps?
-The entry, colonization, and growth of the microorganism in the host
-results in detrimental outcomes for the host
Why does our body need some bacteria?
You want bacteria there since they keep the nasties from taking over-competition and all that good stuff
Where are common habitats for bacteria in humans?
-skin, mouth, respiratory tract, intestinal tract, and urogenital tract, are all typical bacterial habitats for bacteria
Where is there usually no bacteria in our body?
Organs, blood, lymph, and the nervous system
Define the steps of adherence and give an example
-The ability of a bacteria to “stick” either specifically or nonspecifically to a surface
-involves an interaction between a molecule on the bacterial cell surface and a receptor or other cell surface protein on the host cell
Define the steps of invasion and give an example
-The ability of a pathogen to enter an organism and spread
-Often through breaks or lesions in either the epithelium or the mucosal membrane
-two kinds of pathogens: Intracellular and extracellular
-Invasion by intracellular pathogens generally requires that they enter host cells
Define the steps of colonization and give an example
-Multiplication of a pathogen within the host
-dependent on the availability of nutrients and growth tractors and is generally limited to specific tissues to which the microorganism is well adapted
-assisted by pathogen-specific factors like siderophores (iron chelating compounds) and help the bacterium strip iron from host-derived iron-binding proteins like transferrin
What is bacteremia? How does it differ from a location infection?
-systemic bacterial infection and the shedding of bacteria into the blood
What are virulence factors
any pathogen-derived compound or proteins that aid in the establishment or maintenance of disease
Why should we study and care about endotoxins give examples
What does C. botulinum cause? How does it do this?
-Causes the disease botulism
-severe food poisoning
What is C. botulinum endotoxin and what does this lead to?
The primary virulence factor in the disease is an endotoxin (Botox) that causes flaccid paralysis
What are PAMPS? Where are they found? What recognizes them? Are they conserved or variable? Why is this helpful?
-pathogen-associated molecular patterns
Give two examples of PAMPS
lipoteichoic acid and lipopolysaccharide
Can viruses reproduce on our skin? How about our nails? Why or why not? What protein is important in this?
What is SALT (besides NaCl)? What does it stand for, and where is it located?
-It is a specific defense system that is connected to the skin
-Skin Associated Lymphoid Tissue
-it is located just below the surface of the skin
What specific cells initiate the SALT response and what do they do if a pathogen or foreign entity is sensed?
The specific response is initiated by Langerhans cells, phagocytic cells that engulf and destroy microbes they also signal other immune cells that there is trouble
What are three ways our skin can be breached?
-Insect (mosquito bite)
-Cut
-burn
What is our mucosal membrane? Where is it found in the body and what constitutes it?
-A thin lining in areas such as the intestinal tract, respiratory tract, vaginal tract, and bladder that are constantly exposed to material from the external environment
-The lining consists of a single layer of mucosal cells.
What is mucus? What is the primary competent of it?
-consist of a mixture of proteins and polysaccharides
-traps microbes and prevents them from reaching epithelial cells
Define lactoferrin
An iron-binding protein
Define lysozyme and defensins
small proteins that make pores in microbial cell membranes
What does MALT stand for? What actually is it?
-Mucosa-Associated Lymphoid Tissue
-like the skin, the mucous membrane is also associated with specific host defenses
What is GALT? What is it, and what does it stand for?
-Same as MALT but in the intestinal tract
What are natural killer cells? What do they target? What do they kill, and how do they do that?
-they are the body’s second line of defense
-target intracellular pathogens including viruses
-NK cells attach to infected cells and kill them by releasing granules containing molecules that are toxic to human cells
What are neutrophils? What do they target? What do they kill? Where are they produced, where do they live, and for how long?
-The body’s second line of defense
-target extracellular microbes
-they are produced in bone marrow
-They are short-lived but numerous
What are the unique anatomical features of a neutrophil?
-Have a multilobed nucleus, lysosome, and an endoplasmic reticulum
-“polymorphonuclear”: refers to the multilobed structure of the nucleus
What are the steps of a neutrophil attack (think about 5 steps)?
1) The microbe is engulfed by the neutrophil and enclosed in the phagosome
2) The interior of the phagosome acidified in response to the active transport of protons into the compartment by a membrane ATPase
3) The neutrophil also contains granules called lysosomes. Lysosomes contain substances that are toxic to the microbe including proteases and defensins as well as myeloperoxidase
4) Upon fusion of the phagosome and the lysosome myeloperoxidase is activated and produces hypochlorous acid (HOCl) from hydrogen peroxide (H2O2) and chloride anion (Cl-). Peroxide and superoxide are produced by the non-mitochondrial respiratory burst
5) These radicals and enzymes kill bacterial cells. They are toxic to the host as well and must be contained in the lysosome
What is a complement?
The complement system directs the circulating neutrophils to the site of infection
What does MAC do? What is MAC effective against?
-MAC makes holes in the cell membrane of gram-negative bacteria, effectively killing them
-MAC is responsible for some bacteria being “serum sensitive” while others that have altered their LPS are “serum resistant”
How does MAC matter for serum sensitivity or serum resistance?
MAC insertion typically is not enough to lyse Gram-positive bacteria due to their super thick cell walls. They are thus “serum resistant”
What happens when complement is activated?
it activates MAC
What is pus made of?
Pus is made up of DNA and protein from damaged human cells
What are cytokines? What do they do?
-Small secreted proteins produced by many cell types, especially the endothelial cells that line the blood vessels and macrophages
-further stimulate the neutrophils to kill the microbial invaders
What is septic shock? How does this happen? Can it be reversed? What is the typical pathway, and what are three main outcomes?
-The neutrophil defense is designed for local infections where a little collateral damage is acceptable
-If the inflammatory response is triggered all over the body, septic shock will develop
-during septic shock neutrophils attach to blood vessels throughout the body and exit the bloodstream leading to blood fluid loss into surrounding areas
-Patients suffer irreversible damage to the heart and other major organs
-three outcomes include: DIC, damage to organs, or hypotension
Can septic shock be controlled? Is so, how? If not, why not?
What are three ways microbes can avoid being killed via phagocytosis?
How can microbes combat the complement system (two ways)?
How can microbes resist phagocytosis via a specific response?
How can bacteria protect themselves from toxicity? What are come molecules that bacteria can make
