| How do bacteria present in an infection? | Bacteria are ubiquotus (found everywhere)
Some get inside the cells and are facultative intracellular to escape the immune system
May be parasitic (intracellular or extracellular)
They usually take advantage of the digestive and respiratory system aided by flora to infect us |
| What are bacteriocins? | Substances produced by bacteria to destroy other bacteria |
| What is an antigen? | It is a substance that induces an immune response. |
| What cells does innate immune response include? | Normal flora |
| What cells does adaptive immune response include? | Lymphocytes |
| What cells produce cytokines? | Leukocytes, endothelial cells and fibroblasts |
| What is clonal selection? | It is the process by which a T cell becomes able to be activated by one certain antigen, when T cell mature in the thymus, they are cloned to attack one type of antigen each.
It takes 2 weeks. |
| What are TLRs of the innate immune system? | Toll-like receptors, sensors that bind to certain molecules
Has many types ( each bind to a specific molecule)
F.E: TLR1 and 2 bind triacyl lipopeptide, TLR3 dsRNA... |
| How does the innate immune system function? | Doesn't need adaptive immunity, will react regardless of the type of antigen present creating an inflammation by releasing cytokines |
| What is pathogen-associated molecular patterns? | They are molecules recognized by TLRs and NOD-like receptors |
| How does the skin contribute to the innate immune system? | Skin is not only a barrier, it has keratin, hair cells, sweat glands... that give acidity to stop pathogens
There are flora in the skin adapted to its acidity that form symbiotic relationship with it. |
| How does mucus contribute to the innate immune system? | Mucus is found in the respiratory tract, secreted by goblet cells, and the mucus escalation is done by cilia and goblet cells.
This escalation is increased for smokers.
This mucus entraps antigens, has flora and antibodies IgA that stop any potential infectious agent for the lungs. |
| What contributes to the innate immune system in the GI tract? | It has acidity, mucus and flora making an innate immune system unit. |
| What leukocytes are considered as part of the innate immune system? | Neutrophils, Induced by infections (bacterial usually), bone marrow disorders (leukemia, myeloid) and autoimmune disorders (rheumatoid arthiritis) |
| What is neutrophilia? | Neutrophil excitement
Neutrophils are the stupidest cells, they are weak but directly attack any antigen, the death of them and antigens cause formation of white puss |
| What role is played by peroxidase in innate immune system? | Found in some cells, produce free radicals to kill other cells, free radical are extremely toxic, so they may cause immunopathological disease. |
| What are the 5 cardinal signs of inflammation? | Nociception (pain), Chaleur (heat), Erythema (redness), edema (swelling), loss of function
(they don't usually occur all together) |
| What causes each cardinal sign of inflammation? | Nociception: release of cytokines and fluids.
Redness and Heat: extra flow of blood into the infected area for leukocytes to act there
Edema: The extra blood flow will cause entry and diffusion of protein molecules and water into the inflamed area |
| A px has a foot cut, signs of redness and swelling appear around the cut, but inside it appears a whitish substance of puss.
Is this white part a part of the inflammation? | No, its part of the infection, the product of the fight between neutrophils and the infectious agent (antigen) |
| What is necrotizing fasciitis? | Aggressive tissue eating by a microorganism
(F.E: streptococcus pyogene which is flesh eating bacteria) |
| Are the sign of inflammation only tells for inflammation? | No they may be due to autoimmune. |
| What is oxidative respiration? | Immune response by neutrophils.
Respiration since it uses consumed O2 |
| Describe the process of oxidative respiration. | O2 in converted into a O2 radical called superoxide by NADPH oxidase.
These are harmful substances, then they are converted into peroxide (H2O2) by superoxide dimutase.
Then these H2O2 can be converted by myeloperoxidase into HOCl to kill the bacteria invading the body.
These are happening in phagolysosome of the neutrophils. |
| What is opsonization? | binding an antibody to an antigen (in case of adaptive immunity)
or molecule to an antigen (in case of innate immunity - for example: CRP protein which primarily binds to bacterial infection) |
| 2 pxs, one presents with 10,000 WBC count, 30% neutrophils and 4CRP molecules, while another presents with the same amount of WBC, 80% neutrophils and 75 CRP molecules.
What do these numbers mean in terms of infection types? | Px 1 has viral infection (high WBC count)
Px 2 has bacterial infection (high CRP) |
| Where does CRP exert its actions? | In blood attach to bacteria, so they dont bind to viruses since they live intracellularly and not in blood. |
| What do we mean by pyogenic? | Pus-producing neutrophilic reaction debris |
| What are pyrogens? | Molecules that increase body temperature, by acting on the hypothalamus, they may be exogenous (LPS, teichoic acids) or endogenous (IL1, IL6, TNF- alpha)
These are proinflammatory cytokines |
| What are ILs? | interleukins, parts of cytokines with specific functions |
| What cells are active in the adaptive immunity? | T cells and B cells
(First at feta life produced by liver, and then by bone marrow, T matured in thymus and clone formation occurs there)
B cells are activated by T helper to become a plasma cell that forms antibodies.
Immune system has self-recognition |
| What are haptens? | small molecule that stimulates the production of antibody molecules only when conjugated to a larger molecule, called a carrier molecule |
| How do bacteria infect the body? | . |
| What parts of immune system are NK and Cytotoxic T cells? | NK: innate
Cytotoxic T: adaptive |
| Talk about type I hypersensitivity. | Due to allergies (strawberry, peanuts...) cause anapholactic shocks
Hydatid cysts (kyes kleb) when bursted contain substances that we are allergic to and eventually cause anapholaxis. |
| Talk about type II hypersensitivity. | Antibodies confuse normal cells with bacteria because of shared antigens between them, for example streptococcus and heart tissue in rheumatic fever |
| Talk about type III hypersensitivity. | Antigen-Antibody complex stuck in a tissue, (kidney, blood vessel, lung, joint causing inflammations (vasculitis, brochitis, arthiritis, nephritis. |
| What is immune system evasion? | They are ways for bacteria to avoid the immune system. |
| List ways of immune system evasion. | Intracellular habitat
mimicking self antigens (for example attaching bodies sugars into bacterial LPS as a camoflage)
encapsulation (calyx)
antigen variation
Usage of virulence factors to inhibit : phagocytosis, cytokine production and complement cascade activation |
| What are the stages of progression of a disease? | Transmission (until an inoculum is there)
Incubation period (btw transmission and symptom may be years - viruses)
Disease and symptoms
Convalescence (either clearance or latency) |
| What do we mean by inoculum? | Number of cells needed for infection to occur.
(F.e: 1,000 bacteria for shigella, 10^7 for E. coli) |
| What do we mean by reservoir? | place or host involved in transmission.
Soil, human, animals... |
| What is prodrome? | Early stages of infection, they are non-specific symptoms, that present before the period of the illness.
Caused by cytokine release by innate immune system |
| Progression of disease. | . |
| What did Koch do? | He worked on TB, and was the first person to visualize killer infection process. |
| What are Koch's postulates? | They are used to identify whether a microorganism causes a disease or not
For it to be a pathogen there should be 4 conditions:
1-Bacteria should be present for every diseased preson
2-bacteria should be able to grow in a culture
3-Bacteria from the culture should be able to cause the disease as well
4-Organisms should recover from experimentally infected hosts |
| What are the flows of Koch's postulates? | Not all bacteria grow in vitro (we use mice legs in this case)
Some bacteria only infect humans (sych as mycelia gonorrhea) which is unethical work |
| What are molecular postulates? | We study the virulence of a bacteria by studying its genes.
1. Virulence gene or end-product present only in diseased.
2. V. gene must transform a non-pathogen to pathogen.
3. V. gene expressed during disease.
4. Antibodies present against the gene or product. |
| What are modes of transmission of bacteria? | Direct contact (herpes/ staph aureus)
Indirect contact (infected surfaces like COVID droplets)
Air bourne (inhaled germs found in the atmosphere of a room floating - dry feces)
Ingestion (bacilis cereus food poisoning)
Fecal-oral (from mouth into feces excreted like vibrio cholera)
Sexual contact (gonorrhea)
Injections (IV)
Transplacentally (mother to child)
Breastfeeding (HIV)
Animal-Human (rabies)
Vector-borne (need vehicles like insects and malaria)
Already latent infections
Intoxication (ingest toxins) |
| What is aspiration? | The flow of liquid into respiratory tract (F.E: mucus escarate) |
| Talk about intracellular and extracellular bacteria. | We have obligate intracellular (these have no vaccines, like rickettsia, chlamydia,....
Facultative intracellular (Salmonelly, shigella, brucella, listeria, heliobacter...
Extracellular (Streptococcus, E.coli, vibrio treponema...)
And spore forming ; clostridium and bacillus |
