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Virus
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an infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host.
(google definition because the notes are ass)
(google definition because the notes are ass)
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What do viruses do?
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Viruses enter cells and divert the synetic process of these cells to their own replication. (in some cases they can kill the cells)
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Are virsuses alive?
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no
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Are bacteria alive?
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yes, they have a tight cell wall with cytoplasm and their genetic material is organized in circular chromosomes.
They have their own DNA and RNA, and are able to self-repilacate.
They have their own DNA and RNA, and are able to self-repilacate.
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Do bacteria have a nucleus?
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no, the chromosomes are just free floating, which makes the bacteria a prokaryote
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What is a prokaryotic cell?
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a cell without a nucleus (genetic material is floating in the cell)
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Eukaryote
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A cell that contains a nucleus and membrane bound organelles
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Fungi
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Pathogens that csan cause infection in humans
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Normal Bacterial Flora
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A bacterial population that is "normal" for the human body. It will not cause an infection or illness, or other potentially harmful effects.
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Resident Flora
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the flora that live in your body and decide that your body is the best living place. They stay here until your body dies. (Long-term)
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Transient Flora
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the flora that yu pick up by eating, touching or breathing. they live inside you for a little but they don't like the environment so they just die off.
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where is a place where you normally find large amounts of flora?
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the large intestine, mouth, skin and lungs
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where would you find no flora?
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in the brain and circulatory system
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why is there no bacteria in the stomach?
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it is too acidic (pH 2) and flora would rather an alkaline environemnt (pH of 7-8)
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why is it important to have bacteria in the body?
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well established bacteria can aid you immune system in the event of a bacterial infection. they will "protect" their home and fight against the invasive organisms
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name the ways in which normal flora (nm) is clinically important:
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1. healthy nm will protect a person from invasive organisms (to an extent)
2. nm of the urinary tract participates in metabolic process
3. disturbances in the ecology and balane of nm may be produced by the antibiotic C
4. nm is controlled by various host defences and defiences may result in infections by non patholgenic organism
5. the presence of nm in clutues can confuse lab results
2. nm of the urinary tract participates in metabolic process
3. disturbances in the ecology and balane of nm may be produced by the antibiotic C
4. nm is controlled by various host defences and defiences may result in infections by non patholgenic organism
5. the presence of nm in clutues can confuse lab results
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Define pathogen
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disease causing microorganism (bacteria), and they never mean to do bad things. ei- why would you kill your host
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do organisms invade the body outside their normal territory?
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no, they stick to one site
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what happens when bacteria invades a nm site?
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a bacterial infection of the sterile or preoccupied site.
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what are the important immune responses to agressive bacteria?
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phagocytosis, antibodies (humoral immunity), complement, cell mediated immunity and endo/exo-toxin production
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what is the mechanical barriers?
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it is the skin, which acts like a wall between deep tissues and bacteria. (bacteria on the surface may cause infection if they reach deeper layers of the skin)
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adherence
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the first requirement for bacterial invasion which lets bacteria adhere to the host.
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phagocytosis
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macrophages and neutrophils will engulf bacteria and kill them as a defence mechanism.
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how to bacteria prevent phagocytosis?
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some bacteria surround themselves in polysaccharide capsules.
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opsonization
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coating antigen with antibody enhances phagocytosis- the antigen or antibody will latch onto the surface and allows phagocytosis.
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antibodies to bacteria
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people may form antibodies against bacteria. antibodies may function as an opsonin or may kill organisms directly.
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complement
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a complex system of plasma proteins that will work together and resist bacteria infection. it will enhance immune response.
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cell mediated immunity
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some nacteria species are killed by activeted macrophages- they were activated by cell mediated immunity. (vital in defence against bacteria)
*examples bacteria killed by this are mycobacterium tuberculosis and legionella
*examples bacteria killed by this are mycobacterium tuberculosis and legionella
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exotoxin production
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bacteria may produce exotoxins that can damage host tissue. they are proteins that are synthesized by bacteria and then released. they can affect areas far away from the origin site AND the host defence is antibodies
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interactions between pathogenicity mechanisms and the host defence
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nm is held in check and invasive disease is prevented in the healthy indevidual by the previously mentioned defences.
invasive infection is determined by the interaction between host and pathogenicity mechanisms of bacteria
invasive infection is determined by the interaction between host and pathogenicity mechanisms of bacteria
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metastatic spread
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when bacteria is distributed around the body from a single focus of infection through the bloodstream. **these spreading organisms by the blood stream can cause clinical symptoms in places away rfom the origin
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compromised patients
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patients defeicent in antimicrobial defences. these defiencies may be due to a disease or to medial/surgical procedures
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name examples were defiencey will lead to infections (when the host defence is missing)
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phagocytic cells (eg. leukopenia) --> staphylococcus aureus and streptococcus pneumoniae
antibody mediated immunity --> streptococcus pneumoniae and viral infection
cell mediatd immnity --> tuberculosis, legionella and AIDS
antibody mediated immunity --> streptococcus pneumoniae and viral infection
cell mediatd immnity --> tuberculosis, legionella and AIDS
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define microorganism
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organisms invisible to the naked eye. (normally harmless and many are useful- only a very small portion are harmful)
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define infection
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penetration of a microorganism or a part of it capable of multiplication into a host. there will be either an aparent or inaparent chance.
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apparent infection
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infection that presents symptoms
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inaparent infection
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an infection with no aparent symptoms.
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colonization
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establishment and multiplication in/on the body of a microogranism without producing any apparent/inapparent change.
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contamination
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deposition of microorganims without multiplication, ex is contamination of a sterile dressing
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clinical infection
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a disease that occurs when the balance bwteen host and microorganism is disturbed
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subclinical infection
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a harmful infection that is inapparent or asymptomatic.
*whether something is clinical or not depends on the pathogenicity
*whether something is clinical or not depends on the pathogenicity
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pathogenicity
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the ability to produce disease
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virulence
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relative capacity to cause damage (the degree of pathogenicity)
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pathogensis of infectious disease
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when microorganisms enter the body, two opposing forces are set into action:
- the microorganim is stiriving to multiply and invade
- the host will strive to block invasion and destroy the microorganism
- the microorganim is stiriving to multiply and invade
- the host will strive to block invasion and destroy the microorganism
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what is the capacity of a microorganism to produce infection and disease dependant on
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transmissibility, pathogenicity and invasiveness
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transmissibility
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the transfer of an effective amount from a source to a host
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what are the routes of entry for transmissibility?
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inhalation, ingestion, break in protective barrier and direct deposit
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invasiveness
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ability of a bacterial pathogen to rapidly spread through tissue and overcome host defense mechanism
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ways in which the bacteria evade the host:
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-surface structures: adhere to specific receptors on body cell surfaces
-capsules: usually polysaccharides that protect microorganisms against leukocytes
-capsules: usually polysaccharides that protect microorganisms against leukocytes
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enzyme function in bacteria evasion:
answer
contribute towards the virculence of pathogens that elaborate them. the contributions are: coagulation, hyalunronidase and toxigenicity
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coagulation
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the accelaration of blood clotting arounf infection to act as a protective basrrier for the infection
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hyaluronidase
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digests polysaccharides that hold cells together
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toxigenicity
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ability to produce a toxin- there are two classes in toxigenicity
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what are the two toxigenicity classes?
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exotoxin and endotoxin
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exotoxins
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proteins secreted by lving bacterial cells. they have specific affinities for host system and are active in small amounts
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are exotoxins thermomobile?
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yes- they react and thrive in heat
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endotoxins
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toxin substances associated with the bacterial cell and liberated only when the cell disintegrates.
these are less specific and potent than exotocins but they will create clinical effects such as fever, sickness or vasomotor disorders (shock)
these are less specific and potent than exotocins but they will create clinical effects such as fever, sickness or vasomotor disorders (shock)
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are endotoxins thermomobile?
answer
no, they are resistant and therefore thermostable
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are endotoxins as toxic as exotoxins?
answer
no, they are less toxic than exotocins which are HIGHLY toxic.
question
how can you get infected by a lot of exotoxins?
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by taking a large amount of antibiotics
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