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105 Cards in this Set
- Front
- Back
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What does Predisposing factors mean?
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May make people more or less susceptible to certain diseases
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What are some examples of Predisposing factors?
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Gender, Genetic background, State of the host in terms of nutrition.
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Give an example of gender as a predisposing factor?
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Females may have higher incidences of UTIs
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Give an example of genetic background as a predisposing factor?
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Sickle-cell and thalassemia...which may give you resistance to malaria but you will have enough problems to deal with.
Cystic fibrosis which causes pseudonymous |
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Give an example of state of the host in terms of nutrition as a predisposing factor?
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Preexisting conditions..
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What is the definition of the development of disease?
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Certain sequences of events that occur once the disease has been established in the host.
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What are the sequences for the development of disease?
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Incubation period, Prodromal period, Period of disease, period of decline, and convalescence.
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What is Incubation period
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Time between infection and visible symptoms, depends on the hosts health and virulence of pathogen
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What is the prodromal period
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time after incubation period, short with mild symptoms
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What is the period of illness
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Most acute stage of disease, strong symptoms
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What is the period of decline
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If the host overcomes illness symptoms subside.
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What is the period of convalescence
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It is when body start to return to prediseased state
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Explain epidemiology
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Study of how diseases occur and how they are transmitted throughout the population. Determines the etiology of disease, factors involved in disease, patterns of disease, and possible outbreaks.
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CDC?
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Center for disease control
CDC where most epidemiological studies of infectious diseases occur. |
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What is parasitism
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Type of symbiosis where the pathogen adversely affects the host.
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What is disease
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An intense contest between pathogen and host immune defenses.
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What are the factors involved in disease?
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Virulence of pathogen, numbers of pathogen, and the health and age of host.
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What is pathogenicity
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Pathogens ability to cause disease.
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What is virulence
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Degree or intensity of pathogenicity
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What is invasiveness
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ability of pathogen to spread to other tissues in body
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What is taxigenicity
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Ability of pathogen to secrete toxins.
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What is ID50
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Infectious dose 50 Which is a measure of virulence, the number of pathogens required to cause disease in half of the infected hosts.
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The lower the ID50....the?
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The more virulent/pathogenic the pathogen.
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What is the ID50 in chickens for Pasteurella Multocida
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10
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What is the host's Defense?
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Defenses that allow the host to combat the invading pathogens
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What are the two types of host defenses?
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Non-specific host defenses and Specific host defenses.
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What are some examples of non specific defense system?
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Skin, mucosal surfaces, normal flora, inflammation, decreased availability of iron and fever, phagocytic cells which are macrophages.
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What is the most important nutrients that is needed by pathogens?
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IRON!!! xD
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What is the normal temperature of our body?
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37 degrees C
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What happens when you are above 37C degrees
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It is called a fever and is caused by exogenous pyrogens
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What is exogenous pyrogens produced by?
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By invading pathogens
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What do Exogenous pyrogens have?
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LPS, parts of peptidoglycan, soluble enterotoxins, other protein or carbohydrate molecules.
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Why is fever a defense mechanism?
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because it stimulates phagocytic cells and triggers the host to decrease the amount of iron which is needed as food by the pathogen...It also enhances B and T cell response
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What is the specific Defense system?
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Humoral immune response which is antibody mediated.....Cell mediated immune response
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What is susceptibility about?
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It is all about receptors..which you are born with.
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Why does Haemophilus Influenzae only infect humans
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Because the receptors only interact with the receptors on humans...
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Why does P. Multi infect everything
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because their receptors are universal
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How do Pathogens interact?
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They interact at the molecular level and they specifically react with the surface receptors of a given tissue type. Different hosts have different cell surface receptors, meaning certain pathogens will only infect certain species.
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What does the Phenotype (types) of cell surface receptors depend on?
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It depends on the genotype of he host.
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Is it possible that certain people can be immune to certain pathogens
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Yes it is
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Some people who have disorders such as sickle cell anemia and thalassemia may be immune to what?
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Malaria
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What happens if you do not have the CCR-5 Receptor
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Then you can never be infected with HIV
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Does malnutrition increase hosts susceptibility to infections?
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Yes
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At what age are you more prone to susceptibility
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At a very young age or very old age
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What is hyperferremia
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Too much iron in the host which invites microbes to a Christmas dinner
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How can prior infections cause more susceptibility?
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Host may carry antibiotic strains or past infections may have caused tissue destruction.
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Example of a genetic disorder that makes the body more susceptible to disease
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Cystic fibrosis ...which makes people more susceptible to Pseudomonas infections
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What is microbial pathogenicity?
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The structural and biochemical mechanisms that allow pathogens to cause disease.
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What is Pathogenicity in bacteria associated with
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Structural features of the cells which are fimbriae, flagella, capsules, LPS, outer membrane proteins, etc
Secreted substances that either damage host tissues which are toxins or protect bacteria against host defenses |
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What all all the steps to cause disease within a host
CAIPGE |
Contact with the host and enter the host
Attach to the host tissues Invade the host tissues and cause infection Produce toxins to allow it to produce disease Grow and survive within host until it finds another host Evade the host immune system |
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How are diseases transmitted?
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Direct contact by sneezing, coughing, touching, airborne, in the soil, and also through vectors.
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Rabies virus?
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Rabid animal bites
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Plague
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Yersinia pestis transmitted by flea bites
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Streptococci, hepatitis B virus and Pseudomonas infects what?
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Cuts, abrasions, or wounds.
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Most pathogens are expelled or rapidly phagocytized by macrophages that we breathe in but what are some pathogens that get in successfully?
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Legionella Pneumophila and Mycobacterium tuberculosis are able to survive within macrophages in lungs
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Helicobacter pylori?
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Grow in stomach and cause ulcers. we eat it
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Vibrio cholerae, shigella, and salmonella ?
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Via food and are able to bypass the mucosal layer and bind to the epithelial layer.
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Neisseria gonorrhea?
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infects urinary tract in men and may not show symptoms and can still infect others
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What is required for bacterial adherence?
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A receptor from the host and an adhesin from the pathogen
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What are receptors?
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Specific carbohydrates or peptide residues on the host cell surface
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What is a bacterial adhesin
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typically a protein or glycoprotein found on the cell surface which interacts with the host cell receptor
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What is true about adhesion's?
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Only infect certain tissue types, hosts, or subspecies of hosts.
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Fimbriae
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Filamentous appendages that extend out of the cell surface of bacteria and are composed of proteins
Their main role is adhesins to host cells and are needed to initiate bacterial colonization |
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Type 1 Fimbriae
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In Enterobacteriacae which bind specifically to mannose terminated glycoproteins on eukaryotic cell surfaces
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Type 4 Fimbriae
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such as Psuedomonas, Vibrio cholera, Neisseria spp., Pasteurella multocida, and are directly involved in attachment and are required for further invasion of the host.
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E coli has type 1 and type 4 fimbriae?
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yes
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Capsule
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for adhesion and is a polysaccharide material which may mediate specific or nonspecific attachment
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Lipopolysaccharide LPS
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Gram negative bacteria it is used for adhesin as well as a pyrogen.
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Teichoic acids and lipoteichoic acids LTA
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Gram positive and are involved with nonspecific and specific adherence
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How does Streptococcus Pyogenes (Group A streptococci) attach?
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Nonfimbrial protein F mediates streptococcal adherence to the mucosal surface on the pharyngeal epithelium.
*****It attaches the Streptococci on the Pharyngeal epithelium***** |
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How dose Staphlococcus Aureus attach?
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It has specific outer membrane protein that is bound to the cell interacts with fibronectin on the mucosal epithelium
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Invasion factors
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enable bacteria to invade host cells and facilitate entry at mucosal surfaces and are usually extracellular substances
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What do invasins do?
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They damage but do not kill the host cells enables the immediate spread of the pathogen. They act on cells where the bacteria is actively growing.
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Hyaluronidase
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produced by gram positives and is good for skin and gets rid of wrinkles. It attacks the connective tissue between cells which break apart the tissue
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Collagenase
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produced by Clostridium spp. and it breaks down collagen
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Neurominidase
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produced by gram negatives and breaks down intracellular cement which is the neuroaminic acid of the epithelial cells found in the intestinal mucosa
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Coagulase
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Produced by Staphylococcus spp. and it converts fibrinogen to fibrin which causes clotting of the blood. The fibrin is found on the surface of the bacteria and is thought to make the cell resistant to phagocytes.
The fibrin goes on the cell wall making the bacteria hidden so it looks like self and not nonself. ;) Breaks down Bcells and also has food since its blood clots allova the place |
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Toxigenesis
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different to infection, disease cause specific pathogen's toxins
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Toxins
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products of a pathogen that destroys the host cells vital tissue, allowing the pathogen to grow and spread.
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What are the three types of toxins
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Endotoxin
Exotoxin Haemolysins |
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Endotoxins?
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LPS of the gram negative is bound to the cells. And the toxicity is associated with the Lipid A
LPS sheds off to create more |
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What are the three components of the LPS
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Lipid A = Core Polysaccharide = O antigen
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Lipid A?
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anchors the LPS and its structure is highly conserved among all gram negatives.
And is a pyrogen which causes fever. Can cause tissue necrosis, blood coagulation, and toxic shock |
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Exotoxin
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Travels and targets specific cells.
Proteins are secreted from the bacterial cell into the extracellular environment. Because these proteins are soluble, they are carried throughout the body in the blood or lymph damaging areas at a distance from the infection site. |
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Can Exotoxins kill cells? Why or Whynot?
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Yes they can because they are often cytotoxic.
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What are some examples of exotoxins
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Diptheria toxin(in back of throat) which blocks protein synthesis in host cells. Toxin production only occurs if the bacterium is infected with a certain bacteriophage.
So even though it sits in the back of your through until it is infected with the bacteriophage which HOLDS the toxins..it is harmless |
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What is the diptheria toxin produced by?
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Cornebacterium diptheriae
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What is the deadliest toxin and why?
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Botulism Toxin Because it is a neurotoxin
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Botulism Toxin
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Inhibits acetylcholine release from motor nerve endings and kills the nerve cells. It causes Flaccid paralysis where you cannot move the heart stops. It also is spore forming.
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What does Clostridium botulinum produce? And does it need a bacterium to be toxic?
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Botulism toxin and no it does not.
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Tetanus toxin
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It blocks the function of certain nerve cells which leads to spastic paralysis in the host where you cannot move. The spore grows in an open wound and then slowly spreads.
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What does Clostridium Tetani produce?
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Tetanus toxin
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Haemolysins
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These enzymes act on animal cell membranes they create a pore in the host cell and releases bacteria which attached to the host cell and all the cell stuff pour out of the cell which lyses it....."red blood cells"
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Examples of Haemolysins
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Staphlococci = alpha toxin
streptococci = streptolysin E. Coli = RTN |
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The growth and survival of pathogens?
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Each pathogen grows in a specific tissue type.
In order to successfully parasitize the host the pathogen must grow and replicate and while doing this they must also evade the immune system and regulate genes are switched on or off during infections. |
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What is the success of the pathogen dependent on?
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The set of genes it possesses
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Where are virulence genes encoded on?
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Chromosomal DNA, bacteriophage DNA, plasmids, and transposons
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What is the kilobase of plasmid in Shigella spp
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140kb and it carries all the genes necessary to invade cells and cause disease.
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E. Coli spp contain plasmids that encode what?
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Heat liable enteroxin LTI genes
and Type 4 fimbrial genes |
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How are virulence genes acquired?
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via Bacteriophage infection
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What are some examples of how virulence genes are acquired
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Cornebacterium diptheriae only has the diptheria toxin gene when introduced by a bacteriophage.
The same goes for Streptococcus pyogenes which has the erythrogenic toxin gene And last is the Clostridium botulinum which has the botulinum toxin |
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What toxin gene does streptococcus pyogenes linked to?
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Erythrogenic toxin gene....scarlet fever
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What toxin gene does clostridium botulinum linked to?
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Botulinum toxin
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What are pathogenicity islands (PI)
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Large DNA fragments in pathogens chromosome which contains a number of virulence genes and range between 20-200kb
And PI's increase the virulence of the bacteria. |
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How many PI's does salmonella have in one strain
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5
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