Term
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Definition
| plant/animal which lives upon or within another living organism, at whose expense it obtains some advantage |
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Term
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Definition
| ability of an organism to colonize tissue |
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Term
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Definition
| ability of an organism to cause disease. Low grade pathogens only affect immunocompromised host which leads to opportunistic infections. High grade pathogens (virulent) affected healthy hosts as well. |
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Term
| rank the structural complexity, ranging from prions to arthropods. |
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Definition
| prions -> viruses -> intracellular bacteria -> mycoplasma -> bacteria -> fungi -> protozoa -> metazoa -> arthropods |
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Term
| describe the classifications of viruses, bacteria, fungi, protozoa/metazoan |
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Definition
viruses: type of genetic material, presence of envelope
bacteria: shape, gram stain, and oxygen requirement
fungi: yeasts, hyphae, moulds, or dimorphic
protozoa, metazoan: structural characteristics |
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Term
| describe the three sites of multiplication and which infectious agents are associated with them. |
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Definition
OBLIGATE INTRACELLULAR ORGANISMS
- prions, viruses, rickettsia, Chlamydia requires host cells to grow and multiply, using hosts metabolic machinery for growth
- usually infect parenchymal cells
EXTRACELLULAR ORGANISMS
- most of other pathogens
- multiply outside of cells
FACULTATIVE INTRACELLULAR ORGANISMS
- mycobacteria, some fungi
- can growth both inside (usually macrophages)and outside of cells |
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Term
| for the organism to be successful as a parasite, must be transmissible as well as capable of multiplication and intimation of disease in a new host. true or false |
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Definition
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Term
| what are the four principal methods of spread of infection? |
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Definition
physical contact
airborne infection
food-borne infection
insect-borne infection |
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Term
| what are the three possible outcomes upon invasion of an infectious agent, and what is it influenced by? |
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Definition
- the invader dies due to non-specific defences and immune response
- the invader survives without obvious clinical disease, still immune response (sub clinical infection)
- the invader survives, multiplies, and produces clinical disease (clinically apparent infection)
- influenced by virulence of the organism, status of primary defences of the host, and immune status of the host, as well as previous exposure |
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Term
| briefly list the four host barriers to infection |
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Definition
skin
urogenital tract
respiratory tract
intestinal tract |
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Term
| describe skin as a host's barrier to infection, and how/when it is penetrated |
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Definition
- outer keratinized skin layers are constantly shed and renewed; low pH and fatty acids inhibit microbial growth
- organisms can penetrate through breaks in the skin
- heat and humidity favour entry through the skin |
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Term
| describe the urogenital tract as a host's barrier to infection, and how/when it is infected |
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Definition
-normally is sterile because of regular flushing
- increased chance of infection occurs in women, during obstruction of flow, and reflux
- pathogens need to be able to adhere well to the epithelium |
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Term
| describe the respiratory tract as a host's barrier to infection, and how/when infected. |
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Definition
-distance traveled is inversely proportional to size: if trapped in mucociliary blanket, transported back to throat, and swallowed.
- if it is small, it will travel to alveoli where it will undergo phagocytosis by alveolar macrophages/neutrophils
- damage to epithelium leads to the opportunistic fungi, or secondary infections |
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Term
| describe how the intestinal tract is a host barrier to infection, and what it defends against |
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Definition
defends against food/drink contaminated with fecal material
- defences:
- gastric juice, mucus, enzymes, IgA (from B cells in MALTs)
- these defences are weakened by low acidity, antibiotics or obstruction |
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Term
| infection of the bloodstream contains the presence of which four micro-organisms in the blood? What two was are they carried? |
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Definition
viremia(viruses enter the bloodstream), bacteremia, fungemia or parasitemia.
carried free in plasma or attached to or within blood cells or leucocytes(White blood cells) |
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Term
| define septicemia. what is associated with it (symptoms)? |
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Definition
severe condition in which large numbers of bacteria have overwhelmed the body's defines mechanisms and are multiplying in the bloodstream. toxins may also be present.
associated with high fever, increased HR, low BP, shock and DIC (Disseminated intravascular coagulation, a pathological activation of coagulation (blood clotting) mechanisms that happens in response to a variety of diseases) |
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Term
| diseases associated with infection of the bloodstream may result from which two things? |
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Definition
| the effects of the organism on the host and the effects of the host response to the organism |
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Term
| the Energy, substrates, and synthetic machinery for viral growth are provided from where? |
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Definition
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Term
| infection of specific cells with viruses are due to? |
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Definition
| the presence or receptors on their cell membranes which are recognized by proteins on the virus surface (ligands) |
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Term
| list the 6 steps in the viral life cycle |
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Definition
~ virus binds to Rc via ligands
~ penetration of the cell: fusion with PM, Rc-mediated endocytosis, or translocation across PM
~ Uncoating inside the cell: genome separates from structural elements
~ initiation of nucleic acid transcription and translation cycle using specific enzymes
~ synthesis of new viral proteins and genome replication
~ assembly of new virions and their release directly or by budding |
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Term
true or false
viral infections often damage tissue sufficiently to render them more susceptible to bacterial pathogens such as secondary bacterial infections |
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Definition
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Term
| describe and give an example of cell necrosis as caused by cytopathic viruses |
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Definition
lethal change in cell function and dispersion of virions by cell lysis.
example: ebola virus (a filorvirus; RNA, env+)
- affects endothelial cells, leading to hemorrhage
- carried by monkeys and arthropods
- fever, muscle pains, anorexia, rashes, abdominal pain, DIC(Disseminated intravascular coagulation, a pathological activation of coagulation (blood clotting) mechanisms that happens in response to a variety of diseases) |
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Term
| with regards to viruses, slow cell necrosis occurs over an extended period because of what? |
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Definition
| because of persistent (chronic) viral infections |
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Term
| what is slow cell necrosis (due to injury caused by viruses) followed by? give a detailed example of a virus that follows this path. |
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Definition
followed by fibrosis (formation of excess fibrous connective tissue)
example:
- hepatitis C virus
- major cause of liver disease
- causes cirrhosis (loss of normal lobular (a clear division only visible histologically) architecture of the liver due to necrosis followed by scarring and nodular regeneration as a result of chronic injury to the liver
- HCV transmission occurs via inoculated blood transfusions
- asymptomatic infection or mild acute hepatitis
- chronic relapsing hepatits, leading to persistent chronic infection or fulminant (event or process that occurs suddenly and quickly, and is intense and severe to the point of lethality) hepatitis
- persistent chronic infection may lead to cirrhosis (consequence of chronic liver disease characterized by replacement of liver tissue by fibrosis, scar tissue and regenerative nodules)
-hepatocellular carcinoma (most common type of cancer) |
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Term
| briefly list the 6 types of injury caused by viruses. |
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Definition
- cell necrosis
- slow cell necrosis
- cell swelling
- inclusion body formation (aggregates of stainable substances in biological cells)
- giant cell formation
- latent viral infections |
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Term
| regarding inclusion body formation (a type of injury caused by viruses), when is it formed? what does it consist of? where can it occur? can it be useful diagnostically? |
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Definition
- formed during the process of viral replication
- consists of either assembled viral particles, or parts of viral nucleic synthesis
- can occur in both nucleus and cytoplasm
- useful for diagnostics. |
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Term
| regarding giant cell formation (a type of injury caused by viruses), what is it caused by? can it be used diagnostically? |
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Definition
- caused by fusion of cell membranes of affected cells
- useful diagnostically |
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Term
| regarding latent viral infections (type of injury caused by viruses), describe what is occurring. briefly name two possible outcomes. |
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Definition
- viral genes ramin in cell but are not expressed
- reactivation and development of neoplasms (abnormal mass of tissue as a result of neoplasia. Neoplasia is the abnormal proliferation of cells.) |
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Term
| in regards to reactivation (a possible outcome of latent viral infections [a type of injury caused by viruses]), list the possible stimulatory factors, and give a detailed clinical example. |
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Definition
stimulatory factors: stress, age, nutritional/hormonal imbalance, trauma, immunodeficiency
example:
- herpesviruses:
- severity of cytopathic effects varies
- HSV-1 causes primarily oral lesions, HSV-2 primarily causes genital lesions.
-HSV-1:
- virus latent state in sensory nerve ganglia -> stress leads to travel via sensory nerves to skin which leads to replication -> lysis of infected cells which results in cold sore. |
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Term
| what are the two main responses of the body after multiplication of viruses? |
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Definition
| inflammation and immune response |
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Term
| what do obligate intracellular pathogens do? |
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Definition
induce acute response characterized by lymphocytes, plasma cells and macrophages, but few neutrophils(most abundant type of white blood cells)
- lack of chemotactic (direct their movements according to certain chemicals in their environment) factors |
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Term
| characteristics of chronic viral infection |
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Definition
chronic inflammation characterized by lymphocytes and plasma cells
- cell necrosis followed by fibrosis |
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Term
| when/what are IFNs (Interferons) made by? what does it do? |
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Definition
by CD4+ lymphocytes in the DTH ( delayed type hypersensitivity as the reaction takes two to three days to develop) response
- its a potent macrophage activator, enhancer of NK (Natural killer cells) activity and interferes with viral translation |
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Term
| what is chlamydia trachomatis ? |
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Definition
| major cause of non-gonococcal (bacteria responsible for the sexually transmitted infection gonorrhoea) urethritis(inflammation of the urethra.), as well as neonatal blindness and major infectious cause of female sterility |
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Term
| what is chlamydia psittaci? |
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Definition
| cause of psittacosis, a zoonotic disease that can be passed from birds to man |
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Term
| rickettsia (type of bacteria) require what for transmission? |
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Definition
| arthropod (invertebrate [do not develop a vertebral column.] animal having an exoskeleton) vectors. |
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Term
what is R.prowazekcii?
what is the primary reservoir of infection for rickettsia? |
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Definition
| the causal agent of typhus (spotted fever), with the rat being the primary reservoir of infection. |
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Term
| name two other diseases similar to rickettsia, and the process of the disease. |
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Definition
two other diseases: Rockey mountain spotted fever and Q fever
process: injures to he vascular endothelium lead to thrombosis (formation of a blood clot ) and hemorrhage (loss of blood or blood escape from the circulatory system) |
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Term
an infectious prion protein originates from what?
describe process. |
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Definition
it is a modified form of a normal structural protein in the nervous system.
process:
- normal prion protein (PrPc) undergoes conformational change to become an abnormal protein (PrPsc).
- combines with normal host proteins on surface of neurones, inducing formation of abnormal complexes that are internalized into neurones
- development of spongiform encephalopathies(disorder or disease of the brain). it's characteristic vacuolar degernation seen in brain
- damage leads to dysfunction of affected brain tissue and neuronal loss |
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Term
| name the three ways of contracting a prion based disease |
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Definition
| sporadic, inherited, or transmitted. |
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Term
true or false
prions are associated with an inflammatory response |
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Definition
false
there is no inflammatory response to prion. |
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Term
| describe the diseases contracted through prions. give some examples. |
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Definition
diseases are slow, generative neurological diseases, that are characterized by progressive loss of function, ending in death.
examples: scrapie of sheep, BSE of cattle, chronic wasting disease (CWD) in elk or mule deer, CJD and GSS in humans. |
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Term
| opportunistic bacteria (take advantage of certain situations. usually do not cause disease in a healthy host. A compromised immune system, however, presents an "opportunity" for the pathogen to infect.) are constituents of what? |
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Definition
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Term
| antibacterial agents kill outside of host how? |
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Definition
| by denaturing bacterial proteins or interfering with metabolism |
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Term
| antibiotics have specific activity against what? broad-spectrum antibiotics are effective against what? |
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Definition
specific activity against bacteria
- broad spectrum antibiotics effective against wide variety or bacteria |
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Term
| bacterial infections produce cell/tissue injury by: |
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Definition
adhering to host cells
release of locally acting as well as remotely acting toxins.
production of local vasculitis(destroy blood vessels by inflammation) |
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Term
| extent and severity of injury due to bacterial infections depends on |
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Definition
- ability to attach and enter host cell
- capability of toxin production
- genes encoding adherence proteins and toxins are often co-regulated by specific environmental conditions because their precise coordination is very important for bacterial influence. |
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Term
what are bacterial adhesins?
name and describe the three types |
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Definition
molecules that bind bacteria to host cell
GRAM +VE
- bind by lipotechoic acids and protein F. also have surface M proteins that prevent phagocytosis by macrophages
GRAM -VE
- have surface fimbraie (appendage shorter than a flagellum) which: adhere to host cells and determine it, and sex pili, which exchange genes carried on plasmids or transposons.
FACULTATIVE INTRACELLULAR BACTERIA
- restricted tropism(growth or turning movement in response to stimulus) of epithelial cells and macrophages
- bind to host cell PM integrins or ECM proteins |
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Term
| list the functions of locally acting toxins (enzymes). name and describe two examples |
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Definition
break down complex food materials
allow tissue invasion
cause tissue injury by breaking down substrates
examples:
STAPHYLOCOCCUS AUREUS
- produces coagulase: fibrinogen--> fibrin coating of bacteria--> resist phagocytosis
CLOSTRIDIUM PERFRINGENS
- ferments sugars in muscle leading to gas formation in tissue plus other enzymes |
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Term
| name the three remotely acting toxins that travel via blood stream |
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Definition
endotoxins
exotoxins
enterotoxins |
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Term
what make up the endotoxins of bacteria?
these endotoxins can result in what?
endotoxic shocks accompines what? |
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Definition
lipopolysacchardie components of the cell walls of gram -ve bacteria, which are released into the blood following bacterial death and lysis.
result in:
- generalized peripheral vasodilation (leaping to septic shock)
- endothelial cell injury and activation of the coagulation cascade, leading to DIC
- acute respiratory distress syndrome
- fever results from release of 1L-1 by macrophages
- endotoxic shock accompaies sever UTIs, inestinal surgey, or any Gram -ve infection |
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Term
exotoxins are secreted by what and thusly absorbed by what?
name two characteristics of exotoxins |
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Definition
secreted by living bacteria and absorbed in the blood
- are highly antigenic and will thus induce formation of specific antibodies
- heat labile |
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Term
| describes the steps of staphylococcus aureus (an exotoxin) needed to deliver clinical symptoms |
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Definition
| TSST binds to MHC II molecules on APCs-> stimulus of T cells -> excess IL-2 production -> excess TNF -> systemic disturbances, fever, shock |
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Term
| describe clostridium tetani (an exotoxin) |
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Definition
is the tetanus toxin
- survies as spores for long periods and is acquired by contamination of wound
- interferes with release of inhibitory neurotransmitters which lead to muscle spasms |
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Term
| describe clostridium botulinum (an exotoxin) |
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Definition
the botulism toxin
- disease acquired by ingesting pre-formed toxin
- highly resistant spores found in soil; acquired in food poisoning
- blocks release of Ach-> progressive paralysis |
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Term
| describe group a streptococci (an exotoxin) |
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Definition
necrotizing fasciitis-"Flesh eating disease"
- spreads in subcutaneous tissues and into deep fascia -> thrombosis of vessels , gangrene
- rapid progression: without treatment, death follows
- also cause strep throat, scarlet fever, puerperal sepsis, erysipelas |
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Term
| briefly list the four examples of exotoxins. |
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Definition
staphylococcus aureus
clostridium tetani
clostridium botulinum
group a streptococci |
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Term
| enterotoxins exter their effect on what? list steps leading up to clinical signs. |
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Definition
| exert their effects on intestinal mucosal cells (enterocytes) and then bind to Rc -> structural damage or functional alterations -> diarrhea, cramping, and abdominal pain |
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Term
| list (briefly) the 4 specific species of enterotoxins taught. |
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Definition
vibrio cholerare
enteropathogenic E coli
infection type food poisioning
toxin type food poisoning |
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Term
| describe vibrio cholerae (an entrotoxin) |
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Definition
a cholera toxin.
- iso-osmotic fluid secretion leads to extensive loss of water |
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Term
| describe e.coli (an enterotoxin) |
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Definition
verocytotoxin
- in contaminated meat, milk or vegetables
- hermorrhagic colitis and haemolytic uremic syndrome |
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Term
| describe the two types of food poisoning (aka acute gastroenteritis) (caused by exotoxins) |
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Definition
INFECTION TYPE
- bacteria in contaminated food multiply and produce toxins in the bowel
- signs appear 12-24 hours post ingestion
TOXIN TYPE
- bacteria in food produce toxins, which are then ingested
- signs appear 2-6 hours |
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Term
| with regards to bacteria, how can production of local vasculitis lead to clinical symptoms? |
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Definition
| highly virulent bacteria can invade and cause thrombosis of small blood vessels -> ischemic necrosis of the area around the infection |
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Term
| what mechanism does the body use in response to bacterial infection? |
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Definition
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Term
| acute inflammation (a type of suppurative inflammation; a common response to bacterial infection) accompanies what type of infections? what can be seen? |
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Definition
accompanies acute infections
- increased vascular permeability and large numbers of neutrophils can be seen |
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Term
| describe suppurative inflammation (the bodies response to bacterial infections) |
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Definition
- both acute and chronic)
- liquefactive necrosis and formation of pus, maybe abscesses
- evoked by pyogenic bacteria: G+ve cocci, G-ve rods
- likely when anatomical factors inhibit drainage and the resolution of acute inflammation
- inflammatory response of host can be the cause of many disease signs |
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Term
what are koch's postulates?
list them. |
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Definition
criteria necessary to establish an etiologic association between the presence of a microorganism and the presence of disease.
- organism is regularly found in the lesions of the disease
- organism can be isolated as single colonies on solid medium
- inoculation of this culture causes disease in experimental animal
- organism can be recovered from lesions in the animal. |
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Term
| what are the growth requirements of fungal infections? |
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Definition
| humidity, warmth and oxygen |
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Term
| use of antibiotics has what effect on fungal infections? |
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Definition
| alters normal bacterial flora -> increased incidence of fungal infections |
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Term
| immunosuppressive therapy and chemotherapy have what effect on fungal infections? |
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Definition
| lead to opportunistic fungal infections |
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Term
| what is tissue injury caused by when responding to fungal Ags? |
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Definition
| induction of DTH response |
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Term
| systemic fungal disease are rare, but a problem for which types of individuals? |
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Definition
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Term
| name and describe the two types of superficial fungal diseases |
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Definition
DERMATOYCOSES
- aka ringworm
- highly contagious
CANDIDASIS
- oral cavity, GI, gentialia |
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Term
| eosinophilia and granulomatous inflammation are often seen in assocaition with which type of infections? |
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Definition
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Term
| differentiate definitive host from intermediate host for parasites. |
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Definition
DEFINITIVE HOST
- host of the mature, reproducing form of parasite
INTERMEDIATE HOST
- host of immature form |
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Term
| what is a protoza and how is it transmitted |
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Definition
one celled organisms (IC or EC parastie able to assume varity of forms within the host).
transmitted through isnect vectors or by ingestion |
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Term
| what is the life cycle of malria in man, and what are its disctive clincial features? (malaria is a protozoa) |
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Definition
cycle:
mosquito bite-> infection of liver cells -> rapid multiplication-> released to infect RBCs -> asexual reprodcution inside -> escape by destroying RBCs
clinical features:
- spikes of shaking, chills and fever
- haemolytic anemia
- discolaortion of spleen, liver, lymph nodes and bone marrow
- hyperlasia of mononuclear phagocyte system reflected in massive splenomegaly |
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Term
| what were the two specific protozoas disused? |
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Definition
| malaria and toxoplasmosis |
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Term
| what is the definitive host of toxoplasmosis (a protozoa)? what does it lead to? |
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Definition
definitive host is cats. leads to ingestion of fecal infected material by humans -> disease.
cogential infections can lead to deaht in utero or birth defects. |
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Term
what are helminths?
- what does the type of disease they induce depend on?
- do these organisms behave as opportunisitc pathogens? |
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Definition
multicellular parasites with well defined life cycles that are able to infect many different animal species.
- the type of disease they induce depends on stage of life cycle and organ affected.
- don't act as opprotunistic pathogens |
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Term
| what are the three main types of helminths? |
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Definition
nematodes (roundworms)
cestodes (tapeworm)
trematodes (flukes) |
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Term
| do nematodes (a type of helminth) require an intermediate host? |
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Definition
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Term
| list and describe the three main types of nematodes (a type of helminth) taught. |
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Definition
HOOKWORM DISEASE
- aka ankylostomiasis
- larval form lives in moist soil -> burrow through skin in bare feet -> lung via blood -> trachea -> pharynx-> swallowed -> SI -> attach to mucosa -> and feed by sucking blood -> anemia
ROUNDWORM DISEASE
- aka ascariasis
- ingestion of eggs of parastie -> penetration of intestinal wall -> travel around the body, get back to SI to mature -> bowel obstruction, bile duct and pancreatic duct inflammation
PINWORM DISEASE
- aka anal irritation, aka trichonisi, aka filariais
- lymphatic obsturction -> chronic edema -> elephantisis |
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Term
| describe cestodes (a type of helminth) |
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Definition
long, flattened. segmented worms
- transmitted through inadequalty cooked meat -> maturation and reprudction in SI -> excretion of eggs in feces -> infection of animals
- rarely causes disease signs in human host |
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Term
do trematodes (a type of helminth) require an intermediate host?
describe its example |
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Definition
yes, its often a snail.
- schistosomiasis is a fluke that lives in viens of pelvis and bladder. it leads to hematuira and predispostion to cancer. |
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Term
| decribe and give examples of external parasites (anthropods) |
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Definition
scabies, lice, and fleas
- can cuase itching-> scractching -> injruy to skin -> secondary bacterial infection
- can cause HS rxns to bites -> extreme itching response
- vectors of a variety of bacterial, rickettsial and prozoal diseases
- important disease carriers that can act in two ways:
MECHANICAL VECTOR
- picks up infecting agents and either depsoists on exposed foods or passes it on via contamination of biting mouth parts
BIOLOIGCAL VECTOR
- essential role in completion of life cycle of infecting agent |
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