lesson 1 Flashcards
number of bacterial species can reside in animal hosts, either as a
commensals or as potential pathogen
can interact with host tissues in ways that result in disease
pathogenic bacteria
- acquired soon after birth
- able to adhere to body surfaces.
- form stable polymicrobial communities that are present as ‘normal microflora’ lives skin and in the hollow organs whose surfaces and cavities are open to the environment
commensal organism
can exist as a commensal in the rumen but when it’s transfers to the liver of feedlot cattle it can act as a pathogen that causes hepatic abscesses
Fusobacterium necrophorum
virulence factors includes adhesins, toxins and capsules whose genes are expressed only when their products are required in a process called?
phase variation
Animals may be exposed to infection from 2 sources of infection
endogenous or exogenous sources
arise when bacteria that live on the skin or mucous membranes as harmless commensals take advantage of impaired antimicrobial defenses of the host and behave as opportunistic pathogens
endogenous infection
are example of obligate intracellular pathogens
- Chlamydiae
- rickettsiae
are example of facultative intracellular pathogen that can invade and replicate in non-phagocytic epithelial cells.
- Brucella species
- uropathogenic E. coli
- Salmonella species
- Listeria monocytogenes
this type of fimbriae can attach to urinary bladder.
Type I fimbriae of uropathogenic E. coli
This type of fimbriae attach to epithelial cells in the kidney
P fimbriae
The capsule of Bacillus anthracis is
composed of ________ _____; it is anti-phagocytic and is regarded as an essential
virulence factor
polyglutamic acid
integral constituents of the bacterial cell wall not released until the microorganisms are lysed
endotoxins
produced and secreted by viable bacteria
exotoxins
________ stimulate the production of prostaglandins and leukotrienes which are mediators of inflammation.
Cytokines
subunit that possesses toxic enzymatic activity
A subunit
subunit that is responsible for binding the exotoxin to specific receptors on the host cell membrane and may help in the transfer of the B subunit across the cell
B subunit
toxins that has A–B subunit structure
tetanus toxin and botulinum toxins
the principal challenge for the host is to?
detect the pathogen & mount a rapid defensive response
The cells of the innate immune system express
various________ ______ ______capable of detecting conserved molecular ‘patterns’ that are unique to microorganisms and are not expressed by the
hosts
pattern recognition receptors
Pattern recognition receptors is also called ?
pathogen associated molecular patterns
if the pathogen is not excreted i the faeces the host is describe as ?
latent carrier
if the pathogen is excreted i the faeces & is continiously or intermittently the host is cosidered as?
active carrier
route that is by the passage through intercellular spaces, this can be taken by bacteria that are able to disrupt the intercellular tight junction.
paracellular route
during this time bacteria are present transiently the bloodstream without replicating.
Bacteraemia
while this time pathogenic microorganism multiply & persist in the bloods stream producing systemic disease.
Septicaemia
the pathogens enter the epithelial cells through the _____ formed by the host cell membranes in response to signals generated by the pathogens.
membrane-bound vacuoles
this type of induced uptake mechanism is induced by specific ligand-receptor interactions at the cell membrane
zipper mechanism
this type of induced uptake mechanism is induced by effector molecules delivered into the cell by a type 3 secretory system.
trigger mechanism
_____ usually have a short severe clinical course, often a matter of days, & the invadimg bacteria are usually cleared from the body bu the hosts immune response.
acute infections
_____ produce clinical effects or less intensity
subacute infections
_____ tend to occur when the host fails to eliminate the pathogen
chronic infections
Endotoxins is composed of 3 parts:
- Hydrophobic glycolipid (LIPID A)
- Hydrophilic polysaccharide composed of (oligosaccharide )
- Opolysaccharide (O antigen)
toxicity redsides in?
Lipid A portion
Toll- like receptor is composed of:
- mononuclear phagocytosis
- neutrophils
- platelets
- dendritic cells
- B-lymphocytes
Release of cytokines induce & stimulate _____ that divide & produce antibodies:
Induced:
1. fever
2. active macrophages
3. clotting factor XII
Stimulate:
1. B cells
Categories of exotoxins:
- toxins that act on the extracellular matrix
- toxins that act on the plasma membrane of their target cells, where they interfere w/ transmembrane signaling pathways or alter membrane permeability
- toxins that act inside the cells where they modify signaling pathways or the activities of the cytoskeleton
- toxins that cause dysfunction of the immune system called “superantigens”
TLR’s is expressed in: 6 immune cells & 3 non-immune cells
Immune cells:
1. macrophages
2. dendritic cells
3. neutrophils
4. mast cells
5. b cella
6. specific t cells
non-immune cells:
1. epithelial cells
2. endothelial cells
3. fibroblast
this ______ is competent to detect microorganism
Innate immune system
this ______ detect the molecular signatures of microbial pathogens, they orchestrate the innate immune response, & they help the adaptive immune response.
TLR’s
this pathogen in cattle herds, can establish long term residence in both latent carriers & active carriers.
Salmonella dublin
______ bacteria produces high lethal toxins that kill the host, which then becomes an anaerobic substrate in which the bacteria multiply & from which they can be disseminated spores.
Clostridium species
this type of foriegn recognition is expressed in the surface by the microbes.
PAMPS
while this type of recognition is expressed by own cell, example injured cells that is needed to be removed or get rid off.
DAMPS
the strain of this microorganism is enterotoxigenic, it adhere to the epithelial cells of the small intestine in newborn farm animals, not invasive but they induced profuse quantities of watery diarrhoea.
Escherichia coli
_____ can contaminate a wound in any region of the body, producing a neurotoxins.
Clostridium tetani
secretes a number of toxin that degrade the epithelial barrier & allow the opportunistic pathogen to enter the sub epithelial barrier & allow the opportunistic pathogen to enter sub epithelial tissues.
pseudomonas aeruginosa
occur after direct or indirect transmission form an infected animal or from the environment.
Exogenous infection
