Pathogenesis Flashcards
To learn about the various ways microbes interact with humans
What are the ways humans interact with microbes
Colonization
Infection
Elimination
What is Colonization?
This is a means of interaction whereby the host tolerates the microbe
How about Elimination?
This involves the removal of the microbe from the body via the immune system
Infection?
This is a situation where there is an injury at the cellular level as a result of the presence of microbes
When does Colonization start?
at birth
5 examples of body surfaces that are colonized
conjunctiva, skin, large intestine, vagina, external ear
What about places that do not come in contact with the environment?
brain, muscle, blood and bone
What is Normal Body Flora
These are a group of microorganism that exist naturally within cerain anatomical site in a healthy person.
They can be classified based
Time at location
Relationship with host
What are the ones based on time at location
Transient
Permanent
What about relationship to host
Commensalism
Mutualism
Opportunistic
human factors affecting microbes at any anatomic site
genetics sex age nutrition and diet pH temperature
Microbial factors affecting microbes at any sites
Biofilm
Specific Adherence
Tissue tropism
Tissue tropism
this is the ability of an organism to infect a specific tissue, organ or set of organs.
Specific Adherence
Specific adherence involvescomplementary chemical interactions between the host cell or tissue surface and the bacterial surface
Biofilm
Biofilm formation is aprocess whereby microorganisms irreversibly attach to and grow on a surface and produce extracellular polymersthat facilitate attachment and matrix formation, resulting in an alteration in the phenotype of the organisms with respect to growth rate and gene transcription
What microbes can be found on Skin
staphylococcus, cornyebacteria
Microorganism on Conjunctiva
gram positive cocci
Micro organism in Vagina
Lactobacillus
Oral cavity microbes
Lactobacillus and streptococcus
Microbes in GIT
H.pylori, bifidobacteria enterococci
benefits of normal flora
synthesis of vitamins
stimulation of certain tissues
stimulation of the production of antibodies
preventing attachment of other microbes
killing of other bacteria via bacteriocin
Bacteriocin
Bacteriocins area kind of ribosomal synthesized antimicrobial peptides produced by bacteria, which can kill or inhibit bacterial strains closely-related or non-related to produced bacteria, but will not harm the bacteria themselves by specific immunity proteins.
Harmful effects of Normal flora
Low grade toxemia Bacterial Synergism Opportunistic Infections Transfer to Susceptible host Competition for nutrients
clinical significance of normal flora
difficulty in interpretation of culture results
applicable specimens
knowledge of patients clinical condition
pathogenesis
changes that occur in the body from the point an infective agent interacts with the body to the manifestation of the disease
pathogenicity
the ability of a microbe to cause diseases
pathogen
these are the agent that cause disease
virulence
degree of pathogenicity
invasiveness
the ability of a microbe to penetrate deep into tissues
toxigenesis
ability of a microbe to produce toxins
attributes of a pathogenic microbe
transmitability invasiveness toxigenesis adhesiveness host immune system evasion production tissue degrading enzymes
transmitablity
ability to move from the infected host to a new susceptible host or reservoir
mode of transmission
airborne contact vector droplets common vehicle transmission
difference between airborne and droplets
droplets have particles above 5 microns and airborne particles are below 5 microns
maintainace of transmitabilty
animal reservoirs transmission vehicles asymptomatic carriers clinical symptoms portal way of entry
adherence
ability of a microbe to attach to cell surface
types of adherence
Specific Adherence
NonSpecific Adherence
NonSpecific Adherence
reversible attachment to a eukaryotic cell surface (docking)
Specific Adherence
irreversible attachment to a eukaryotic surface. (anchoring)
streptococcus pyogenes attach where
pharnyngeal epithelium causes sore throat
adhesin is protein F receptor amino terminus of fibronectin
streptococcus mutans
adhesin glycosyl transferase
receptor salivary glycoproteins
attachment site pellicle of tooth
disease dental cavities
invasiveness types
active: induced by pathogen
passive: induced by host cell e.g Listeria monocytogenes.
types of bacterial toxins
exotoxins: are released from bacterial cells and may act at tissue sites or remote from bacterial cells Endotoxins aka(LPS) are cell associated and are released from growing bacterial cells
Host Immune Evasion mechannism
antigen heterogeneity
antigenic variation
capsule formation
IgA proteases formation
