11. microbial pathogenesis I Flashcards
when a micro-organism is growing and multiplying on or within a larger organism, known as the host, it is said to have an ______
infection
this is any change from a state of health in which part or all the host is incapable of carrying on its normal functions due to the presence of a pathogen or its products (toxins)
infectious disease
an organism that causes a disease is known as a ________
pathogen
the ability for a pathogen to cause a disease is called ________
pathogenicity
an organisms _________ is the degree of harm (pathogenicity) inflicted on its host
virulence
what factors does microbial virulence involve?
think “APIT”
- adherence
- persistence
- invasion
- toxigenicity
what are the two types of pathogens
extracellular and intracellular
these are pathogens that grow and multiply within host cells (inside the body cells such as macrophages, neutrophils and tissue cells). they can be subdivided into two groups: facultative and obliagate
intracellular pathogens
these are pathogens that remain in tissues and fluids but never enter host cells
extracellular pathogens
a type of intracellular pathogen that reside within the cells of the host but can also be grown in pure culture without host-cell support (in vitro)
facultative intracellular pathogens
- think can be studied in lab thus “faculty” therefore “facult”ative
a type of intracellular pathogen incapable of growth and multiplication outside the host cell.
obligate intracellular pathogens
true/false: all viruses are obligate intracellular pathogens
true
__________ are examples of protozoa that require host cells (RBC’s) for growth
malarial parasites
this is a micro-organism that does not causes disease
non pathogen
this is an agent capable of causing disease, only when the host’s resistance is impaired (e.g. immunocompromised).
opportunistic pathogen
true/false: opportunistic pathogens can be part of your normal microbiota
true
what are some characteristic of bacteria that are pathogenic?
- aderence
- persistence
- invasion
- toxigenicity
- transmissibility
- ability to survive in the hosts immune system
this scientist proposed a series of postulates that have been applied broadly to link many specific bacterial species with particular diseases
Robert Koch
what are Koch’s postulates
- the microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms
- the microorganism must be isolated from a diseases organisms and grown in pure culture
- the cultured microorganism should cause disease when introduced into a healthy organism
- the microorganism must be preisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
what are Koch’s molecular postulates
- the phenotype or property under investigation should be significantly associated with pathogenic strains of a species and not with nonpathogenic strains
- specific inactivation of the gene or genes associated with the suspected virulence trait should lead to a measurable decrease in pathogenicity or virulence
- reversion or replacement of the mutated gene with the wild-type gene should lead to restoration of pathogenicity or virulence.
this is the location from which the pathogen is transferred to the host
the source of the pathogen
the source of the pathogen can be either _____ (humans or animals) or ______ (water or food)
animate or inanimate
this is the natural environmental location in which the pathogen resides
reservoir
these are diseases where infectious agents are transmitted from animals to humans
zoonoses
