wk2- host-microbe interactions Flashcards
what determines the outcome of a symbiotic interaction? 3
host immune response, microbe, environment
types of interactions between humans and microorganisms/agents
mutualistic - benefits both
commensal- benefits agent and doesn’t harm human
parasitic- benefits agent, harms human
what do endogenous microbiota do for the host 4
-immune priming
-competitive inhibition
-vitamin synthesis
-terminal differentiation of gut mucosa
dysbiosis define
disruption to the balance in the endogenous microbiota at a specific anatomical niche
imbalances that cause dysbiosis are (3
- changes in composition of microbial community
- changes in the functional capacity and metabolic active of the endogenous microbiota
- a shift in the local distrubtiiton patterns of the microbiota
eubiosis define
homeostasis, balance
when do opportunisitic infections occur
-when low abundance of commensal members of endogenous microbiota overgrow the usually more abdunent/ protective microbial community members due to lack of competition.
steps to transmission (3)
- source of infectious agents
- susceptible hosts
- mode of transmission
classification of microorganisms/infectious agents
living and nonliving
living:
bacteria,
fungi,
parasites
nonliving
viruses
pions
what is a reservoir
the source/ environement in which the infectious agent persists. these could be humans, animals or non-living environments like water, soil, biofilms
bacteria are what
prokaryotes (largest group of infectious agents)
fungi are what?
diverse group of eukaryotes
transmission occurs between individuals via what methods? 4
direct contact
indirect contact with reservoir
common vehicle
vector
direct contact transmission
when susceptible hosts come into contact with the skin or bodily secretions of an infected person
indirect contact transmission
when susceptible host touches an inanimate object (fomite) that has been contaminated with an infectious agent
vehicle transmission
transmission through a large area by air, water, or food. difference between indirect contact and vehicle is vehicle infects large masses through a single vehicle contaminated
vector transmission
vectors are living organisms that transit infectious agents from one host to another. they are usually anthropods. can be either
mechanical vectors - mode of transport between hosts. coacroach or
biological vectors- that participate in the lifecycle of infectious agent. mosquitoes/ticks
major portals of exit and entry in the human host ? 2
- natural openings related to physiological function (nasal, ear, mouth)
- beaches of barrier integrity (incisions, breaks, bites)
2 main barriers for the body and what do they consist of
- skin- keratin aids waterproofing, keeps inside in/outside out and resistant to bacterial enzymes/toxins. dermis inhibits growth of infectious agents through its sturctures.
- mucous membranes- mucous covers the tightly packed epithelial cells providing a chemical defense against infectious agents
portals of entry can occur through what?
- respiratory tract
- gastrointestinal tract
- skin (injuries)
- congenital infections
- urogenital tract
natural openings, skin and congenital infections
but infectious agents must enter host via a specific portal of entry to initiate a new infection as infectious agents have specific tropism
portal of exits /shedding can occur through
urine
emsis (vomit)
deification
tidal breathing
blood
coughing
sneezing
list features that create a susceptible host 6
- extremes in age (over 70, under 2years)
- nutrition (inadequate protein/micronutrients)
- illness (disrupt physiological function)
- immunosuppression (immunity suppressed)
- genetics (physiological function)
- anatomical defects (physiological function)
can commensalism turn into a parasitic interaction?
yes
what are biofilms
liquid-solid interface providing a physical protection for the infectious agent against, temp, pH, disinfection, sheering forces, antimicrobial treatment, immune recognition
