intro to micro host microorganism interactions

colonization

growth of microbiota in or on a body site without the production of damage or notable symptoms

indigeous microbioa

microorganism that are commonly found on or in body sites of healthy person

resident microbiota

colonized an area for months or years

transient microbiota

present at site temporarily

carrier state

condition in which pathogenic organisms establish themselves in a host w/o causing symptoms

how is microbial biota establish in body sites

pH, moisture level, amount or types of nutrients available

what is the role of normal flora

nutrient metabolism, inhibit colonization of extraneous pathogens by competition for nutrients and secretion of bacteriocins

bacteriocin

toxin a bacteria produces which inhibits growth of closely related bacteria

what are some members microbiota

opportunists

opportunistic infection

caused by microbe that normally does not causes infection about is able to in immunocompromised individuals or when habitat is new or disrupted

endogenous infection

microbe from host’s normal flora causes infection

exogenous infection

microbe from outside the host environment enters host and causes infection

iatrogenic infection

occurs as result of medical treatment or procedure

nosocomial infection

healthcare associated infection (HAI)

community acquired infection

infection acquired outside a healthcare environment

what is infection

organism enters host and multiplies beyond host ability to eliminate the organism

infectious diease

an infection that causes harm to host with visible sign and symptoms

pathogenicity

ability of microbe to cause diease

virulence

degree of pathogenicity

high virulence

greater severity of disease with low infective dose (# of organisms required to cause infection)

what are virulence factors

allows pathogen to evade host defense and cause diease

true pathogen

causes disease in healthy indiviudal’s

Invasion

the ability of a pathogen to penetrate and grow in tissue

Dissemination

ability of a pathogen to spread to distant sites from the original infection site

what are some routes of transmission

airborne, fomites, hand to hand, contaminated food/water, close contact, congenital, cuts, bites

how are capsules helpful for phagocytosis avoidance

mask cell surface structures by prevent recognition by phagocytic cell receptors and prevent binging of complement proteins and inhibiting complement activation

what are other ways bacteria interfere with phagocytosis

cell wall proteins and release toxins that kill phagocytes

what are adhesion factors

microbes that must attach to host cell before causing infection

adhesion

attachment cell surface structures

fimbriae (pili)

contains adhesion protein on their tips that bind to cell surface receptors

what are intracellular pathogens

bacteria that can survive and multiply in the phagocyte

what do intracellular pathogens survive

prevent fusion of phagosome and lysosome, escape from phagosome into the cytoplasm, and resistant to effect of lysosomal contents

toxins

poisonous substance produced by microbe that disrupts host cells and causes harm

exotoxins

produced by gram-neg and pos,

protein toxin found inside bacterial cell and excreted or released up lysis cell,

species specific,

heat labile (destroy by heat)

low dose to be fatal

endotoxin

produced by gram-neg (LPS)

not species specific

causes fever, hypotension, septic shock

heat stable

requires higher dose to be fatal

what is lipid A

it is the immunogenic component of LPS, causes the bad effects