colonization

• growth of an organism in the host

infection

• the outcome of the growth in the host organism

disease

• an injury caused by the infection
• has to have some kind of negative effect

parasite 

• an organism that grows either on or in a host organism 

pathogen

• microbial parasite

obligate pathogen

• only can be found in humans
• only grows in the host
• always causes disease in the host

opportunistic pathogen

• may grow in other places
• often do not cause disease
• but can impair the host in some way

benefits of microflora

• synthesize vitamins
• stimulate the immune system development
• produces products that inhibit pathogens (because they compete with pathogens for nutrients)
• synthesize antimicrobials
• keep bad microflora out

microflora of the skin

• gram + cocci
• such as staphylococcus

microflora of the upper respiratory tract
(mouth/nose/throat) 

• gram + cocci
• such as staphylococcus and streptococcus

microflora of the lower respiratory tract 

(bronchia/lungs)

• usually relatively sterile with little microflora colonization
• macrophages work to clear bacteria and flora out of the lungs

microflora of the gastrointestinal tract

(stomach/small intestine/colon)

• largest amount of microflora found in colon
• helicobacter: stomach, ulsers
• bacteroides: colon, break down polysaccharides
• C. difficile: colon, if growth because too much it can become bad - largest hospital gained infection, spreads so easily because of spores
• E. coli: colon, not problem causing until it enters other parts of the body than the colon
• Methano-brevubacteria: gut, produce methane

factors that affect microflora growth

• pH
• O2 levels

microflora of the upper genitourinary tract

• usually very sterile, not microflora growth

microflora of the lower genitourinary tract

(urethra)

• gram - rods
• such as E. coli

microflora of the vagina

• changes over the lifetime of a woman
• prepuberty/post-menopause: high pH, staphylococcus and streptococcus
• fertile years: lower pH, lactobacilli