Commensal and Pathogenic Flora

protective microbes grow on

1st on skin, 2nd on oropharynx, 3rd on GI tract, 4th mucosal surfaces called microbial flora

functions of microbial flora

protection from infection by virulent microoranisms, stimulate immune response, aid in metabolism, provide essential growth factors

balance of microbes is influenced by

diet, overall health, hormonal change, personal hygiene

any change in balance of microbes

can make us sick

microorganism exposure outcomes

transient colonization, permanent colonization, disease

Microorganisms that colonize humans

don’t interfere with normal bodily functions

disease occurs

when microorganisms cause damage to a human host

pathogen

microorganisms that can cause disease

staphylococcus aureus can cause

food poisoning, pneumonia, or a wound infection

meningitis can be caused by

bacteria, viruses, fungi, parasites

always pathogenic organisms are

rabies virus, plasmodium species, bacillus anthracis

disease from an external source

exogenous infection (influenza virus)

disease from human’s own microbial flora

endogenous infection (majority of human diseases)

Factors for endogenous infection

site of exposure, virulence of organism (degree of pathology), host’s ability to respond to the organism

Opportunistic pathogen

part of normal microbial flora, take advantage of a weakened immune system, disrupted microbial flora, breached behavior introduced by a wound