02 Mar

Normal Flora

When microbiologists refer to the normal flora of the human body they are referring to the microorganisms that live on our skin by outcompeting harmful pathogens.  The microorganisms that live on our skin can be placed into three categories: diptheroids, staphylococci, and yeasts/fungi.  Diptheroids are non pathogenic gram positive bacteria.  Propionibacterium acnes lives in the hair follicle and breaks down the oily secretion that prevents the hair from drying out.  Another group is called Staphylococci.  An exmple is Staphylococci epidermis which is non-pathogenic.  These organisms protect the skin from other pathogens by outcompeting them for space on the skin and by secreting substances that inhibit the growth of other organisms.  The third group, yeast and fungi ,include organisms that degrade lipid secretions from certain glands.  Some fungi and yeasts can cause opportunistic infections.  Dermatophytes are fungi that infect the hair, skin and nails causing athlete’s foot.