Please enable JavaScript.
Coggle requires JavaScript to display documents.
Human Host (Flora
-Normal resident flora, AKA "Microflora"…
Human Host
Flora
-Normal resident flora, AKA "Microflora" or "Commensals"
-Include a variety of normal residents, such as bacteria, fungi, protozoa + viruses & arthropods
Acquisition
-Earliest contact occurs at birth when infant makes contact w/ immediate environment
-Main habitats are the skin & mucous membranes, the alimentary tract & openings to the surface of the GU, respiratory & reproductive tracts (large intestine has the highest no. of bacteria)
-Organs & fluids inside the body cavity & CNS are free of normal flora due to host defense mechanisms
Colonization of the Newborn
-Breaking of the fetal membranes exposes the infant to microbes
-8 to 12 hrs after delivery, the infant is colonized by bacteria such as streptococci, staphylococci & lactobacilli primarily acquired from the mother
-Bottle-fed infants tend to acquire mixed coliform populations, lactobacilli, enteric streptococci & staphylococci
-Breast-fed infants tend to acquire bifidobacterium, favoured by growth factors from the breastmilk
-Contact w/ pathogens is dangerous since the neonate is not yet protected by a full complement of flora due to immature immune defenses
Effects
-To protect & nourish by altering pH & O2 tension, excreting chemicals & inhibiting potential pathogens via antagonism & competition for nutrients
-Certain normal flora bacteria in the intestine can release residual vitamins
-Can also serve as a reservoir for bacterial pathogens
-
Germ-free Animals
-Germ-free animals live longer & have fewer diseases than normal controls, IF they remain in a sterile environment
-Flora contribute significantly to the development of the immune system
-Germ-free animals are less tolerant of microbes & can die from infections by relatively harmless species
-Germ-free animals have lower counts of WBCs + a slower antibody response
-Germ-free animals are highly susceptible to experimental infection by enteric pathogens
-Conclusion = Normal flora is not needed for survival, but an axenic/germ-free life is highly impractical
*GNOTOBIOTIC = Inoculation of 1 type of microbe to study its effect