Chapter 14: Microbiome Flashcards
total community of microbes associated with an organism
microbiome/microbiota
the microbiome is composed of
bacteria, archaea, fungi, protozoa, viruses
organs and tissues that harbor microbiomes
skin, eyes, mouth, nose, oropharynx, stomach, intestines, genitourinary tract
organs and tissues that should be kept sterile
bloodstream, respiratory tract (excluding lungs), certain parts of the genitourinary tract
number of microorganisms that typically inhabit an environment
bioburden
most prominent microbial ecosystems in the body
skin, oral/nasal cavities, genitourinary tract, intestine
area of the human body with the highest bioburden
intestine
anaerobes outnumber aerobes because they can occur without the presence of _______, making it advantageous in environments where ________ are low or absent
oxygen; oxygen levels
the more anaerobic the body site, the more _______ are present
anaerobes
even aerobic sites contain __________
anaerobes
skin limits microbial growth by
being acidic (pH 4-6), having high salt, low moisture content, and enzymes like lysozyme
___________ bacteria are more likely to colonize because they are resistant to salt/dryness
gram-positive
imbalance in microbiome composition, leads to skin diseases like rashes, acne, dermatitis, etc.
dysbiosis
dysbiosis leads to disease because the imbalanced microbiota is unable to protect itself from ___________ that trigger inflammation, toxins, and carcinogenic metabolites
pathogenic organisms
tears contain ____________ such as lysozyme; constant bathing in tears washes away ________
antimicrobial compounds; germs
harbors microbes in the eye
tear and oil glands/ducts and eyelash follicles
dysbiosis in the eye
infections of the eye surface (conjunctivitis), inflammation against normal microbiota (styes, blepharitis)
________ is a strong defense against microbial growth in the mouth, contains antimicrobial compounds like hydrogen peroxide and lysozymes, _______ the mouth, making the environment difficult to adhere to
saliva; washes
provide a surface for bacteria to adhere and grow biofilms
teeth
aerobic surface in mouth
surface of teeth
anaerobic surface in mouth
spaces in between teeth
dysbiosis in mouth
can lead to bacteria entering the bloodstream (bacteremia) and lead to toxic shock syndrome and multi-organ failure
aerobic surface in oronasopharynx
nasopharynx and oropharynx are oxygen-rich, harbor streptococcus and staphylococcus
anaerobic surface in oronasopharynx
small pits along the tonsils contain crypts
dysbiosis in oronasopharynx
streptococcus progenies can colonize in the throat and tonsils, establishing a severe infection that can lead to bacteremia and multi-organ failure (aerobic microbiota is colonizing in the wrong spot, causing an imbalance)
lungs maintain a low bioburden to the
mucociliary escalator
mechanism responsible for clearing the respiratory tract of most foreign debris and microbes
cilia move bacteria in and out of the airways, keeping most microorganisms in the nasopharynx
bacteria that enter the trachea are trapped by ______, protects the lungs from this entry
mucus
dysbiosis in the lungs
inhalation of too many pathogenic microbes will overwhelm the mucociliary escalator, leading to infection of the lung
the stomach inhibits microbial growth due to the
low pH (~2) of the stomach acid
bacteria (H. pylori - pathogenic to stomach and first part of intestines) that have pH ______ and can access the ___________ can colonize in the stomach
5-6; mucus lining
the intestinal microbiome is fully ________ and has a _______ pH
anaerobic; neutral
only anaerobes and facultative anaerobes can survive here; anaerobes are the most _________
intestinal microbiome; abundant
the numbers and diversity of the ____________ are greater than any other human microbiome
intestinal microbiome
benefits of intestinal microbiome
we absorb 15-20% of our daily calorie intake as microbial byproducts, vitamins and hormones are produced by microbes and absorbed by cells
nerves in the GI tract connect the CNS to form the __________ (signaling), bidirectional
microbiome-gut-brain axis
neurochemicals from the brain travel to nerves in the gut to alter _________ and __________
gut function and microbiome balance
gut microbiome produces __________ that can alter brain function, affecting mood and behavior
neurotransmitters
dysbiosis in gut
diseases like depression, parkinsons, and alzheimers
microbiomes are constantly _______: normal bacteria compete with pathogens for _________ and ________, and will produce __________ to kill pathogens
changing; binding space and resources; antimicrobial compounds
outcomes of severe intestinal dysbiosis
deadly infections from bacteria like C. difficile, inflammatory bowel diseases like Crohn’s, bacteremia and organ infection
the female genital tract inhibits bacterial growth because
it is slightly acidic (pH 4-5)
the bioburden of the genital tract _______ closer to the external environment
increases
most dominant bacteria in the vaginal microbiome
acid-tolerant Lactobacillus crispatus or other lactobacilli (prevent invasion of pathogens)
dysbiosis of genitourinary microbiome
UTI - bacteria from the urethra can invade the bladder/kidneys
yeast infection - fewer lactobacilli in the vagina can lead to colonization of pathogenic bacteria or fungus
proposes that dramatic changes in human behavior have influenced the makeup of our microbiota
hygiene hypothesis
human behaviors that can dramatically alter our microbiota composition
use of preterm antibiotics -> consequence: reduces vaginal transmission
increased bathing/showering, using antimicrobial soaps -> consequence: accelerates change of skin microbiome composition
ways to restore a balanced intestinal microbiota
prebiotics, probiotics, fecal microbiota transplant, phage therapies
food or supplements that provide plant fibers that can be digested by beneficial bacteria (in natural foods like fruits, veggies, whole grains)
prebiotics
food or nutritional supplements that contain live organisms to promote colonization by beneficial bacteria (lactobacillus and bifidobacterium species)
probiotics
transfer of the microbiome of a healthy person to a person with severe intestinal disease
fecal microbiota transplant
may be a possible alternative to antibiotics in targeting pathogenic bacteria
phage therapies
