Exam 1 Lecture 2 Flashcards
Pathogen relationship with host (3 things)
Colonize, multiply, transmission
Human relationship with pathogen (2 things)
Infection; Disease
Symbiosis
biological association of 2 or more species that may benefit each
Commensal
One species benefits, the other remains unharmed
Mutualism
both species benefit (vast majority of indigenous microbiota most accurately characterized as mutualistic relationship)
Parasitism
parasite benefits at the expense of the host
Residents
Bacteria that generally stay for a long time in 1 location/1 body
Carrier state
used to describe an individual that would carry a pathogen but not show symptoms
Transient
Pathogens that temporarily colonize us
ex: microorganisms that colonize the skin of our hands, which can be removed by handwashing
Why are fetuses microbiologically sterile?
There are no viable microbes in or on our body in utero
Where do newborn babies acquire their microbiome?
Birth canal, and the skin/respiratory microbiota of hospital personnel and the environment
Neonates initially have a ____ group of microbes able to maintain colonization, then as they age, they microbiome is shaped by their environment
Broad
What are factors determining the nature of microbiota?
- Local physio and ecology (microbes present in our GI tract is different than in our nose)
- Microbial attributes
- Microbial interactions (competition) - which is crucial because normal microbiota can compete with and exclude pathogens from colonizing
True or false: Microorganisms can be possible contaminants, especially problematic for diagnostic purposes
True
What is an example of skin microorganisms?
Staphylococcus epidermis, Propionibacterium, Diphtheroids
What is an example of conjunctiva microorganisms?
S. epidermidis, non-pathogenic corynebacteria
What is an example of mouth microorganisms?
Streptococcus mutans, specifically adhere to teeth
How many microorganisms are present per mL of saliva?
10^8 organisms/mL
Strict ____ and _____ organisms are associated with the gingival crevice.
anaerobes, microaerophilic
What 2 organs are sparsely inhabited by microorganisms?
stomach (pH of 2) and small intestine (site of intense immune surveillance, lots of immune cells here)
How much bacteria/mL is present in the colon?
10^10 to 10^11
90% of bacteria in the colon are ____, 10% are ____ _____.
anaerobes, facultative anaerobes
What is the name of the bacteria that is commonly found in the GI microbiota of breast-fed infants?
Bifidobacterium
True or False: A study showed that Bifidobacterium is enriched in exclusively breast fed infants compared to mixed-fed infants.
True
True or False: A study showed that Bifidobacterium had no protective advantage against E. coli O157.
False - the mice given probiotic Bifidobacteria were able to fight off O157 infection and survive!
True or False: Bifidobacterium makes small molecules that help build epithelial resistance to O157 and thus go against the propagation of E. coli
True
Why was the Bifidobacterium [without probiotic effect] significant to our knowledge regarding Bifidobacterium?
The mice without the probiotic effect died off, despite Bifidobacterium being present in their GI tract - thus, the presence of the bacteria itself does not boost survival, but rather there is some activity happening (activity is related to its probiotic effect)
Human breastmilk contains ____ which feed bacteria, specifically a bacteria called _______. At the same time, the bacteria helps promote the gut barrier function and specifically protects against the effects of ___.
- human milk oligosaccharides (HMOs)
- Bifidobacterium
- E coli O157
Bifidobacterium expresses ___, which degrades lacto-N-tetraose, an abundant ____…thus, Bifidobacterium feeds on HMOs present in breastmilk.
LnbX
HMO
What is the microbiome of the nares (nostrils) similar to and what pathogen do the nares contain?
- Skin
- Contains Staphylococcus aureus
What is the microbiome of the nasopharynx similar to and what pathogens does the nasopharynx contain?
- Mouth
- Contains Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae (these all act commensally)
What structure is the larynx, middle ear, and sinuses protected by?
Mucociliary escalator
True or False: Men are more prone to STIs than women.
False - Women have a shorter urethra than men, which shortens the distance that bacteria must travel to reach the bladder AND the urethra in females is proximal to the vagina and the rectum which is microbiologically rich
_____ has an impact on infection.
Anatomy
What are some examples of bacteria present in the vagina during the child bearing years?
Lactobacillus, anaerobic GNRs, GPC, Gardnerella, Mycoplasma, Ureaplasma
Generally, how are the bacteria present in the vagina before puberty or after menopause different than during child bearing years?
They are mixed and are non-specific from skin, the colon, and perineum
List 3 benefits of the normal microbiome
- Primes our immune system
- The exclusionary effect (excluding pathogenic organisms from colonizing the host). This is demonstrated by the antibiotic effect.
- Nutrition: Bacteria can help with digestion (like Bifidobacterium in the GI of infants). There could be malabsorption if too many microorganisms are present. Also, vitamin K is crucial for many proteins in our body that help w/ coagulation.
