Normal microbiome of humans Flashcards
Most microoganisms in human microbiome are
Most are commensals, few contribute to health (beneficial) and fewer pose direct threats to health
When do humans are colonized with microbiome and changes with
Colonized at birth
Changes over time and according to the condition of the host (diet, environment, sex, occupation, etc.)
Microorganisms in human gut are usually associated with
Human body tissue
What is the change of the microbiome through 2 years of life
- At first only firmicutes (first 5 days)
- Then changes when there is fever or when introduced to solid food
What is the stability of the microbiome throughout the life
In infancy- the diversity is very low and the stability is low
Throughout the childhood and into the adulthood the stability increases
From the adulthood into the senior stability decreases
What is microbial cloud
The microbes that the person are emitting the organisms and you can differentiate two people with this clouds
Explain the structure of the skin
The upper layer->dead layer
Then underneath -> living actively replicating cells
Subaceous glands, apocrine sweat glands: secretes salt water, with various amounts of proteins, lipids, and sugars. Secrections are slightly acidic and have some antimicrobial effects (lipids and proteins)
Sebaceous glans surrounds the hair follicle
What is the purpose of the dead cell layer
Forms a tough layer barrier that prevents microorganisms from penetrating deeper tissues
What is the usual conditions on the skin
Dry, acid environment that does not support the growth of most microorganisms
The ducts that carry secretions to the surface are colonized by
A few well-adapted species (gram-positive)
The normal microbiome of the skin secretes
Bacteriocin that kills incoming competitors and protects- to a certain extent- against colonization by harmful bacteria
What anaerobes (aerotolerant) bacteria inhibit the skin
Propionobacterium acnes (in hair canals)
What organisms populate the skin
Yeasts, molds, bacteria
What organisms in specific populate the skin
Actinobacteria and firmicutes (gram-positive)
Proteobacteria -(gram-negative)
The type of microbiome on the skin depends on
The type of skin ( moist, etc.)
What bacteria populate the skin
Mycobacterium
Staphylococcus
Streptococcus
What niches are there in oral cavity
Aerobic and anaerobic
The teeth consist of
A mineral matrices (enamel) surrounding living tissue (dentin and pulp)
How bacteria colonize teeth surfaces
Firstly, they attach to acidic glycoproteins deposited there by saliva
What is the dental plaque
Streptococci- a thick layer
In the presence of sucrose-from diet- Streptococcus mutans synthesizes extracellular polysaccharides (dextran) that aid its attachment to the tooth surface (form extracellular matrix,ECM)
How do we get dental cavities
Plaque develops->anaerobic bacterial species begin to grow.
S.mutans and various lactobacilli-ferment sucrose and produce lactic acid that demineralizes the tooth enamel (solubilizes calcium)
What is pH in 3 regions of GI tract
Stomach-2
Small intestine- pH4-5
Colon- pH-7
What microorganisms you can find in the stomach, small intestine and colon
Stomach- helicobacter
Small intestine- enterococci, lactobacilli
Colon-Ruminococcus!!!
In what microorganisms we can find Ruminococcus
Cows
Termites
Humans
How mocroorganisms can get though to colonize the lower intestine if stomach is very acidic
In food particles
What microorganisms can be found in colon
Mostly strict anaerobes or facultative aerobes: Bacterioides, enteric bacteria (E.coli),yeasts, anaerobic protozoa (Entamoeba coli)
Firmicutes (64%)
What is the happening with microorganisms in the human colon and food?
Microorganisms digest complex carbohydrates (cellulose, starch, etc.) and produce volatile FAs
Intestinal microorganisms of the large intestina ferment VFAs and produce gas (CO2 and H2). Methanogens convert CO2 and H2 to CH4 (found in 1/3 of adults)
Sulfates and we do use serious and organisms that can ferment cysteine and methionine produce H2S. Organic sulfur compounds mythanethiol are responsible for the smell
Intestinal microorganisms carry out a variety of essential metabolic functions what are they
- Amino acids
- Vitamin (B12, K , thiamine, riboflavin, etc.)
- Contribute to maturing of GI
- Affect early development, health, and predisposition to disease
- May play role in obesity
What is the difference in bacterial population in fat mice
Fat->less bacteroidetes
Microbiome of the nose is similar to
Nasopharynx and mouth
What is the microbiome in mouth and nose
Staphylococci, streptococci, corynebacteria
What microorganisms may harbor potential pathogens that are under control by the host immune system for a healthy carrier
Streptococcus pneumoniae
Haemophilus influenzae
Neisseria meningitidis
What the recent research found about lower respiratory tract
it was thought that it is sterile, but recent study showed that it harbors a microbiome (low biomass)
Sterile zones in human body normally
Blood
Spinal fluid
Internal portion of urinary tract
Peritoneal cavity (gut cavity)
Pleural cavity(lung cavity)
Sinuses
Interior region of other body tissues (bones)
Why genitourinary tract of men and the urinary tract of woman are generally free of microorganisms
Due in part to the flushing action of urine
What can cause potential pathogens in the urethra to multiply and cause disease
change in pH
WHat normal microorganisms of the gastrointestinal tract can cause urinary tract infections
E.coli
Proteus mirabilis
What control the glycogen concentration of the vaginal epithelium
Hormones
What do microorganisms do in vagina
Degrade glycogen and produce lactic acid which reduced the pH of the vaginal tract to 4.5
What is the glycogen level and pH of vaginal secretion before puberty, sexually mature and after menopause
Before puberty and after menopause->low glycogen and alkaline environment
Sexually mature->high glycogen and acidic pH
Microbial flora in vagina before puberty, sexually mature and after menopause
Before and after->staphylococci,streptococci,coliforms,corynebacteria
Mature->lactobacilli,streptococci,corynebacteria,Candida albicans
