10. normal microbiota Flashcards
the population of microorganisms that inhabit the skin, intestinal tract and mucus membrane of a healthy normal person
normal microbiota
the ___ rRNA gene sequencing and an advanced technology associated with next-generation nucleotide sequencing and metagenomics are used to study the microbiota
16S
this is the collective genomes of the normal microbiota in the body
microbiome
__________ was launched in 2007 by the National Institutes of Health (NIH) in USA
human microbiome project (HMP)
what were the 2 main goals of the human microbiome project?
to understand….
1. the range of the genetic and physiologic diversity of the human microbiome
2. the factors that influence the distribution and evolution of the microbiota
what was the main outcome of the HMP?
main outcome: there is no single healthy microbiome. rather, each person harbours a unique collection of microorganisms that assemble from a lifetime of interaction with their environment, diet, medications and many other factors
T/F: a healthy fetus is sterile
true
infants delivered ____ harbour microbiota that are most similar in composition to the vaginal microbiota of the mothers
vaginally
infants delivered _____ harbour microbiota from the skin of the mothers and from the skin of the caretakers (nurses, doctors, midwives, parents, etc)
C-sectiom
what bacteria colonize the infant intestinal tract early on?
E. coli and streptococci
E.coli and streptococci that colonize the infant intestinal tract establish the growth of anaerobes such as:
bifidobacteria and bacteriodetes.
this bacteria is dominant in a breastfed infants gut. it is able to transport and ferment breast milk sugars which provides calories for the growing baby. It is able to synthesize all amino acids and other required growth factors. it is found that a robust immune response to vaccination is linked to the presence of ___________ in an infants gut
bifidobacteria
T/F: bifidobacteria raises the gut pH
false - it lowers the gut pH which helps limit the growth of certain pathogens
T/F: bottle fed babies have a much smaller proportion of intestinal Bifidobacteria
true
T/F: switching to cows milk or solid food results in the loss of Bifidobacteria predominance in the infants gut
true
the initial microbiome changes with the host age, gender and the associated physiological and anatomical differences until a stable resident microbiota is formed. Around what age is the normal/resident microbiota formed?
around 3-4 years old
the normal microbiota for each individual is heavily influenced by what factors?
- genetics
- developmental changes (e.g. puberty, menopause)
- anatomical site
- diet
- personal hygiene
- life events (antimicrobial use, travel, occupation, sexual partners, etc)
what are the five major phyla related to the human microbiota?
- actinobacteria
- bacteroidetes
- firmicutes
- fusobacteria
- proteobacteria
this group of microbiota consists of relatively fixed types of microorganisms regularly found in a given area at a given age; if disturbed, they reestablish themselves
the resident microbiota
this group of microbiota consists of non-pathogenic or potentially pathogenic microorganisms that inhabit the skin or mucous membranes for hours, days, or weeks.
- derived from the environment
- does not establish itself permanently
- are generally of little significance as long as the normal resident microbiota remain intact
the transient microbiota
T/F: if the resident microbiota is disturbed, transient microqogransims may colonize, proliferate and produce disease
true
what are the 3 types of normal microbiota?
- commensal microbiota
- mutualistic microbiota
- opportunistic microbiota
this type of normal microbiota, under normal conditions, lives as commensal but they cause disease if the opportunity arises. e.g. E.coli normal flora of GI tract causes UTI when changing it habitat
opportunistic microbiota
this type of normal microbiota gets benefits from the host and at the same time gives benefits to the host. e.g. microbiota in the intestinal tract -> synthesize vitamins and bioactive compounds
mutualistic microbiota
this type of normal microbiota gets benefits from the human host and seems that is has no direct benefits for the host. e.g. the microbiota that is present on some body surface
commensal microbiota
what are some beneficial roles of normal microbiota?
- prevent attachment and penetration of pathogens
- compete with pathogens for habitat and nutrition
- produce antimicrobial secretions
- immunity
- produces enzymes and vitamins
- helps in metabolism
- oxidation and hydrolysis of steroids
this has a slightly acidic pH, a high concentration of sodium chloride, a lack of moisture in many areas, an oily lubricant sebum and antimicrobial peptides.
skin surface or epidermis
what are the three environmental niches on the skin surface?
moist sites (typically skin creases)
dry sites (flat surfaces)
sebaceous/oily sites
the predominant resident microbiota of the skin are ______ and ______
aerobics and anaerobic
what is the causative agent of acne?
diptheroid bacilli Cutibacterium acnes
what are two examples of non-hemolytic aerobic and anaerobic staphylococci found in the microbiota of the skin
staphyloccous epidermidis
staphylococcus aureus
_____ and _____ are often present in skin folds
fungi and yeasts
what are some examples of the predominant resident microbiota of the skin
- cultibacterium acnes
- staphylococcus epidermis
- enterococcus species
etc.
what are some facts that may be important for eliminating transient bacteria from the skin?
- the low (acidic) pH
- the fatty acids in sebaceous secretions
- lysozyme (in tears, salvia and milk)
true/false: profuse sweating or washing and bathing can eliminate the normal resident microbiota
false
true/false: the number of superficial microbiota may be diminished by vigorous daily washing with soap containing hexachlorophene or other disinfectants
true
anaerobes and aerobic microbiota often join to form ________ infections (gangrene, necrotizing factors, and cellulitis) of skin and soft tissues
synergistic
name some species found the mouth
- Viridians streptococci
- Lactobacilli
- Staphylococcus
- Streptococcus sanguis (dental plaque)
- Streptococcus mutans (dental plaque)
- yeasts (candida)
what parts of the upper respiratory tract are usually sterile?
the small bronchi and alveoli
the stomachs acidity keeps the number of flora at a minimum (10^2-10^3/mL of contents); only “this type” of bacteria persists in this environment which cause stomach ulcers
Helicobacter pylori
in the intestine, there is a pH change compared to the stomach; does the resident flora gradually increase or decrease in the intestine
increase
where in the intestinal tract has the least and the most bacteria?
least - stomach
most - cecum and transverse colon
in the adult colon, 96-99% of the resident bacterial flora consists of ____________ (aerobes or anaerobes)
anaerobes
this is an archae and produces methane. it is found in the colon microbiota in a low abundance and has a role in stabilizing gut microbial communities
Methanobrevibacter smithiiare
______ and _____ are found in the colon flora, whose functions are less well understood than archaeologists like Methanobrevibacter smithiiare
protozoans and fungi
what class of viruses are most likely found in the colon
phages
long term treatment with antibiotics could cause diarrhea, and in severe cases it could cause ____________
Pseudomembranous colitis
the feeding of large quantities of ______, which is also found in yoghurt, may help the reestablishment of the microflora in the gut
Lactobacillus acidophilus
soon after birth, aerobic _________ appear in the vagina and persist as long as the pH remains acidic (usually several weeks)
Lactobacilli
when the pH in the vagina becomes neutral (remaining so until puberty) after birth, a mixed biota of _____ and _____ is present
cocci and bacilli
at puberty, aerobic and anaerobic _________ reappear in large numbers and contribute to the maintenance of acid pH to prevent the vagina from harmful microbes
Lactobacilli
if Lactobacilli are suppressed in the vagina by some antibiotics, then yeasts or various bacteria can cause irritation and inflammation (vaginitis) or ________________
bacterial vaginosis
