E4 Gut microbiology: the human microbiome Flashcards
what is a microbiome?
the community of microorganisms that inhabit our bodies and coexist with us without causing harm
what are the 3 types of microorganisms in microbiomes?
commensal
symbiont
pathobiont
describe commensal microorganisms
microorganism that derives food / other benefits from another organism without hurting or helping it
describe symbiont microorganisms
microoganism that lives together in harmony with another organism, providing a benefits to one / both organisms
describe pathobiont microorganisms
microorganism that can cause disease in certain conditions (opportunistic pathogens) but not typically if healthy
what is understanding the microbial make up of a person important for?
for when considering how microbes influence human disease
state parts of the body that microbiomes are found in
nose
ear
conjunctiva
mouth
oesophagus
breastmilk
lungs
stomach
urinary tract
large intestine
small intestine
vagina
skin
state 2 of the many functions of microorganisms in the body
- protecting the body by establishing themselves as normal residents
- aiding in digestion and the maturation / development of our immune system (eg. some can digest fibre which humans cannot digest themselves
regarding bacteria, what happens to newborns within 12 hours of delivery?
they are colonised by many species of bacteria as well as fungi and protozoa
are babies in a sterile environment prior to birth?
- yes, the uterus
- unless, in utero infection is passed from mother via placenta
compare the differences in bacteria on babies delivered vaginally vs. caesarean
vaginal delivery
- babies covered in microbes as they pass through the birth canal (including bacteria that help babies digest their first meal)
- eg. Lactobacillus
caesarean
- babies colonised mainly by skin microbes of different species because they do not come through the birth canal
- eg. Staphylococci, Streptococci
describe the microbiomes of babies in the first 6 months of life
- within weeks, microbes start to specialise in different parts of the body that are suited for certain species
- further exposures mean microbes compete
- eating solids causes population changes of microbes
how does a baby starting solids cause changes in microbes?
- different microbes grow best on differs types of food and require different nutrients
- before solid foods, only bacteria that could thrive on milk would be highly prevalent
describe the microbes of breast-fed babies in their first 6 months of life
- acquire a wide spectrum of gut bacteria
- some species help metabolise sugars into acids that protect the baby from certain intestinal infections (helps nurture and strengthen immune system)
- will be exposed to increased bacteria due to mouth coming into contact with bacteria around mum’s nipple
describe the microbes of formula-fed babies in their first 6 months of life
- acquire mainly mix of Lactobacilli, Staphylococci, enteric Streptococci and coliforms
- some formula milk is fortified with probiotics (microbes) and prebiotics
- microbes in the air and atmosphere may end up in formula
- won’t be as many or as much variety as in breastfed babies
what happens to the species of microbes in children between 6 months and 3 years of age?
- continually increase in number
- approx 100 species of microbes in the gut of young infants
- by 3 years old, the microbiome looks a lot more like an adult’s, just on a smaller scale
why does the microbiome of 6 months - 3 years old children continually change?
several factors including:
- nutrition, infection, medications and environment
- microbiome variation is highest during childhood
other than age and environment, what else can influence our microbiome?
parents, family and relatives
- sharing of environments and other lifestyle factors
- influence of the mother is lessened over time and young children’s microbiomes come to resemble both parents
- as children get older and spend less time around their parents, their microbiome resembles their parents’ less
approximately how many species of microbes are present in our guts by the time we become adults?
approximately 1000
state a feature of adult microbiomes
more stable than child microbiomes
what is the adult microbiome affected by?
a range of factors
- biological factors
- environmental / external factors
what biological factors affect adult microbiomes?
age
hormones
genetics
what environmental / external factors affect adult microbiomes?
diet
drug therapy
climate
occupation
how does age affect the adult microbiome?
variation decreases following adulthood and after age 65, the number of microbial species decreases more rapidly
how do hormones affect the adult microbiome?
changes during puberty, pregnancy and menopause take affect
how do genetics affect the adult microbiome?
biological sex and individual genetic variation
how does diet affect the adult microbiome?
massive change in diet (eg. omnivore to vegan) causes a big shift in microbiome
describe the microbiome of the oral cavity
- mouth is populated with a diverse range of commensal microbes that contribute to our health (over 600 different species)
- there are many microhabitats within the mouth
what microhabitats exist within the mouth?
cheek epithelium
tongue
floor of mouth
tooth enamel
what is plaque in the mouth?
- soft biofilm on teeth containing saliva, food particles and diverse community of bacteria
- bacteria ferment sugars to lactic acid, causing damage to enamel
- fermentation combined with bacterial proteolytic enzymes leads to tooth decay
what is tartar in the mouth?
- hard yellow to brown matrix of biofilm that is difficult to remove
- will develop if plaque is not regularly removed
what is gingivitis?
gum inflammation
what is periodontitis?
gum disease
what can plaque and tartar build ups lead to?
gingivitis and periodontitis
which comes first, gingivitis or periodontitis?
gingivitis can lead to periodontitis
what can periodontitis result in?
- chronic inflammation of gums (can cause gums to bleed)
what may happen to bacteria in the oral cavity and what may this cause?
- may enter bloodstream
- increases the risk of cardiovascular disease and stroke (CVD examples: pericarditis, endocarditis)
describe what Streptococci can do if it enters the systemic circulation
- can activate platelets in the blood, making them clump together and form blood clots
- this is why there is an increased risk of CVD if certain bacteria enter the bloodstream
other than CVD, what else have studies suggested that oral cavity dysbiosis is associated with?
liver disease
GI disease
dementia
what can pharmacists do to prevent oral cavity dysbiosis?
advise patients on maintaining good dental health and establishing good oral hygiene practices
what 4 things regarding hygiene can help the oral cavity microbiome?
- regularly remove plaque
- visit dentist regularly for check-ups and hygienist
- antiseptic and / or plaque inhibiting mouthwashes
- practice healthy lifestyle habits
what should be used to regularly remove plaque?
toothbrush
fluoride toothpaste
interdental brushes
floss
why should people visit the dentist regularly to maintain hygiene in the oral cavity?
- check oral health and for gum disease
- professional teeth cleaning by dental hygienist to remove tartar
what healthy lifestyle habits should be practiced to maintain oral cavity hygiene?
- avoid food / drinks that accelerate tooth decay (high sugar content)
- avoid smoking
why should smoking be avoided to maintain hygiene in the oral cavity?
- smoking alters the oral cavity microbiome
- resulting in more anaerobic species and fewer aerobic species
- increases risk of periodontitis
describe the changes in pH along the GIT
oral cavity: 7
stomach: 2
small intestine: 7
large intetsine: 8
what happens to anaerobicity as you move through the GIT?
it increases
what is the main site of the human microbiome?
- the large intestine
- more than 30% of faecal volume is bacteria
- many species ferment waste to generate vitamins
what can bacterial digestive enzymes do?
- break down sugars
- aid steroid metabolism
what is the difference between prebiotics and probiotics?
prebiotics
- indigestible food ingredients that act as a food source for probiotics
probiotics
- tiny health-promoting organisms like certain bacteria and yeast that reside in the gut
state 5 benefits o the gut microbiome
- digestion of plant carbohydrate into short chain fatty acids
- synthesis of a range of essential vitamins
- metabolism of drugs and toxins
- competition with pathogens and suppress their growth
- programming of the immune system
describe via an image what the gut microbiome digests plant carbohydrates into
- short chain fatty acids
- acetate, propionate, butyrate
give examples of vitamins that the gut microbiome can synthesise and state the function of each. give 4 examples
biotin (B7)
- coenzyme for carboxylase enzymes
pantothenic acid (B5)
- required for CoA synthesis
folic acid (B9)
- involved in production of nucleotides
precursor for vitamin K
- involved in blood clotting
