Lecture 5- Microbiome Part II Flashcards
Microbiota + Microbiome
Microbiota= living microorganisms found in a defined environment; oral + gut microbiota
Microbiome= collection of genomes from all the microorganisms; microbial structural elements, metabolites etc
Site specific
-urbanised vs indigenous= reduction in microbial diversity
-location (common diet in location) = affects microbial diversity
Dysbiosis
-imbalance in the microbiota= causes a disease or reflects a disease state
-can be anywhere in the body
-commonly used in reference to the GI tract microbiota
-linked to a number of diseases in infants; asthma, Crohn’s disease, IBD or type 1 diabetes
Intestinal microbiota as we age
-little diversity in infants; increases to around 3 years + largely stabilised from 12 years old
-changes when pregnant but reverts to original after delivery
-changes when old age
Microbiota matures with us
-colonisation begins during birth; GI tract must be colonised before adequate immune function can develop
-lifestyle choices + medical history = affect microbiota
Newborn microbiota
-after birth; infant begins to be colonised
-vaginal flora= deoxygenate the gut
-first bacteria= birth canal + surroundings; flora of the female genital tract, sanitary conditions, med staff etc
-skin to skin contact
-type of feeding= breast vs bottle
Infant gut colonisation
-initial colonisers= enterobacteria + streptococci; first weeks + facultative anaerobes
-followed strict anaerobes= bifidobacteria + bacteroides
-facultative anaerobes= make intestine anaerobic= allows colonisation by strict anaerobes
-stabilised at 4 weeks until weaning takes place= breast fed infants have a more dramatic change than bottle fed infants
Impact CS delivery
-decrease in bacteroides etc
-increase in clostridium difficile + skin bacteria
-differences remain significant up to 1 year after birth
Stratergies
-some immune/allergic diseases + infections = greater after CS delivery;IBD, T1D, coeliac disease, asthma + obesity
-infant gut dysbiosis= decrease the risks
Breast vs bottle
-breast milk= stimulates healthy gut development through presence of prebiotics, immunoglobulins, cytokines etc
-important for growth + development of the immune system
-antimicrobial factors= present in human milk
-human milk= lower buffering capacity; allows the gut contents to acidify more easily
Slides 16-18
Formula
-commonly fortified with prebiotics/probiotics to mimic breast milk
-prebiotics= nondigestible oligosaccharides that stimulate bacterial growth
-probiotics= reduce antibiotic-associated diarrhoea + colic symptoms
Formula fed babies
-formula generates significantly different microbiomes
-microbiome shifted towards that of an adult
-more E.coli seen in bottle fed babies
Other influences
Physical environment, geographical location, air quality + pets
- early exposure to animals= higher immunity + low prevalence of allergy and asthma
The elderly
-changes in microbiota as you get older
-can contribute to increased susceptibility to disease + infection ; recovery from disease etc
-imbalance in the microbial structure (dysbiosis) = common accomplice of age-related disorders- leading to disability or mortality issues
*contributing factors in the elderly; slide 29-30
Effects of changes to microbiota with aging
-intestinal microbiome = linked to disorders of the brain, heart, endocrine, musculoskeletal + immune system
- ^ link to inflammation = infamm-aging
The skin
*exposed skin; dry, acidic, saline, aerobic
-does not support extensive microbial growth
-influenced by; secretion of fatty acids + lysozyme and presence of oxygen
Resident microorganisms
-survive and proliferate
-inhibit pathogenic species
-processing of skin proteins, free fatty acids + sebum
The hand microbio
-more variable + less stable to other skin sites
-hard to know what is normal or healthy
Scabies
-mite
-allergic reaction to mites -> rash like symptoms
-crowded living conditions = increase risk of spread
*treatment= anti parasitic drug
Upper respiratory tract
-composed of nasopharynx, oral cavity + throat
-microbiota bathed with secretions of the mucous membranes
-residents trapped in nasal passages
*staphylococci, streptococci, diptheroid bacilli + gram-negative cocci
Lower respiratory tract
-sterile= inability to culture resident bacteria
-presence of microbes = infections
-important defences= cilia, mucin, igA + macrophages
Conclusions
-lungs of healthy smokers = significant + diverse microbiome; distinct from that in the oral cavity+ nasopharynx
-diversity is often lower in lungs with decreased function
Vaping
-changes the composition of the microbiome
*haemophilus = increased in conventional cigarette users, however significantly greater inflammatory response is shown compared to cigarette users
Oral cavity
-maintains larger population of bacteria; nutrients, epithelial debris + secretions
-range of habitats; teeth surface, mucus membranes
-heavily influenced by diet
-habitats evolve with age; develop with age
Plaque
-can grow on tooth surfaces in thick layers
-forms a biofilm on the teeth surface
-plaque microorganisms = produce adherent substances
-acid produced by microorganisms in plaque = damages tooth surfaces
Gastrointestinal Microbiota
-highly diverse environment= reflected by microbes present
-highly diverse normal flora
-implicated by a numerous metabolic syndromes= diabetes, IBS, ulcerative colitis + Crohn’s disease
Healthy gut microbiome
-enriched in bacteria= able to produce short chain fatty acids (SCFA’S)
-SCFA’s promote;
*intestinal integrity, energy homeostasis via absorption by epithelial cells, induction of regulatory T cells; reduces inflammation, control glucose homeostasis + management of immunological compounds
Enterotypes
-3 different human enterotypes
-not dictated by age, gender, weight, geography
*type 1= bacteroides
*type 2= few bacteroides but prevotella are common
*type 3= high levels of ruminococcus
Faecal transplantation
-most commonly used to treat C.dif infection
-also transplant propensity for obesity + increase risk of Alzheimer’s
