L30 - Introduction To The Human Microbiota And Barriers To Infection Flashcards
What is the microbiome?
Microorganisms present on all of our body surfaces
What is microbiota?
Groups of microorganisms living in a specific environment
What is microbiota like?
- not usually harmful, often vital to health
- individuals microbiota usually unique
- indigenous human commensals
What are indigenous human commensals like?
- beneficial for bacter and the host
- provides some protection against pathogens
What is the gut microbiome essential for?
Essential for breakdown of our food
What does the gut microbiome do?
synthesise essential vitamins B12 and vitamin K
What does reserach suggest the gut microbiome is invovled in?
Obesity, allergies, mental health, immune disorders, etc.
What are opportunistic pathogens?
Indigenous human commensals causing harm when the status quo perturbed
What are examples of opportunistic pathogens?
- burn patients - pseudomonous aeruginosa, gram neg
- colonic bacteria - UTI - Ecoli, gram neg
- skin flora - wound infection - staph, gram pos
- oral flora - tooth decat - strep, gram pos
What are normal human microbiota?
- skin
- upper resp tract - nose and throat
- lower resp tract
- digestive system - mouth/stomach/SI/LI
- urinary tract
- adult femal genital tract
What are the 3 microenvironments that the skin is divided into?
- dry skin - arms and legs
- moist skin areas - armpits
- areas rich in sebaceous glands
What are natural colonisers to skin?
Gram pos bacteria // staph, strept
What is the microbiota in the nose and throat?
- extensive bacteria flora
- natural colonisers - strept, staph, //neiseria and haemophilus
What causes bacterial meningitis in the nose and throat?
- streptococcus pneumoniae
- neisseria memningitidis
- haemophilus influenza
What is the lower respiratory tract like?
- usually sterile
- common site of infection // chest infection, pneumonia, tuberculosis (mycobacterium tuberculosis)
What is the mouth (digestive system) microbiota like?
- gingival groove - anaerobes // bacteroides,, actinomyces = gum disease
- tooth enamel - facultative aerobes // strep = plaque, tooth decay
- cheek and gums - facultative aerobes // strep = colonise saliva
What is the stomach (digestive system)microbiota like?
Acidic <10cfu/ml
Helibacter pylori
What is the small intestine (digestive system) microbiota like?
- duodenum - 10^3-10^4 cfu/ml, still acidic/still enzymes
- ileum - 10^5-10^7 cfu/ml, less acidic
What is the large intestine (digestive system) microbiota like?
- 10^12 microorgs/g faeces
- gram pos, and gram neg bacteria 3000 dif species
- anaerobes and facultative anerobes // bacteroides fragilis, enterococcus faecalis, e.coli
What is the urinary tract microbiota like?
- kidneys, ureters and bladder - usually sterile
- urethra - lightly colonised, staphylococcus epidermidis
- frequent site of UTI, E.coli, enterococcus faecalis, proteus mirabilis
What is the adult femal genital tract microbiota like?
- complex microbiota
- depends ona ge, childbirth, menopause and menstrual cycle
- // lactobacillus pH 5.5-6.5, candida albicans
What are non specific defences agsint infection?
Barriers
- skin
- mucosal surface
- blood and tissues
What are defences like in commensals?
Pathogen must compete with natural microflora for adhesion sites and food
What are probiotics?
Live microorgs that prevent/treat conditions // antibiotic associated dirrhoea
