Normal microbiota Flashcards
What are the types of symbiosis?
- Mutualsim= both benefit
- Neutralism= nobenefit or harm to either
- Commensalism= one benefitsother doesn’t benefit or harm
- Parasitism=one benefits at the expense of the other
What are non-sterlie and sterile sites?
- non-sterlie= have normal flora
- sterile= no normal flora
Where are non-sterile sites?
- Exposed to environment
- No mechanism to maintain sterility
- Skin, vagina, GI tract, nasopharynx, conjunctiva
Where are sterile sites?
-Sterility maintained by:
surface cleaning= Lower respiratory tract
Barriers that allow uni-directional flow= Upper genital tract, cervix, urethra, urinary tract, middle ear, eustachian tube
Physical separation from non-sterile sites (closed cavities)= plural, peritoneal cavity, spinal cord, meninges
Name some skin floral bacteria
- Coagulase-negative staphylococci
- Staphylococcus aureus
- Propionibacterium species
What flora can be found in the nostrils and pharynx?
- Nostrils= skin flora& s. aureus
- Pharynx= Strep pyogenes (groupA), Haemophilus influenzae, Strep pneumoniae, S aureus, Neisseria
What flora is found in the vagina?
- Pre puberty= skin flora, lower GI flora, e.coli
- Post puberty= glycogen produced due to circulating oestrogens, lactobacillus maintains pH, skin flora, few c.albicans
Describe the flora in the GI tract (stomach & s.intestine)
- Low gastric pH inhibit bacterial growth
- H.pylori, acid-tolerant lactobacilli
- predominantly aerobic bacteria few anaerobic
Describe the flora of the GI tract (l.intestine)
- mostly anaerobes= bacteroides, clostridium, bifidobacteria
- aerobic bacteria= enteric gram negative bacilli, escherichia coli, klebsiella, enterobacter, proteus, citrobacter
What are the benefits of normal flora?
- Synthesis & excretion of vitamins
- Colonisation resistance
- Antibacterial agents
- Induction of cross-reactive antibodies
Microbes in the human biome help protect against what disorders?
- IBD
- Metabolic disorders
- Diabetes
- Cancer
- Obesity
- Infection (C.Diff)
- Hypertension
Describe C.Diff infection and one of the treatment options
- main risk= antibiotic treatment
- Perturbation of normal colonic microflora allowing overgrowth
- Leads to toxin production
- Diarrhoea & pseudomembranous colitis
- Recurrent C.Diff infection treated with faecal transplant (standard vancomycin treatment w/bowel lavage & donor faeces infusion)
What diseases can a faecal transplant be used for?
- MS
- Chronic fatigue syndrome
- Idiopathic thrombotic purpura
- Ulcerative colitis
- Irritable bowel syndrome
- Diabetes mellitus
- C.Diff
What can go wrong with normal flora? give examples
- Overgrowth=vaginal thrush
- Translocation=conjunctivitis, Intravascular catheter infection
- Cross-infection=MRSA
What are clinical conditions caused by normal flora?
- Abscesses
- Pneumonia
- Gastroenteritits/peritonitis
- Urogenital infections
- Endocarditis
- Dental caries, peridontal disease, pharyngitis
