Flashcards in MOD 10 - Normal Flora Deck (27):
How much microbe there is in the body?
definition of normal flora
organisms found in a given location in a state of health
definition of colonisation
establishment at a site in the body
definition of symbiosis
2 or more organism co-exist in close physical association
definition of mutualism
both organisms benefit from symbiosis
definition of neutralism
neither organism derives benefits or ham
definition of commensalism
one organism benefits, the other derives neither benefit nor harm
definition of parasitism
parasite benefits at the expense of the host
definition of non-sterile sites
have normal flora
definition of sterile sites
no normal flora
how does a non-sterile site become non-sterile
exposed to the environment directly or indirectly & no mechanisms in place to maintain sterility
where are some of the non sterile sites
conjunctiva, nasopharynx, GI tract, skin, vagina, lower respiratory tract
how is lower respiratory tract maintain sterility
by surface cleaning (ciliated epithelium and then coughing etc)
definition of tissue tropism
propensity for a particular organism to grow in particular habitat
where does most bacteria colonise in the skin
sweat glands - moist and nutrient
what are some examples of normal skin flora?
coagulase -ve staphylococci, staphylococcus aureus (esp. in nasal carriers, propionibacterium species
what is the flora near body orifice?
similar to those in the orifice
what are some examples of normal mouth flora?
anaerobes, viridan/oral steptococci
what are some examples of normal nasopharyngeal flora?
nostrils - skin flora, Straphycoccus aureus
pharynx - respiratory - streptococcus pyogenes, haemophilius influenzae, streptococcus pneumoniae, neisseria meningitidis, straphycoccus aureus
what are some examples of normal stomach and small intestine flora
low pH - less bacterial growth, mainly aerobic bacteria
acid-tolerant lactobacilli, H.pylori
what are some examples of normal stomach and large intestine flora
95-99% anaerobes - bacteroide spp., clostridium spp., difidobacteria spp.
aerobic bacteria - enteric gram -ve bacilli - E. Coli, klebsiella spp., enterobacter spp. protues spp. etc
what are some examples of normal vaginal flora
pre-puberty - skin flora, lower GI flora (E.Coli)
post-puberty - glycogen produced due to circulating oestrogens - lactobacillus spp. lactobacillus acidophilus, skin flora, C. albicans
what are some of the benefits of normal flora
- synthesis and excretion of vitamins - vitamin K and B12 secreted by enteric bacteria
- colonisation resistance - less possible opportunity for outsider bacteria to colonise
- induction of cross-reactive antibodies - may have a protective effect
what is one possible treatment for C.diff infection
how can normal flora cause diseases?
overgrowth of normal flora, translocation of normal flora - ie present at the wrong sites, cross-infection
which bacteria can cause URTI and conjunctivitis at the same time (translocation)