microbiology- the human microbiome Flashcards
define the human microbiome
microbes that live on and in the human body
define the resident microbiota
the organisms normally found in health
define colonisation
establishment at a side in the body
define symbiosis
two or more organisms co exist in a close physical association
define dysbiosis
imbalances in the resident human microbiota or our responses to them
define opportunistic infections
infection caused by an organism that is a member of the normal microbiota or normally inhabits the external environment
define tissue tropism
propensity for a particular organism to grow on a particular habit
give examples of different types of host relationships
parasitism
commensalism
mutualism
what is a parasitism relationship
unilateral benefit which has a high degree of damage to the host
what is a commensalism relationship
involves one member getting benefits such as food and shelter but the other is unaffected
what is a mutualism relationship
reciprocal benefit with a lower degree of damage to the host
which relationship does the host community try to maintain
a beneficial relationship
give examples of some detrimental relationships
parasitism
amensalism
competition
give examples of non sterile sites
GI tract
skin
vagina
conjunctiva
what do we mean by non sterilised sites
colonised by normal microbial populations
exposed directly/indirectly to the environment
no mechanism in place to maintain sterility
what do we mean by a sterile site
there are no microbes at all
what are the three types of sterile site
sterile due to surface cleaning
sterility maintained by barriers allowing one way flow
sterility maintains by physical separation
give example of a sterile area which remains sterile due to surface cleaning
lower respiratory tract
give examples of a area sterility is maintains due to a barrier which allows one way flow only
by sphincters
eg sphincter of Oddi- hepatobillary tract
middle ear- eustachian tube
upper GI tract- cervix
give examples when sterility is maintained from physical barriers
pleural cavities
peritoneal cavity
what else do anatomical locations contain
microenvironment eg skin has toe webs scalp palms
what are the early colonisers of the oral microbiota
Strep oralis
S mitis
S salivarious
which bacteria can we find in the nasophangeal area
S aureus is found in the nose as a main carrier
describe which bacteria we can find in the pharynx
strep pyogenes
H influenzae
strep pneumoniae
S aureus
describe bacteria found in the small intestine
higher count of bacteria found in the end of the tract than at the start
low pH inhibits growth
predominantly facultative anaerobic
few/non obligate anaerobes
describe bacteria found in the LI
95-99% anaerobes such as bacteriocides and clostridium spp
how many organisms are found per gram of stool
10^9-10^11
describe clostridium spp
can take over the gut of patients who are already unwell and cause GI issues
the patients can have reduced resident microbiota and therefore can only recover when they stop taking antibiotics
what is one unusual treatment for c diff
foecal transplant
describe microbiota in the vagina
microbiota is similar to skin and lower GI in pre puberty
what happens to the bacterial shift in the vagina post puberty
post puberty glycogen is produced due to circulation oestrogen- lactobacillus attracted which uses glycogen to ferment and maintain low pH and prevent overgrowth of species
what is the ph of the vagina
3
what is the benefits of the resident human microbiota
→ Competitive exclusion of exogenous pathogens
→ Antagonism of exogenous pathogens
→ Promotion of normal development of immune system
→ Promotion of normal human cellular physiology and nutrition
→ Enhancement of epithelial barrier function, cellular proliferation and would healing responses
→ Induction of cross reactive antibodies
→ Modulate immune system to prevent over stimulation
when can opportunistic infections occur
When there is damage to the epithelia Presence of foreign body Transfer to another site Disturbance of immune system Disruption of resident microbiota Impairment of host responses
what else can happen to bacteria
it can translocate to another site
eg conjunctivitis- spread from upper respiratory tract infection
which bacteria cause caries
streptococcus mutans
lactobacillus
Actinomyces aggrebacteur
which bacteria causes periodontal disease
p gingival
tannerella forsythia
aggregeribactium actinomycetecomintans
spirochetes
which bacteria cause aspiration pneumonia
Staphylococcus spp
anaerobes
which bacteria cause infection endocarditis
a haemolytic streptococci
staphylococcus
which bacteria cause abscesses
streptococci
actinomyces spp
gram -ve anaerobes
which bacteria cause candidiosis
candida spp
what are the 6 classes of AMR phenotypes found in the oral microbiome
phenicol sulphonamide liconsamide-macrolide streptogramin aminoglycoside tetracycline beta lactam
