Lecture 9 - Pathogenicity of bacteria Flashcards
what type of bacteria is pseudomonas aurginosa and what does it cause
oppurtunistic pathogen
infects severe burns patients
and
infects lungs of cystic fib patients
what effects can staphylococcus epidermis cause and how
can form biofilm on catheter
because
blood plasma proteins coat the catheter
and then bacteria multipies on the plasma proteins
and this is antibiotic resistant oh dear
why is s.epidermis on a catheter antibiotic resistant
it can form extracellular polymers
which is like sticky
and antibiotics cant penetrate the biofilm it forms
what can cause risk of neisseria meningitis causing disease
usually is commensal
but smoking, having a cold can cause risk of disease
what causes the shift from neisseria meningitidis to meningococcal septicemia
bact spreads through bloodstream into whole body
causing systemic infection
only 10-20% surivive
where to m.tuberculosis replicate and what does this form
in alveolar macrophages (cuz is obligate intracellular pathogen) in the lung to form granulomas (Ghon complex)
why is TB worse now
new strains emerged that are more drug resistant (XXDR-TB etc.)
whats an example of a disease that causes diseases in different phases
treponema pallidum
ie syphillis
waht are stages of syphillis
- primary lesion (2 weeks after infection)= chancres (sores)
- secondary stage (after 10 weeks) = bacteria spreads, rash
- latent phase (many years later) = 40% will develop tertiary syphillis
insanity and death
steven has syphillis
what is a kochs postulates
swabbing things like lesions
then grown outside in a lab
and then given back to an organism (usually sheep)
then reisolated
what are 3 problems encoutered with Kochs postulates
- some diseases cant be grown on lab media e.g. leprosy
- ethical problems
- sometimes no suitable animal model
what is virulence
measure of pathogenicity
what is viruelence measured by
LD50
lethal dose
does to kill 50% of animals in given time
what is virulence determinants for anthrax
capsule
and
toxins
what is capsule made of
poly-D-glutamic acid
forms mucoid colonies
how does a capsule inhibit phagocytosis
similar charge to phagocytes
so repels them
what are 2 functions of toxins
supresses immune cell responses
and later on, induces toxic shock and death
how do bacteria adhere to host
attach via fimbriae
which have adhesins on the ends of it
and attach to mannose receptors on surface of epithelial cells
how can adhesion be seletive
diff fimbriae bind to diff things
what fimbriae do pathogenic e.coli use, and where does this attach
CFA fimbria
attach to duodenal mucosa
release toxins
examples of diseases caused by non-fimbrial adhesins
streptococcal pyogenes
causes sore throat and rheumatic fever
what does this non-fimbrial bacteria use instead to bind to surfaces
M protein
