How microbes cause disease Flashcards
what do microbes need to do to survive
adherance/colonisation
resist/avoid defence
persist and grow
exit&transmit to new host
what is the period with vague symptoms before illness called
prodromal
where do pathogens want to reach and how do they get there
sterile body sites, breach barriers eg BBB, skin, mucosal membrane
who competes with pathogens
natural flora
what chemicals do tears, saliva and mucus have in them which is antibacterial
lysozymes
what other ways do we get rid of toxins/pathogens
cilia/urinary flushing/antimicrobial FAs in skin, mucus and phagocytes in lungs
bacteria use more than one adherance mechanisms to stick to the host. give some examples
pili/fimbriae
outer membrane proteins eg adhesin&invasin
where does e coli keep its adhesin
tip of the pili
what are biofilms made of, what are they, give an example of a biofilm in action
slime layer, (Extracellular polymeric substances) polymer EPS, pseudonomas in CF - opportunistic infection
how else that pili and fimbriae can pathogens adhere to host cell
via host ECM
Internalins Listeria monocytogenes bind E-Cadherin and C-met
- M proteins Strep. pyogenes bind to receptor on respiratory mucosa
what are the two main problems with biofilms
avoiding host immunity
resistance to antibiotics
what do bacteria use to form lesions
degradative enxymes
what do degradativeenzymes do and not do
mess up tissue - hyaluronase and collagenase
do not kill cells
what are the two types of invasion into host cells
trigger zipper
who uses trigger and who uses zipper
T:salmonella, shigella
Z: listeria
what is the complement
part of innate immune system 30 circulatory proteins
what are the 3 things the complement does
opsonisation - tag path with IGG - cleared by pahogcytes
membrane attack complex - hole in bacterial membrane - lysis
enhancing inflammation - mast calls attract phagocytes to the area
what is in lysosomes
NO, H2O2
which cells have Fc receptors
almost all leukocytes
how does a bacterail capsule lead to evasion of phagocytosis
prevents opsonisation
how does Staph aureus avoid phagocytosis
binds to Fc region of antibody so the antibody can’t bind to phagocyte
what’s the test for Staph aureus
catalase test - bubbles when you put H2O2 on it bc catalase turns it into H20 and O2
what is the name of the pathogens that steal iron form the host
siderophores
what is the commensal and how does it normally live
one organism benefits from the other and teh other is unaffected. Normal flora of the gut
what is virulence
quantatitive ability of a pathogen to cause disease
what are protozoae; give examples of parasitic protozoic diseases
unicellular EUKARYOTES eg malaria, leishmanaisis, Chagas, trypanosomiasis, cryptosporidiosis
what are the shapes of different bacteria
cocci - spherical
vibrio - spiral tail
bacillues - rodlike
what stain is used to identify bacteria? What colour do they go
Gram stain
gram-ve pink
gram+ purple
describe gram -ve and +ve bacteria
+ve thick peptoglycan outer wall, no extra membrane
-ve thin peptoglycan wall, extra membrane
how would you identify bacteria
microscope - size, shape, colour, gram stain
what is the bacteria responsible for syphilis and how do you identify it
spirochaetes and darkfield microscopy
which stain is needed to identify TB bacteria and what bacteria is it
mycobacteria, Ziehl-Nielsen stain
how do staphylococci and streptococci look different under a microscope?
strepp: chains of spheres
staph: clusters of spheres
which two common bacteria are gram +ve
staphylococci and streptococci
how do you differentiate between staph and strep?
catalase test. chuck bleach on it. Stapg is catalase +ve, bubbles form
what is staphylococcus aureus
bad bacteria, causes abcesses, wound infections, really gross, can go to bones
how does staph aureus cause TSS
superantigen causing cytokine cascade
what do you get in the first stage of syphilsi
a gross swelling called a chancre at the site of where the spirochaetes enter the body
when do fungi cause a problem
in immunocompromised people
what is aspergillosis
fungal pneumonia only in immunosuppressed
what is aspergillosis
fungal pneumonia only in immunosuppressed
what are some things you need to mention to the lab about a patient
travel, symptoms, contact, food, drugs, animals
what is a MALD-TOF machine
desktop maspec. provides fingerpirnt of all bacteria in the database
what is the 1,2,3 of teh complement
1)opsonisation - microbes are coated with IGG as a tag for phagocytosis C3B
2)membrane attack complex C5B - hole in bacterial membrane - lysis
3)inflammation enhancement - mast cell attract phagocytes to the area
