lecture 4 bacterial pathogenicity Flashcards
(38 cards)
what are the events involved in the establishment of bacterial infaction
| > reservoir v
| > transport to host v
| adhrence&colonisation v
^tissue damage < invasion
of tissueswhat are some key bacterial factors involved in host colonisation and tissue damage
competition for nutrients
surface attachment sites
(in)direct effects of bacterial pathogens
induction of autoimmune response
pathogen
organism that causes disease by impairing or interfering with the normal physiological activities of the host
what are oppertunistic pathogens
only cause serious disease when host defenses are impared
what are reservoirs
where the pathogen lives and reproduces before it is in a host for example humans animals environment like soil
how are pathogens transferred between hosts
direct
indirect
vehicles
host
organism which supports the growth of viruses, bacteria and other parasites
infection
bacteria persist in host without nessisarily causing damage
what is colonisation
establishment of a stable population in the host
what is adherence
to overcome flushing mechanisms bacteria must adhere to host cell surfaces(or other sufaces)
what is the role of iron
essential for growth
tissues don’t have enough, more must be acquired
bacteria have high affinity iron uptake systems eg siderophores n direct binding
barriers to infection in the body
flora competes eyes (lysosomes) skin antimicrobials n flora mucus in lungs trachea stomach pH flushing of urinary tract
what is invasion
penetrate into, through or between cells = invasion of host cells & tissues
what are antibodies
they are produced by b cells and complement the microbe. they attract phagocytes and aid engulfment. they neutralise toxins
how do pathogens avoid antibodies and avoid complement
capsules antigenic variation degredation of antibodies capsules lipopolysaccharides (gram negatives)
how do bacteria resist phagocytes and macrophages
producing structures that prevent effective contact eg capsules, proteins
survival inside engulfed phagocytic cells
how do bacteria resist phagocytes and macrophages
producing structures that prevent effective contact eg capsules, proteins
survival inside engulfed phagocytic cells. can kill from inside
what are endotoxins
action is indirect: activates many host systems that cause damage
gram -ve only
what are exotoxins
act on specific target eg protein synthesis
gram +ve and -ve
adhesins example
pili
slime capsules
flagella
lipotechioic acids
host receptors include
blood group antigens
extracellular matrix proteins eg collagen, fibroconnectin
advantages of invasion
aid in survival
spread to other body sites
required for colonisation
how how is invasion accomplishes
lytic compounds that attack host tissue
invasivness determined by
evasion of host defenses
