MICROBIAL MECHANISMS OF PATHOGENICITY Flashcards
the ability of an organism to cause disease
pathogenicity
the severity or harmfulness of a disease
virulence
portals of entry
mucous membranes, skin, parenteral routes
microorganisms can gain access in the GIT in food and water via ___
contaminated fingers
portal of entry for pathogens that are contracted sexually
gut
preferred portal of entry of salmonella typhi
mouth - swallowed
preferred portal of entry of stretococcus pneumoniae
nose / mouth - inhaled
preferred portal of entry of yersinia pestis
more than one portal of entry - can cause plagues
number of invading microbes - virulence
ID 50
number of invading microbes - toxin potency
LD 50
number of microbes to cause cutaneous anthrax
10-50 endospores
number of microbes to cause inhalation anthrax
10,000 - 20,000 endospores
number of microbes to cause gastrointestinal antrax
250,000 - 1M endospores
lethal dose of botulinum toxin in mice
0.03 ng/kg
lethal does of shiga toxin
25 ng/kg
ability of microorganisms, such as bacteria or viruses, to attach to host cells or surfaces
adherence
attaches to teeth by means of its glycocalyx which is primarily made up of dextran
streptococcus mutans
have fimbriae that adhere to the glycocalynx of s. mutans
actinomyces
have adhesions on fimbriae that adhere only to specific kinds of cells in the small intestine
shigella and e. coli
uses tapered end as a hook to attach to host cells
treponema pallidum
produces an edhesion for a specific receptor on a host cell
listeria monocytogenes
has a fimbriae with adhesions
neisseria gonorrhoae
has a mechanism of adherence that resembles viral attachment
staphylococcus aureus
- protective layers surrounding some bacteria that enhance their ability to evade the host’s immune system
- help bacteria avoid phagocytosis by immune cells and may facilitate adhesion to host tissues
capsules
enzyme that coagulates blood
coagulase
enzyme that digest fibrin clots
kinases / fibrinolysin
enyme that hydrolyzes hyaluronic acid
hyaluronidase
enzymes that hydrolyzes collagen
collagenase
enzyme that destroys IgA antibodies
IgA proteases
enzyme that breaks down RBC
hemolysis
enzymes that breaks down phospholipids, and destroy the plasma membrane of RBC
lecithinase