6A Requirements for Infection Flashcards
name 5 requirements/steps for successful infection
- entry: getting in
- establishment: staying in
- defeat host defenses
- damage the host: release resources
- exit host to transmit to other host
what are portals of entry? name 3 examples
any point at which a pathogen enters
- mucous membranes
- skin
- parenteral route
mucous membranes are in direct contact with ____
external environment
name 3 places mucous membranes are found in the order of most to least common portal of entry
- respiratory tract
- GI tract
- genitourinary tract
name 8 common respiratory pathogens
- adenoviruses: streptococcus pneumoniae, staphylococcus aureus, myobacterium tuberculosis, bordetella pertussis
- influenza
- rubella
- varicella-zoster
name 10 common GI pathogens
- E(scherichia) coli
- clostridium botulinum
- enterococcus faecalis
- shigella spp
- salmonella
- helicobacter pylori
- candida
- poliovirus
- norovirus
what is the portal of entry of sexually transmitted infections?
genitourinary tract
why are urinary tract infections more common in women than men?
- shorter urethra
- proximity to anus
name 8 common genitourinary pathogens
- myobacterium smegmatis
- chlamydia trachomatis
- neisseria gonorrheae
- trichomonas vaginalis
- herpesviruses
- human immunodeficiency virus
- E(scherichia) coli
- candida
what is the cause of 90% of UTIs?
E(scherichia) coli
what is the largest organ OF the body?
skin
what is the impermeable barrier unless broken, where many microorganisms reside?
skin
what does the parenteral route refer to?
breaks in skin that allow passage of microbes
normal flora causing infection are called ____
opportunistic pathogens
opportunistic pathogens entering via the parentral route depend on…
- cuts
- abrasions
- injections
- wounds
- surgical incisions
how do pathogens attach to the surface or cells or tissues?
- use virulence structures such as capsules or fimbraie
- use adhesins to attach to tissues
name an example of an adhesion beginning a process resulting in an accumulation of bacteria called a biofilm
plaque on teeth
(life activities of bacteria plus their presence results in formation of plaque)
how do spirochetes enter tissues?
lengthy process of corkscrewing
some pathogens can double their numbers every ____
20 mins
how do bacteria reproduce?
binary fission
what is passive defense?
using intrinsic features of the pathogen to protect themselves
(eg. cell walls, lipopolysaccharide mem, or extrinsic factors produced from existing resources at expense of host (capsules, M protein))
name an example of a passive defense
bacterial cell walls (peptidoglycans)
name an example of how a pathogen with a gram+ cell wall defends itself
streptococcus spp
- uses M proteins to increase adhesion to host tissue and inhibit phagocytosis
how do pathogens with a gram- cell wall defend themselves?
- very thin but compensate by having outer lipopolysaccharide membrane (endotoxin)
- endotoxin lipid A elicits very powerful immune response
name an example of how acid-fast organisms protect themselves
myobacterium species (tuberculosis, leprae)
- inhibits phagocytosis
- inhibits antibiotics
capsules protect against ____
phagocytosis
what is active defense?
attacking host defenses
- produced by microbes solely for “attack” (eg. toxins & enzymes)
why do pathogens hide inside host cells?
as a way to defeat the host
- protection from host immune response
- viruses are obligate intracellular parasites
what do bacteria use as a transport system?
cell microtubules and microfilaments
name 2 types of damage to a host
- presence and activity of pathogens (eg. pus)
- host defense mechanisms (eg. vomitting, diarrhea, sneezing)
direct damage to the host…
- is obvious
- includes destruction of host cells & tissues
- controlled by host immune response
indirect damage to the host…
involves systemic infection as a result of toxin production by the pathogen
active defense involves the production of ____ which function to…
- extracellular enzymes
- increase protection against host defenses
- enable spread of infection by attacking and killing host defensive cells
name 6 examples of bacterial enzymes
- leukocidins
- hemolysins
- coagulase
- kinase
- hyaluronidase
- collagenase
function of leukocidins
destroy WBCs
function of hemolysins
attack both RBCs and WBCs
function of coagulase
formation of fibrin clots (wall away tissue)
function of kinase
breaks down fibrin and destroys clots
function of hyaluronidase
breaks down CT
function of collagenase
breaks down collagen
name 2 types of bacterial toxins
- exotoxins
- endotoxins
name 3 characteristics of bacterial toxins
- very poisonous
- soluble in aqueous solutions
- easily diffusible into blood & lymph causing distal pathology
outcomes of bacterial toxins
- can be fatal
- S&S: fever, shock, diarrhea, cardiac & neuro trauma, destruction of BVs
characteristics of bacterial endotoxins
- produced by and exported from certain pathogens and then enter host cells
- some of most lethal substances known
- usually an enzymatic protein soluble in blood & lymph
- rapidly diffuse into tissues where they inhibit metabolic function
what are plasmids?
genes coding for toxin production
name 3 types of exotoxins
- cytotoxins
- neurotoxins
- enterotoxins
function of cytotoxins
kill cells
function of neurotoxins
interfere w neurological signaling
(produce exotoxins for affinity for CNS tissue)
function of enterotoxins
affect lining of digestive tract
name 2 examples of cytotoxins
- bacillus anthracic
- corynebacterium diphtheraie
characteristics of bacillus anthracis
- gram+ spore-forming bacillus
- increases vascular permeability in host tissues
- cytotoxin
characteristics of corynebacterium diphtheraie
- gram+ bacillus
- inhibits protein synthesis
- single molecule can kill a host cell (cytotoxin)
