Infection (325E1) Flashcards
what is an infection
colonization of a host by a microbial species
localized infection
specific to one place
systemic infection
spread to several regions/areas of the body
common causes of an infection
virus (only DNA ot RNA, surrounded by a protein shell), needs a host or cannot (ex: covid, aids, flu, chxn pox)
bacteria causes of an infection
larger than a virus, single celled organism. it has 1 strain of dna and can replicate w/o a host and it can adapt & supress the bodies defense mechanisms (strep, uti, tb)
causes of an infection: fungal
(rare) spore forming organisms (ex: yeast infection)
causes of an infection: protozoa
(rare) typically live in water / environment (malaria)
causes of an infection: helminths
(rare) parasitic worms
causes of an infection: prions
(rarest) proteinaceocus infectious particles, only composed on protein. it is tiny misfolded DNA (mad cow)
reservoir
habitat where organism usually lives & grows (microorganism must have; can be humans, animals, infects, environment)
direct modes of transmission
kissing, sex, direct contact w/ contaminated substances (hook warms, STDs), drop
indirect modes of transmission
airborne, vehicle (through water, food or blood, ex Hep A) vector borne (mosquitos, fleas, ticks)
portal of entries
-oropharynx & nasopharynx (airways, lungs, stomach & GI *very common)
-GU tract (STDs, catheters)
-skin
what is the bodies biggest barrier
skin but is also the biggest vulnerability if you get cuts or wounds
portal of entry: translocation
movement of bacteria across the intestinal lining, occurs frequently in the peritoneal cavity from bacteria leaking from gut and also occurs in the bloodstream
portal of entry: blood
contamination blood given in a transfusion and also needle sticks
portal of entry: maternal fetal transmission
cross the placenta barrier and directly to fetus (ex: zika, listeria)
stages of infection: incubation period
time from getting into the body to when symptoms first appear (no symptoms in this stage)
stages of infection: prodromal stage
onset of non specific symptoms
stages of infection: acute stage
specific signs & symptoms of microbe (sick, can’t get out of bed)
stages of infection: convalescent stage
symptoms are improving, illness is leaving
stages of infection: resolution phase
pathogen is eliminated from the body some pathogens never get to this point (ex: chx pox)
the infectious process is also known as what
the inflammatory process (it is when your body is fighting what is going on)
phases of the infectious process
1) injury
2) increased permeability
3) immigration of leukocytes
4) phagocytosis
5) exudate
6) systemic symptoms
infectious process: injury
initial insult to area occurs, short period of vasoconstriction to stop the bleeding & prevent movement of organisms which is then followed by a prolonged period of vasodilation to bring WBC to the area and this contributes to the symptoms of inflammation
signs of inflammation
heat, swelling, redness, pain, & 1 more (figure it out)
stages of infection: increased permeability
at the site of the injury, fluid is pulled out of the vascular space, becomes permeable and then goes into the tissue (aka the place of injurt)
what is the purpose of the fluid becoming permeable during the infection process
allows the good WBC to get out of the blood and into the area of injury bc it rarely happens within the blood vessel
stages of infection: immigration of leukocytes
neutrophils (wbc) are attracted to area of injury. they attach to the endothelium of injured cells and move through into surrounding tissues
what other cells, besides neutrophils, might be involved during the immigration of leukocytes
eosinophils, NK cells, monocytes
stages of infection: phagocytosis
leukocytes are now at the site and in this phase they recognize, engulf and destroy invading organisms
stages of infection: exudate
transports the leukocytes to injured area, dilute toxins that might be present and transport nutrients for the healing process
exudate
the stuff that comes from fluid leaking from blood vessels, along with cells and debris from phagocytosis (at the beginning it is good but can turn into a bad thing)
stages of infection: systemic symptoms
can if infectious process doesn’t remain localized (not resolved after first 5 stesps), it is a total body response that stimulates the hypothalamic fever set point
what is the purpose of the hypothalamic fever
it is a protective factor
when the fever set point increases
-helps body converse heat
-stimulates defense mechanisms to help rid body of organism
-some bacteria less virulent & divide slow
-improves own immune system
what happens when an infection sticks around after the systemic phase
colonization ( the pathogen inhibits a specific body site but does not cause S/s, ex: non symp staph) “you are not sick with it”
can a person be colonized without having an active infection?
yes, colonization can occur without an active infection but it can turn from colonized to active
how do we know when there is an infection?
VS (always do first & they usually increase), labs (one of the best things to do)
gram stain
takes a stain of the bacteria and shows whether it is gram + or gram - within hours (also shows shape and arrangement)
is gram positive or negative more dangerous
gram negative b/c their outer membrane are often hidden by capsules or slime layers which hides antigens harder to fight
culture and sensitivity
do a sensitivity of the gram stain, basic results back in 24 hr and full ID + sensitivity pattern may take up to 72 hr (tells us the exact bacteria & what antibiotic they’re sensitive too)
what can you culture
sputum, urine and blood (do this to know where the infection is)
culturing blood
- do aerobic & anaerobic
-2 different sticks (ideally peripheral)
septic means
infection in the blood
what is expected in urine
-pH: 5.0-9.0
-<5 RBC, WBC, & epithelial cells
-nitrites are abnormal (expected is negative)
-leukocytes are abnormal (expected is negative)
what do nitrites in the urine indicate
bacteria in the urine
what do leukocytes indicate in the urine
infection
RBC & WBC >5 in urine indicates what
infection
epithelial cells >5 in the urine indicate what
cancer
nosocomial
infections that occur while in the healthcare facility
characteristics of a nosocomial infection
-more virulent ( cause more disruption & spread quickly)
-become drug resistance
examples of nosocomial infection
MRSA, CRE (a class, very big deal) , MDRO
superinfection
new infection that occurs during treatment typically caused by a resistant organism antibiotics were given, killed or inhibited normal flora and then the resistant ones proliferated and become a huge infection (ex: C.diff & candidiasis)
C.diff
normal intestinal flora killed by antimicrobial administration but c. diff isn’t killed and grows out of control causing intense diarrhea & cramping for days to months we do not what to stop diarrhea bc we want the body to get rid of it
what test do we use to diagnose C.diff
polymerase chain reaction (PCR) and it looks for DNA marker bc we do not culture stool
what isolation is C.diff
contact D; must wear gown & gloves & wash hands w/ soap
how to treat C.diff
PO/IV metronidazole (flagyl) or PO vancomycin
complications of C.diff
pseudomembranous colitis which is life threatening -> might dilation of the colon which may need to be decompressed
