Infection (325E1) Flashcards by Jane Daum

what is an infection

colonization of a host by a microbial species

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localized infection

specific to one place

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systemic infection

spread to several regions/areas of the body

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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)

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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)

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causes of an infection: fungal

(rare) spore forming organisms (ex: yeast infection)

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causes of an infection: protozoa

(rare) typically live in water / environment (malaria)

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causes of an infection: helminths

(rare) parasitic worms

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causes of an infection: prions

(rarest) proteinaceocus infectious particles, only composed on protein. it is tiny misfolded DNA (mad cow)

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reservoir

habitat where organism usually lives & grows (microorganism must have; can be humans, animals, infects, environment)

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direct modes of transmission

kissing, sex, direct contact w/ contaminated substances (hook warms, STDs), drop

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indirect modes of transmission

airborne, vehicle (through water, food or blood, ex Hep A) vector borne (mosquitos, fleas, ticks)

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portal of entries

-oropharynx & nasopharynx (airways, lungs, stomach & GI *very common)
-GU tract (STDs, catheters)
-skin

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what is the bodies biggest barrier

skin but is also the biggest vulnerability if you get cuts or wounds

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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

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portal of entry: blood

contamination blood given in a transfusion and also needle sticks

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portal of entry: maternal fetal transmission

cross the placenta barrier and directly to fetus (ex: zika, listeria)

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stages of infection: incubation period

time from getting into the body to when symptoms first appear (no symptoms in this stage)

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stages of infection: prodromal stage

onset of non specific symptoms

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stages of infection: acute stage

specific signs & symptoms of microbe (sick, can’t get out of bed)

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stages of infection: convalescent stage

symptoms are improving, illness is leaving

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stages of infection: resolution phase

pathogen is eliminated from the body some pathogens never get to this point (ex: chx pox)

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the infectious process is also known as what

the inflammatory process (it is when your body is fighting what is going on)

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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