INFECTIOUS DISEASE Flashcards
(57 cards)
- infectious agents
- situations for infection
agents: virus, bacteria, fungi, protozoans, helminths
situations:
- organ system specific
- immunosuppressed (HIV, neutropenic)
- DM
- sickle cell ds
- prosthetic devices
- travel
direct stains
GRAM STAINING
- gram pos stains purple
- gram neg stains red
- non bacterial cells (like WBC), show staining characteristics of cell type
color, shape, arrangement of bacteria in analysis
culture
gold standard
- isolate pure organism
- DEFINITIVE identification and antimicrobial susceptibility
- determine MIC
- typical bacteria
antigen detection
- surface protein
- does NOT require growing the organism
- immunoassays detect soluble antigens
- immunoassays that detect organism by reaction to reagent antibodies
antigen detection
direct v. indirect
direct- fluorescent labeled antibody. binds to antigen, read slide w microscope
indirect- antigen bind with unlabeled antibody, add secondary fluorescent labeled antibody, second antibody will bind to primary antibody (complex seen under microscope)
indirect just uses secondary fluorescent antibody to bind to original antibody
- antigen is target of interest
nucleic acid detection
- good for detecting what kind of organisms?
- example
RNA of infectious agent identitifed
- detect difficult to grow or slow grow organisms
- HIV viral load
- ONLY look for specific organism
serology
- example
detects host antibodies produced in response to infx w/particular infectious agent
- immune markers
- syphillis
sepsis happens when?
places infx may start?
when an infection you alr have triggers a chain rxn throughout your body
- may start in lung, urinary tract, skin, or GI tract
SIRS criteria
2 or more:
- temp >38C or <36
- HR>90
- RR >20
- WBC >12,000 or <4000
Sepsis criteria
systemic response to infection
- SIRS + documented or high suspicion of infection
severe sepsis criteria
sepsis+ evidence of organ dysfunc, hypoperfusion, or hypotension
septic shock criteria
sepsis induced hypotension
- SBP <90 despite fluid resusc
- evidence of organ dysfunc, hypoperfusion, or hypotension
septic shock symptoms and tx
RAPID ONSET of mental confusion and disorientation
- hypotension
- pale/cool arms and legs
- chills
- difficulty breathing
- dec urine output
tx: O2, IV fluid, abx, other meds
bacteremia
- cause
- testing
infx in an organ can introduce bacteria into blood stream
- cause subsequent sepsis
- do blood cultures
- skin prep and 2 SAMPLES taken
blood cultures
- detect?
- normal conditions v. presence of microorganisms
detect bacteria or fungi in blood
- normal conditions: no microorganisms in blood, sterile
- presence: indicate infx like bacteremia or fungemia, can lead
antimicrobial sensitivity tests
- 2 types
- how do they work and what do the results tell you
determine which abx are likely to effectively eliminate an infectious organisms by exposing the organism to diff abx in vitro
- dilution method: bacteria in tubes w abx, incubate and see where bacteria stops growing, lowest amt that stops growing is MIC
- disc diffusion method: bacteria spread on agar plates and incubated, abx that work will have clear zones (no bacterial growth)
—>larger clear zone= better abx
tick transmission
- agents
- general testing
- agents: lymes, rickettsia, ehrlichia, anaplasma
- PCR and serological testing
lymes, rocky mountain spotted fever, ehrlichia, anaplasma
- type of tick
- test names
- rocky mountain: rash w/endothelial vasculitis, serologic test
- ehrlichia: lone star tick, nucelic acid amp
- anaplasma: deer tick, nucleic acid amp
- lymes: two step testing process
two tiered lyme ds testing
- first and second
- pos (2 options) vs. neg test
first test: EIA (enzyme immunoassay) or IFA (immunofluorescence)
- if pos or equivocal result: SS <=30 days—> do IgM+IgG western blot
- if pos/equivocal: SS>=30 days —> IgG western blot
- if NEG: alt dx or pt w SS consistent with lyme ds for <=30 days, obtain convalescent serum
how does EIA testing work with positive results
- tier 1 v. 2
first tier EIA based on Borrelia antigens
- detects total IgM and IgG antibodies
second tier, for pos results
- detects total antibodies without differentiating between the antibody classes
IF EITHER IS POS–> pt is pos for lymes
fungemia
- normal fungus?
- labs
- causes
- labs: neutropenia
causes:
- candida normal flora in oral and GI tract
- start with indwelling lines (central venous catheters)
- abx therapy
parasitic infections- 2 examples
- transmission
- SS
- Dx
plasmodium(malaria)
- febrile illness
- mosquito transmission
- seen on smears in RBCs
babesiosis
- tick transmission, infects RBC
- SS: hemolysis, fever, ano, HA
- self limiting
pathogenesis malaria
bite from mosquito, parasites travel to liver and lie dormant, then leave liver and infect blood cells (SS start to show)
viral blood infections
- types
- mononucelosis/EBV
- cytomegalovirus
- parvovirus B19
