16: diagnosing infection Flashcards
microscopy
a phenotypic method. observe cell morphology, differential staining procedure
cell culture
phenotypic method. examine colony traits, selective & differential media narrow possibilites
biochemical test
major player of classical ID. testing for genes needed to conduct metabolic process
what is the nucleic acid method?
involves genetic analysis (PCR)
specifically, DNA or RNA genome analysis
Pathogens geend tb culturable
(+)/ (-): antigen vs antibody
(-) antigen = foreign material recognized by immune system
antibody = blood protein created in response
(+) immunologic methods involve serological analysis
what occurs in light microscopy?
gram staining the first step to diagnosis
followed by differential test bcs many pathogens inna group
biochemical test to narrow down
how to handle specimen collected in tissues & fluids
- use asceptic technique to collect + transport essential
- label specimen vitals
- consider temp of specimens
detect the presence or absence of substrates or end products of enzymatic activity or metabolic pathway
biochemical test
what is PCR and why 1 would choose it for active infection?
amplies tiny amount of nucleic acid in genome
Bcs has rapid result when testing high risk patients bt cannot distinguish living from the dead
what is antigen identification and why 1 would choose it for active infection/
identifies the presence of viral protein: surface spikes, nucleocapsid proteins
=> synthetically produce antibodies, will produce proteins if present
Choose it over PCR bcs its non-pricey & no equipment, on the spot even if less accurate than PCR
2 examples of biochemical test
biolog system can detect an org’s ability to utiilize 95 diff substrate
MALDI-TOF mass sepctrometry: laser scatter around c cultured microbes, produce a specific biomaker pattern
presumptive vs confirmatory test
see if pathogen is present vs see if analyses based on presumptive test is correct; more correct
differential vs etiological diagnosis
infection distinguished from others w/ similar presentation vs w/ dangerous disease to find exact **causative agent **
many pathogens grown & ____ as pure ____
diverse culture media then used to analyze _______
differential media: visible ___ btw _____
selective…: some microbe inhibited
isolated / culture
pathogen
differences / microbes
immune testing involves several types of (____ ____) : analyze (what) for ____ ____ interaction
confirm other procedures
can detect ____ in ___ tissues, past/present infections
serological analyses / patient’s fluid sample / antigen-antibody
pathogens / host / past
