Lecture 2 9/1/23 Flashcards
How can infecting agents be detected?
-microscopic examination
-isolation and ID
-antigen and toxin detection
-nucleic acid detection
How can host immune response be detected?
-detecting antibodies
-detecting cellular response (IFN-gamma, PPD skin test)
When can the infectious agent be detected?
-entry of pathogen
-dissemination of pathogen
-colonization and disease
When can antibodies be detected?
-colonization and disease
-pathogen elimination
What are the characteristics of microscopic pathogen detection?
-cost effective
-provides info. on number and morphologic characteristics
-provides info. on likelihood of infection, likely pathogens, predominant organisms
What are the downfalls of microscopic pathogen detection?
-low sensitivity
-low specificity
-some bacteria do not stain
Why do gram neg. bacteria show up pink?
-thin peptidoglycan allows for primary stain to be washed out
-counterstain is picked up
Why do gram pos. bacteria show up purple?
-thick peptidoglycan holds the primary stain in
-counterstain color does not dominate primary stain
Why do acid fast pos. bacteria stain pink?
presence of mycolic acid holds onto the primary stain
Why do acid fast neg. bacteria stain blue?
absence of mycolic acid prevents primary stain from sticking
What are the routine culture procedures?
-aerobic culture
-anaerobic culture
-microaerophilic culture
-fungal culture
Why are special culture procedures valuable?
they provide very specific results regarding individual pathogens
Why is timing an important factor when deciding whether or not to culture?
not all pathogens multiply fast enough to provide culture results in a timely manner
Which bacteria cannot be cultured on lab media?
obligatory intracellular bacteria
Which bacteria types require oxygen for growth?
-aerobic
-microaerophilic
-capnophilic
