Diagnostics Flashcards
Following anamnesis, PE, and examination of clinical samples, the clinician must formulate a _____________________.
Presumptive diagnosis and DDX list
Diagnostic tests that detect the infectious agent:
Direct: Microscopy/staining, Ab staining
Isolation and identification
Direct detection of Ag or metabolites (toxins)
Molecular techniques detect bacterial DNA
Diagnostic tests that detect host immune response
Serology: humoral immunity
Detection of cell-mediated immunity
Sample collection should take place _____ antimicrobial therapy and during the ______ stage of the disease.
before, acute/early
Collection of transudates, exudates, pus, and discharges:
Syringe/sterile container/culturette swab. Use anaerobic transport medium if necessary.
Collection of lavages and washes:
Use buffered solution (saline or LRS)
Collection of feces:
2-3mg. Repeat sampling for shedding or chronic infections.
Best method of urine collection:
Cystocentesis
During necropsy, when should you collect samples for culture?
Before anything else to prevent contamination.
What is the most important and cost effective procedure used in identifying number of bacteria, morphology, and host cellular response??
Microscopy!
Limitations of light microscopy
Low sensitivity (need ^^ organisms)
Less sensitive for blood and CSF
Some bacteria don’t stain (mycoplasma and spirochetes)
Limitations of culture
Time consuming
Supplies and expertise ($)
Bacteria that require special culture requests
Mycoplasma Salmonella Listeria Mycobacterium Campylobacter
Nutrient broth, peptone broth, and trypticase soy agar are examples of ______ media.
Culture (for growth of non fastidious bacteria)
Phenylethyl Alcohol agar (Gram +), MacConkey agar (Gram -), and Sabourad’s dextrose agar (fungi) are examples of _____ media.
Selective