Flashcards in Bacteriology Deck (35)
Describe acid fast bacteria
Rarely diagnosed in vet practice.
Have a waxy (mycolic acid) outer layer.
Highly resistant to staining and treatment.
Gram positive bacteria.
Ziehl neelsen stain required ( red on blue background.)
All other organisms stain blue.
e.g. mycoplasma, mycobacterium tuberculosis, m leprae, nocardia
Can be zoonotic
What is sensitivity training?
Indicates which antimicrobial is most appropriate to eliminate infection
Allows the patient to be treated quickly and effectively
Reduces the risks associated with antimicrobial resistances
Describe disc agar infusion
Most commonly used method to determine the susceptibility of a microorganism to a specific antimicrobial agent (efficiency, cost and convenience)
Antimicrobial agent diffuses into the solid medium from the filter paper resulting in the inhibition of reproduction of the microorganism on its surface.
A zone of inhibition forms around the disc, beyond this zone an unaffected area of normal microbial growth is present
What is the method for disc agar infusion?
A bacterial colony from loop or swab is spread over an agar plate
A manufactured disc containing a range of antibiotics is applied to the plate surface.
Incubate for 18-24hrs at 37 ̊C
The resistance zone cut off is specific to each antibiotic.
Accurate measurement of the zone diameter and comparison to an interpretation chart is necessary to properly interpret this test.
Depending on these results the isolate will be classed as being susceptible, intermediate or resistant to that specific antimicrobial agent