Labs Flashcards
What is hemolysis?
Bacteria’s ability to lyse RBC
How is hemolysis used to identify bacteria?
It is based on how ‘see thru’ the hemolysis is from the bacteria
What does alpha hemolysis look like?
Partial disruption of RBC by bacteria results. It may have a greenish hue
What does beta hemolysis look like?
Bacteria secrete enzymes that eliminate the RBC, creating this clear look
What does gamma hemolysis look like?
It does not affect the RBC so there is no change
What does delta hemolysis look like?
It creates a ‘double hemolysis’
What do we use for antiB sensitivity testing?
Mueller-Hinton agar plate
Why should you use the chart to interpret the size of the zone of inhibition?
The size does not determine which antiB is best. So, you need to use the chart to determine which will work best.
What is the significance of spores?
THey are resistant to heat, desiccation, chemicals, radiation, and other harsh environmental elements.
Spores may help protect bacteria so it can stay alive in this “dormant” phase (ex: lepto in dried puddle that then rehydrates)
What disease does Clostridium tetani cause? Name and symptoms
Tetanus
Lock-jaw, fever, stiff muscles
Who is affected by tetanus?
Carnivores, pigs, cattle, & horses
What disease does B. burgdorferi cause? Name and symptoms
Lyme disease
Stiffness, rash
What animals are affected by Lyme disease?
Dogs, cats, horses, cattle
How is Lyme disease contracted?
Ticks!
Testing w a DTM jar, how should the sample be placed? How should the lid be secured on? Why?
- On top of the medium
- Lid should be lightly screwed on
- This is so it can ‘breathe’ but not escape
What color change occurs if dermatophyte grows?
Red
Max no of days you should observe bottle/plate for growth w a DTM sample?
7 to 10 days. Check it daily
What can cause positive color reactions on DTM besides dermatophytes?
Contaminates & non pathogenic fungi
most common dermatophyte identifies on canine/feline species?
Ringworm AKA M. canis
A positive DTM plate should look like…
Red in color
How long should a wood’s lamp warm up for?
5min
What should the woods lamp detect on a positive patient?
Hyphae in hair shafts
T/F: All dermatophytes will fluoresce under a woods lamp
False! Only 50% will
What is the common name for Microsporum canis?
Ringworm
What is a Microsporum?
A genus of fungi & type of fungi imperfecta
Purpose of crystal violet?
To stain G+ by retaining dye on the thick peptidoglycan
Purpose of Iodine?
Acts as a mordant (glue) to adhere crystal violet stain to G+ bacteria
Purpose of alcohol/ethanol?
Decolorizer & will dissolve outer membrane of G- cells
Purpose of Safrorin?
Stains G- bacteria pink/red
What type of media is blood agar?
Enriched!
What is it called if a patient contracts an infection of a sort from the hospital?
Nosocomial
What is the mechanism of action for Chlorhexidine?
Disrupts cell membranes
Name two pathogenic bacteria that can produce endospores.
- Bacillus
- Clostridium
What is the significance of endospores? How do they specifically benefit the bacteria?
- Endospores produce bacteria/toxins
- This makes it very difficult to treat and decontaminate
Name two reasons to heat fix smears on a microscope slide before gram staining.
- Kills bacteria
- Protects/preserves cell morphology (shape)
What is the goal of the four-quadrant streaking pattern? (2)
- Spread out the colonies
- Isolate the colonies
