Bacteriology (pics) Flashcards
Selective medium for Staphylococcus, mannitol salt agar
Positive result would show a peach-cultured medium turns yellow.
Sensitivity testing
We put antibiotic and a lawn of bacteria, and after 24 hours we measure the zones. Generally, the larger the zone the more sensitive is the bacterium.
Colonial Morphology
Ex: Staph aureus are usually larger than Strep. So Staph can be pinhead and Strep can be pinpoint
Graciela on BAP
Serratia. Contains red pigment
Eosin methylene blue agar
The specimen above is E. coli because of the characteristic green metallic sheen on its colony.
**MacConkey agar. A selective (will only allow the growth of gram (-) because it will prevent the growth of gram (+) because it contains inhibitors) and differential (because it will differentiate lactose fermenters from non-lactose fermenters) medium. Lactose fermenters are color red, non-lactose fermenters are colorless.
Microscopic Morphology
Blood Agar
- Left: Microscopic: Gram (+) cocci in chains (In gram staining, there is no scientific name because we cannot identify it unless we do the work-up)
- Right: Beta-hemolytic colonies because of complete zone around them
Spores in bacilli
Organism is positive (+) for lactose fermentation
Organism is negative(-) for lactose fermentation
Sulfur Indole Motility Medium (SIM)
Organism on the far left is positive for hydrogen sulphide production, Organism on the second from left tube is E. Coli and is indole positive.
S. aureus ferments mannitol
The left side of the left plate turns yellow while S. Epidermidis is not capable of fermenting mannitol, right side of the left plate. The Staphylococcus species thrives under high salt concentration (left plate) while the Streptococcus species growth is hindered by high salt concentration (right plate)
