Gram-Positive Cocci (Staphylococcus) Flashcards
Bacteria that are circular in shape
Cocci
Three in general of cocci which has medical importance or pathogenic to human
- Genus staphylococcus
- genus Streptococcus
- Genus Neisseria
what is color for gram positive bacteria
Purple or blue
Note: gram positive, meaning they take up their primary stain which is your crystal violet
A key diagnostic tool in micro laboratory
Gram Staining
Note: the principle behind is based on cell wall differences
GRAM POSITIVE: thicker peptidoglycan and take up more stain
GRAM NEGATIVE: thin peptidoglycan
What is the color of gram NEGATIVE bacteria
Pink or Red
Note: crystal violet will absorb but when you do decolorizer the outer membrane portion will be washed out leaving the organism to be colorless, once it will be stained by the secondary stain it will take up the color pink or red which is the color of safranin the secondary stain.
What test should you perform to differentiate staphylococcus, streptococcus and micrococcus
Catalase test
Catalase POSITIVE reaction
- micrococcus
- staphylococcus
Note: MICROCOCCUS form regular pockets of four or tetrads while STAPHLOCOCCUS are groups clusters.
Catalase NEGATIVE reaction
Streptococcus
To differentiate micrococcus and staphylococcus you need to perform
Glucose degradation or oxidation fermentation test
Oxidation reaction positive
Micrococcus
Fermentation positive
Staphylococcus
Test that is used to determine class and bacteria, if the bacteria metabolize carbohydrate oxidatively by fermentation or non-saccharolytic and therefore have no ability to use carbohydrates in te media
Glucose degradation test or oxidative fermented test
Used to detect the presence of cytochrome oxidase enzyme
-the principle behind is because of the main reagent here is Hydrogen peroxide or agua oxinada you add this to the small amount of bacterial growth from your culture medium if the reaction is bubbling or effervescence then that is positive because of the release of oxygen and if the reaction is just normal suspension without bubbles then that is negative
Catalase test
note: they will employ this test after doing gram staining. The main purpose is to differentiate the members of the family micrococci, streptococcus and staphylococcus
What is the main reagent for Catalase test
Hydrogen peroxide or agua oxinada
What is the difference between Micrococci and Staphylococci
Micrococci are either oxidative or inert, while Staphylococci are fermentative, they ferment glucose
