Staph and Strep Flashcards
What is the gram stain morphology that represents staphlococci?
Gram positive cocci in clusters
Which is the most virulent species of staphlococci?
S. aureus
Where can S. epidermidis be found normally on the body?
skin surface and mucus membranes
How will S. aureus appear on sheep blood agar?
Creamy, white or light gold, buttery looking
May be beta hemolytic (species dependent)
Name 2 supportive media and 2 selective media that may be useful when cultivating staphylococci.
Supportive - Blood agar and chocolate agar
Selective - CNA and PEA agar
Which staphylococcus is associated with UTI in young females?
S. saprophyticus
Which simple test will separate Staphylococci from Streptococci?
Catalase
How can you differentiate Micrococcus from coagulase negative staphylococci like S. epidermidis?
Microdase disk
Staphylococci is considered resistant to Novobiocin if the zone is less than ______?
< 10 mm
Which organism may give a pseudocatalase positive result?
E. faecalis
Why is it useful to perform both a slide and tube coagulase?
To tell the difference between bound and free coagulase.
Staphylococcus aureus morphology
Gram positive cocci clusters; beta hemolytic
Streptococcus pneumonia morphology
Gram positive cocci in pairs; alpha hemolytic
Staphylococcus epidermidis morphology
Gram positive cocci clusters; gamma hemolytic
Streptococcus pyogenes morphology
Gram positive cocci in chains; beta hemolytic
Micrococcus luteus morphology
Gram positive cocci in clusters; gamma hemolytic
Enterococcus faecalis morphology
Gram positive cocci in chains; alpha or gamma hemolytic
What reagent is used to determine the presence of catalase?
Hydrogen Peroxide
Which organisms will be differentiated with the catalase test?
Staphylococcus and streptococcus
Expected results of catalase positive
Bubbles
Expected results of catalase negative
No bubbles
Expected results of Tube coagulase negative
Clotting
Expected results of Slide coagulase positive
Clumping
The microdase test will differentiate between which 2 organisms?
Micrococci and staphlococci
Which enzyme is detected by the microdase reagent?
Oxidase enzyme
Which organism is lysed by optochin?
S. pneumoniae
Name a beta hemolytic streptococcus that is PYR positive.
S. pyogenes
What are the expected results of positive bile esculin?
blackening of the media
What are the expected results of negative salt tolerance?
No turbidity and no color change
What are the expected results of positive salt tolerance?
Visible turbidity in the broth, with or without a color change
