Catalase Positive GPCs Flashcards
Three genera of catalase positive GPCs
Staphylococcus, Micrococcus, Rothia
Purpose of CNA (or PEA) and SBA
For specimen w/ normal flora
Purpose of Mannitol Salt Agar
For outbreaks
- Staphylococcus aureus is mannitol positive
Two types of catalase test
Slide catalase and plate catalase
What happens during a catalase test?
H2O2 dissociates to H2 + O2
- Positives will bubble
Coagulase test purpose
Major test to separate Staphylococci into 2 categories
- Coagulase positive Staph
- Coagulase negative Staph (CoNS/CNS)
What is coagulase?
Enzyme that creates a thrombin-like substance, clots human or rabbit PLASMA
Oxidation-Fermentation (OF) Test Principle
One oiled tube and one not
Fermenter: yellow in oiled and unoiled tube
Oxidizer: yellow in ONLY unoiled tube
Non-oxidizer/asaccharolytic: no acid in either tube
Novobiocin/Furazolidone susceptibility test
Determines susceptibility/resistance to antibiotic
- Zone of inhibition is measured after 18-24 hours
Lysostaphin test
Lysis Staphylococcus
- positive = clear (lysis)
- negative = turbid (no lysis); Micrococcus
Catalase results for
- S. aureus
- S. epidermidis
- S. saprophyticus
- Micrococcus
- positive
- positive
- positive
- positive
Fermenter or oxidizer?
- S. aureus
- S. epidermidis
- S. saprophyticus
- Micrococcus
- Fermenter
- Fermenter
- Fermenter
- Oxidizer
Susceptibility or resistance to Furazolidone
- S. aureus
- S. epidermidis
- S. saprophyticus
- Micrococcus
- susceptible
- susceptible
- susceptible
- resistant
Susceptibility or resistance to novobiocin
- S. aureus
- S. epidermidis
- S. saprophyticus
- Micrococcus
- susceptible
- susceptible
- resistant
- susceptible
Coagulase (slide/tube)
- S. aureus
- S. epidermidis
- S. saprophyticus
- Micrococcus
- positive
- negative
- negative
- negative
Slide coagulase
- Other names?
Clumping factor or bound coagulase
Tube coagulase
- Other names?
Staphycoagulase or free coagulase
Micrococcus
- Common colonial characteristics
Yellow/orange or “sticky”
Staphylococcus aureus
- common colonial characteristics
Large, opaque, may be “golden”, usually beta hemolytic
Coagulase negative Staph
- Common colonial characteristics
Large, opaque, usually white, usually alpha or gamma hemolytic
Name the main S. aureus infections
Skin infection Wound infection Food poisoning Scalded Skin Syndrome Toxic Shock Syndrome