TESTS FOR IDENTIFICATION OF STAPHYLOCOCCI (Biochemical methods of identification) Flashcards
memorization
A biochemical test for differentiating Staphylococcus and Streptococcus
Catalase test
Catalase test
positive result: ________
negative result:________
Catalase test:
positive: rapid continuous bubbles/effervescence
negative: lack of bubble formation 30 seconds later
Enumerate the Catalase-Positive organisms:
- Nocardia
- Pseudomonas
- Listeria
- Aspergillus
- Candida
- E. coli
- Staphylococcus
- Serratia
- Burkholderia cepacia
- H. pylori
mnemonic: “CATs Need PLACESS to Belch their Hairballs”
Coagulase is a test for:
S. aureus vs other Staphylococcus (S. epidermidis, S. saprophyticus)
S. aureus - catalase (+)
Coagulase slide test detects:
Coagulase tube test detects:
Slide test: detects bound coagulase (clumping factor)
Tube test: detects free coagulase
Positive coagulase test appearance:
Positive: white fibrin clots in plasma
A test for S. saprophyticus vs other CoNS (Coagulase Negative Staphylococcus)
Novobiocin Susceptibility Test
In the novobiocin susceptibility test, S. saprophyticus is:
Novobiocin Susceptibility Test:
S. saprophyticus: Resistant
S. epidermidis: Susceptible
Mnemonic: No StRES
No - Novobiocin
S - saprophyticus is
t
R - Resistant
E - epidermidis is
S- Susceptible
Susceptible zone diameter in novobiocin:
Resistant zone diameter in novobiocin:
Susceptible: >16 mm
Resistant: <16
DNase positive organisms:
S. aureus
Moraxella catarrhalis
Serratia marcescens
mnemonic: SMS
Positive result in DNase test:
Hydrolysis of the surrounding medium, resulting in a clear zone
Selective and differential for Staphylococcus species:
Mannitol Salt Agar
A Staphylococcus spp that can ferment mannitol and turns phenol-red into yellow in MSA:
MSA (Mannitol Salt Agar)
Staphylococcus aureus: red—>yellow
Other Staph: red
