MIDTERMS: L2 - STAPHYLOCOCCI Flashcards
T OR F
- Collect at least 60 mL from 3 sites with 10 mL per bottle and 20 mL per site
- 10 mL for aerobic and another 10 mL for anaerobic
TRUE
T OR F
Delivery time is at maximum, 2 hours
TRUE
Best sample for urine is ______
Best sample for urine is midstream clean catch early morning urine
MOTF
SAU
1. Catalase (+), Coagulase (+)
2. Bacitracin susceptible
1 true
2 false, bacitracin resistant
Test used to differentiate staphylococcus from micrococcus
Modified oxidase (SAU = negative - )
Test used to differentiate staph from strep
Catalase test
SAU - positive
T or F
Staphylococcus epidermidis
- Susceptible to NOVOBIOCIN
True
Test to differentiate SAU from Cons
Coagulase
SAU - coagulase +
Resistant to 5 ug NOVOBIOCIN
Staphylococcus saprophyticus
T OR F
6mm zone size - means resistant or no zone of inhibition
TRUE
- True for staphylococcus saprophyticus
CNA
- Disrupts cell membrane of gram (-)
Colistin
CNA
- Blocks DNA replication and membrane of gram negative
Nalidixic
What makes MSA selective and differential?
Selective - presence of high salt concentration (7.5%)
Differential - presence of mannitol and the indicator phenol red
MSA
- SAU color
- S. epidermidis and S. saprophyticus color
SAU - pink (acid change)
S epi and S sap - yellow (no color change)
T or F
Micrococcus luteus and Enterococcus can also produce yellow colonies in MSA
True
To Differentiate S. saprophyticus from S. aureus
Coagulase test
To Differentiate Staphylococcus and Micrococcus
Modified oxidase
To differentiate Staphylococcus from Enterococcus
Catalase test
Chromogenic agar
- Staphylococcus aureus color
- Staphylococcus saprophyticus
- Staphylococcus epidermidis
- SAU - pink
- Staph - turquoise
- Epidermidis - partially or completely inhibited
Pigment responsible for golden yellow color of SAU
Staphyloxanthin
Positive result and indication:
- Catalase test
- Coagulase test
- Dnase test
- Novobiocin susceptibility test
- Germ tube test
- Effervescence or bubbling - positive for staph
- Coagulase test - clot and gel (slide and tube) - detect bound and free
- positive for sau - DNASE test
No indicator - clear
Methyl Green - colorless at ph 7.5
Toluidine Blue O - Bright pink color - Novobiocin - saphro is resistant (zone < or = 16mm) no zone or less than or equal to 16mm
- Germ tube - presence of germ tube indicates candida organism
