GRAM POSITIVE COCCI Flashcards
Differentiates Staphylococci from Streptococci
Catalase Test
Positive Catalase Test
bubbles: Staphylococcus
Negative Catalase Test
no bubbles: Streptococcus
detects clumping factors or bound coagulase, screening test
Slide coagulase
free coagulase, unbound, confirmatory test
Tube Coagulase
Uses rabbit plasma
coagulase test
Normal inhabitant of the skin, intestine and mucous
membrane (nasopharynx and anterior nares)
“Golden grape-like clusters”, NM, NS, NE
S. aureus
S. aureus on Nutrient agar
oil paint appearance
S. aureus on Baird Parker
jet black colonies
Golden yellow pigment
Non staphylo cytin
Marker of virulence
free coagulase
hyaluronidase or spreading factor
Duran Raynal Factor
fibrinolysin : lyses the fibrin clot
Staphylokinase
toxic shocked syndrome toxin like endotoxin F
TSST-1
Exfoliative toxin; Ritter’s disease, mostly occur on children
SSSS
Has toxic effects on neutrophils
Urease
Inititates skin infection
Lipase
Exotoxin that kills WBC
Leucocidin
MSA Mannitol Salt Agar
7% NaCl
Indicator: Phenol Red
Result: Yellow
(+) : mannitol are fermented
Voges-Proskauer
Differentiates S. aureus from S. intermedius
S. aureus – (+)
S. intermedius (-)
end product: acetyl carbinol
Modified Oxidase test/ Microdase test
Tetramethyl-p-phenylenediamine dihydrochloride in dimethylsulfoxide
(+) blue or purple in 2 minutes
No DMSO
Cytochrome Oxidase/Indophenol oxidase
Micrococci – S (10 mm)
Staph - R
Bacitracin
can used in blood agar plate
100ug
Micrococci – R
Staph – S (15 mm)
Furazolidone Susceptibility
Micrococci – R
S. aureus – S (10-16 mm)
Lysostaphin Sensitivity
2 methods
Methyl green
Toluidine blue
(+) clearing of agar
(+) : aureus, moraxiella and serratia
DNASE test
Beta lactamase test /
Cephalosporinase test
Reagent: Cefinase disk
Substrate: Nitrocefin
(+) result: pink to red
(-) result: yellow
community acquired or super bug; seen in patient that stay long in hospital
MRSA
CoNS
Coagulase Negative Staphylococcus
Normal skin flora
Prosthetic heart valve, UTI, stitch abscess, Neonatal sepsis, endocarditis
Biofilm
S. epidermidis
Pyelonephritis and cystitis
Community acquired UTI
Indwelling catheters
S. saprophyticus
Low virulence; tetrads, NM
Lysostaphin & Furazolidone – Resistant
Micrococci
Most frequent cause of endocarditis;
slide coagulase (+)
confused with staph aureus
S. lugdunensis
Pinpoint translucent colonies
Young cultures – presence of capsule
NM, NS, capnophilic
Bile insoluble, inulin (-)
Catalase and Oxidase (-)
STREPTOCOCCI
Substrate: leucine-beta-naphthylamide
Reagent: cinnamaldehyde
(+) result: Red/Pinkish red
(-) result: no color or slight yellow
presumptive test for catalase(-) and Gram (+) cocci
LAP TEST
Based on cell wall C polysaccharide
ALL ARE HIPPURATE (-) EXCEPT
Lancefield Classification
based on temperature
Pyogenic (37 degC, produce PUS)
Viridans
Enterococci
Lactic group
Academic or Bergey’s
S. pyogenes / Group A Beta-hemolytic streptococci
Main component of Strep capsule
Hyaluronic acd
Throat pathogen
Catalase (-)
PYR (+)
Bacitracin (S)
Reservoir: throat and skin
S. pyogenes /Group A Beta-hemolytic streptococci
Principal virulence factor of S. pyogenes /Group A Beta-hemolytic streptococci
M protein
responsible for SUB SURFACE HEMOLYSIS, of S. pyogenes / Group A Beta-hemolytic streptococci
highly antigenic
Streptolysin O
spreading factor of S. pyogenes / Group A Beta-hemolytic streptococci
Hyaluronidase
not highly antigenic, responsible for Surface hemolysis
Streptolysin S
Dissolves /digest fibrin clot
Streptokinase
Degrades DNA
Streptodornase
degrades proteins
mediates scarlet fever
implicated in flesh eating streptococci
Erythrogenic/Pyogenic toxins
Exotoxin B
streptococcal toxic shock syndrome
Erythrogenic/Pyrogenic Toxins
Causes lethal shock
A, B, C
AKA Protein F
Adhesion molecule
Fibronectin Binding Protein
Main source of streptokinase (animal pathogen)
ex: Strep. equi, strangles in horses (upper respiratory)
Group C streptococci
S. anginosus
Honeysuckle odor
Bacteremia and liver abscess
Group G – normal flora of GI, vaginal tract
Groups F and G
Reagent: Esculin + 1-4% bile salt
(+) Result: black color complex in agar
Bile Esculin Hydrolysis
Salt Tolerance Test (6.5%)
(+) Result: turbidity (Enterococci) [withstand high salt]
(-) Result: Non-Enterococci [not inhibited high salt]
